Dynamic beam shaping of optical phased array with noise correction

Abstract

To provide a system and a method for noise correction and phase correction in dynamically shaped beams produced by a laser beam phased array.SOLUTION: A laser system comprises: a seed laser which is an optical phased array laser; and a laser beam splitting and combining subsystem receiving laser output from the seed laser and providing a combined laser output. The laser beam splitting and combining subsystem varies the phase of the combined laser output and focuses the combined laser output onto the substrate, and the combined laser output is not focused onto a substrate when there is no phase variation in the combined laser output.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] Cross-reference of related applications Israeli Patent Application No. 255496, filed November 7, 2017, entitled "OPTICAL PHASED ARRAY DYNAMIC BEAM SHAPING WITH NOISE CORRECTION"; Israeli Patent Application No. 256107, filed December 4, 2017, entitled "SEED LASER FAILURE PROTECTION SYSTEM"; U.S. Patent Provisional Application No. 62 / 594,167, filed December 4, 2017, entitled "LASER BACK-REFLECTION PROTECTION USING OPTICAL PHASED ARRAY LASER"; and "SCALED PHASE MODIFICATION, PHASE CALIBRATION AND SEED LASER PROTECTION IN OPTICAL PHASED Israeli Patent Application No. 258936, entitled “ARRAY”, U.S. Provisional Patent Application No. 62 / 684,341, entitled “MULTIPLE DETECTORS AND CORRESPONDING MULTIPLE CLOSELY SPACED OPTICAL PATHWAYS IN OPTICAL PHASED ARRAY LASER,” filed June 13, 2018, and U.S. Provisional Patent Application No. 62 / 702,957, entitled “DETECTOR MASK IN OPTICAL PHASED ARRAY LASER,” filed July 28, 2018, are referenced herein, all of which are incorporated herein by reference, and all of which are claimed herein in accordance with 37 CFR 1.78(a)(4) and (5)(i).

[0002] U.S. Patent No. 9,893,494 is also referenced, and its disclosures are incorporated herein by reference.

[0003] The present invention generally relates to laser coherent beam coupling, and more specifically to optical phased arrays. [Background technology]

[0004] Various types of optical phased arrays are known in this field. [Overview of the project]

[0005] The present invention aims to provide a system and method for noise correction and phase correction in a dynamically shaped beam generated by a laser optical phased array.

[0006] Accordingly, according to a preferred embodiment of the present invention, a laser system is provided comprising: a seed laser; a laser beam splitting and coupling subsystem that receives output from the seed laser and provides a coupled laser output having noise; and a noise cancellation subsystem that operates to provide a noise-canceled phase-corrected output based on taking into account noise in intermittent time, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output during time intervals between intermittent time.

[0007] According to another preferred embodiment of the present invention, a laser system is further provided, comprising: a seed laser; a laser beam splitting and coupling subsystem that receives output from the seed laser and provides a coupled laser output having noise; and a noise cancellation subsystem that operates to provide a noise-canceled phase-corrected output based on taking into account noise at a noise sampling rate, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output at a phase change rate exceeding the noise sampling rate.

[0008] Preferably, at least one of the noise sampling rate and the phase shift rate changes over time.

[0009] Preferably, the noise sampling rate is predetermined.

[0010] According to a preferred embodiment of the present invention, the laser beam splitting and coupling subsystem modulates the phase of the coupled laser output to provide spatial modulation of the coupled laser output.

[0011] Preferably, spatial modulation of the coupled laser output is provided in combination with mechanical spatial modulation of the coupled laser output, and spatial modulation combined with mechanical spatial modulation is faster than mechanical spatial modulation without spatial modulation.

[0012] Additionally or alternatively, spatial modulation of the coupled laser output is provided in combination with mechanical spatial modulation of the coupled laser output, and spatial modulation combined with mechanical spatial modulation is more accurate than mechanical spatial modulation without spatial modulation.

[0013] Preferably, the spatial modulation includes modulation of at least one of the shape and diameter of the coupled laser output.

[0014] Preferably, the laser beam splitting and coupling subsystem provides laser beam amplification downstream of splitting and upstream of coupling.

[0015] According to a more preferred embodiment of the present invention, the noise-canceling phase-corrected output is calculated based on applying at least two phase shifts sequentially to at least one constituent beam of the coupled laser output and identifying one of the at least two phase shifts corresponding to the maximum output intensity of at least one constituent beam.

[0016] Preferably, the system also includes at least one detector coupled to work with the noise cancellation subsystem to detect at least a portion of the coupled laser output.

[0017] Preferably, at least one detector performs detection continuously.

[0018] According to an additionally preferred embodiment of the present invention, the noise-canceling phase-corrected output cancels intensity noise in the coupled laser output.

[0019] Preferably, the system also includes at least one intensity modulator for changing the intensity of the coupled laser output.

[0020] According to an additionally preferred embodiment of the present invention, the noise-canceling phase-corrected output cancels position noise in the coupled laser output.

[0021] Preferably, the system also includes at least one position modulator for changing the position of the coupled laser output.

[0022] Preferably, the laser cutting system includes the laser system of the present invention.

[0023] Additionally or alternatively, a laser additive manufacturing system includes the laser system of the present invention.

[0024] Additionally or alternatively, the laser welding system includes the laser system of the present invention.

[0025] Additionally or alternatively, the free-space optical communication system includes the laser system of the present invention.

[0026] Another preferred embodiment of the present invention also provides a method for performing noise correction on a phase-changed laser output, comprising: receiving an output from a seed laser; splitting and combining the outputs to provide a combined laser output having noise; applying a noise-canceling phase-corrected output to the combined laser output based on taking into account noise in intermittent time; and changing the phase of the combined laser output during a time interval between the intermittent time.

[0027] According to another preferred embodiment of the present invention, a method for performing noise correction on a phase-shifted laser output is further provided, comprising: receiving an output from a seed laser; splitting and combining the outputs to provide a combined laser output having noise; applying a noise-canceling phase-corrected output to the combined laser output based on taking into account noise at a noise sampling rate; and changing the phase of the combined laser output at a phase shift rate exceeding the noise sampling rate.

[0028] Preferably, at least one of the noise sampling rate and the phase shift rate changes over time.

[0029] Preferably, the noise sampling rate is predetermined.

[0030] According to a preferred embodiment of the present invention, the phase change provides spatial modulation of the coupled laser output.

[0031] Preferably, spatial modulation of the coupled laser output is provided in combination with mechanical spatial modulation of the coupled laser output, and the spatial modulation combined with mechanical spatial modulation is faster than mechanical spatial modulation without spatial modulation.

[0032] Additionally or alternatively, spatial modulation of the coupled laser output is provided in combination with mechanical spatial modulation of the coupled laser output, and spatial modulation combined with mechanical spatial modulation is more accurate than mechanical spatial modulation without spatial modulation.

[0033] Preferably, the spatial modulation includes modulation of at least one of the shape and diameter of the coupled laser output.

[0034] Preferably, the method also includes amplifying the output downstream of the split and upstream of the combination.

[0035] According to another preferred embodiment of the present invention, the method also includes calculating a noise-canceling phase-corrected output based on: continuously applying at least two phase changes to at least one constituent beam of a coupled laser output; and identifying one of the at least two phase changes that corresponds to the maximum output intensity of at least one constituent beam.

[0036] Preferably, the method also includes detecting at least a portion of the combined laser output.

[0037] Preferably, detection is carried out continuously.

[0038] According to yet another preferred embodiment of the present invention, the noise-canceling phase-corrected output cancels intensity noise in the coupled laser output.

[0039] Preferably, the method also includes modulating the output intensity downstream of the split and upstream of the coupling.

[0040] According to yet another preferred embodiment of the present invention, the noise-canceling phase-corrected output cancels position noise in the coupled laser output.

[0041] Preferably, the method also includes modulating the output position downstream of the split and upstream of the combination.

[0042] Preferably, the method for laser cutting includes the method of the present invention.

[0043] Additionally or alternatively, methods for additive manufacturing include the methods of the present invention.

[0044] Furthermore, additionally or alternatively, methods for laser welding include the methods of the present invention.

[0045] Furthermore, additionally or alternatively, methods for free-space optical communication include the methods of the present invention.

[0046] According to another preferred embodiment of the present invention, also provided is a laser system comprising: a seed laser; a laser beam splitting and coupling subsystem that receives output from the seed laser and provides a coupled laser output, wherein the laser beam splitting and coupling subsystem modifies the phase of the coupled laser output; a plurality of detectors that detect the coupled laser output intermittently during the phase modification of the coupled laser output; and a plurality of optical paths between the coupled laser output and the plurality of detectors, wherein the plurality of optical paths are for providing the coupled laser output along the plurality of optical paths to the plurality of detectors, and the spatial density of the plurality of optical paths is greater than the spatial density of the plurality of detectors.

[0047] Preferably, the coupled laser output has noise, and the laser system also includes a noise cancellation subsystem that operates to provide a noise-canceling phase-corrected output based on taking into account the noise of the coupled laser output detected by multiple detectors at intermittent times during phase changes of the coupled laser output.

[0048] Preferably, the multiple optical paths include multiple optical fibers, and the ends of the optical fibers are arranged at a spatial density greater than the spatial density of the multiple detectors.

[0049] Preferably, the multiple optical paths are spaced apart by a distance of 20 to 1000 microns.

[0050] Preferably, the detectors among the multiple detectors are spaced apart by a distance of 5 to 50 mm.

[0051] In another preferred embodiment of the present invention, a method for detecting a laser output is additionally provided, comprising: receiving an output from a seed laser; splitting and combining the output to provide a combined laser output; changing the phase of the combined laser output; and providing the combined laser output to a plurality of detectors along a plurality of optical paths, wherein the spatial density of the plurality of optical paths is greater than the spatial density of the plurality of detectors.

[0052] Preferably, the coupled laser output has noise, and the method also includes providing a noise-canceling phase-corrected output based on taking into account the noise in the coupled laser output detected by multiple detectors during a phase change of the coupled laser output.

[0053] Preferably, the multiple optical paths include multiple optical fibers, and the ends of the optical fibers are arranged at a spatial density greater than the spatial density of the multiple detectors.

[0054] Preferably, the multiple optical paths are spaced apart by a distance of 20 to 1000 microns.

[0055] Preferably, the detectors among the multiple detectors are spaced apart by a distance of 5 to 50 mm.

[0056] A laser system is further provided, comprising: a seed laser; a laser beam splitting and coupling subsystem that receives output from the seed laser and provides a coupled laser output, wherein the laser beam splitting and coupling subsystem modifies the phase of the coupled laser output; at least one detector that detects the coupled laser output during the phase modification of the coupled laser output; and an optical mask comprising at least one of a transmission region and a reflection region, for providing the coupled laser output to at least one detector through and from at least one of the transmission region and the reflection region, respectively.

[0057] Preferably, at least one of the transmission region and the reflection region is configured according to at least one of the shape and trajectory of the combined laser output.

[0058] Preferably, the system also includes a focusing subsystem that interfaces the optical mask with at least one detector in order to focus the combined laser output onto at least one detector.

[0059] Preferably, the focusing subsystem includes at least one focusing lens.

[0060] Preferably, at least one detector includes a single detector.

[0061] According to a preferred embodiment of the present invention, the transparent region has non-uniform transparency.

[0062] Preferably, the non-uniform transparency of the transmission region compensates for non-noise-related non-uniformity in the intensity of the coupled laser output.

[0063] Preferably, the optical mask includes an electrically modulated device in which at least one of the transmission region and the reflection region is electronically modifiable.

[0064] Preferably, the optical mask includes an LCD screen.

[0065] According to another preferred embodiment of the present invention, the reflective region has a non-uniform reflectivity.

[0066] Preferably, the non-uniform reflectivity of the reflective region compensates for non-noise-related non-uniformity in the intensity of the coupled laser output.

[0067] Preferably, the reflective region includes a DMM.

[0068] Preferably, the coupled laser output has noise, and the laser system also includes a noise cancellation subsystem that operates to provide a noise-canceling phase-corrected output based on taking into account the noise in the coupled laser output detected by at least one detector during a phase change of the coupled laser output.

[0069] A method for detecting a laser output is further provided, comprising: receiving an output from a seed laser; splitting and combining the output to provide a combined laser output; changing the phase of the combined laser output; providing the combined laser output to at least one detector by an optical mask, wherein the optical mask includes at least one of a transmission region and a reflection region, and provides the combined laser output to at least one detector through and from at least one of the transmission region and the reflection region, respectively; and detecting the combined laser output during the phase change by at least one detector.

[0070] Preferably, at least one of the transmission region and the reflection region is configured according to at least one of the shape and trajectory of the combined laser output.

[0071] Preferably, the method also includes focusing the combined laser output onto at least one detector.

[0072] Preferably, the method also includes providing a focusing lens that interfaces an optical mask with at least one detector in order to perform focusing.

[0073] Preferably, at least one detector includes a single detector.

[0074] According to a preferred embodiment of the present invention, the transparent region has non-uniform transparency.

[0075] Preferably, the non-uniform transparency of the transmission region compensates for non-noise-related non-uniformity in the intensity of the coupled laser output.

[0076] Preferably, the optical mask includes an electrically modulated device in which at least one of the transmission region and the reflection region is electronically modifiable.

[0077] Preferably, the optical mask includes an LCD screen.

[0078] According to another preferred embodiment of the present invention, the reflective region has a non-uniform reflectivity.

[0079] Preferably, the non-uniform reflectivity of the reflective region compensates for non-noise-related non-uniformity in the intensity of the coupled laser output.

[0080] Preferably, the reflective region includes a DMM.

[0081] Preferably, the coupled laser output has noise, and the method also includes providing a noise-canceling phase-corrected output based on taking into account the noise in the coupled laser output detected by at least one detector during a phase change of the coupled laser output.

[0082] A laser system is also provided, according to yet another preferred embodiment of the present invention, comprising: a seed laser; a laser splitting and coupling subsystem that receives the output from the seed laser and combines the outputs to provide a combined laser output; a phase modulation subsystem for changing the phase of the combined laser output; and a voltage-to-phase correlation subsystem for correlating a voltage applied to the phase modulation subsystem with a phase-modulated output generated by the phase modulation subsystem and providing a voltage-to-phase correlation output useful for calibrating the phase modulation subsystem, wherein the correlation is performed periodically during the phase change.

[0083] Preferably, the phase modulation subsystem includes a plurality of phase modulators.

[0084] Preferably, the voltage is applied to multiple phase modulators by a phase modulation control module.

[0085] Preferably, the voltage includes a voltage intended to produce a phase shift of the 2π coupled laser output.

[0086] Preferably, the correlation includes measuring the change in intensity of the far-field intensity pattern of the coupled laser output after the application of voltage, and deriving a relationship between the voltage and the phase shift corresponding to the change in intensity.

[0087] Preferably, the voltage is continuously applied to one of the phase modulators among the multiple phase modulators.

[0088] Preferably, the correlation is performed at a slower rate than the phase change.

[0089] Preferably, phase changes are performed at a rate of 1 million times per second, and correlation is performed at a rate of 1 time per second.

[0090] An additionally preferred embodiment of the present invention provides a method for performing phase calibration of a laser system, comprising: receiving an output from a seed laser; splitting and combining the output to provide a combined laser output; changing the phase of the combined laser output by a phase modulation subsystem; periodically applying a voltage to the phase modulation subsystem during the phase change and correlating the voltage with a phase-modulated output generated by the phase modulation subsystem; and providing a voltage-to-phase correlation output useful for calibrating the phase modulation subsystem.

[0091] Preferably, the phase modulation subsystem includes a plurality of phase modulators.

[0092] Preferably, the voltage is applied by a phase modulation control module.

[0093] Preferably, the voltage includes a voltage intended to produce a phase shift of the 2π coupled laser output.

[0094] Preferably, the correlation includes measuring the change in intensity of the far-field intensity pattern of the coupled laser output after the application of voltage, and deriving a relationship between the voltage and the phase shift corresponding to the change in intensity.

[0095] Preferably, the method also includes continuously applying a voltage to one of the phase modulators.

[0096] Preferably, the correlation is performed at a slower rate than the phase change.

[0097] Preferably, phase changes are performed at a rate of 1 million times per second, and correlation is performed at a rate of 1 time per second.

[0098] In another preferred embodiment of the present invention, a laser system is also provided, comprising: a seed laser; a laser beam splitting and coupling subsystem that receives output from the seed laser, splits the output into a plurality of subbeams, and provides a combined laser output comprising the plurality of subbeams; and a phase modulation subsystem that groups at least a portion of the plurality of subbeams into a plurality of subbeam groups, wherein the phase modulation subsystem modulates the phase of each group in parallel across the plurality of subbeam groups, changing the phase of each group in relation to the phases of other subbeams in the group, and changing the phase of each group in relation to the phases of other groups in the plurality of groups, thereby changing the phase of the combined laser output.

[0099] Preferably, the phase modulation subsystem includes at least one cylindrical lens for performing grouping.

[0100] Alternatively, the phase modulation subsystem includes an array of mirrors and corresponding focusing lenses for performing grouping.

[0101] Preferably, the phase modulation subsystem includes a plurality of phase modulators for changing the phase of the subbeam.

[0102] Preferably, the phase modulation subsystem includes at least one electronic control module for controlling the operation of multiple phase modulators.

[0103] Preferably, the phase modulation subsystem includes a number of detectors corresponding to the number of groups in order to detect the far-field intensity pattern of each of the number of groups.

[0104] According to a preferred embodiment of the present invention, the system also includes a plurality of optical masks for masking corresponding detectors among a plurality of detectors, each optical mask comprising at least one of a transmission region and a reflection region, for providing far-field intensity patterns to corresponding detectors among the plurality of detectors through and from at least one of the transmission region and the reflection region.

[0105] Preferably, multiple detectors perform detection simultaneously with each other, at least partially.

[0106] Preferably, the phase modulation subsystem includes additional auxiliary detectors for detecting a combination of multiple groups of far-field intensity patterns.

[0107] Preferably, the phase modulation subsystem includes a number of additional phase modulators, each of which is common to all subbeams within each group in order to change the phase of each group relative to the phases of other groups within the group.

[0108] Preferably, the phase modulation subsystem includes additional electronic control modules for controlling the operation of a number of additional phase modulators.

[0109] According to another preferred embodiment of the present invention, each detector of the plurality of detectors includes a plurality of detectors.

[0110] Preferably, the system includes multiple optical paths between each of a number of groups of far-field intensity patterns and each of a number of detectors, for providing the far-field intensity patterns to the number of detectors along the multiple optical paths, and also includes multiple optical paths where the spatial density of the multiple optical paths is greater than the spatial density of the number of detectors.

[0111] Preferably, changing the phase of the coupled laser output includes maximizing the intensity of the coupled laser output.

[0112] Preferably, the phase change of the coupled laser output provides spatial modulation of the coupled laser output without mechanical spatial modulation of the coupled laser output.

[0113] Preferably, the laser beam splitting and coupling subsystem provides laser beam amplification downstream of splitting and upstream of coupling.

[0114] A further embodiment of the present invention provides a method for performing a phase change of a laser output, comprising: receiving a laser output from a seed laser; splitting the laser output into a plurality of subbeams and combining the plurality of subbeams to provide a combined laser output; grouping at least a portion of the subbeams of the plurality of subbeams into a plurality of subbeam groups; changing the phase of each group in parallel across the plurality of subbeam groups with respect to the phase of the other subbeams in the group; and changing the phase of each group with respect to the phase of the other groups in the plurality of groups, thereby changing the phase of the combined laser output.

[0115] Preferably, the grouping is carried out by at least one cylindrical lens.

[0116] Alternatively, grouping is performed by an array of mirrors and corresponding focusing lenses.

[0117] Preferably, the phase change of the subbeam is performed by multiple phase modulators.

[0118] Preferably, the method also includes controlling multiple phase modulators with at least one electronic control module.

[0119] Preferably, the method also includes detecting the far-field intensity patterns of each of a number of groups by a corresponding number of detectors.

[0120] According to a preferred embodiment of the present invention, the method includes providing a far-field intensity pattern to a corresponding detector among a number of detectors by means of a number of optical masks, each optical mask comprising at least one of a transmission region and a reflection region, and providing the far-field intensity pattern to the corresponding detector among the number of detectors through and from at least one of the transmission region and the reflection region.

[0121] Preferably, detection is performed on multiple groups at least partially simultaneously with each other.

[0122] Preferably, the method also includes detecting a combination of multiple groups of far-field intensity patterns using an auxiliary detector.

[0123] Preferably, the change in the phase of one group relative to the phase of other groups is performed by a number of additional phase modulators, each of which is common to all subbeams within each group.

[0124] Preferably, the method also includes controlling a number of additional phase modulators by an additional electronic control module.

[0125] According to another preferred embodiment of the present invention, each detector of the plurality of detectors includes a plurality of detectors.

[0126] Preferably, the method also includes providing each of the far-field intensity patterns of a plurality of groups to each of a plurality of detectors along a plurality of optical paths, wherein the spatial density of the plurality of optical paths is greater than the spatial density of the plurality of detectors.

[0127] Preferably, changing the phase of the coupled laser output includes maximizing the intensity of the coupled laser output.

[0128] Preferably, the phase change of the coupled laser output provides spatial modulation of the coupled laser output without mechanical spatial modulation of the coupled laser output.

[0129] Preferably, this method also includes amplifying the laser output downstream of the splitting and upstream of the coupling.

[0130] According to another preferred embodiment of the present invention, a laser system is also provided, which includes an optical phased array laser comprising a seed laser and a laser beam splitting and coupling subsystem that receives the output from the seed laser and provides a coupled laser output, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output to focus the coupled laser output onto a substrate, and the coupled laser output would not be focused onto the substrate if there were no phase change.

[0131] Preferably, the system also includes an optical element that receives the combined laser output from the laser beam splitting and coupling subsystem and focuses the combined laser output to a focal point that does not coincide with the substrate.

[0132] Preferably, the laser beam backscattered from the substrate is not focused onto the optically phased array laser.

[0133] A further preferred embodiment of the present invention provides a method for focusing a laser beam in a laser system, comprising: receiving a laser output from a seed laser; splitting and combining the laser output to provide a combined laser output; and changing the phase of the combined laser output to focus the combined laser output onto a substrate, such that the combined laser output would not be focused onto the substrate if there were no phase change.

[0134] Preferably, the method also includes using an optical element to focus the coupled laser output to a focal point that does not coincide with the substrate.

[0135] Preferably, the laser beam backscattered from the substrate is not focused onto the laser system.

[0136] An additionally preferred embodiment of the present invention provides a laser amplifier system comprising: a seed laser that provides a laser output; an amplification subsystem that receives the laser output from the seed laser along a first optical path and provides an amplified laser output; and a detector subsystem that receives the laser output from the seed laser along a second optical path and operates to deactivate the amplification subsystem when the detector subsystem detects at least one fault in the laser output, wherein the first time of flight of the laser output from the seed laser to the amplification subsystem along the first optical path is greater than the combination of the second time of flight of the laser output from the seed laser to the detector subsystem along the second optical path and the time required for the detector subsystem to deactivate the amplification subsystem.

[0137] Preferably, the first optical path includes a coiled optical fiber.

[0138] Preferably, at least one of the failures includes at least one of a reduction in laser power output and a degradation in laser linewidth.

[0139] Preferably, the amplification subsystem includes a power amplifier, and the laser amplifier system includes a MOPA.

[0140] An even more preferred embodiment of the present invention further provides a method for preventing damage to an amplification subsystem in a laser system, comprising: receiving a laser output from a seed laser along a first optical path; amplifying the laser output to provide an amplified laser output; receiving a laser output from a seed laser along a second optical path; detecting at least one fault in the laser output received along the second optical path; and stopping the amplification upon detection of at least one fault in the laser output, wherein the first time of flight of the laser output along the first optical path is greater than the combination of the second time of flight of the laser output along the second optical path and the time required for the stopping of amplification to be carried out.

[0141] Preferably, the first optical path includes a coiled optical fiber.

[0142] Preferably, at least one of the failures includes at least one of a reduction in laser power output and a degradation in laser linewidth.

[0143] Preferably, the amplification subsystem includes a power amplifier, and the laser amplifier system includes a MOPA.

[0144] Also provided is a laser amplifier system comprising: a seed laser providing a laser output; a first amplifier configured to receive a laser output from the seed laser, the first amplifier providing a first amplified laser output when receiving a laser output from the seed laser, and providing one of amplified spontaneous emission and an additional laser output when receiving a laser output from the seed laser is stopped; and a second amplifier receiving one of the first amplified laser output, amplified spontaneous emission, and an additional laser output from the first amplifier, and providing a second amplified laser output, wherein the amplification provided by the second amplifier is greater than the amplification provided by the first amplifier.

[0145] Preferably, the system also includes a filter structure downstream of the seed laser and upstream of the first amplifier.

[0146] Preferably, the filter structure includes a beam splitter for splitting a laser output along first and second optical paths, wherein the first optical path is longer than the second optical path; a detector for detecting the combined laser output from the first and second optical paths; an electronically controlled module coupled to the detector for receiving the output from the detector; and a phase control module positioned along one of the first and second optical paths, wherein the phase control module is operated by the electronically controlled module to correct the phase of the laser output in response to the detection of interference in the combined laser output by the detector.

[0147] A method for preventing damage to an amplifier in a laser system is further provided, comprising: receiving a laser output from a seed laser; providing a first amplified laser output by a first amplifier when receiving the laser output from the seed laser; providing one of amplified spontaneous emission and additional laser output by the first amplifier when receiving the laser output from the seed laser is stopped; and receiving and providing one of the first amplified laser output, amplified spontaneous emission, and additional laser output by a second amplifier, wherein the second amplified laser output is greater than the first amplified laser output.

[0148] Preferably, the method also includes filtering the laser output downstream of the seed laser and upstream of the first amplifier.

[0149] Preferably, filtering involves splitting the laser output along first and second optical paths, wherein the first optical path is longer than the second optical path; detecting the combined laser output from the first and second optical paths with a detector; receiving the output from the detector with an electronic control module; and correcting the phase of the laser output along one of the first and second optical paths in response to the detector's detection of interference in the combined laser output.

[0150] According to another preferred embodiment of the present invention, a laser amplifier system is also provided, comprising: a seed laser that provides a first laser output having a first power; an amplification subsystem that receives the first laser output from the seed laser and provides an amplified laser output; and an auxiliary laser subsystem that provides a second laser output when at least the first laser output is stopped, wherein the second laser output has a second power lower than the first power.

[0151] Preferably, the auxiliary laser subsystem includes an additional seed laser that provides a second laser output to the amplification subsystem at least simultaneously with providing a first laser output.

[0152] Alternatively, the amplification subsystem includes an inlet from which a first laser output is received and an outlet from which an amplified laser output is provided, and the laser amplifier system includes a first reflection grating positioned at the inlet and a second reflection grating positioned at the outlet, and the first and second reflection gratings are combined with the amplification subsystem, which includes an auxiliary laser subsystem.

[0153] The first and second reflection gratings are reflective in the wavelength range of 1090 nm to 1100 nm.

[0154] Preferably, the second laser output has a different wavelength from the first laser output.

[0155] Preferably, the system also includes filters downstream of the seed laser and upstream of the amplification subsystem.

[0156] Preferably, the filter includes a beam splitter for splitting a first laser output along a first optical path and a second optical path, wherein the first optical path is longer than the second optical path; a detector for detecting the combined laser outputs from the first and second optical paths; an electronically controlled module coupled to the detector for receiving the output from the detector; and a phase control module positioned along one of the first and second optical paths, wherein the phase control module is operated by the electronically controlled module to correct the phase of the first laser output in response to the detection of interference in the combined laser output by the detector.

[0157] Preferably, the system also includes a detector subsystem for detecting a first laser output from a seed laser.

[0158] Preferably, the detector subsystem includes a divider that divides a first laser output into a first part and a second part; an additional amplifier that amplifies the second part and provides an amplified output; and an optical fiber that receives the amplified output, the optical fiber being configured to exhibit a nonlinear effect when the linewidth of the first laser output becomes unacceptably narrow.

[0159] Preferably, the optical fiber has a length of 25 m and a core diameter of 6 microns.

[0160] In another preferred embodiment of the present invention, a method for preventing damage to an amplifier in a laser system is further provided, comprising: providing a first laser output having a first power; amplifying the first laser output with an amplifier to provide an amplified laser output; and providing a second laser output when the provision of at least the first laser output is stopped, wherein the second laser output has a second power lower than the first power.

[0161] Preferably, the provision of the second laser output is performed at least simultaneously with the provision of the first laser output.

[0162] Preferably, the amplifier includes an inlet where a first laser output is received and an outlet where an amplified laser output is provided, and also includes positioning a first reflection grating at the inlet and a second reflection grating at the outlet, wherein the first and second reflection gratings are combined with an amplifier that provides a second laser output.

[0163] Preferably, the first and second reflection gratings are reflective in the wavelength range of 1090 nm to 1100 nm.

[0164] Preferably, the second laser output has a different wavelength from the first laser output.

[0165] Preferably, the method also includes filtering the first laser output upstream of the amplification of the first laser output.

[0166] Preferably, the method includes splitting a first laser output along first and second optical paths, wherein the first optical path is longer than the second optical path; detecting the combined laser output from the first and second optical paths with a detector; receiving the output from the detector with an electronic control module; and correcting the phase of the first laser output along one of the first and second optical paths based on the output from the detector and in response to the detector's detection of interference in the combined laser output.

[0167] Preferably, the method also includes detecting a first laser output.

[0168] Preferably, the detection includes dividing a first laser output into a first portion and a second portion, amplifying the second portion and providing an amplified output, and receiving the amplified output by an optical fiber, wherein the optical fiber is configured to exhibit a nonlinear effect when the linewidth of the first laser output becomes unacceptably narrow.

[0169] Preferably, the optical fiber has a length of 25 m and a core diameter of 6 microns. [Brief explanation of the drawing]

[0170] This invention will be more fully understood and recognized based on the following detailed description in conjunction with the drawings. [Figure 1A] This is a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping, constructed and operating according to a preferred embodiment of the present invention. [Figure 1B-1C] Figure 1A shows a simplified graphical representation of phase shifting and noise correction in the type of system shown. [Figure 2A] This is a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping, constructed and operating according to another preferred embodiment of the present invention. [Figure 2B-2C] Figure 2A shows a simplified graphical representation of phase shifting and noise correction in the type of system shown. [Figure 3A] This is a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping, constructed and operating according to a more preferred embodiment of the present invention. [Figure 3B-3C] Figure 3A shows a simplified graphical representation of phase shifting and noise correction in the type of system shown. [Figure 4A] This is a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping, constructed and operating according to yet a more preferred embodiment of the present invention. [Figure 4B-4C] Figure 4A shows a simplified graphical representation of phase shifting and noise correction in the type of system shown. [Figure 5A-5G] Figures 1A to 4C are simplified schematic diagrams of the possible far-field motion of the output of any of the types of optically phased array laser systems shown. [Figure 6] This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple tightly spaced optical paths, constructed and operating according to yet another preferred embodiment of the present invention. [Figure 7] This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple tightly spaced optical paths, constructed and operating according to yet another preferred embodiment of the present invention. [Figure 8] This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple tightly spaced optical paths, constructed and operating according to yet a more preferred embodiment of the present invention. [Figure 9] This is a simplified schematic diagram of an optical phased array laser system, including a detector mask configured according to an exemplary laser beam trajectory, constructed and operating according to a preferred embodiment of the present invention. [Figure 10] Figure 9 is a simplified schematic diagram of the type of detector mask shown, illustrating various levels of transparency. [Figure 11] This is a simplified schematic diagram of an optical phased array laser system, including a detector mask configured according to an exemplary laser beam shape, constructed and operating according to another preferred embodiment of the present invention. [Figure 12] Figure 11 is a simplified schematic diagram of the type of detector mask shown, illustrating various levels of transparency. [Figure 13] This is a simplified schematic diagram of an optical phased array laser system including a voltage-phase correlation function, constructed and operating according to a preferred embodiment of the present invention. [Figure 14]Figure 13 is a simplified flowchart showing the steps for implementing voltage-phase correlation in the type of system shown. [Figure 15] This is a simplified schematic plan view of an optical phased array laser system, including a dynamic beam scaled phase correction, constructed and operating according to an additional preferred embodiment of the present invention. [Figure 16] This is a simplified schematic plan view of an optical phased array laser system including a dynamic beam scaled phase correction, constructed and operating according to yet another preferred embodiment of the present invention. [Figures 17A-17B] Simplified top and perspective views of an optical phased array laser system including scaled phase correction of a dynamic beam of the type shown in Figure 15 or Figure 16. [Figure 18] This is a simplified schematic plan view of an optical phased array laser system, including a dynamic beam scaled phase correction, constructed and operating according to a more preferred embodiment of the present invention. [Figure 19] This is a simplified schematic plan view of an optical phased array laser system, including a dynamic beam scaled phase correction, constructed and operating according to a more preferred embodiment of the present invention. [Figures 20A-20B] Simplified top and perspective views of an optically phased array laser system, including scaled phase correction of a dynamic beam of the type shown in Figure 18 or Figure 19. [Figure 21] This is a simplified schematic plan view of an optical phased array laser system including a dynamic beam scaled phase correction, constructed and operating according to yet a more preferred embodiment of the present invention. [Figures 22A-22B] This is a simplified schematic diagram of the first and second focal states of an optically phased array laser system constructed and operating according to a preferred embodiment of the present invention. [Figure 23] Figures 22A and 22B show a simplified representation of backscatter in the type of optically phased array laser system shown. [Figure 24] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to a preferred embodiment of the present invention. [Figure 25] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to another preferred embodiment of the present invention. [Figure 26] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to a more preferred embodiment of the present invention. [Figure 27] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet another preferred embodiment of the present invention. [Figure 28] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet another preferred embodiment of the present invention. [Figure 29] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet another preferred embodiment of the present invention. [Figure 30] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet a more preferred embodiment of the present invention. [Figure 31] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to further preferred embodiments of the present invention. [Figure 32] This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, which is constructed and operates according to an additional preferred embodiment of the present invention. [Figure 33] These are simplified schematic diagrams of sensors useful in any of the types of laser amplification systems shown in Figures 24 to 32. [Modes for carrying out the invention]

[0171] Next, we refer to Figure 1A, a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping constructed and operating according to a preferred embodiment of the present invention, and Figures 1B and 1C, which are simplified graphical representations of phase shifting and noise compensation in a system of the type shown in Figure 1A.

[0172] As shown in Figure 1A, an optical phased array (OPA) laser system 100 is provided hereby provided as an example for use in a laser cutting system 102. The laser cutting system 102 may include the OPA laser system 100 mounted spaced apart from a multi-axis positioning table 104, on which articles such as article 106 can be cut using the laser system 100, as detailed below. Although the laser cutting system 102 is shown herein in the context of table 104, it will be understood that the system 102 can be embodied as any type of laser cutting system, as will be understood by those skilled in the art.

[0173] As is best seen in magnification 110, the OPA laser 100 preferably comprises a seed laser 112 and a laser beam splitting and coupling subsystem 114. The splitting and coupling subsystem 114 preferably receives the output laser beam from the seed laser 112 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 116. Here, for the sake of illustration, the output from the seed laser 112 is shown to be split into 10 subbeams along 10 channels 116, but it is understood that the splitting and coupling subsystem 114 may include fewer or more channels along the channels to which the output of the seed laser 112 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0174] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 118 positioned along each of the channels 116. Each phase-modulated subbeam generated by splitting the output of the seed laser 112 and subsequent phase modulation preferably propagates toward the collimating lens 119. The individually collimated and phase-modulated subbeams are then combined, for example, in a focusing lens 120 to form the output beam 122.

[0175] The splitting and combining subsystem 114 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 112 into subbeams and before combining the subbeams to form the output beam 122. Herein, as an example, the splitting and combining subsystem 114 is shown to include a plurality of optical amplifiers 124 positioned along the corresponding channels of the channels 116 for amplifying each subbeam. However, it is understood that such amplification may be optional and omitted depending on the power output requirements of the OPA laser 100.

[0176] The phase of the output beam 122, and therefore the position and shape of its far-field intensity pattern, is controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 122. In many applications, such as laser cutting as shown in Figure 1A, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. This may be achieved in the laser system 100 by having the laser splitting and coupling subsystem 114 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 122 and dynamically controlling the position and shape of its far-field intensity pattern.

[0177] The relative phase of the subbeam is preferably predetermined according to a desired laser power pattern for cutting article 106. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 130. The phase control subsystem 130 preferably forms part of a control electronic module 132 within the OPA laser 100 and preferably controls each phase modulator 118 to dynamically modulate the relative phase of the subbeam along channel 116.

[0178] Due to noise inherent in the OPA system 100, the output beam 122 is noisy. The noise in the output beam 122 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 124 is located within the OPA system 100. A particular feature of a preferred embodiment of the present invention is that the laser system 100 includes a noise cancellation subsystem 140 which operates to provide a noise-canceling phase-corrected output to cancel noise in the output beam 122 in the manner detailed below.

[0179] Particularly preferably, the noise cancellation subsystem 140 uses an algorithm to detect and correct phase noise in the coupled laser output. The noise-canceling phase-corrected output is preferably provided by the noise cancellation subsystem 140 to the phase modulator 118 to correct the phase noise in the output beam 122, and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 122 that would otherwise be caused by the noise. The noise cancellation subsystem 140 may be included in the control electronic module 132.

[0180] It is understood that the output beam 122 may be affected by additional or alternative types of noise other than phase noise, including intensity noise. In the case of the output beam 122 having intensity noise, the noise cancellation subsystem 140 may operate to provide a noise-canceling phase-corrected output to cancel the intensity noise of the output beam 122. In such a case, the OPA laser system 100 may optionally additionally include an intensity modulator 142 along channel 116 to modulate the intensity of each subbeam along channel 116.

[0181] It is understood that the output beam 122 may be affected by mechanical noise that may, additionally or alternatively, affect the relative position of the subbeams. In the case of the output beam 122 having position noise, the noise cancellation subsystem 140 may operate to provide a noise-canceling phase-corrected output to cancel the position noise of the output beam 122. In such a case, the OPA laser system 100 may optionally additionally include a position modulator 144 along channel 116 to modulate the position of each subbeam along channel 116.

[0182] To facilitate the application of phase shifting and noise correction to the output beam 122, a portion of the output of the OPA laser 100 is preferably extracted and directed toward at least one detector, shown here as a single detector 150. Detector 150 may alternatively be embodied as multiple detectors, as detailed below with reference to Figures 6-8 and 15-21. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the required noise correction and / or phase shifting can be calculated. In the embodiment shown in Figure 1A, multiple subbeams along the channel 116 are directed toward a beam divider 160. The beam divider 160 preferably divides each subbeam into a transmittance portion 162 and a reflectance portion 164 according to a predetermined ratio. For example, the beam divider 160 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0183] The transmitted portion 162 of the sub-beam preferably propagates toward the focal lens 120, where the sub-beam is combined to form an output beam 122 having a far-field intensity pattern 166 that is incident on the surface of the article 106. The reflected portion 164 of the sub-beam preferably reflects toward an additional focal lens 168, where the sub-beam is combined to form an output reference beam 170 having a far-field intensity pattern 172 that is incident on the surface of the detector 150.

[0184] It is understood that the specific structures and configurations of the beam splitting and recombining elements shown herein, including the beam splitter 160 and the focusing lenses 120 and 168, are illustrative and are shown in a highly simplified form. It is understood that the OPA laser system 100 may include a variety of such elements, as well as additional optical elements, including, but merely as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0185] As described herein, the shape and position of the far-field intensity pattern 166 of the output beam 122, and the corresponding shape and position of the far-field intensity pattern 172 of the reference beam 170, are constantly changing due to the ongoing changes in the relative phase of the subbeams. As a result, the far-field intensity pattern 172 is not fixed to the detector 150, but rather is constantly moving relative to the detector 150 according to the combined relative phase of the constituent subbeams. However, in order for the detector 150 to provide the required noise-canceling phase-corrected output, the far-field intensity pattern 172 must be incident on the detector 150 so that the detector can measure the intensity of the far-field intensity pattern 172 and, therefore, apply noise correction accordingly, resulting in a fixed output beam.

[0186] The conflict between the dynamic nature of the far-field intensity pattern 172 due to its phase shift and the fixed nature required of the far-field intensity pattern 172 for deriving and applying noise correction is advantageously resolved in the present invention by providing noise cancellation and phase shift at mutually different times and rates.

[0187] The noise-canceling phase-corrected output is provided based on taking into account the noise measured at the detector 150 at the noise sampling rate. The output beam 122 is controlled such that the far-field intensity pattern 172 is incident on the detector 150 at a rate equal to or greater than the requested noise sampling rate during the process of dynamic changes in the shape and position of the output and reference far-field intensity patterns 166, 172. The noise of the reference beam 170 is taken into account during these intermittent times when the far-field intensity pattern 172 is returned to the detector 150.

[0188] During the intermittent time intervals in which the far-field intensity pattern 172 is incident on the detector 150, the phases of the combined output beams 122 and 170 are changed to dynamically alter the shape and position of the far-field intensity pattern in terms of its phase, as required to perform laser cutting of the article 106. The combined laser output is changed at a phase change rate exceeding the noise sampling rate to rapidly alter the phase, and therefore the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be around 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0189] Different rates and time scales at which noise cancellation and phase shifting are preferably performed in embodiments of the present invention can be best understood by referring to Graph 180 shown in Figure 1A and its enlarged version shown in Figure 1B.

[0190] As is most clearly seen in Figure 1B, graph 180 includes an upper portion 182 showing the change in intensity over time of the far-field intensity pattern 172 measured by detector 150, and a lower portion 184 showing the change in the relative phase of a number of subbeams contributing to the output beam 122 and the reference beam 170 over the same time period. For simplicity, the relative phases of 10 subbeams are shown in graph 180, but it will be understood that the OPA system 100, and therefore the description provided herein, is applicable to fewer, or more typically, a much larger number of subbeams.

[0191] As seen in the upper portion 182, the intensity peak 186 represents the measured intensity of the reference beam 170 as the far-field intensity pattern 172 passes over the detector 150. As seen in the lower portion 184, the intensity peak 186 represents the intermittent time T at which the relative phase of each subbeam is zero. i This occurs, meaning there is no phase shift between the subbeams, the position of the combined output beam does not change, and the far-field intensity pattern 172 is therefore directly incident on the detector 150. It is understood that the detector 150 may, alternatively, be positioned such that the relative phase of the subbeams therein is non-zero. Furthermore, multiple detectors may be used to measure the far-field intensity pattern 172 at multiple positions along them, as will be detailed below with reference to Figures 6-8 and 15-21.

[0192] The far-field intensity pattern 172 is moved to either side of the detector 150 and therefore does not directly incident on the detector 150, so the measured intensity is close to zero between the intensity peaks 186. As can be understood from the consideration of the upper portion 182, the magnitude of the intensity peaks 186 is not constant due to the presence of noise in the laser output beam, and this noise degrades the far-field intensity pattern 172.

[0193] As seen in the lower portion 184, the relative phase of the subbeam is intermittent over time T. i Time interval T betweenThe phase shift function described herein is shown to change the relative phase of the subbeam in a periodic and regular repeating pattern in which equal phase shifts are applied in the positive and negative directions. It should be understood that such a simplified pattern is merely illustrative, and the phase shift does not necessarily have to repeat regularly, nor is it necessarily symmetrical in the positive and negative directions. Furthermore, the time interval T between This is an intermittent period of time T. i It is preferable, but not necessarily required, that there be overlap. Additionally, it is understood that at least one of the phase shift rate and noise sampling rate may be constant or may change over time.

[0194] The noise cancellation subsystem 140 preferably operates over an intermittent time T. i It operates by taking into account noise in intermittent time T i A noise-canceling phase-corrected output is provided based on the noise detected. The noise-canceling subsystem 140 preferably uses an algorithm to detect noise and correct the detected noise accordingly.

[0195] According to one exemplary embodiment of the present invention, the noise cancellation subsystem 140 uses an algorithm in which, during each cycle of the movement of the far-field intensity pattern 172 relative to the detector 150, the relative phase of one channel is modified by a given phase change Δφ. Following a number of such cycles in which a different phase change Δφ is applied to a selected subbeam over each cycle, the algorithm checks the maximum output intensity over all cycles and finds the optimal phase change Δφ that produced this maximum intensity. The phase change of the selected subbeam is then fixed to the optimal phase change Δφ for subsequent cycles, and the algorithm proceeds to optimize another subbeam.

[0196] Graph 180 shows noise cancellation by this exemplary algorithm in channels A, B, and C of three sub-beams or a total of ten sub-beams. For simplicity, sub-beams A, B, and C are shown individually in FIG. 1C. In FIG. 1C, for the purposes described later in this specification, to assist in distinguishing between the various sub-beams, the line styles of the lines representing the phase changes and noise corrections of sub-beams A, B, and C are modified compared to FIGS. 1A and 1B, respectively, as will be understood.

[0197] First seen in the case of channel A and most clearly understood from consideration of the enlarged view 190, the dashed line represents the pattern of change in the relative phase of sub-beam A that would be applied by the phase control subsystem 130 in the absence of any noise correction. This line is sometimes referred to as A uncorrected The dotted and dashed lines represent the actual relative phase of sub-beam A modified by the noise correction algorithm to find the optimal phase noise correction. This line is sometimes referred to as A corrected The modified relative phase of A is shifted by a different Δφ corrected only relative to the unmodified relative phase of A over the first five cycles of sub-beam A. The intensity 186 measured by detector 150 changes over the first five cycles of optimization of sub-beam A due to the intentional change in the relative phase shift. uncorrected A A After the first five cycles of sub-beam A, the algorithm checks for the maximum intensity and finds the phase change Δφ

[0198] that generates the maximum intensity. In this case, the maximum intensity is seen to be IA A generated by the second phase shift Δφ A The phase change applied to the relative phase change of sub-beam A is thus fixed at the second phase shift Δφ max for subsequent cycles, and the algorithm proceeds to optimize sub-beam B. A

[0199] ​During the continuous optimization cycle of subbeam A, it is understood that the relative phases of the rest of the subbeam are changed as usual, each at a phase change rate far exceeding the noise sampling rate at which noise in subbeam A is taken into account.

[0200] As can be seen further in the case of sub-beam B, and as is most clearly understood from the considerations in enlarged figure 192, the thicker line during the optimization of channel B represents the relative phase change pattern of sub-beam B that would be applied by the phase control subsystem 130 in the absence of any noise correction. This line is B uncorrected It is sometimes called this. The thin line during the optimization of channel B represents the actual relative phase of subbeam B corrected by the noise correction algorithm to find the optimal phase noise correction. This line is B corrected It is sometimes called B. corrected The corrected relative phase of B is over 5 cycles of the optimized subbeam B. uncorrected Different Δφ for the uncorrected relative phase B Only the phase shift occurs. The intensity 186 measured by detector 150 changes over these five cycles of optimized subbeam B due to the intentional change in the relative phase shift.

[0201] After these five cycles of subbeam B, the algorithm checks for maximum intensity and determines the phase change Δφ that generates the maximum intensity. B Find it. In this case, the maximum intensity is the fourth phase shift Δφ B IAB generated by max It appears that the phase shift applied to the relative phase change of subbeam B then results in a fourth phase shift Δφ for subsequent cycles. B With this fixed, the algorithm proceeds to optimize subbeam C.

[0202] During the five optimization cycles of sub-beam B, it is understood that the relative phases of the rest of the sub-beam are changed as usual, each at a phase change rate far exceeding the noise sampling rate at which the noise of sub-beam B is taken into account.

[0203] Preferably, a similar optimization process is performed for sub-beam C, where a phase change Δφ is applied over several cycles to optimize the output beam intensity caused by phase noise in sub-beam C and to compensate for its intensity degradation. C This applies.

[0204] At least one detector 150 can operate continuously to continuously optimize the relative phase of the subbeam and correct for phase noise therein. However, due to the finite response time of the detector 150, the detector 150 only considers noise in the reference beam 170 at intermittent times, with a relatively slow noise sampling rate. The noise sampling rate is preferably predetermined, but not necessarily so. Alternatively, the noise sampling rate may be random.

[0205] As those skilled in the art will understand, the specific parameters of the noise correction algorithm shown in Graph 180 are merely illustrative and can be easily modified. For example, the phase shift Δφ may be optimized over more or fewer cycles than shown herein, each subbeam may be fully optimized each time it passes through detector 150, or some or all of the subbeams may be optimized during each cycle in which the far-field intensity pattern passes through detector 150. Furthermore, discontinuous noise correction optimization algorithms, including but not limited to stochastic parallel gradient descent optimization algorithms, may be implemented as alternatives.

[0206] Using dynamically shaped and noise-corrected optical phased array output beams for laser cutting offers significant advantages, enabling rapid beam steering, high-speed power modulation, high-speed beam focusing, and beam shape adjustment. Compared to conventional laser cutting methods, using dynamically shaped and noise-corrected optical phased array output improves both the speed and quality of material cutting. It is understood that, due to the provision of noise correction according to preferred embodiments of the present invention, the shape and position of the optical phased array output beam are degraded, thereby degrading the quality, speed, and accuracy of the laser cutting process.

[0207] To maintain output beam intensity as the beam's far-field intensity pattern shifts, the movement of the output beam can be controlled to compensate for the reduced power transfer at lower intensity locations, which is advantageous for certain laser cutting applications. Additionally or alternatively, an intensity profile mask, such as a neutral density (ND) filter, may be applied to the output beam to modify its intensity.

[0208] Next, we refer to Figure 2A, a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping configured and operating according to another preferred embodiment of the present invention, as well as Figures 2B and 2C, which are simplified graphical representations of phase shifting and noise compensation in a system of the type shown in Figure 2A.

[0209] As shown in Figure 2A, an optical phased array (OPA) laser system 200 is provided hereby provided as an example for use within an additive manufacturing system 202. The additive manufacturing system 202 may include the OPA laser system 200 mounted in a spaced relationship with respect to a scanning mirror 203 and a multi-axis positioning table 204, on which articles such as article 206 may be additively manufactured using the laser system 200. Although the additive manufacturing system 202 is shown herein in the context of the scanning mirror 203, it will be understood that the system 202 can be embodied as any type of additive manufacturing system, as will be understood by those skilled in the art.

[0210] As best seen in enlarged figure 210, the OPA laser 200 preferably comprises a seed laser 212 and a laser beam splitting and coupling subsystem 214. The splitting and coupling subsystem 214 preferably receives the output laser beam from the seed laser 212 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 216. Here, for the sake of illustrative purposes only, the output from the seed laser 212 is shown to be split into 10 subbeams along 10 channels 216, but it is understood that the splitting and coupling subsystem 214 may include fewer or more channels along the channels to which the output of the seed laser 212 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0211] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 218 positioned along each of the channels 216. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 212 preferably propagates toward the collimating lens 219. The individually collimated and phase-modulated subbeams are then combined, for example, in a focusing lens 220 to form the output beam 222.

[0212] The splitting and combining subsystem 214 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 212 into subbeams and before combining the subbeams to form the output beam 222. Here, as an example, the splitting and combining subsystem 214 is shown to include a plurality of optical amplifiers 224 positioned along the corresponding channels of the channels 216 for amplifying each subbeam. However, it is understood that such amplification may be optional and omitted depending on the power output requirements of the OPA laser 200.

[0213] The phase of the output beam 222, and therefore the position and shape of its far-field intensity pattern, is controlled, at least partially, by the relative phases of the constituent subbeams coupled to form the output beam 222. In many applications, such as laser additive manufacturing as shown in Figure 2A, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 200 by having the laser splitting and coupling subsystem 214 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 222 and dynamically controlling the position and shape of its far-field intensity pattern.

[0214] The relative phase of the subbeam is preferably predetermined according to a desired laser output pattern for 3D printing of article 206. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 230. The phase control subsystem 230 preferably forms part of a control electronic module 232 within the OPA laser 200 and preferably controls each phase modulator 218 to dynamically modulate the relative phase of the subbeam along channel 216.

[0215] Due to noise inherent in the OPA system 200, the output beam 222 is noisy. The noise in the output beam 222 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 224 is located within the OPA system 200. A particular feature of a preferred embodiment of the present invention is that the laser system 200 includes a noise cancellation subsystem 240 which operates to provide a noise-canceling phase-corrected output to cancel noise in the output beam 222 in the manner detailed below.

[0216] Particularly preferably, the noise cancellation subsystem 240 uses an algorithm for detecting and correcting phase noise in the coupled laser output. The noise-canceling phase-corrected output is preferably provided by the noise cancellation subsystem 240 to the phase modulator 218 to correct the phase noise in the output beam 222, and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 222 that would otherwise be caused by the noise. The noise cancellation subsystem 240 may be included in the control electronic module 232.

[0217] It is understood that the output beam 222 may be affected by additional or alternative types of noise other than phase noise, including intensity noise. In the case of the output beam 222 having intensity noise, the noise cancellation subsystem 240 may operate to provide a noise-canceling phase-corrected output to cancel the intensity noise of the output beam 222. In such a case, the OPA laser system 200 may optionally additionally include an intensity modulator 242 along channel 216 to modulate the intensity of each subbeam along channel 216.

[0218] It is understood that the output beam 222 may be affected by mechanical noise that may, additionally or alternatively, affect the relative position of the subbeams. In the case of the output beam 222 having position noise, the noise cancellation subsystem 240 may operate to provide a noise-canceling phase-compensated output to cancel the position noise of the output beam 222. In such a case, the OPA laser system 200 may optionally additionally include a position modulator 244 along channel 216 to modulate the position of each of the subbeams along channel 216.

[0219] To facilitate the application of phase shifting and noise correction to the output beam 222, a portion of the output of the OPA laser 200 is preferably extracted and directed toward at least one detector, which is shown here as a single detector 250. The detector 250 may alternatively be embodied as multiple detectors, as detailed below with reference to Figures 6-8 and 15-21. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the required noise correction and / or phase shifting can be calculated. In the embodiment shown in Figure 2A, multiple subbeams along the channel 216 are directed toward a beam divider 260. The beam divider 260 preferably divides each subbeam into a transmission portion 262 and a reflection portion 264 according to a predetermined ratio. For example, the beam divider 260 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0220] The transmitted portion 262 of the sub-beam preferably propagates toward the focusing lens 220, where the sub-beam is combined to form an output beam 222 having a far-field intensity pattern 266 that is incident on the scanning mirror 203. The reflected portion 264 of the sub-beam preferably reflects toward an additional focusing lens 268, where the sub-beam is combined to form an output reference beam 270 having a far-field intensity pattern 272 that is incident on the surface of the detector 250.

[0221] It is understood that the specific structures and configurations of the beam splitting and recombining elements shown herein, including the beam splitter 260 and the focusing lenses 220 and 268, are illustrative and are shown in a highly simplified manner. It is understood that the OPA laser system 200 may include a variety of such elements, as well as additional optical elements, including, but merely as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0222] As described herein, the shape and position of the far-field intensity pattern 266 of the output beam 222, and the corresponding shape and position of the far-field intensity pattern 272 of the reference beam 270, are constantly changing due to the ongoing changes in the relative phase of the subbeams. As a result, the far-field intensity pattern 272 is not fixed to the detector 250, but rather is constantly moving relative to the detector 250 according to the combined relative phase of the constituent subbeams. However, in order for the detector 250 to provide the required noise-canceling phase-corrected output, the far-field intensity pattern 272 must be incident on the detector 250 so that the detector can measure the intensity of the far-field intensity pattern 272 and, therefore, apply noise correction accordingly, resulting in a fixed output beam.

[0223] The conflict between the dynamic nature of the far-field intensity pattern 272 due to its phase shift and the fixed nature required of the far-field intensity pattern 272 for deriving and applying noise correction is advantageously resolved in the present invention by providing noise cancellation and phase shift at mutually different times and rates.

[0224] The noise-canceling phase-corrected output is provided based on taking into account the noise measured at the detector 250 at the noise sampling rate. The output beam 222 is controlled such that the far-field intensity pattern 272 is incident on the detector 250 at a rate equal to or faster than the requested noise sampling rate during the process of dynamic changes in the shape and position of the output and reference far-field intensity patterns 266, 272. The noise of the reference beam 270 is taken into account during these intermittent times when the far-field intensity pattern 272 is returned to the detector 250.

[0225] During the intermittent time intervals in which the far-field intensity pattern 272 is incident on the detector 250, the phases of the combined output beams 222, 270 are changed to dynamically change the shape and position of the far-field intensity pattern as required to carry out the additive manufacturing of article 206. The combined laser output is changed at a phase change rate exceeding the noise sampling rate in order to rapidly change the phase, and therefore rapidly change the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be around 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0226] Different rates and time scales at which noise cancellation and phase shifting are preferably performed in embodiments of the present invention can be best understood by referring to graph 280 shown in Figure 2A and its enlarged version shown in Figure 2B.

[0227] As is most clearly seen in Figure 2B, graph 280 includes an upper portion 282 showing the change in intensity over time of the far-field intensity pattern 272 measured by detector 250, and a lower portion 284 showing the change in the relative phase of a number of subbeams contributing to the output beam 222 and the reference beam 270 over the same time period. For simplicity, the relative phases of 10 subbeams are shown in graph 280, but it will be understood that the OPA system 200, and therefore the description provided herein, is applicable to fewer, or more typically, a much larger number of subbeams.

[0228] As seen in the upper portion 282, the intensity peak 286 represents the measured intensity of the reference beam 270 as the far-field intensity pattern 272 passes over the detector 250. As seen in the lower portion 284, the intensity peak 286 represents the intermittent time T at which the relative phase of each subbeam is zero. i This occurs, meaning there is no phase shift between the subbeams, the position of the combined output beam does not change, and the far-field intensity pattern 272 is therefore directly incident on the detector 250. It is understood that the detector 250 may alternatively be positioned such that the relative phase of the subbeams therein is non-zero. Furthermore, multiple detectors may be used to measure the far-field intensity pattern 272 at multiple positions along them, as detailed below with reference to Figures 6-8 and 15-21.

[0229] The far-field intensity pattern 272 is moved to either side of the detector 250 and therefore does not directly incident on the detector 250, so the measured intensity is close to zero between the intensity peaks 286. As can be understood from the consideration of the upper portion 282, the magnitude of the intensity peaks 286 is not constant due to the presence of noise in the laser output beam, and this noise degrades the far-field intensity pattern 272.

[0230] As seen in the lower portion 284, the relative phase of the subbeam is intermittent over time T. i Time interval T betweenThe phase change is modified by the time interval T. In the phase change functions shown herein, the relative phase of the subbeam is shown to change in a periodic and regular repeating pattern in the positive and negative directions with equal phase shifts applied. It should be understood that such a simplified pattern is merely illustrative, and the phase change does not necessarily have to repeat regularly, nor does it necessarily have to be symmetrical in the positive and negative directions. Furthermore, the time interval T between This is an intermittent period of time T. i It is preferable that these overlap, but it is understood that they do not necessarily have to overlap. Additionally, it is understood that at least one of the phase shift rate and the noise sampling rate may be constant or may change over time.

[0231] The noise cancellation subsystem 240 preferably operates over an intermittent time T. i It operates by taking into account noise in intermittent time T i A noise-canceling phase-corrected output is provided based on the noise detected. The noise-canceling subsystem 240 preferably uses an algorithm to detect noise and correct the detected noise accordingly.

[0232] According to one exemplary embodiment of the present invention, the noise cancellation subsystem 240 uses an algorithm in which, during each cycle of the movement of the far-field intensity pattern 272 relative to the detector 250, the relative phase of one channel is changed in such a way that the relative phase is modified by a given phase change Δφ. Following a number of such cycles in which a different phase change Δφ is applied to a selected subbeam over each cycle, the algorithm checks the maximum output intensity over all cycles and finds the optimal phase change Δφ that produced this maximum intensity. The phase change of the selected subbeam is then fixed to the optimal phase change Δφ for subsequent cycles, and the algorithm proceeds to optimize another subbeam.

[0233] Graph 280 shows noise cancellation by this exemplary algorithm in channels A, B, and C of three subbeams or a total of ten subbeams. For simplicity, subbeams A, B, and C are shown individually in Figure 2C. In Figure 2C, it will be noticed that the line style of the lines representing the phase shift and noise correction of subbeams A, B, and C has been modified, respectively, compared to Figures 2A and 2B, to aid in distinguishing between the various subbeams for the purposes of later discussions in this specification.

[0234] As first observed in the case of channel A, and most clearly understood from the considerations in enlarged figure 290, the dashed line represents the relative phase change pattern of sub-beam A that would be applied by the phase control subsystem 230 in the absence of any noise correction. This line is A uncorrected It is sometimes called this. The dotted and dashed lines represent the actual relative phase of subbeam A corrected by a noise correction algorithm to find the optimal phase noise correction. This line is A corrected It is sometimes called A corrected The corrected relative phase of A is over the first 5 cycles of subbeam A. uncorrected Different Δφ for the uncorrected relative phase A It is shifted by only that much. The intensity 286 measured by detector 250 changes over the first 5 cycles of subbeam A optimization due to the intentional change in the relative phase shift.

[0235] After the first 5 cycles of subbeam A, the algorithm checks for maximum intensity and determines the phase change Δφ that generates the maximum intensity. A Find it. In this case, the maximum intensity is the second phase shift Δφ A IA generated by max It appears that the phase shift applied to the relative phase change of subbeam A is therefore the second phase shift Δφ for the subsequent cycle. A With this fixed, the algorithm proceeds to optimize subbeam B.

[0236] During successive cycles of optimization of sub-beam A, it is understood that the relative phases of the remaining portions of the sub-beams are each changed as usual at a rate of phase change far exceeding the noise sampling rate at which noise in sub-beam A is considered.

[0237] As can be further seen in the case of sub-beam B, and most clearly understood from consideration of enlarged view 292, the thicker line during optimization of channel B represents the pattern of change in the relative phase of sub-beam B that would be applied by phase control subsystem 230 in the absence of any noise correction. This line is sometimes referred to as B uncorrected The thinner line during optimization of channel B represents the actual relative phase of sub-beam B corrected by the noise correction algorithm in order to find the optimal phase noise correction. This line is sometimes referred to as B corrected The corrected relative phase of B is shifted by a different Δφ corrected only relative to the uncorrected relative phase of B over 5 cycles of optimizing sub-beam B. The intensity 286 measured by detector 250 changes over these 5 cycles of optimizing sub-beam B due to the intentional change in relative phase shift. uncorrected B

[0238] After these 5 cycles of sub-beam B, the algorithm checks for the maximum intensity and finds the phase change Δφ B that produces the maximum intensity. In this case, the maximum intensity is seen to be IAB B produced by the fourth phase shift Δφ max . The phase change applied to the relative phase change of sub-beam B is then fixed at the fourth phase shift Δφ B for subsequent cycles, and the algorithm proceeds to optimize sub-beam C.

[0239] ​​During the five cycles of optimization of sub-beam B, it is understood that the relative phases of the remaining portions of the sub-beams are each changed as normal at a rate of phase change far exceeding the noise sampling rate at which the noise of sub-beam B is considered.

[0240] Preferably, a similar optimization process is performed for sub-beam C, where a phase change Δφ is applied over several cycles to optimize the output beam intensity due to the phase noise of sub-beam C and to correct its intensity degradation. C is applied.

[0241] Detector 250 can operate continuously to continuously optimize the relative phase of the sub-beams and correct the phase noise therein. However, due to the finite response time of detector 250, detector 250 only considers the noise in reference beam 270 at intermittent times at a relatively slow noise sampling rate. The noise sampling rate is preferably pre-determined, but does not necessarily have to be pre-determined. Alternatively, the noise sampling rate may be random.

[0242] As will be understood by those skilled in the art, the specific parameters of the noise correction algorithm shown in graph 280 are merely illustrative and can be easily modified. For example, the phase shift Δφ may be optimized over a greater or fewer number of cycles than shown herein, each sub-beam may be fully optimized each time the sub-beam passes through detector 250, or some or all of the sub-beams may be optimized during each cycle that the far-field intensity pattern passes through detector 250. Further, a discontinuous noise correction optimization algorithm, including but not limited to a stochastic parallel gradient descent optimization algorithm, may be implemented alternatively.

[0243] Using dynamically shaped and noise-corrected optical phased array output beams in laser additive manufacturing offers significant advantages, enabling rapid beam steering, high-speed power modulation, high-speed beam focusing, and beam shape adjustment. Compared to conventional laser 3D printing methods, using dynamically shaped and noise-corrected optical phased array output improves both the speed and quality of the articles that can be manufactured. Without noise correction provided by a preferred embodiment of the present invention, the shape and position of the optical phased array output beam would degrade, thereby degrading the quality, speed, and accuracy of the laser additive manufacturing process.

[0244] To maintain output beam intensity as the beam's far-field intensity pattern shifts, the movement of the output beam can be controlled to compensate for the reduction in power delivery at lower intensity locations, which is advantageous in certain additive manufacturing applications. This allows the beam to spend more time at lower intensity locations. Additionally or alternatively, intensity profile masks, such as ND filters, may be applied to the output beam to modify its intensity.

[0245] Next, we refer to Figure 3A, a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping constructed and operating according to a more preferred embodiment of the present invention, as well as Figures 3B and 3C, which are simplified graphical representations of phase shifting and noise compensation within the type of system shown in Figure 3A.

[0246] As shown in Figure 3A, an optical phased array (OPA) laser system 300 is provided here, as an example, for use in a free-space optical communication system 302. The free-space optical communication system 302 may include an OPA laser system 300 mounted in an outdoor location, such as a building, spaced apart from a receiver 303 for receiving optical signals emitted from the OPA laser 300. Although the free-space optical communication system 302 is shown herein in the context of communication between two fixed points, it will be understood by those skilled in the art that the free-space optical communication system 302 may be adapted for use in communication between two locations moving relative to each other. Although the free-space optical communication system 302 is shown herein in the context of terrestrial communication, it will be understood by those skilled in the art that the free-space optical communication system 302 may be adapted for use in extraterrestrial communication.

[0247] The free-space optical communication system 302 is shown in Figure 3A, for simplicity only, as comprising only a single OPA laser 300 and a receiver 303, and it is understood that, depending on the communication requirements of the system 302, it may include a greater number of single OPA lasers 300 and receivers 303. Furthermore, it is understood that the receiver 303 may be an OPA laser of a type similar to the OPA laser 300 and having a receiving function. Moreover, the OPA laser 300 may include a receiving function to enable dual operation of the OPA lasers 300 and 303 for the transmission and reception of optical signals between them.

[0248] As best seen in enlarged figure 310, the OPA laser 300 preferably comprises a seed laser 312 and a laser beam splitting and coupling subsystem 314. The splitting and coupling subsystem 314 preferably receives the output laser beam from the seed laser 312 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 316. Herein, for the sake of illustration only, the output from the seed laser 312 is shown to be split into 10 subbeams along 10 channels 316, but it is understood that the splitting and coupling subsystem 314 may include fewer or more channels along the channels to which the output of the seed laser 312 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0249] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 318 positioned along each of the channels 316. Each phase-modulated subbeam generated by splitting the output of the seed laser 312 and subsequent phase modulation preferably propagates toward the collimating lens 319. The individually collimated and phase-modulated subbeams are then combined, for example, in a focusing lens 320 to form the output beam 322.

[0250] The splitting and combining subsystem 314 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 312 into subbeams and before combining the subbeams to form the output beam 322. Here, as an example, the splitting and combining subsystem 314 is shown to include a plurality of optical amplifiers 324 positioned along the corresponding channels of the channels 316 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output requirements of the OPA laser 300.

[0251] The phase of the output beam 322, and therefore the position and shape of its far-field intensity pattern, is controlled, at least partially, by the relative phases of the constituent subbeams coupled to form the output beam 322. In many applications, such as free-space optical communications as shown in Figure 3A, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 300 by having the laser splitting and coupling subsystem 314 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 322 and dynamically controlling the position and shape of its far-field intensity pattern.

[0252] The relative phase of the subbeam is preferably predetermined according to a desired laser output pattern for transmission to the receiver 303. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 330. The phase control subsystem 330 preferably forms part of a control electronic module 332 in the OPA laser 300 and preferably controls each phase modulator 318 to dynamically modulate the relative phase of the subbeam along the channel 316.

[0253] Due to noise inherent in the OPA system 300, the output beam 322 is noisy. The noise in the output beam 322 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 324 is located within the OPA system 300. A particular feature of a preferred embodiment of the present invention is that the laser system 300 includes a noise cancellation subsystem 340 which operates to provide a noise-canceling phase-corrected output to cancel noise in the output beam 322 in the manner detailed below.

[0254] Particularly preferably, the noise cancellation subsystem 340 uses an algorithm for detecting and correcting phase noise in the coupled laser output. The noise-canceling phase-corrected output is preferably provided by the noise cancellation subsystem 340 to the phase modulator 318 to correct the phase noise in the output beam 322 and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 322 that would otherwise be caused by the noise. The noise cancellation subsystem 340 may be included in the control electronic module 332.

[0255] It is understood that the output beam 322 may be affected by additional or alternative types of noise other than phase noise, including intensity noise. In the case of the output beam 322 having intensity noise, the noise cancellation subsystem 340 may operate to provide a noise-canceling phase-corrected output to cancel the intensity noise of the output beam 322. In such a case, the OPA laser system 300 may optionally additionally include an intensity modulator 342 along channel 316 to modulate the intensity of each subbeam along channel 316.

[0256] It is understood that the output beam 322 may be affected by mechanical noise that may, additionally or alternatively, affect the relative position of the subbeams. In the case of the output beam 322 having position noise, the noise cancellation subsystem 340 may operate to provide a noise-canceling phase-corrected output to cancel the position noise of the output beam 322. In such a case, the OPA laser system 300 may optionally additionally include a position modulator 344 along channel 316 to modulate the position of each subbeam along channel 316.

[0257] To facilitate the application of phase shifting and noise correction to the output beam 322, a portion of the output of the OPA laser 300 is preferably extracted and directed toward at least one detector, which is shown here as a single detector 350. The detector 350 may alternatively be embodied as multiple detectors, as detailed below with reference to Figures 6-8 and 15-21. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the required noise correction and / or phase shifting can be calculated. In the embodiment shown in Figure 3A, multiple subbeams along the channel 316 are directed toward a beam divider 360. The beam divider 360 preferably divides each subbeam into a transmission portion 362 and a reflection portion 364 according to a predetermined ratio. For example, the beam divider 360 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0258] The transmitted portion 362 of the sub-beam preferably propagates toward the focal lens 320, where the sub-beam is combined to form an output beam 322 having a far-field intensity pattern 366. The reflected portion 364 of the sub-beam preferably reflects toward an additional focal lens 368, where the sub-beam is combined to form an output reference beam 370 having a far-field intensity pattern 372 that is incident on the surface of the detector 350.

[0259] It is understood that the specific structures and configurations of the beam splitting and recombining elements shown herein, including the beam splitter 360 and the focusing lenses 320 and 368, are illustrative and are shown in a highly simplified form. It is understood that the OPA laser system 300 may include a variety of such elements, as well as additional optical elements, including, but merely as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0260] As described above in this specification, the shape and position of the far-field intensity pattern 366 of the output beam 322, and the corresponding shape and position of the far-field intensity pattern 372 of the reference beam 370, are constantly changing due to the ongoing change in the relative phase of the sub-beams. As a result, the far-field intensity pattern 372 is not fixed to the detector 350; rather, it is constantly being moved relative to the detector 350 according to the combined relative phase of the constituent sub-beams. However, for the detector 350 to provide the required noise cancellation phase correction output, the far-field intensity pattern 372 must be incident on the detector 350 in order for the detector to measure the intensity of the far-field intensity pattern 372 and thus apply noise correction accordingly, resulting in a fixed output beam.

[0261] The contradiction between its dynamic nature due to the phase change of the far-field intensity pattern 372 and the fixed nature required for the far-field intensity pattern 372 to derive and apply noise correction is advantageously resolved in the present invention by providing noise cancellation and phase change at mutually different times and rates.

[0262] The noise cancellation phase correction output is provided based on taking into account the noise measured at the detector 350 at the noise sampling rate. The output beam 322 is controlled in such a way that the far-field intensity pattern 372 is incident on the detector 350 at a rate equal to or faster than the required noise sampling rate during the process of the dynamic change in the shape and position of the output and reference far-field intensity patterns 366, 372. The noise of the reference beam 370 is taken into account during these intermittent times when the far-field intensity pattern 372 is returned to the detector 350.

[0263] During the time intervals between the intermittent periods when the far-field intensity pattern 372 is incident on the detector 350, the phases of the combined output beams 322, 370 are changed to dynamically change the shape and position of the far-field intensity pattern in terms of its phase, as required to carry out the additive manufacturing of article 206. The combined laser output is changed at a phase change rate exceeding the noise sampling rate in order to rapidly change the phase, and therefore rapidly change the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be around 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0264] Different rates and time scales for which noise cancellation and phase shifting are preferably performed in embodiments of the present invention can be best understood by referring to graph 380 shown in Figure 3A and its enlarged version shown in Figure 3B.

[0265] As is most clearly seen in Figure 3B, graph 380 includes an upper portion 382 showing the change in intensity over time of the far-field intensity pattern 372 measured by detector 350, and a lower portion 384 showing the change in the relative phase of a number of subbeams contributing to the output beam 322 and the reference beam 370 over the same time period. For simplicity, the relative phases of 10 subbeams are shown in graph 380, but it will be understood that the OPA system 300, and therefore the description provided herein, is applicable to fewer, or more typically, many more, subbeams.

[0266] As seen in the upper portion 382, ​​the intensity peak 386 represents the measured intensity of the reference beam 370 as the far-field intensity pattern 372 passes over the detector 350. As seen in the lower portion 384, the intensity peak 386 represents the intermittent time T at which the relative phase of each subbeam is zero. iThis occurs, meaning there is no phase shift between the subbeams, and therefore the position of the combined output beam does not change, and thus the far-field intensity pattern 372 is directly incident on the detector 350. It is understood that the detector 350 may, alternatively, be positioned such that the relative phase of the subbeams therein is non-zero. Furthermore, multiple detectors may be used to measure the far-field intensity pattern 372 at multiple positions along them, as will be detailed below with reference to Figures 6-8 and 15-21.

[0267] The far-field intensity pattern 372 is moved to either side of the detector 350 and therefore does not directly incident on the detector 350, so the measured intensity is close to zero between the intensity peaks 386. As can be understood from the consideration of the upper portion 382, ​​the magnitude of the intensity peaks 386 is not constant due to the presence of noise in the laser output beam, and this noise degrades the far-field intensity pattern 372.

[0268] As seen in the lower portion 384, the relative phase of the subbeam is intermittent over time T. i Time interval T between The phase change is modified by the time interval T. In the phase change functions shown herein, the relative phase of the subbeam is shown to change in a periodic and regular repeating pattern in the positive and negative directions with equal phase shifts applied. It should be understood that such a simplified pattern is merely illustrative, and the phase change does not necessarily have to repeat regularly, nor does it necessarily have to be symmetrical in the positive and negative directions. Furthermore, the time interval T between This is an intermittent period of time T. i It is preferable that these overlap, but it is understood that they do not necessarily have to overlap. Additionally, it is understood that at least one of the phase shift rate and the noise sampling rate may be constant or may change over time.

[0269] The noise cancellation subsystem 340 preferably operates over an intermittent time T. i It operates by taking into account noise in intermittent time Ti A noise-canceling phase-corrected output is provided based on the noise detected. The noise-canceling subsystem 340 preferably uses an algorithm to detect noise and correct the detected noise accordingly.

[0270] According to one exemplary embodiment of the present invention, the noise cancellation subsystem 340 uses an algorithm in which, during each cycle of the movement of the far-field intensity pattern 372 relative to the detector 350, the relative phase of one channel is changed in such a way that the relative phase is modified by a given phase change Δφ. Following a number of such cycles in which a different phase change Δφ is applied to a selected subbeam over each cycle, the algorithm checks the maximum output intensity over all cycles and finds the optimal phase change Δφ that produced this maximum intensity. The phase change of the selected subbeam is then fixed to the optimal phase change Δφ for subsequent cycles, and the algorithm proceeds to optimize another subbeam.

[0271] Graph 380 shows noise cancellation by this exemplary algorithm in channels A, B, and C of three subbeams or a total of ten subbeams. For simplicity, subbeams A, B, and C are shown individually in Figure 3C. In Figure 3C, it will be noted that, for the purposes of later discussions herein, the line style of the lines representing the phase shift and noise correction of subbeams A, B, and C has been modified, respectively, compared to Figures 3A and 3B, to aid in distinguishing between the various subbeams.

[0272] As first observed in the case of channel A, and most clearly understood from the considerations in enlarged figure 390, the dashed line represents the pattern of relative phase change of sub-beam A that would be applied by the phase control subsystem 330 in the absence of any noise correction. This line is A uncorrected It is sometimes called this. The dotted and dashed lines represent the actual relative phase of subbeam A corrected by a noise correction algorithm to find the optimal phase noise correction. This line is Acorrected It is sometimes called A corrected The corrected relative phase of A is over the first 5 cycles of subbeam A. uncorrected Different Δφ for the uncorrected relative phase A It is shifted by only that much. The intensity 386 measured by detector 350 changes over the first 5 cycles of subbeam A optimization due to the intentional change in the relative phase shift.

[0273] After the first 5 cycles of subbeam A, the algorithm checks for maximum intensity and determines the phase change Δφ that generates the maximum intensity. A Find it. In this case, the maximum intensity is the second phase shift Δφ A IA generated by max It appears that the phase shift applied to the relative phase change of subbeam A is therefore the second phase shift Δφ for the subsequent cycle. A With this fixed, the algorithm proceeds to optimize subbeam B.

[0274] During the continuous optimization cycle of subbeam A, it is understood that the relative phases of the rest of the subbeam are changed as usual, each at a phase change rate far exceeding the noise sampling rate at which noise in subbeam A is taken into account.

[0275] As can be seen further in the case of sub-beam B, and as is most clearly understood from the considerations in enlarged figure 392, the thicker line during the optimization of channel B represents the pattern of relative phase changes of sub-beam B that would be applied by the phase control subsystem 330 in the absence of any noise correction. This line is B uncorrected It is sometimes called this. The thin line during the optimization of channel B represents the actual relative phase of subbeam B corrected by the noise correction algorithm to find the optimal phase noise correction. This line is B corrected It is sometimes called B. corrected The corrected relative phase of B is over 5 cycles of the optimized subbeam B. uncorrectedDifferent Δφ for the uncorrected relative phase B Only the phase shift occurs. The intensity 386 measured by detector 350 changes over these five cycles of optimized subbeam B due to the intentional change in the relative phase shift.

[0276] After these five cycles of subbeam B, the algorithm checks for maximum intensity and determines the phase change Δφ that generates the maximum intensity. B Find it. In this case, the maximum intensity is the fourth phase shift Δφ B IAB generated by max It appears that the phase shift applied to the relative phase change of subbeam B then results in a fourth phase shift Δφ for subsequent cycles. B With this fixed, the algorithm proceeds to optimize subbeam C.

[0277] During the five optimization cycles of sub-beam B, it is understood that the relative phases of the remaining parts of the sub-beam are changed as usual, each at a phase change rate far exceeding the noise sampling rate at which noise in sub-beam B is taken into account.

[0278] Preferably, a similar optimization process is performed for sub-beam C, where a phase change Δφ is applied over several cycles to optimize the output beam intensity caused by phase noise in sub-beam C and to compensate for its intensity degradation. C This applies.

[0279] The detector 350 can operate continuously to continuously optimize the relative phase of the subbeam and correct for phase noise within it. However, due to the finite response time of the detector 350, the detector 350 only considers noise in the reference beam 370 at intermittent times, with a relatively slow noise sampling rate. The noise sampling rate is preferably predetermined, but does not necessarily have to be predetermined. Alternatively, the noise sampling rate may be random.

[0280] As those skilled in the art will understand, the specific parameters of the noise correction algorithm shown in Graph 380 are merely illustrative and can be easily modified. For example, the phase shift Δφ may be optimized over more or fewer cycles than shown herein, each subbeam may be fully optimized each time it passes through the detector 350, or some or all of the subbeams may be optimized during each cycle in which the far-field intensity pattern passes through the detector 350. Furthermore, discontinuous noise correction optimization algorithms, including but not limited to stochastic parallel gradient descent optimization algorithms, may be implemented as alternatives.

[0281] Using dynamically shaped and noise-corrected optical phased array output beams for free-space optical communications offers significant advantages, enabling rapid beam steering, high-speed power modulation, high-speed beam focusing, and beam shape adjustment. Compared to conventional free-space optical communication methods, using dynamically shaped and noise-corrected optical phased array outputs improves both the speed and quality of communication. Without noise correction provided by preferred embodiments of the present invention, the shape and position of the optical phased array output beam would degrade, thereby degrading the quality, speed, and accuracy of the transmitted laser output.

[0282] To maintain output beam intensity as the beam's far-field intensity pattern shifts, the movement of the output beam can be controlled to compensate for the reduction in power delivery at lower intensity locations, which is advantageous for certain optical communications applications. Additionally or alternatively, intensity profile masks, such as ND filters, may be applied to the output beam to modify its intensity.

[0283] Next, we refer to Figure 4A, a simplified schematic diagram of an optically phased array laser system for noise-compensated dynamic beam shaping constructed and operating according to yet another preferred embodiment of the present invention, as well as Figures 4B and 4C, which are simplified graphical representations of phase shifting and noise compensation in a system of the type shown in Figure 4A.

[0284] As shown in Figure 4A, an optically phased array (OPA) laser system 400 is provided here, as an example, for use within a laser welding system 402. The laser welding system 402 may include the OPA laser system 400 mounted on or inside a portion of a laser welding robot 404. Articles such as article 406 may be welded by the laser welding robot 404, as detailed below. Although the laser welding system 402 is shown herein in the context of the welding robot 404, it will be understood, as will be understood by those skilled in the art, that the system 402 may be adapted for use in any welding setting.

[0285] As best seen in enlarged figure 410, the OPA laser 400 preferably comprises a seed laser 412 and a laser beam splitting and coupling subsystem 414. The splitting and coupling subsystem 414 preferably receives the output laser beam from the seed laser 412 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 416. Here, for the sake of illustration only, the output from the seed laser 412 is shown to be split into 10 subbeams along 10 channels 416, but it is understood that the splitting and coupling subsystem 414 may include fewer or more channels along the channels to which the output of the seed laser 412 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0286] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 418 positioned along each of the channels 416. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 412 preferably propagates toward the collimating lens 419. The individually collimated and phase-modulated subbeams are then combined, for example, in a focusing lens 420 to form the output beam 422.

[0287] The splitting and combining subsystem 414 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 412 into subbeams and before combining the subbeams to form the output beam 422. Here, as an example, the splitting and combining subsystem 414 is shown to include a plurality of optical amplifiers 424 positioned along the corresponding channels of the channels 416 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output requirements of the OPA laser 400.

[0288] The phase of the output beam 422, and therefore the position and shape of its far-field intensity pattern, is controlled, at least partially, by the relative phases of the constituent subbeams coupled to form the output beam 422. In many applications, such as laser welding as shown in Figure 4A, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 400 by having the laser splitting and coupling subsystem 414 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 422 and dynamically controlling the position and shape of its far-field intensity pattern.

[0289] The relative phase of the subbeam is preferably predetermined according to a desired laser power pattern for welding article 406. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 430. The phase control subsystem 430 preferably forms part of a control electronic module 432 within the OPA laser 400 and preferably controls each phase modulator 418 to dynamically modulate the relative phase of the subbeam along channel 416.

[0290] Due to noise inherent in the OPA system 400, the output beam 422 is noisy. The noise in the output beam 422 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 424 is located within the OPA system 400. A particular feature of a preferred embodiment of the present invention is that the laser system 400 includes a noise cancellation subsystem 440 which operates to provide a noise-canceling phase-corrected output to cancel noise in the output beam 422 in the manner detailed below.

[0291] Particularly preferably, the noise cancellation subsystem 440 uses an algorithm for detecting and correcting phase noise in the coupled laser output. The noise-canceling phase-corrected output is preferably provided by the noise cancellation subsystem 440 to the phase modulator 418 to correct the phase noise in the output beam 422 and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 422 that would otherwise be caused by the noise. The noise cancellation subsystem 440 may be included in the control electronic module 432.

[0292] It is understood that the output beam 422 may be affected by additional or alternative types of noise other than phase noise, including intensity noise. In the case of the output beam 422 having intensity noise, the noise cancellation subsystem 440 may operate to provide a noise-canceling phase-corrected output to cancel the intensity noise of the output beam 422. In such a case, the OPA laser system 400 may optionally additionally include an intensity modulator 442 along channel 416 to modulate the intensity of each subbeam along channel 416.

[0293] It is understood that the output beam 422 may be affected by mechanical noise that may, additionally or alternatively, affect the relative position of the subbeams. In the case of the output beam 422 having position noise, the noise cancellation subsystem 440 may operate to provide a noise-canceling phase-compensated output to cancel the position noise of the output beam 422. In such a case, the OPA laser system 400 may optionally additionally include a position modulator 444 along channel 416 to modulate the position of each subbeam along channel 416.

[0294] To facilitate the application of phase shifting and noise correction to the output beam 422, a portion of the output of the OPA laser 400 is preferably extracted and directed toward at least one detector, which is shown here as a single detector 450. The detector 450 may alternatively be embodied as multiple detectors, as detailed below with reference to Figures 6-8 and 15-21. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the required noise correction and / or phase shifting can be calculated. In the embodiment shown in Figure 4A, multiple subbeams along the channel 416 are directed toward a beam divider 460. The beam divider 460 preferably divides each subbeam into a transmission portion 462 and a reflection portion 464 according to a predetermined ratio. For example, the beam divider 460 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0295] The transmitted portion 462 of the sub-beam preferably propagates toward the focusing lens 420, where the sub-beam is combined to form an output beam 422 having a far-field intensity pattern 466 that is incident on the article 406. The reflected portion 464 of the sub-beam preferably reflects toward an additional focusing lens 468, where the sub-beam is combined to form an output reference beam 470 having a far-field intensity pattern 472 that is incident on the surface of the detector 450.

[0296] The specific structures and configurations of the beam splitting and recombining elements shown herein, including the beam splitter 460 and the focusing lenses 420 and 468, are to be understood as merely illustrative and are shown in a highly simplified form. The OPA laser system 400 may include a variety of such elements, as well as additional optical elements, including, but merely as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0297] As described herein, the shape and position of the far-field intensity pattern 466 of the output beam 422, and the corresponding shape and position of the far-field intensity pattern 472 of the reference beam 470, are constantly changing due to the ongoing change in the relative phase of the subbeams. As a result, the far-field intensity pattern 472 is not fixed to the detector 450, but rather is constantly moving relative to the detector 450 according to the coupled relative phase of the constituent subbeams. However, in order for the detector 450 to provide the required noise-canceling phase-corrected output, the far-field intensity pattern 472 must be incident on the detector 450 so that the detector can measure the intensity of the far-field intensity pattern 472 and, therefore, apply noise correction accordingly, resulting in a fixed output beam.

[0298] The conflict between the dynamic nature of the far-field intensity pattern 472 due to its phase shift and the fixed nature required of the far-field intensity pattern 472 for deriving and applying noise correction is advantageously resolved in the present invention by providing noise cancellation and phase shift at mutually different times and rates.

[0299] The noise-canceling phase-corrected output is provided based on taking into account the noise measured at the detector 450 at the noise sampling rate. The output beam 422 is controlled such that the far-field intensity pattern 472 is incident on the detector 450 at a rate equal to or faster than the requested noise sampling rate during the process of dynamic changes in the shape and position of the output and reference far-field intensity patterns 466, 472. The noise of the reference beam 470 is taken into account during these intermittent times when the far-field intensity pattern 472 is returned to the detector 450.

[0300] During the time intervals between the intermittent periods when the far-field intensity pattern 472 is incident on the detector 450, the phases of the combined output beams 422, 470 are changed to dynamically alter the shape and position of the far-field intensity pattern as required to perform laser welding of article 406. The combined laser output is changed at a phase change rate exceeding the noise sampling rate to rapidly alter the phase, and therefore the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be around 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0301] Different rates and time scales at which noise cancellation and phase shifting are preferably performed in embodiments of the present invention can be best understood by referring to graph 480 shown in Figure 4A and its enlarged version shown in Figure 4B.

[0302] As is most clearly seen in Figure 4B, graph 480 includes an upper portion 482 showing the change in intensity over time of the far-field intensity pattern 472 measured by detector 450, and a lower portion 484 showing the change in the relative phase of a number of subbeams contributing to the output beam 422 and the reference beam 470 over the same time period. For simplicity, the relative phases of 10 subbeams are shown in graph 480, but it will be understood that the OPA system 400, and therefore the description provided herein, is applicable to fewer, or more typically, many more, subbeams.

[0303] As seen in the upper portion 482, the intensity peak 486 represents the measured intensity of the reference beam 470 as the far-field intensity pattern 472 passes over the detector 450. As seen in the lower portion 484, the intensity peak 486 represents the intermittent time T at which the relative phase of each subbeam is zero. i This occurs, meaning there is no phase shift between the subbeams, and therefore the position of the combined output beam does not change, and thus the far-field intensity pattern 472 is directly incident on the detector 450. It is understood that the detector 450 may, alternatively, be positioned such that the relative phase of the subbeams therein is non-zero. Furthermore, multiple detectors may be used to measure the far-field intensity pattern 472 at multiple positions along them, as detailed below with reference to Figures 6-8 and 15-21.

[0304] The far-field intensity pattern 472 is shifted to either side of the detector 450 and therefore does not directly incident on the detector 450, so the measured intensity is close to zero between the intensity peaks 486. As can be understood from the consideration of the upper portion 482, the magnitude of the intensity peak 486 is not constant due to the presence of noise in the laser output beam, and this noise degrades the far-field intensity pattern 472.

[0305] As seen in the lower section 484, the relative phase of the subbeam is intermittent over time T. i Time interval T betweenThe phase change is modified by the time interval T. In the phase change functions shown herein, the relative phase of the subbeam is shown to change in a periodic and regular repeating pattern in the positive and negative directions with equal phase shifts applied. It should be understood that such a simplified pattern is merely illustrative, and the phase change does not necessarily have to repeat regularly, nor does it necessarily have to be symmetrical in the positive and negative directions. Furthermore, the time interval T between This is an intermittent period of time T. i It is preferable that these overlap, but it is understood that they do not necessarily have to overlap. Additionally, it is understood that at least one of the phase shift rate and the noise sampling rate may be constant or may change over time.

[0306] The noise cancellation subsystem 440 preferably operates over an intermittent time T i It operates by taking into account noise in intermittent time T i A noise-canceling phase-corrected output is provided based on the noise detected. The noise-canceling subsystem 440 preferably uses an algorithm to detect noise and correct the detected noise accordingly.

[0307] According to one exemplary embodiment of the present invention, the noise cancellation subsystem 440 uses an algorithm in which, during each cycle of the movement of the far-field intensity pattern 472 relative to the detector 150, the relative phase of one channel is changed in such a way that the relative phase is modified by a given phase change Δφ. Following a number of such cycles in which a different phase change Δφ is applied to a selected subbeam over each cycle, the algorithm checks the maximum output intensity over all cycles and finds the optimal phase change Δφ that produced this maximum intensity. The phase change of the selected subbeam is then fixed to the optimal phase change Δφ for subsequent cycles, and the algorithm proceeds to optimize another subbeam.

[0308] Graph 480 shows noise cancellation by this exemplary algorithm in channels A, B, and C of three sub - beams or a total of ten sub - beams. For simplicity, sub - beams A, B, and C are shown separately in FIG. 4C. In FIG. 4C, for the purposes of the following description herein, the line styles of the lines representing the phase changes and noise corrections of sub - beams A, B, and C are modified compared to FIGS. 4A and 4B to assist in differentiating between the various sub - beams, as will be understood.

[0309] First seen in the case of channel A and most clearly understood from consideration of the enlarged view 490, the dashed line represents the pattern of the change in the relative phase of sub - beam A that would be applied by the phase - control subsystem 430 in the absence of any noise correction. This line is sometimes referred to as A uncorrected The dotted and dashed lines represent the actual relative phase of sub - beam A that has been corrected by the noise - correction algorithm in order to find the optimal phase noise correction. This line is sometimes referred to as A corrected The corrected relative phase of A corrected is shifted by a different Δφ uncorrected relative to the uncorrected relative phase of sub - beam A over the first five cycles of sub - beam A. The intensity 486 measured by detector 450 changes over the first five cycles of the optimization of sub - beam A due to the intentional change in the relative phase shift. A After the first five cycles of sub - beam A, the algorithm checks for the maximum intensity and finds the phase change Δφ

[0310] that produces the maximum intensity. In this case, the maximum intensity is seen to be IA A produced by the second phase shift Δφ A The phase change applied to the relative - phase change of sub - beam A is thus fixed at the second phase shift Δφ max for subsequent cycles, and the algorithm proceeds to optimize sub - beam B. A

[0311] ​During successive cycles of optimization of sub-beam A, the relative phases of the remaining portions of the sub-beams are each changed as normal at a rate of phase change far exceeding the noise sampling rate at which noise in sub-beam A is considered.

[0312] As is further seen in the case of sub-beam B, and most clearly understood from consideration of the enlarged view 492, the thicker line during optimization of channel B represents the pattern of change in the relative phase of sub-beam B that would be applied by phase control subsystem 430 in the absence of any noise correction. This line is sometimes referred to as B uncorrected The thinner line during optimization of channel B represents the actual relative phase of sub-beam B modified by the noise correction algorithm to find the optimal phase noise correction. This line is sometimes referred to as B corrected The modified relative phase of B is shifted by a different Δφ corrected relative to the unmodified relative phase of B over five cycles of optimizing sub-beam B. The intensity 486 measured by detector 450 changes over these five cycles of optimizing sub-beam B due to the intentional change in relative phase shift. uncorrected B After these five cycles of sub-beam B, the algorithm checks for the maximum intensity and finds the phase change Δφ

[0313] that produces the maximum intensity. In this case, the maximum intensity is seen to be IAB B produced by the fourth phase shift Δφ B . The phase change applied to the relative phase change of sub-beam B is then fixed at the fourth phase shift Δφ max for subsequent cycles, and the algorithm proceeds to optimize sub-beam C. B

[0314] ​​During the five optimization cycles of sub-beam B, it is understood that the relative phases of the rest of the sub-beam are changed as usual, each at a phase change rate far exceeding the noise sampling rate at which the noise of sub-beam B is taken into account.

[0315] Preferably, a similar optimization process is performed for sub-beam C, where a phase change Δφ is applied over several cycles to optimize the output beam intensity caused by phase noise in sub-beam C and to compensate for its intensity degradation. C This applies.

[0316] The detector 450 can operate continuously to continuously optimize the relative phase of the subbeam and correct for phase noise within it. However, due to the finite response time of the detector 450, the detector 450 only considers noise in the reference beam 470 at intermittent times, with a relatively slow noise sampling rate. The noise sampling rate is preferably predetermined, but does not necessarily have to be predetermined. Alternatively, the noise sampling rate may be random.

[0317] As those skilled in the art will understand, the specific parameters of the noise correction algorithm shown in Graph 480 are merely illustrative and can be easily modified. For example, the phase shift Δφ may be optimized over more or fewer cycles than shown herein, each subbeam may be fully optimized each time it passes through the detector 450, or some or all of the subbeams may be optimized during each cycle in which the far-field intensity pattern passes through the detector 450. Furthermore, discontinuous noise correction optimization algorithms, including but not limited to stochastic parallel gradient descent optimization algorithms, may be implemented as alternatives.

[0318] Using dynamically shaped and noise-corrected optical phased array output beams for laser welding offers significant advantages, enabling rapid beam steering, high-speed power modulation, high-speed beam focusing, and beam shape adjustment. Compared to conventional laser cutting methods, using dynamically shaped and noise-corrected optical phased array output improves both the speed and quality of material cutting. Without noise correction provided by preferred embodiments of the present invention, the shape and position of the optical phased array output beam would degrade, thereby degrading the quality, speed, and accuracy of the laser cutting process.

[0319] To maintain output beam intensity as the beam's far-field intensity pattern shifts, the movement of the output beam can be controlled to be advantageous for specific laser cutting applications. This allows the beam to spend more time at lower intensity locations, compensating for the reduction in power delivery there. Additionally or alternatively, intensity profile masks, such as ND filters, may be applied to the output beam to modify its intensity.

[0320] Next, referring to Figures 5A to 5G, these are simplified schematic diagrams of the possible far-field motion of the output of the type of optical phased array laser system shown in Figures 1A to 4C.

[0321] As detailed above, using dynamically shaped and noise-corrected optical phased array output beams in a variety of laser applications, including but not limited to laser cutting, laser additive manufacturing, laser welding, and laser free-space optical communications, is highly advantageous as it enables rapid beam steering, fast power modulation, fast beam focusing, and beam shaping. Exemplary far-field patterns demonstrating rapid beam steering according to embodiments of the present invention are shown in Figures 5A and 5B. These beam steering patterns may be provided in combination to complement mechanical space modulation of the beam, such as mechanical beam steering. Mechanical beam steering may result from motion provided by a positioning table 104 shown in Figure 1A, from mirror scanning such as in an additive manufacturing system of the type shown in Figure 2A, from mechanical motion between the laser system 300 and receiver 303 shown in Figure 3A, from motion provided by a robot 404 shown in Figure 4A, or from any other cause of mechanical motion.

[0322] The mechanical motion may be a desirable motion or an undesirable motion. Preferably, the far-field rapid beam steering provided by embodiments of the present invention complements the mechanical motion to achieve a desired combined beam motion. The desired combined motion may be faster and / or more precise than that produced as a result of mechanical beam modulation alone.

[0323] As shown in Figure 5A, the dynamically shaped and noise-corrected optical phased array output beam may exhibit rapid multipoint jumps, as indicated by the first beampath 502, which complement the beam motion resulting from mechanical scanning, represented by the second beampath 504.

[0324] For example, such multi-point jumps can be advantageous in material processing where it takes time for energy to be absorbed at each point of the material being processed. Multi-point jumps allow the beam to jump between points and return to each point multiple times, thus facilitating parallel processing of a large number of points. As another example, such multi-point jumps can be advantageous in communication systems because they allow for parallel transmission to multiple locations.

[0325] As shown in Figure 5B, the use of a dynamically shaped and noise-corrected optical phased array output beam also facilitates rapid scanning, as indicated by the third beam path 506, which complements the beam motion resulting from mechanical scanning represented by the fourth beam path 508. Such rapid scanning facilitates continuous and smooth mechanical beam motion, whose fine features can be provided by far-field dynamic shaping according to embodiments of the present invention. Furthermore, to compensate for any inaccuracies that may exist in the mechanically modulated beam pattern, dynamically noise-corrected far-field modulation can be provided in combination with mechanical beam motion.

[0326] Figure 5C shows an exemplary far-field beam pattern demonstrating electro-optic beam wobble according to a preferred embodiment of the present invention. As seen in Figure 5C, a dynamically shaped and noise-corrected optical phased array output beam is controlled to exhibit a rapid beam wobble 510 along the direction of the beam motion 512, which is particularly useful in laser welding systems such as those shown in Figure 4A.

[0327] Exemplary far-field beam patterns demonstrating dynamic modification of the depth of focus according to a preferred embodiment of the present invention are shown in Figures 5D to 5F. As seen in Figures 5D to 5F, the depth of the beam focus may be dynamically changed by the system of the present invention, enabling variable beam focal lengths for scanning (Figure 5E) and deep cutting (Figures 5D and 5F), which is particularly useful in cutting, additive manufacturing, and welding systems of the types shown in Figures 1A, 2A, and 4A, for example.

[0328] Figure 5G shows an exemplary far-field beam pattern demonstrating dynamic beam shaping according to a preferred embodiment of the present invention. As seen in Figure 5G, the beam shape may be dynamically changed to produce a desired beam shape output. This may be particularly useful in cutting, additive manufacturing, and welding systems of the types shown in Figures 1A, 2A, and 4A, as well as in other contexts. As is well known in the art, the quality and speed of laser cutting, welding, and 3D printing are typically affected by the size and shape of the beam. The present invention makes it possible to dynamically adapt the beam to an optimal shape at any point.

[0329] It is understood that all of the various far-field beam motion patterns shown in Figures 5A to 5G are preferably generated by the system of the present invention using digital electronic control without requiring any moving parts.

[0330] Next, referring to Figure 6, Figure 6 is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple tightly spaced optical paths, constructed and operating according to a preferred embodiment of the present invention.

[0331] As shown in Figure 6, an optical phased array (OPA) laser 600 is provided. The OPA laser 600 may generally be of the type shown in any of Figures 1A to 4C, and preferably includes a seed laser 612 and a laser beam splitting and coupling subsystem 614. The splitting and coupling subsystem 614 preferably receives the output laser beam from the seed laser 612 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 616. Here, for the sake of argument only, the output from the seed laser 612 is shown to be split into four subbeams along four channels 616, but it is understood that the splitting and coupling subsystem 614 may include fewer or more channels along the channels to which the output of the seed laser 612 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0332] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 618 positioned along each of the channels 616. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 612 preferably propagates toward the collimating lens 619. The individually collimated and phase-modulated subbeams are then combined, for example, in a focusing lens 620 to form the output beam 622.

[0333] The splitting and combining subsystem 614 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 612 into subbeams and before combining the subbeams to form the output beam 622. Herein, as an example, the splitting and combining subsystem 614 is shown to include a plurality of optical amplifiers 624 positioned along the corresponding channels of the channels 616 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output usage of the OPA laser 600.

[0334] The phase of the output beam 622, and therefore the position and shape of its far-field intensity pattern, is controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 622. As described above herein with reference to Figures 1A to 5G, in many applications such as laser cutting, laser welding, laser additive manufacturing, and optical free-space communication, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 600 by having the laser splitting and coupling subsystem 614 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 622 and dynamically controlling the position and shape of its far-field intensity pattern.

[0335] The relative phase of the subbeam is preferably predetermined according to a desired laser power pattern. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 630. The phase control subsystem 630 preferably forms part of a control electronics module 632 in the OPA laser 600 and preferably controls each phase modulator 618 to dynamically modulate the relative phase of the subbeam along channel 616, as described above herein with reference to phase control subsystems 130, 230, 330, and 430 in Figures 1A, 2A, 3A, and 4A, respectively.

[0336] Due to noise inherent in the OPA system 600, the output beam 622 is noisy. The noise in the output beam 622 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 624 is located within the OPA system 600. The OPA system 600 preferably includes a noise cancellation subsystem 640 that operates to provide a noise-canceling phase-compensated output to cancel the noise in the output beam 622 in the manner detailed below.

[0337] Particularly preferably, the noise cancellation subsystem 640 uses, though not necessarily required, an algorithm of the type described herein above with reference to Figures 1A to 4C for detecting and correcting phase noise in the coupled laser output. The noise-canceled phase-corrected output is preferably provided by the noise cancellation subsystem 640 to the phase modulator 618 to correct the phase noise in the output beam 622 and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 622 that would otherwise be caused by the noise. The noise cancellation subsystem 640 may be included in the control electronics module 632.

[0338] To facilitate the application of phase shifting and noise correction to the output beam 622, a portion of the output of the OPA laser 600 is preferably extracted and directed toward a plurality of detectors 650. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the required noise correction and / or phase shifting can be calculated.

[0339] According to a preferred embodiment of the present invention, a plurality of subbeams along the channel 616 are directed toward a beam divider 660. The beam divider 660 preferably divides each subbeam into a transmittance portion 662 and a reflectance portion 664 according to a predetermined ratio. For example, the beam divider 660 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0340] The transmitted portion 662 of the sub-beam preferably propagates toward the focal lens 620, where the sub-beam is combined to form an output beam 622 having a far-field intensity pattern 666. The reflected portion 664 of the sub-beam preferably reflects toward an additional focal lens 668, where the sub-beam is combined to form an output reference beam 670 having a far-field intensity pattern 672 that is incident on one or more surfaces of the plurality of detectors 650.

[0341] As described above herein with reference to Figures 1A to 4C, the noise-canceling phase-corrected output is provided, preferably, on the basis of taking into account the noise measured at the detector 650 at the noise sampling rate. The output beam 622 is controlled such that the far-field intensity pattern 672 is incident on the detector 650 at a rate equal to or faster than the requested noise sampling rate during the process of dynamic changes in the shape and position of the output and reference far-field intensity patterns 666, 672. The noise of the reference beam 670 is taken into account during these intermittent times when the far-field intensity pattern 672 is returned to the detector 650.

[0342] During the time intervals between the intermittent periods when the far-field intensity pattern 672 is incident on the detector 650, the phases of the combined output beams 622, 670 are changed to dynamically alter the shape and position of the far-field intensity pattern. The combined laser output is changed at a phase change rate exceeding the noise sampling rate to rapidly alter the phase, and therefore rapidly alter the shape and position of the far-field intensity pattern. Thus, noise cancellation and phase change are preferably provided at different times and rates from each other.

[0343] The use of multiple detectors 650 rather than a single detector has been found to be very advantageous in certain embodiments of the present invention, resulting in various benefits detailed below. However, if the focal length of the additional focal lens 668 is relatively short, as is desirable for forming a compact system 600, the detectors among the multiple detectors 650 preferably need to be positioned very closely to one another. The desired spacing between detectors may be on the order of a few microns. Such a high spatial density arrangement of detectors 650 is typically impractical, especially in the case of conventional detectors having dimensions much larger than the preferred spacing between detectors.

[0344] To enable high spatial density sampling of the far-field intensity pattern 672 by multiple detectors 650, the OPA system 600 preferably includes multiple optical paths, which are embodied here, for example, as multiple optical fibers 680 and accordingly connected to the multiple detectors 650. The reference beam 670 preferably enters one or more of the multiple open ends 682 of the optical fiber 680 and travels along it to the corresponding detectors among the detectors 650. The multiple ends 682 of the multiple optical fibers 680 are preferably arranged to have a spatial density greater than the spatial density of the multiple detectors 650, meaning that the spacing between the open ends 682 of adjacent optical fibers 680 is smaller than the spacing between corresponding adjacent detectors of the detectors 650. This allows the detectors 650 to detect the far-field intensity pattern 672 that is closely spaced along them, without the detectors themselves needing to be physically positioned at closely spaced locations on the detectors 650 where the far-field intensity pattern 672 is sampled.

[0345] For example, the ends 682 of the optical fiber 680 may be spaced a few microns apart, while the detector 650 connected to the corresponding optical fiber 680 may be spaced a few millimeters apart. Such an arrangement is understood to allow the use of conventional detectors in system 600 and eliminate the need for expensive, complex, and miniaturized detection systems.

[0346] It has been found that including multiple detectors 650, which are effectively spaced close together as facilitated by the actual physically close spacing of the ends 682 of the optical fiber 680, is highly advantageous in preferred embodiments of the present invention. In particular, using multiple detectors 650 rather than a single detector 150, as shown in Figures 1A, 2A, 3A, and 4A, makes it possible to sample the far-field intensity pattern 672 at multiple locations rather than just a single location. This facilitates more efficient and / or more frequent noise correction during dynamic changes of the output beam 622.

[0347] It is understood that the tightly spaced optical paths are not limited to being embodied as multiple optical fibers 680, where the ends 682 are very tightly spaced and the end spacing between fibers is smaller than the spacing between detectors 650. Rather, the scope of the present invention is extended to include any preferred multiple optical paths, along which the far-field intensity reference pattern 672 can be delivered to the multiple detectors 650 and can be arranged at a sufficiently large spatial density.

[0348] As an example, as shown in Figure 7, multiple closely spaced optical paths may be embodied as multiple lenses 780. The multiple lenses 780 may be very closely spaced to focus portions of the far-field intensity reference pattern 672 toward multiple more closely spaced detectors 650. Further as an example, as shown in Figure 8, multiple closely spaced optical paths may be embodied as multiple mirrors 880 working in cooperation with the corresponding multiple lenses 882. The multiple mirrors 880 may be very closely spaced to reflect portions of the far-field intensity reference pattern 672 toward multiple more closely spaced detectors 650.

[0349] It is understood that an OPA laser system of the type shown in any of Figures 6 to 8, which includes multiple detectors, may be incorporated into an OPA laser system of the type shown in any of Figures 1A, 2A, 3A, and 4A to provide more efficient and / or more frequent noise correction to its phase-shifted output.

[0350] Next, referring to Figure 9, Figure 9 is a simplified schematic diagram of an optically phased array laser system, including a detector mask configured according to an exemplary laser beam trajectory, constructed and operating according to a preferred embodiment of the present invention.

[0351] As shown in Figure 9, an optical phased array (OPA) laser 900 is provided. The OPA laser 900 may be substantially similar to the OPA laser 600 in Figure 6 in its relevant embodiments, except for the detector arrangement used therein. The OPA laser 600 preferably uses multiple detectors that receive the output beam through a corresponding set of tightly spaced optical paths, while the OPA laser 900 does not necessarily use multiple detectors.

[0352] A particular feature of a preferred embodiment of the present invention shown in Figure 9 is that the OPA laser 900 preferably includes an optical mask 980 having at least one transmission region 982 for providing at least one detector 650 with a reference beam 670 output through the transmission region 982, where the OPA laser 900 is shown here to comprise a single detector 650. The optical mask 980 is preferably an optically opaque element that is transparent to the beam 670 only in the transmission region 982. Here, as an example, the transmission region 982 is shown to be formed as a star-shaped transmission path configured according to the star-shaped trajectory of the output and reference far-field intensity patterns 666, 672.

[0353] The output reference beam 670 preferably passes through the transmission region 982 and is focused to the detector 650 by a focusing subsystem, which here, for example, is embodied as a focusing lens 990. The noise-canceling phase-corrected output is preferably provided by the noise-canceling subsystem 630, based on taking into account the intensity of the far-field intensity pattern 672 focused and incident on the detector 650.

[0354] More specifically, the phases of the output and reference beams 622 and 670 are preferably dynamically changed by the phase control subsystem 630 so that the output and reference beams 622 and 670 traverse predetermined trajectories, such as star-shaped trajectories corresponding to the shape of the star-shaped transmission region 982. If there is no noise in the OPA laser 900, the trajectories traversed by the output and reference beams 622 and 670 will correspond at least almost exactly to the shape of the transmission region 982, and as a result, the intensity of the far-field intensity pattern 672 detected by the detector 650 will be the maximum non-degraded intensity. However, due to the presence of noise in the output and reference beams 622 and 670, the trajectories and shape of the far-field intensity pattern 672 deviate somewhat from the shape of the transmission region 982, and as a result, a portion of the reference beam 670 is incident on the opaque region of the mask 980 rather than on the transmission region 982, and therefore does not pass through the transmission region 982 to the detector 650. In such cases, the intensity of the far-field intensity pattern 672 detected by the detector 650 is lower than the maximum intensity that would be detected if noise were absent.

[0355] Therefore, the degradation of the intensity of the far-field intensity pattern 672 measured by the detector 650 preferably indicates noise composite distortion of the trajectories of the output and reference beams 622, 670, which may be used to derive the required noise cancellation phase correction output applied by the noise cancellation subsystem 640.

[0356] The arrangement of the detector 650 positioned behind the mask 980 is understood to allow the use of only a single detector 650 to detect the output intensity of the reference beam 670 along its beam trajectory, and to apply a noise-canceling phase-corrected output based on that. This is in contrast to alternative detector arrangements that do not include the mask 980, such as those described herein with reference to Figures 6-8, where multiple detectors may be used to provide sufficiently efficient and / or frequent noise correction during dynamic changes of the output beam 622.

[0357] In addition to the change in the intensity of the reference beam 670 measured by the detector 650 due to beam trajectory distortion caused by noise, the intensity of the reference beam 670 may also change along its trajectory, typically due to intrinsic intensity changes in the far-field intensity pattern 672. This can complicate the noise compensation feedback provided by the detector 650, as the change in the intensity of the reference beam 670 may be due to noise or intrinsic intensity changes unrelated to noise.

[0358] To improve the reliability of the noise correction feedback provided by the detector 650, the transmission region 982 of the mask 980 may be provided with regions of varying transparency, the transparency levels of which are set to compensate for inherent intensity changes in the reference beam 670 along its trajectory.

[0359] A highly simplified representation of a transparent region 982 of a mask 980 having non-uniform transparency is shown in Figure 10. As seen in Figure 10, the first portion of the transparent region 982 defined between a first point P1 and a second point P2 may have a first transparency T1. The second portion of the transparent region 982 defined between a second point P2 and a third point P3 may have a second transparency T2 that is different from the first transparency T1. The third portion of the transparent region 982 defined between a third point P3 and a fourth point P4 may have a first transparency T1. The fourth portion of the transparent region 982 defined between a fourth point P4 and a fifth point P5 may have a third transparency T3 that is different from the first and second transparencys T1 and T2. The fifth point of the transparent region 982 defined between the fifth point P5 and the first point P1 may have a second transparency T2.

[0360] It is understood that different parts of the transmission region 982 may have discretely different transparency values, or the transparency of the transmission region 982 may be stepped across its different parts in accordance with the intensity compensation requirements of the far-field intensity pattern 672.

[0361] Preferably, though not strictly necessary, the mask 980 is an electronically modulated device such as an LCD screen or a similar device. Thus, the characteristics of the transmission region 982 may be easily modified electronically according to the output characteristics of the reference beam 670.

[0362] The specific shapes of the transmission region 982 shown in Figures 9 and 10 are merely illustrative, and it is understood that the transmission region 982 may be configured according to any trajectory of the output and reference far-field intensity patterns 666 and 672. Additionally, it is understood that the transmission region 982 may include multiple transmission regions. In such a case, a single detector 650 can be used to receive light from all transmission regions, or a corresponding number of detectors can be positioned for each transmission region.

[0363] Furthermore, as detailed with reference to Figures 11 and 12, it is understood that the transmission region 982 may be configured additionally or alternatively according to the shape of the output and reference far-field intensity patterns 666 and 672, rather than its trajectory.

[0364] Next, referring to Figure 11, Figure 11 is a simplified schematic diagram of an optically phased array laser system, including a detector mask configured according to an exemplary laser beam shape, constructed and operating according to another preferred embodiment of the present invention.

[0365] As shown in Figure 11, a system 1100 that is generally similar to system 900 in its relevant aspects may include an optical mask 1180 having at least one transmission region 1182 that replaces the optical mask 980 in Figures 9 and 10. The optical mask 1180 may be similar to the optical mask 980 in all its relevant embodiments, except that the transmission region 1182 is configured according to the shape of the reference beam 670 rather than its trajectory. Here, as an example, the transmission region 1182 is shown to be a bowtie-shaped transmission region configured according to bowtie-shaped output and reference far-field intensity patterns 666 and 672.

[0366] The transmission region 1182 may have non-uniform transparency, a very simplified representation of which is shown in Figure 12. As seen in Figure 12, a first portion of the transmission region 1182 may have a first transparency T1, and a second portion of the transmission region 1182 may have a second transparency T2 different from the first transparency T1. Various levels of transparency of the transmission region 1182 may be used to compensate for inherent intensity changes of the output beam 670 and thus improve the noise-corrected output provided based on the intensity detected by the detector 650, as detailed herein with reference to Figure 10.

[0367] It is understood that the transmission regions 982 and 1182 of masks 980 and 1180 may, additionally or alternatively, be embodied as reflection regions from which the output reference beam 670 is reflected toward the detector 650. In such an arrangement, appropriate modifications and / or additions to a focusing subsystem, which hereby are embodied as a focusing lens 990, for example, are required to direct the output reference beam 670 from the reflection regions 982, 1182 toward the surface of the detector 650. The reflection regions of masks 980 and 1180 may have a uniform reflectance. Alternatively, as described above herein, the reflection regions of masks 980 and 1180 may have a non-uniform reflectance to compensate for inherent intensity changes in the output reference beam 670.

[0368] If masks 980 and 1180 include reflective regions, masks 980 and 1180 may be embodied as electrically modulated devices such as digital micromirror devices (DMDs) or other similar devices.

[0369] An OPA laser system of the type shown in any of Figures 9 to 12, which includes at least one detector that receives the output reference beam through a transmission or reflection optical mask, can be incorporated into an OPA laser system of the type shown in any of Figures 1A, 2A, 3A, and 4A to provide more efficient noise correction to its phase-shifted output.

[0370] Next, we refer to Figure 13, a simplified schematic diagram of an optical phased array laser system including a voltage phase correlation function, constructed and operating according to a preferred embodiment of the present invention.

[0371] As shown in Figure 13, an OPA laser system 1300 is provided. The OPA laser 1300 may have a type that is generally similar to the OPA lasers 100, 200, 300, and 400 described herein with reference to Figures 1A to 4C. The OPA laser 1300 preferably comprises a seed laser 1312 and a laser beam splitting and coupling subsystem 1314. The splitting and coupling subsystem 1314 preferably receives the output laser beam from the seed laser 1312 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 1316.

[0372] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 1318 positioned along each of the channels 1316. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 1312 preferably propagates toward the collimating lens 1319. The individually collimated and phase-modulated subbeams are then combined, for example, at the focal plane of lens 1320 to form the output beam 1322.

[0373] The splitting and combining subsystem 1314 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 1312 into subbeams and before combining the subbeams to form the output beam 1322. Here, as an example, the splitting and combining subsystem 1314 is shown to include a plurality of optical amplifiers 1324 positioned along the corresponding channels of the channels 1316 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output usage of the OPA laser 1300.

[0374] The phase of the output beam 1322, and therefore the position and shape of its far-field intensity pattern, are controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 1322. In many applications described herein, such as laser cutting, laser welding, free-space optical communication, and laser additive manufacturing, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. As described herein with reference to Figures 1A to 4C, dynamic modification of the output beam parameters can be achieved by dynamically changing the relative phases of the individual subbeams along the channel 1316, thereby changing the phase of the coupled laser output 1322 and dynamically controlling the position and shape of its far-field intensity pattern.

[0375] The relative phase of the subbeam is preferably predetermined according to a desired laser output pattern. Particularly preferably, the relative phase to be changed is applied by a phase modulation control module 1330. The phase modulation control module 1330 preferably provides a voltage to the phase modulator 1318 so that the phase modulator 1318 generates a desired phase modulation of the subbeam along channel 1316. The phase modulation control module 1330, in combination with the phase modulator 1318, forms a particularly preferred embodiment of a phase modulation subsystem 1332, which is understood to preferably operate to change the phase of the coupled laser output 1322.

[0376] To facilitate the application of phase shifts to the output beam 1322, a portion of the output of the OPA laser 1300 is preferably extracted and directed toward at least one detector 1350. The extracted portion of the output beam preferably serves as a reference beam based on characteristics that allow the required phase shift to be calculated. In the embodiment shown in Figure 13, a plurality of subbeams along the channel 1316 are directed toward a beam divider 1360. The beam divider 1360 preferably divides each subbeam into a transmit portion 1362 and a reflect portion 1364 according to a predetermined ratio. For example, the beam divider 1360 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0377] The transmitted portion 1362 of the sub-beam preferably propagates toward the focal lens 1320, where the sub-beam is combined to form an output beam 1322 having a far-field intensity pattern 1366. The reflected portion 1364 of the sub-beam preferably propagates toward an additional focal lens 1368, where the sub-beam is combined to form an additional reference beam 1370 having a far-field intensity pattern 1372 that is incident on the surface of the detector 1350.

[0378] Detector 1350 preferably samples the far-field intensity pattern 1372 incident thereon. Although detector 1350 is shown in Figure 13 as a single detector directly receiving the far-field intensity pattern 1372, it is understood that multiple detectors may be used alternatively according to any of the multiple detector arrangements shown in any of Figures 6 to 8. Alternatively, a single detector such as detector 1350 may be used with an optical mask according to any of the arrangements shown in any of Figures 9 to 12.

[0379] The detector 1350 works in cooperation with the phase modulation subsystem 1332 to optimize the relative phase of the subbeam, preferably to achieve a desired far-field intensity pattern 1372 and the corresponding far-field intensity pattern 1366. Various algorithms suitable for phase optimization include sequential or non-sequential optimization algorithms, including the phase optimization regimes described herein with reference to Figures 1A to 4C.

[0380] In the operation of the phase modulation subsystem 1332, the phase modulation control module 1330 preferably applies a voltage to each of the phase modulators 1318 and the phase modulation control module 1330, thereby generating a phase modulation output corresponding to the applied voltage. It is understood that in order for the phase modulators 1318 to generate the phase shift necessary for the far-field intensity pattern 1366 to be dynamically shaped according to a predetermined pattern, the phase modulation control module 1330 must precisely apply a voltage to each phase modulator 1318 that corresponds to a specific phase modulation output that needs to be generated by each phase modulator 1318.

[0381] To ensure that the voltage applied to the phase modulator 1318 by the phase modulation control module 1330 generates the required and intended phase-modulated output by the phase modulator 1318, the OPA laser 1300 preferably includes a voltage-to-phase correlation subsystem 1380. The voltage-to-phase correlation subsystem 1380 preferably operates to correlate the voltage applied to the phase modulation subsystem 1332 with the phase-modulated output generated by the phase modulation subsystem 1332, more specifically by its phase modulator 1318.

[0382] Furthermore, the voltage-to-phase correlation subsystem 1380 preferably operates to provide a voltage-to-phase correlation output useful for calibrating the phase modulation subsystem 1332. Preferably, the voltage-to-phase correlation subsystem periodically performs correlation between the voltage and the phase modulation output during the process of changing the phase of the coupled laser output 1322.

[0383] It is understood that including correlation and calibration subsystems, such as a voltage-to-phase correlation subsystem 1380, in the OPA laser 1300 is highly advantageous because it ensures that the voltage applied to the phase modulator 1318 is the voltage required to produce the desired phase shift of the output beam 1322, and consequently, the shape of the far-field intensity pattern 1366. This is particularly important considering that phase modulators suitable for use in preferred embodiments of the present invention are typically highly sensitive devices, and those that are different typically exhibit different voltage-phase relationships. Furthermore, the voltage-phase relationships of individual phase modulators are not constant and may change over time depending on the operating conditions.

[0384] The phase modulation and calibration provided by the phase modulation control module 1330 and the voltage-phase correlation control module 1380 are not necessarily required, but are preferably performed in cooperation with the application of noise correction to the output of the OPA laser 1300 when the output of the laser 1300 is noisy. In this case, the phase modulation control module 1330 and the voltage-phase correlation control module 1380 can be considered to form a combination of particularly preferred embodiments of phase control subsystems such as 130 (Figure 1A), 230 (Figure 2A), 330 (Figure 3A), and 430 (Figure 4A).

[0385] An exemplary voltage-phase correlation and calibration regime suitable for use in the present invention is shown in flowchart 1400 of Figure 14. However, it is understood that the specific steps in flowchart 1400 are merely illustrative, and the voltage-phase correlation subsystem 1380 can be implemented as any suitable subsystem within the OPA laser 1300 that can periodically calibrate the phase modulation subsystem 1332 during phase changes of the output beam 1322. Furthermore, it is understood that the various steps shown in flowchart 1400 do not necessarily have to be performed in the order shown and described, and various steps may be omitted or supplemented by additional or alternative steps, as will be apparent to those skilled in the art.

[0386] As seen in the first step 1402, the phase modulation control module 1330 preferably applies a voltage to the phase modulator 1318 to generate a desired phase shift of the subbeam along the channel 1316. The far-field intensity pattern of the reference output beam 1372 is then measured by the detector 1350, as seen in the second step 1404. The desired phase shift of the subbeam is then confirmed, and the voltage is again applied to the phase modulator 1318. The application of the voltage in the first step 1402 and the measurement of the reference output beam 1372 in the second step 1404 may be repeated a large number of times periodically at a given repetition rate. For example, the first and second steps may be repeated 20 times at a rate of 1 million times per second.

[0387] Following a predetermined number of repetitions of the first and second steps 1402, 1404, for example 20 times, the voltage-versus-phase correlation subsystem 1380 may be activated. As seen in the third step 1406, a voltage intended to produce a phase shift of 2π is preferably applied to one phase modulator 1318. As seen in the fourth step 1408, the intensity of the far-field intensity pattern 1372 is then preferably measured by the detector 1350.

[0388] Next, in the fifth step 1410, the phase shift of the far-field intensity pattern 1372 is checked to see if the phase shift is zero. If the voltage applied in the third step 1406 is indeed a voltage that produces a phase shift of 2π, then the phase shift of the beam 1322 will be zero, and therefore it is understood that the intensity of the far-field intensity pattern 1372 does not change in response to the applied voltage. In this case, the phase modulator 1318 to which a 2π phase shift was applied in the third step 1406 is found to be correctly calibrated, and no further calibration of the particular phase modulator 1318 is required.

[0389] If the voltage applied in the third step 1406 does not produce a phase shift of 2π, the phase shift of beam 1322 will be non-zero, and therefore it is further understood that the intensity of the far-field intensity pattern 1372 will change in response to the applied voltage, as was found in the seventh step 1414. In this case, the relationship between the applied voltage and the resulting phase shift is preferably derived in the seventh step 1414. The phase modulator 1318 is then calibrated according to the voltage-phase relationship derived in the seventh step 1414, preferably as seen in the eighth step 1416.

[0390] As seen in query 1418, following the calibration of a specific phase modulator 1318 in the eighth calibration step 1416 or the confirmation of proper calibration of a specific phase modulator 1318 in the fifth step 1410, the voltage-to-phase correlation subsystem 1380 preferably checks whether a predetermined number of phase modulators 1318 have been calibrated, as seen in a predetermined ninth step 1420, and proceeds to calibrate the next phase modulator as necessary. The voltage-to-phase correlation subsystem 1380 may calibrate all phase modulators 1318 included in the system 1300 sequentially, or it may calibrate a predetermined number of phase modulators 1318, such as N phase modulators 1318, sequentially. Once a predetermined number of phase modulators 1318 have been calibrated, the subsystem 1380 is preferably deactivated, and the phase shift of the output beam 1322 is resumed in step 1402.

[0391] It is understood that the frequency at which the voltage-to-phase correlation subsystem 1380 is activated is preferably considerably lower than the frequency at which the phase shift of the output beam 1322 is performed. For example, the phase shift of the output beam 1322 may be performed 1 million times per second, while the voltage-to-phase correlation may be activated once per second.

[0392] Furthermore, although flowchart 1400 does not include a step for noise correction, it is understood that such noise correction may be applied during the phase shift process of the subbeam contributing to the output beam 1322, as described above with reference to Figures 1A to 4C.

[0393] Next, referring to Figure 15, which is a simplified schematic plan view of an optical phased array laser system including a dynamic beam scaled phase correction, constructed and operating according to an additional preferred embodiment of the present invention.

[0394] As shown in Figure 15, an optical phased array (OPA) laser system 1500 is provided, which may have the type outlined herein with reference to Figures 1A to 4C. The OPA laser 1500 preferably comprises a seed laser 1512 and a laser beam splitting and coupling subsystem 1514. The splitting and coupling subsystem 1514 preferably receives the output laser beam from the seed laser 1512 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 1516. Here, simply as an example, the output from the seed laser 1512 may be split into a 4x4 matrix of 16 subbeams along 16 corresponding channels 1516, of which four subbeams and channels 1516 are shown in the top view of the OPA laser 1500 in Figure 15. However, it is understood that the splitting and combining subsystem 1514 may include fewer or more channels into which the output of the seed laser 1512 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0395] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 1518 positioned along each of the channels 1516. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 1512 preferably propagates toward the collimating lens 1519. The individually collimated and phase-modulated subbeams are then combined, for example, at the focal plane of lens 1520 to form the output beam 1522.

[0396] The splitting and combining subsystem 1514 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 1512 into subbeams and before combining the subbeams to form the output beam 1522. Here, as an example, the splitting and combining subsystem 1514 is shown to include a plurality of optical amplifiers 1524 positioned along the corresponding channels of the channels 1516 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output usage of the OPA laser 1500.

[0397] The phase of the output beam 1522, and therefore the position and shape of its far-field intensity pattern, is controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 1522. As described above herein, in many applications such as laser cutting, laser welding, free-space optical communication, and laser additive manufacturing, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. As described above herein with reference to Figures 1A to 4C, dynamic modification of the output beam parameters can be achieved by dynamically changing the relative phases of the individual subbeams along the channel 1516, thereby changing the phase of the coupled laser output 1522 and dynamically controlling the position and shape of its far-field intensity pattern.

[0398] In the case of the OPA laser 1500, which includes numerous individual subbeams, measuring the phase of each subbeam relative to the phase of all other subbeams and performing corresponding phase correction can be difficult due to the large number of individual subbeams involved. Specifically, due to the large number of individual subbeams contributing to the combined output 1522, the time required to measure and correct the phase of each individual subbeam relative to the other subbeams in order to dynamically control the phase of the combined laser output 1522 can be unacceptably long. Furthermore, the signal-to-noise ratio can become unacceptably low.

[0399] A particular feature of preferred embodiments of the present invention is that the OPA laser 1500 includes a phase modulation subsystem 1530 for performing phase modulation of the combined laser output in an extended manner. More specifically, the phase modulation subsystem 1530 preferably groups at least a portion of the subbeams provided by the laser splitting and coupling subsystem 1514 into groups, and then performs phase modulation within each group of subbeams only with respect to the other subbeams in the group. Such group phase modulation is preferably performed in parallel across various individual groups of subbeams. The phase modulation subsystem 1530 then preferably optimizes the phase of each group of subbeams with respect to the phase of the other groups of subbeams in order to change the phase of the combined laser output 1522 in a manner detailed below.

[0400] The phase modulation subsystem 1530 preferably includes a phase control electronic module 1532 for controlling the operation of the phase modulators 1518. The phase control electronic module 1532 preferably controls each phase modulator 1518 to dynamically modulate the relative phase of the subbeams along the channel 1516 according to a desired far-field intensity pattern of the output beam 1522, as confirmed by the phase modulation subsystem 1530.

[0401] To facilitate the application of phase shift to the output beam 1522, a portion of the output of the OPA laser 1500 is preferably extracted and directed toward a plurality of detectors 1550. The extracted portion of the output beam preferably serves as a reference beam based on characteristics that allow the required phase shift to be calculated. In the embodiment shown in Figure 15, a plurality of subbeams along the channel 1516 are directed toward a beam divider 1560. The beam divider 1560 preferably divides each subbeam into a transmission portion 1562 and a reflection portion 1564 according to a predetermined ratio. For example, the beam divider 1560 can divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0402] The transmitted portion 1562 of the sub-beam preferably propagates toward the focusing lens 1520, where the sub-beams are combined to form an output beam 1522 having a far-field intensity pattern 1566. The reflected portion 1564 of the sub-beam preferably propagates toward the cylindrical lens 1568. The cylindrical lens 1568 preferably receives the reflected portion 1564 of the sub-beams by focusing the sub-beams along the curvature direction of the lens 1568, and operates to group the sub-beams into a number of groups. Here, as an example, the sub-beams are shown to converge into four groups 1570, each group 1570 consisting of four sub-beams.

[0403] Preferably, each group 1570 of subbeams grouped by the cylindrical lens 1568 forms a beam having a far-field intensity pattern 1572 incident on the surface of the corresponding detector among the plurality of detectors 1550. Each detector 1550 preferably samples the group far-field intensity pattern 1572 incident thereon. Each detector 1550 then preferably works with the corresponding control electronics submodule 1574 contained in the control module 1532 to optimize the relative phase of the subbeams within the group of subbeams 1570 sampled therewith relative to the phase of other subbeams within the group 1570. Such sampling and optimization are preferably performed in parallel, preferably simultaneously, for the far-field intensity patterns among the far-field intensity patterns 1572 across all detectors 1550. Various algorithms suitable for phase optimization include sequential or non-sequential optimization algorithms, including noise correction algorithms, as described above with reference to Figures 1A to 4C.

[0404] To optimize the relative phase of each group 1570 with respect to other groups of group 1570, a portion of group 1570 is preferably directed to an auxiliary cylindrical lens 1582 by an auxiliary beam splitter 1580. To focus the subbeam, it is understood that the curvature of the auxiliary cylindrical lens 1582 is preferably orthogonal to the curvature of the cylindrical lens 1568. The auxiliary cylindrical lens 1582 preferably focuses the groups of subbeams 1570 into a single beam 1584 having a far-field intensity pattern 1586 that is incident on an auxiliary detector 1588. The auxiliary detector 1588 then preferably receives a single beam having a far-field intensity pattern 1586 that corresponds to the combined patterns of all groups of subbeams 1570. The auxiliary detector 1588 preferably works in cooperation with an additional phase control electronics submodule 1590 included in the electronic control module 1532 to sample and optimize the phases of groups 1570 relative to each other. Particularly preferred is that one function of the phase control electronic module 1532 is to control each phase modulator 1518 in order to apply a phase shift that maximizes the total power of the auxiliary detector 1588.

[0405] It is understood that performing phase modulation in the extended manner described above, in which the phase of each subbeam is optimized with respect to the phases of the other subbeam members of its group 1570, and the phases of group 1570 are optimized with respect to each other to change the phase of the combined laser output 1522, is far faster and less complex than optimizing the phase of each individual subbeam with respect to the phases of all other subbeams in the OPA 1500. Furthermore, this allows for an improvement in the signal-to-noise ratio, as phase optimization is performed not by a single set of control electronics, but by individual sets of control electronics in each control electronics submodule 1574 coupled to each detector 1550.

[0406] It will be understood that the function of optimizing the relative phase of each group 1570 with respect to other groups of group 1570 may be performed alternatively by an additional group phase modulator operating to modulate the collective phase of each group 1570, rather than by individual phase modulators 1518 operating to modulate the individual phase of each sub-beam member of each group 1570. An exemplary implementation of such an arrangement is shown in Figure 16 and may be substantially similar to the phase modulation configuration described in U.S. Patent No. 9,893,494, the disclosure of which is incorporated herein by reference.

[0407] As shown in Figure 16, system 1500 may be modified by adding a series of group phase modulators corresponding to the number of groups 1570. Here, as an example, as shown in Figure 16, system 1500 may include 16 subbeams, four of which are included in each of the four groups 1570, resulting in a total of four additional group phase modulators 1618 being included in system 1500. Each group phase modulator 1618 is preferably common to four channels 1516 that form part of each group 1570, and provides a phase shift that optimizes the collective group phase of the subbeams along the four channels 1516 connected thereto.

[0408] Preferably, the group phase modulators among the group phase modulators 1618 are controlled by an additional control submodule 1690 included in the control module 1532. The auxiliary detector 1588 is preferably coupled to the additional control submodule 1690. While optimizing the relative phases of the group 1570 by comparing them with each other using the group phase modulator 1618 rather than by the individual subbeam phase modulators 1518 is more efficient and can simplify the phase modulation process, it is understood that this requires the use of additional phase modulators and circuit elements, and therefore increases the cost and complexity of the system 1500.

[0409] A change in the phase of the coupled laser output 1522 preferably provides spatial modulation of the output 1522. Due to the extended nature of the phase modulation performed by the phase modulation subsystem 1530, it is understood that the phase of the coupled laser output 1522 can be changed very rapidly at a rate faster than that achievable by a mechanical spatial modulation mechanism. The spatial modulation provided by the OPA laser 1500 may optionally be augmented by an additional mechanical spatial modulation mechanism, as is known in the art, or it may not include mechanical spatial modulation.

[0410] It is understood that the specific structures and configurations of the optical elements shown herein, including the beam splitter 1560, the focal lens 1520, the cylindrical lens 1568, the auxiliary beam splitter 1580, and the auxiliary cylindrical lens 1582, are merely illustrative and are shown in a highly simplified form. It is understood that the OPA laser system 1500 may include a variety of such elements, as well as additional optical elements, including, simply as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0411] Furthermore, it is understood that the cylindrical lens 1568 may have optical properties that group individual subbeams into mutually similar or identical groups containing an equal number of subbeams. Alternatively, the cylindrical lens 1568 may have optical properties that group individual subbeams into mutually different groups containing different numbers of subbeams.

[0412] An exemplary implementation of an OPA laser system of the type shown in Figure 15 or Figure 16 is shown in Figures 17A and 17B. Referring now to Figures 17A and 17B, an OPA laser system 1700 is provided in which an output laser beam from a seed laser (not shown), such as a seed laser 1512, is split into multiple subbeams along a plurality of corresponding channels 1716. For example, the laser output may be split into a 10 × 10 matrix of 100 subbeams along 100 corresponding channels 1716. For clarity in the presentation, it is understood that only selected subbeams are shown in Figure 17B. The subbeams along the channels 1716 can then be collimated and focused by collimating and focusing elements (not shown), such as collimating and focusing lenses 1519, 1520, to produce a combined output beam.

[0413] To facilitate the application of phase shifts to the output beam, a portion of the output of the OPA laser 1700 is preferably extracted and directed toward a plurality of detectors 1750. The extracted portion of the output beam preferably serves as a reference beam based on characteristics that allow the required phase shift to be calculated. In the embodiments shown in Figures 17A and 17B, a plurality of subbeams along the channel 1716 are directed toward a beam divider 1760. The beam divider 1760 preferably divides each subbeam into a transmission portion 1762 and a reflection portion 1764 according to a predetermined ratio.

[0414] The transmitted portion 1762 of the sub-beam is preferably combined to form an output beam. The reflective portion 1764 of the sub-beam is preferably reflected toward a cylindrical lens 1768, which is a particularly preferred embodiment of a cylindrical lens 1568. The cylindrical lens 1768 preferably receives the reflective portion 1764 of the sub-beam and operates to focus the sub-beam into a number of groups along the curvature direction of the cylindrical lens 1768. For example, with 100 sub-beams, the cylindrical lens 1768 can focus the sub-beams into 10 groups 1770 of 10 sub-beams each.

[0415] Preferably, each group 1770 of subbeams grouped by the cylindrical lens 1768 forms a beam having a far-field intensity pattern incident on the surface of the corresponding detector among the plurality of detectors 1750. For example, the plurality of detectors 1750 may include 10 detectors 1750, each sampling a group beam containing 10 individual subbeams. Each detector 1750 cooperates with a corresponding control electronic module (not shown), such as a control module 1532, to then preferably optimize the phase of the subbeams included in the group 1770 of subbeams sampled by it. Such sampling and optimization are preferably performed in parallel, and preferably simultaneously, across all detectors 1750.

[0416] To optimize the relative phase of each group 1770 with respect to the phase of other groups of group 1770, a portion of group 1770 is preferably directed to an auxiliary cylindrical lens 1782 by an auxiliary beam splitter 1780. It is understood that the auxiliary cylindrical lens 1782 is a particularly preferred embodiment of an auxiliary cylindrical lens 1582. To focus the subbeam, it is understood that the curvature of the auxiliary cylindrical lens 1782 is preferably orthogonal to the curvature of the cylindrical lens 1768. The auxiliary cylindrical lens 1782 preferably focuses the group of subbeams 1770 into a single combined beam 1784 that is incident on the auxiliary detector 1788.

[0417] The auxiliary detector 1788 preferably receives far-field intensity patterns corresponding to the patterns of all group combinations of sub-beams 1770 and, in cooperation with phase control electronics (not shown), samples and optimizes the phases of the groups 1770 relative to one another. It is understood that the optimization of the phases of the groups 1770 relative to one another may be by phase modulation of the phases of individual sub-beams by a phase modulator 1518, as described above with reference to Figure 15, or by phase modulation of the phases of a group of sub-beams by a group phase modulator 1618, as described above with reference to Figure 16.

[0418] Next, referring to Figure 18, which is a simplified schematic plan view of an optical phased array laser system including a dynamic beam scaled phase correction, constructed and operating according to another preferred embodiment of the present invention.

[0419] As shown in Figure 18, an optical phased array (OPA) laser system 1800 is provided, and this OPA laser 1800 may have the type outlined herein with reference to Figures 1A to 4C. The OPA laser 800 preferably comprises a seed laser 1812 and a laser beam splitting and coupling subsystem 1814. The splitting and coupling subsystem 1814 preferably receives the output laser beam from the seed laser 1812 and splits the output laser beam into a plurality of subbeams along a plurality of corresponding channels 1816. Here, simply as an example, the output from the seed laser 1812 may be split into a 4x4 matrix of 16 subbeams along 16 corresponding channels 1816, of which four subbeams and channels 1816 are shown in the top view of the OPA laser 1800 in Figure 18. However, it is understood that the splitting and combining subsystem 1814 may include fewer or more channels into which the output of the seed laser 1812 is split, and may typically include a much larger number of channels, such as 32 or more channels.

[0420] The relative phase of each subbeam may preferably be individually modulated by a phase modulator 1818 positioned along each of the channels 1816. Each phase-modulated subbeam generated by the splitting and subsequent phase modulation of the output of the seed laser 402 preferably propagates toward the collimating lens 1819. The individually collimated and phase-modulated subbeams are then combined, for example, at the focal plane of lens 1820 to form the output beam 1822.

[0421] The splitting and combining subsystem 1814 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 1812 into subbeams and before combining the subbeams to form the output beam 1822. Herein, as an example, the splitting and combining subsystem 1814 is shown to include a plurality of optical amplifiers 1824 positioned along the corresponding channels of the channels 1816 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output requirements of the OPA laser 1800.

[0422] The phase of the output beam 1822, and therefore the position and shape of its far-field intensity pattern, is controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 1822. As described above herein, in many applications such as laser cutting, laser welding, free-space optical communication, and laser additive manufacturing, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam. As described above herein with reference to Figures 1A to 4C, dynamic modification of the output beam parameters can be achieved by dynamically changing the relative phases of the individual subbeams along the channel 1816, thereby changing the phase of the coupled laser output 1822 and dynamically controlling the position and shape of its far-field intensity pattern.

[0423] In the case of the OPA laser 1800, which includes numerous individual subbeams, measuring the phase of each subbeam relative to the phase of all other subbeams and performing corresponding phase correction can be difficult due to the large number of individual subbeams involved. Specifically, due to the large number of individual subbeams contributing to the combined output 1822, the time required to measure and correct the phase of each individual subbeam relative to the other subbeams in order to dynamically control the phase of the combined laser output 1822 can be unacceptably long. Furthermore, the signal-to-noise ratio can become unacceptably low.

[0424] A particular feature of preferred embodiments of the present invention is that the OPA laser 1800 includes a phase modulation subsystem 1830 for performing phase modulation of the combined laser output in an extended manner. More specifically, the phase modulation subsystem 1830 preferably groups at least a portion of the subbeams provided by the laser splitting and coupling subsystem into groups, and then performs phase modulation within each group of subbeams only with respect to the phases of the other subbeams in the group. Such group phase modulation is preferably performed in parallel across various individual groups. The phase modulation subsystem 1830 then preferably optimizes the phase of each group of subbeams with respect to the phases of the other groups of subbeams in order to change the phase of the combined laser output 1822 in a manner detailed below.

[0425] The phase modulation subsystem 1830 preferably includes a phase control electronic module 1832 for controlling the operation of the phase modulators 1818. The phase control electronic module 1832 preferably controls each phase modulator 1818 to dynamically modulate the relative phase of the subbeams along the channel 1816 according to a desired far-field intensity pattern of the output beam 1822, as confirmed by the phase modulation subsystem 1830.

[0426] To facilitate the application of phase shifts to the output beam 1822, a portion of the output of the OPA laser 1800 is preferably extracted and directed toward a plurality of detectors 1850. The extracted portion of the output beam preferably serves as a reference beam based on characteristics that allow the required phase shift to be calculated. In the embodiment shown in Figure 18, a plurality of subbeams along the channel 1816 are directed toward a beam divider 1860. The beam divider 1860 preferably divides each subbeam into a transmission portion 1862 and a reflection portion 1864 according to a predetermined ratio. For example, the beam divider 1860 may divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0427] The transmitted portion 1862 of the sub-beam preferably propagates toward the focal lens 1820, where the sub-beam is coupled to form an output beam 1822 having a far-field intensity pattern 1866. The reflective portion 1864 of the sub-beam is preferably reflected toward an array of mirrors 1868, each mirror 1868 positioned spaced apart from the corresponding focusing lens 1869. For example, the mirror array 1868 may comprise four mirrors 1868 positioned spaced apart from four focusing lenses 1869, two of which are shown in the top view of system 1800 in Figure 18.

[0428] The mirror 1868 is preferably angled to reflect the incident subbeam toward the corresponding focusing lens 1869, thereby grouping the reflected portion 1864 of the subbeam into several groups, which here are embodied as four groups 1870, each group 1870 containing four subbeams, two of which are shown in the top view of system 18100 in Figure 18.

[0429] Preferably, each group of subbeams reflected by each of the mirrors 1868 is focused by a corresponding focal lens 1869 to form a single beam 1870 comprising a group of subbeams and having a far-field intensity pattern 1872 incident on the surface of the corresponding detector among a plurality of detectors 1850. Each detector 1850 cooperates with a corresponding control electronics submodule 1874 contained in a control module 1832 to then, preferably, optimize the relative phase of the subbeams within the group of subbeams 1870 sampled by it, with respect to the phase of other subbeams within the group 1870. Such sampling and optimization are preferably performed in parallel, preferably simultaneously, with respect to the far-field intensity patterns among the far-field intensity patterns 1872 across all detectors 1850. Various algorithms suitable for phase optimization include sequential or non-sequential optimization algorithms, including noise correction algorithms, as described above with reference to Figures 1A to 4C.

[0430] To optimize the relative phase of each group 1870 with respect to other groups of group 1870, a portion of the reflective section 1864 is preferably directed to an auxiliary lens 1882 via an auxiliary beam splitter 1880. The auxiliary lens 1882 preferably focuses the subbeams incident thereon into a single beam 1884 having a far-field intensity pattern 1886 incident on an auxiliary detector 1888. The auxiliary detector 1888 preferably receives a single beam thereon having a far-field intensity pattern 1886 corresponding to the patterns of all combined groups of subbeam 1870. The auxiliary detector 1888 preferably works with a phase control electronics submodule 1890 included in an electronic control module 1832 to sample and optimize the phases of group 1870 relative to each other. Particularly preferred, one function of the phase control electronic module 1832 is to control each phase modulator 1818 to apply a phase shift that maximizes the total power of the auxiliary detector 1888.

[0431] It is understood that performing phase modulation in the extended manner described above, in which the phase of each subbeam is optimized relative to the phases of the other subbeam members of its group 1870, and the phases of group 1870 are optimized relative to each other to change the phase of the combined laser output 1822, is far faster and less complex than optimizing the phase of each individual subbeam relative to the phases of all other subbeams in OP1800. Furthermore, this allows the phase optimization to be performed by individual sets of control electronics within each control electronics submodule 1874 coupled to each detector 1850, rather than requiring a single set of control electronics, thereby improving the signal-to-noise ratio.

[0432] It will be understood that the function of optimizing the relative phase of each group 1870 with respect to other groups of group 1870 may be performed alternatively by an additional group phase modulator operating to modulate the collective phase of each group 1870, rather than by individual phase modulators 1818 operating to modulate the individual phase of each sub-beam member of each group 1870. An exemplary implementation of such an arrangement is shown in Figure 19 and in some embodiments thereof may be substantially similar to the phase modulation configuration described in U.S. Patent No. 9,893,494.

[0433] As shown in Figure 19, system 1800 may be modified by adding a series of group phase modulators corresponding to the number of groups 1870. Here, as an example, as shown in Figure 19, system 1800 may have 16 subbeams, four of which are included in each of the four groups 1870, resulting in a total of four additional group phase modulators 1918 being included in system 1800. Each group phase modulator 1918 is preferably common to four channels 1816 that form part of each group 1870, and provides a phase shift that optimizes the collective group phase of the subbeams along the four channels 1816.

[0434] Preferably, the group phase modulators among the group phase modulators 1918 are controlled by an additional control submodule 1990, preferably included in the control module 1832. The auxiliary detector 1888 is preferably coupled to the additional control submodule 1990. While optimizing the relative phases of the group 1870 by comparing them with each other using the group phase modulator 1918 rather than by the individual subbeam phase modulators 1818 is more efficient and can simplify the phase modulation process, it is understood that this requires the use of additional phase modulators and circuit elements, and therefore increases the cost and complexity of the system 1800.

[0435] A change in the phase of the coupled laser output 1822 preferably provides spatial modulation of the output 1822. Due to the extended nature of the phase modulation performed by the phase modulation subsystem 1830, it is understood that the phase of the coupled laser output 1822 can be changed very rapidly at a rate faster than that achievable by the mechanical spatial modulation mechanism. The spatial modulation provided by the OPA laser 1800 may optionally be augmented by an additional mechanical spatial modulation mechanism, as is known in the art, or it may not include mechanical spatial modulation.

[0436] It is understood that the specific structures and configurations of the optical elements shown herein, including the beam splitter 1860, the focal lens 1820, the mirror array 1868, and the corresponding focal lens 1869, are merely illustrative and are shown in a highly simplified form. It is understood that the OPA laser system 1800 may include various such elements, as well as additional optical elements, including, simply as examples, additional or alternative lenses, optical fibers, and coherent free-space far-field couplers.

[0437] Furthermore, it is understood that the mirror 1868 and the corresponding focal lens 1869 may have similar or identical optical properties so as to group individual subbeams into similar or identical groups containing an equal number of subbeams. Alternatively, the mirror 1868 and the corresponding focal lens 1869 may have different optical properties so as to group individual subbeams into different groups containing different numbers of subbeams.

[0438] An exemplary implementation of an OPA laser system of the type shown in Figure 18 or Figure 19 is shown in Figures 20A and 20B. Referring to Figures 20A and 20B, an OPA laser system 2000 is provided in which an output laser beam from a seed laser (not shown), such as seed laser 1812, is split into multiple subbeams along a plurality of corresponding channels 2016. Here, simply as an example, the laser output may be split into a 10 × 10 matrix of 100 subbeams along the corresponding 100 channels 2016, and for clarity of presentation, only selected subbeams among the subbeams are shown in Figure 20B. The subbeams along the channels 2016 can then be collimated and focused by collimating and focusing elements (not shown), such as collimating and focusing lenses 1819, 1820, to produce a combined output beam.

[0439] To facilitate the application of phase shifts to the output beam, a portion of the output of the OPA laser 2000 is preferably extracted and directed toward a plurality of detectors 2050. The extracted portion of the output beam preferably serves as a reference beam based on characteristics that allow the required phase shift to be calculated. In the embodiments shown in Figures 20A and 20B, a plurality of subbeams along the channel 2016 are directed toward a beam divider 2060. The beam divider 2060 preferably divides each subbeam into a transmission portion 2062 and a reflection portion 2064 according to a predetermined ratio.

[0440] The transmissive portion 2062 of the sub-beam is preferably coupled to form an output beam. The reflective portion 2064 of the sub-beam is preferably reflected toward an array of mirrors 2068, each mirror 2068 positioned spaced apart from the corresponding focusing lens 2069. The array of mirrors 2068 and lens 2069 are understood to be particularly preferred embodiments of the array of mirrors 1868 and focusing lens 1869.

[0441] Mirror 2068 is preferably angled to reflect the subbeam incident thereon toward the corresponding focusing lens 2069, thereby grouping the reflected portion 2064 of the subbeam into a number of groups, which here are embodied as four groups in an example, each group 2070 containing 25 subbeams. Preferably, each set of subbeams reflected by each of the mirrors 2068 is focused by the corresponding focusing lens 2069 to form a single beam containing a group of 25 subbeams 2070. Each group of subbeams 2070 is incident on the surface of the corresponding detector among a plurality of detectors 2050. Each detector 2050 preferably samples the far-field intensity pattern incident thereon. Each detector 2050 cooperates with a corresponding control electronics submodule (not shown), such as control electronics submodule 1874 contained in control module 1832, and then preferably optimizes the phase of the subbeams contained in the group of subbeams 2070 sampled thereby so that the combined phase produces a desired group far-field intensity pattern. Such sampling and optimization are preferably performed in parallel, and preferably simultaneously, for the far-field intensity patterns among the far-field intensity patterns across all detectors 2050.

[0442] To optimize the relative phase of each group 2070 with respect to other groups, a portion of the reflective portion 2064 is preferably directed to an auxiliary lens 2082 by an auxiliary beam splitter 2080. The auxiliary lens 2082 preferably focuses a portion of the reflective portion 2064 into a single beam 2084 incident on an auxiliary detector 2088. The auxiliary detector 2088 preferably receives a single beam having far-field intensity patterns corresponding to all combinations of subbeam patterns. The auxiliary detector 2088 preferably works in cooperation with phase control electronics included in an electronic control module 1832 to sample and optimize the phases of group 2070 relative to each other.

[0443] It is understood that the optimization of the phases of group 2070 relative to each other may be by phase modulation of the phases of individual subbeams by phase modulator 1818, as described above with reference to Figure 18, or by phase modulation of the group phase of subbeams by group phase modulator 1918, as described above with reference to Figure 19.

[0444] In the above-described embodiments of the OPA lasers 1500, 1700, 1800, and 2000 in Figures 15 to 20B, it is understood that phase modulation is performed in an extended manner, preferably using multiple detectors such as detectors 1550, 1750, 1850, and 2050 used to simultaneously perform phase measurements of subbeams in multiple groups, and a single auxiliary detector such as detectors 1586, 1786, 1886, and 2086 used to perform phase measurements of a single beam including multiple groups.

[0445] However, it is understood that a system constructed and operating according to a preferred embodiment of the present invention may be further expandable to include additional layers of detectors and corresponding optical elements, depending on the number of sub-beams involved.

[0446] As an example, as shown in Figure 21, the OPA laser system 1500 may be further modified to include an additional focusing lens 2102 for focusing group 1570 of the subbeams onto intermediate group 2104, which is incident on intermediate detector 2106. The intermediate group 2104 is then further combined and incident on a single detector 2108, where the single detector 2108 intermediate group 2104 is preferably phase-corrected relative to one another.

[0447] It is additionally understood that any of the OPA laser systems described herein with reference to Figures 15 to 21 may be modified to improve output beam sampling by replacing one or more of the individual detectors in the OPA laser system with a plurality of detectors and a corresponding plurality of closely spaced optical paths, in accordance with embodiments of the present invention described herein with reference to Figures 6 to 8. Furthermore, any of the OPA laser systems described herein with reference to Figures 15 to 21 may be alternatively modified to further improve output beam sampling by including a transmission or reflection detector mask that masks one or more of the plurality of detectors used in the OPA laser system, in accordance with embodiments of the present invention described herein with reference to Figures 9 to 12.

[0448] It will be further understood that any of the OPA laser systems described herein with reference to Figures 15 to 21 may be modified to include a voltage-phase calibration function in accordance with preferred embodiments of the present invention described herein with reference to Figures 13 and 14, in order to ensure proper calibration of the phase modulator used therein.

[0449] Next, referring to Figures 22A and 22B, these are simplified schematic diagrams of the first and second focal states, respectively, of an optically phased array laser system constructed and operating according to a preferred embodiment of the present invention.

[0450] As shown in Figures 22A and 22B, preferably, a laser system 2200 is provided which includes an optically phased array (OPA) laser 2202. The OPA laser system 2200 may have the type outlined in U.S. Patent No. 9,584,224 or U.S. Patent Application No. 15 / 406,032, which is assigned to the same assignee as the present invention and whose contents are incorporated herein by reference. Alternatively, the OPA laser system 2200 may be a laser system of the type described by reference to any one or a combination thereof of Figures 1A to 21 above.

[0451] As best seen in enlarged figure 2210, the OPA laser 2202 preferably includes a seed laser 2212 and a laser beam splitting and coupling subsystem 2214 that receives the laser output from the seed laser 2212 and provides a coupled laser output. The laser beam splitting and coupling subsystem 2214 preferably includes a plurality of phase modulators 2218 for changing the phase of the coupled laser output following the splitting of the laser output from the seed laser 2212 and before coupling performed by the splitting and coupling subsystem 2214.

[0452] Each phase-modulated subbeam generated by splitting the output of the seed laser 2212 and subsequent phase modulation preferably propagates toward the collimating lens 2219. The individually collimated and phase-modulated subbeams are then combined, for example, in the focusing lens 2220 to form the output beam 2222.

[0453] The splitting and combining subsystem 2214 may also preferably provide laser amplification of the subbeams after splitting the output beam of the seed laser 2212 into subbeams and before combining the subbeams to form the output beam 2222. Here, as an example, the splitting and combining subsystem 2214 is shown to include multiple optical amplifiers 2224 for amplifying each subbeam. However, it is understood that such amplification is optional and may be omitted depending on the power output usage of the OPA laser 2200.

[0454] The phase of the output beam 2222, and therefore the position and shape of its far-field intensity pattern, is controlled at least partially by the relative phases of the constituent subbeams coupled to form the output beam 2222. As described above herein with reference to Figures 1A to 5G, in many applications such as laser cutting, laser welding, laser additive manufacturing, and optical free-space communication, it is desirable to dynamically move and shape the far-field intensity pattern of the output beam 2222. This can be achieved in the laser system 2200 by having the laser splitting and coupling subsystem 2214 dynamically change the relative phases of the individual subbeams, thereby changing the phase of the coupled laser output 2222 and dynamically controlling the position and shape of its far-field intensity pattern.

[0455] The relative phase of the subbeam is preferably predetermined according to a desired laser power pattern. Particularly preferably, the relative phase to be changed is applied by a phase control subsystem 2230. The phase control subsystem 2230 preferably forms part of a control electronics module 2232 in the OPA laser system 2200 and controls each phase modulator 2218 to dynamically modulate the relative phase of the subbeam, preferably as described above with reference to the phase control subsystems 130, 230, 330, and 430 of Figures 1A, 2A, 3A, and preferably 4A.

[0456] Due to noise inherent in the OPA system 2200, the output beam 2222 may be noisy. The noise in the output beam 2222 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process if the optical amplifier 2224 is located within the OPA system 2200. If the output beam 2222 is noisy, the OPA system 2200 may include a noise cancellation subsystem 2240 that operates to provide a noise-canceling phase-compensated output to cancel the noise in the output beam 2222 in the manner detailed below.

[0457] Particularly preferably, the noise cancellation subsystem 2240 uses, though not necessarily required, an algorithm of the type described herein above with reference to Figures 1A to 4C for detecting and correcting phase noise in the coupled laser output. The noise-canceled phase-corrected output is preferably provided to the phase modulator 2218 by the noise cancellation subsystem 2240 to correct the phase noise in the output beam 2222 and thus avoid distortion of the shape and position of the far-field intensity pattern of the output beam 2222 that would otherwise be caused by the noise. The noise cancellation subsystem 2240 may be included in the control electronics module 2232.

[0458] Alternatively, if the noise in the output beam 2222 is not severe, the noise cancellation subsystem 2240 may be removed from the OPA system 2200, and no noise correction will be performed on it.

[0459] To facilitate the application of phase shifting and noise correction when relating to the output beam 2222, a portion of the output of the OPA laser 2202 is preferably extracted and directed toward at least one detector 2250. Here, as an example, the at least one detector 2250 is shown as being embodied as a single detector 2250. However, it is understood that the at least one detector 2250 may be embodied as a plurality of detectors receiving a portion of the output of the OPA laser 2202 via tightly spaced optical paths, as described above with reference to Figures 6-8, or as at least one detector receiving a portion of the output of the OPA laser 2202 via a transmission or reflection optical mask, as described above with reference to Figures 9-12. The extracted portion of the output beam preferably serves as a reference beam based on characteristics from which the necessary noise correction and / or phase shifting can be calculated.

[0460] According to a preferred embodiment of the present invention, a plurality of subbeams along the channel 2216 are directed toward a beam divider 2260. The beam divider 2260 preferably divides each subbeam into a transmittance portion 2262 and a reflectance portion 2264 according to a predetermined ratio. For example, the beam divider 2260 can divide each subbeam with a transmittance of 99.9% and a reflectance of 0.01%.

[0461] The transmitted portion 2262 of the sub-beam preferably propagates toward the focusing lens 2220, where the sub-beam is combined to form an output beam 2222 having a far-field intensity pattern 2266. The reflected portion 2264 of the sub-beam preferably reflects toward an additional focusing lens 2268, where the sub-beam is combined to form an output reference beam 2270 having a far-field intensity pattern 2272 that is incident on one or more of the surfaces of the plurality of detectors 2250.

[0462] In certain applications, the output beam 2222 is preferably directed toward the substrate 2280, where the far-field intensity pattern 2266 of the substrate 2280 is preferably incident. The substrate 2280 may be a workpiece being processed by the OPA laser 2202. For example, the OPA laser 2202 may operate to additionally fabricate, cut, weld, sinter, or otherwise process the workpiece 2280. The phase control subsystem 2230 preferably modifies the phase of the output beam 2222 to focus the output beam 2222 onto the substrate 2280. It is understood that without such a phase modification by the phase control subsystem 2230, the output beam 2222 will not be focused onto the substrate 2280.

[0463] A particular feature of a preferred embodiment of the present invention is that the focusing lens 2220 is designed so that the output beam 2222 of the OPA laser 2202, when no phase shifting is applied, is not focused by the lens 2220 onto the surface of the substrate 2280. For example, as can be seen from the consideration of Figure 22A, which shows the configuration of the output beam 2222 when no phase shifting is applied, the focusing lens 2220 may be optically designed to focus the non-phase shifted collimated wavefront 2282, including the output beam 2222, onto a focal point 2284 on the surface of the substrate 2280.

[0464] As can be understood from the consideration in Figure 22B, which shows the configuration of the output beam 2222 when a phase change is applied to the output beam 2222, the phase change of the output beam 2222 preferably helps to correct the shape, and thus the focus, of the wavefront 2282, as seen in the case of a typical phase-correcting wavefront 2286, which is preferably focused onto the substrate 2280 via a focusing lens 2220. Therefore, it is understood that the focusing of the output beam 2222 on the substrate 2280 is achieved not only by the focusing lens 2220 but also by its phase change in combination with the focusing lens 2220, as shown in Figure 22B.

[0465] As a result of the focusing of the output beam 2222 on the substrate 2280 being achieved by its phase change, the backscatter originating from the substrate 2280 is not focused onto the OPA laser 2202 by the focusing lens 2220. As is well known in the art, backscatter from a surface treated by a laser beam typically returns to the laser and can damage the laser, particularly in laser amplification systems. In this invention, the focusing lens 2220 does not focus the backscatter toward the OPA laser 2202, and therefore such damage is avoided because the backscatter does not reach and damage the OPA laser 2202.

[0466] An exemplary return path of backscatter from the substrate 2280 toward the OPA laser 2202 is shown in Figure 23. As seen in Figure 23, the backscattered laser beam 2300 emanating from the substrate 2280 preferably reaches the focusing lens 2220. However, the backscattered laser beam 2300 is preferably not focused toward the OPA laser 2202 by the focusing lens 2220, thereby preventing damage to them. If the focusing lens 2220 is designed to focus the non-phase-corrected laser output from the OPA laser 2202 onto the substrate 2280, as is typical in conventional laser systems, then it is understood that the path of the backscattered beam 2300 will accordingly be focused toward the OPA laser 2202 by the focusing lens 2220, and thus could cause damage to the focusing lens 2220.

[0467] In certain embodiments of the present invention, it is understood that focusing the output of the OPA laser 2202 on the substrate 2280 can be achieved solely by appropriate phase shifting of the output beam 2222, eliminating the need for a focusing lens 2220.

[0468] As described herein with reference to Figures 1A to 23, the output from a seed laser may be directed to an amplification system for amplification. As is well known to those skilled in the art, defects in the laser output from the seed laser supplying the amplification system can result in damage to the amplification system. Typical defects in the laser output from the seed laser that cause damage to an amplification system connected to the seed laser include a decrease in the power of the seed laser output and a degradation of the laser linewidth. The resulting damage to the amplification system can occur very rapidly, on the order of nanoseconds, before the response time of any internal sensing mechanisms that may be included in the amplification system.

[0469] A preferred embodiment of the present invention for preventing damage to the amplification system in the event of a failure in the connected seed laser is described below with reference to Figures 24 to 33. The seed laser failure protection system described below can be incorporated into any of the types of OPA lasers described herein with reference to Figures 1A to 23, and it will be understood that it can be incorporated into any other laser system including a seed laser and an amplifier connected thereto.

[0470] Next, referring to Figure 24, as seen in Figure 24, preferably a laser system 2400 is provided which includes a seed laser 2402 that provides a laser output and an amplification subsystem, where, for example, the amplification subsystem is embodied as a power amplifier 2404, which receives the laser output from the seed laser 2402 and amplifies the laser output to provide an amplified laser output 2406. The laser system 2400 may, for example, be embodied as a master oscillator power amplifier (MOPA) laser, or it may be any other laser system which includes a seed laser and a power amplifier. The laser output from the seed laser 2402 preferably reaches the power amplifier 2404 via a first optical path 2408, where, for example, the first optical path 2408 is embodied as including a coiled optical fiber 2410.

[0471] To detect potential defects in the laser output of the seed laser 2402, the system 2400 preferably further includes a detector subsystem that receives the output from the seed sensor 2402, which is preferably embodied as a seed sensor 2420. The laser output from the seed laser 2402 preferably reaches the detector subsystem 2420 via a second optical path 2422. The detector subsystem 2420 may include one or more sensors for sensing characteristics in the laser output, more specifically for detecting potential faults in the laser output. The sensor subsystem 2420 is preferably operably coupled to a power amplifier 2404. The sensor subsystem 2420 is preferably configured to deactivate the power amplifier 2404 when it detects a fault in the laser output from the seed laser 2402.

[0472] A particular feature of a preferred embodiment of the present invention is that the first time of flight (TOF=T1) of the laser output along the first optical path 2408 from the seed laser 2402 to the power amplifier 2404 is greater than the combination of the second time of flight (TOF=T2) of the laser output along the second optical path 2422 from the seed laser 2402 to the sensor subsystem 2420 and the time required for the sensor subsystem 2420 to deactivate the power amplifier 2404.

[0473] As a result of the relatively long time of flight of the laser output from the seed laser 2402 to the power amplifier 2404, the sensor subsystem 2420 detects a fault in the received laser output and deactivates the power amplifier 2404 so that the power amplifier 2404 receives the faulty laser output and thereby prevents damage to the power amplifier 2404.

[0474] The extension of the time of flight of the laser output from the seed laser 2402 to the power amplifier 2404 is achieved by including a fiber coil 2410 along the first optical path, in an embodiment of the present invention shown in Figure 24, to allow time for the sensor 2420 to detect a fault in the laser output and, if necessary, deactivate the power amplifier 2404 before it receives the faulty laser output. For example, the fiber coil 2410 may have a physical length of 10 km, and the time of flight of the laser output along it may be about 50 microseconds. Thus, if a fault occurs in the output from the seed laser 2402, the power amplifier 2404 will continue to receive a fault-free input signal for 50 microseconds after the onset of the faulty output signal from the seed laser 2402.

[0475] The optical path between the seed laser 2402 and the sensor subsystem 2420 may be a direct, and therefore much shorter, optical path that does not include the coil 2410. Thus, the time of flight of the laser output from the seed laser 2402 to the sensor subsystem 2420 is preferably much shorter than 50 microseconds, for example, to the extent of 30 microseconds or less. Therefore, after a fault occurs in the output from the seed laser 2402, the sensor subsystem 2420 can quickly receive the laser output, detect the fault therein, and switch off the power amplifier 2404, thus before the time delay between the seed laser 2402 and the power amplifier 2404 expires. As a result, the power amplifier 2404 is preferably switched off by the sensor subsystem 2420 before it receives the fault signal detected by the sensor subsystem 2420, thereby preventing damage to the power amplifier 2404.

[0476] It is understood that extending the optical path between the seed laser 2402 and the power amplifier 2404, and thus increasing the time of flight along it, is not limited to being achieved by including a fiber coil along the optical path between the seed laser 2402 and the power amplifier 2404, compared to the time and length of the optical path between the seed laser 2402 and the sensor subsystem 2420. Rather, the optical path between the seed laser 2402 and the power amplifier 2404 may be extended by any preferred means, including, for example, including the inclusion of an optical delay line 2500 along it, as shown in Figure 25. Furthermore, as shown in Figure 26, the optical path between the seed laser 2402 and the power amplifier 2404 may also be a free-space optical path 2600, in which case the time of flight along it may be extended by the use of optical elements such as reflective mirrors. However, it is understood that including a coiled fiber 2410 in the first optical path 2408 may be particularly advantageous due to its compact configuration and the maintenance of the optical mode of the seed laser output by the coiled fiber 2410.

[0477] It should be understood that the specific configuration of the coiled fiber 2410 shown in Figure 24 is merely representative and illustrative. The coiled fiber 2410 may be embodied in any preferred form and can be adapted so that the laser output moves unidirectionally or back and forth along the optical path in order to further increase the effective length of the optical path provided by the coiled fiber 2410.

[0478] Referring now to Figure 27, which is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet another preferred embodiment of the present invention.

[0479] As shown in Figure 27, a laser system 2700 is provided which preferably includes a seed laser 2702 that provides a laser output. The seed laser 2702 is preferably connected to a first amplifier 2703, which is preferably connected to a second amplifier 2704, which is preferably embodied here, for example, as a power amplifier 2704, to provide an amplified laser output 2706. The laser system 2700 may be embodied, for example, as a master oscillator power amplifier (MOPA) laser, or it may be any other laser system including a seed laser and a power amplifier.

[0480] As is well known to those skilled in the art, and as described in detail herein, defects in the laser output from the seed laser 2702 can result in damage to the power amplifier 2704. Typical defects in the laser output from the seed laser 2702 that cause damage to the power amplifier 2704 may include a cessation or reduction in the power of the seed laser output and a degradation of the laser linewidth. Such damage to the power amplifier can occur very rapidly, on the order of nanoseconds, before the response time of any internal sensing mechanisms that may be contained in the power amplifier 2704.

[0481] A particular feature of a preferred embodiment of the present invention is the inclusion of an additional amplifier 2703 in the laser system 2700 to avoid damage to the power amplifier 2704 as a result of a defect in the output of the seed laser 2702. Preferably, the additional amplifier 2703 is included in the system 2700 for the purpose of preventing damage to the power amplifier 2704 when the laser output from the seed laser 2702 degrades, rather than for the purpose of amplifying the laser output from the seed laser 2702 itself.

[0482] In the operation of system 2700, the laser output from seed laser 2702 is preferably received by a first amplifier 2703. The first amplifier 2703 preferably provides a first amplified laser output, which is preferably received and amplified by a second amplifier 2704.

[0483] When the laser output of the seed laser 2702 stops, the first amplifier 2703 ceases to receive laser output from the seed laser 2702 due to a malfunction of the seed laser 2702. In this case, the first amplifier 2703 generates amplified spontaneous emission, which is received by the second amplifier 2704. Alternatively, the first amplifier 2703 may be configured to start operating as a laser and generate additional laser output when the laser output from the seed laser 2702 stops.

[0484] Therefore, it is understood that even if the seed laser 2702 ceases to provide laser output, the second amplifier 2704 will continue to receive input signals in the form of amplified spontaneous emission or additional laser output from the first amplifier 2703. The amplified spontaneous emission provided to the second amplifier 2704 by the first amplifier 2703 is sufficient to prevent damage to the second amplifier 2704, which would otherwise occur as a result of the cessation of signal provision to the second amplifier 2704. It is understood that the system 2700 may additionally include a sensor connected to the seed laser 2702 to detect a failure in laser output from the seed laser 2702 and deactivate the second amplifier 2704 accordingly.

[0485] During proper operation of the seed laser 2702, the first amplification provided by the first amplifier 2703 is preferably negligible compared to the second first-order amplification provided by the second amplifier 2704.

[0486] As shown in Figure 27, the laser output from the seed laser 2702 may be supplied directly to the first amplifier 2703. Alternatively, as shown in Figure 28, additional elements can be inserted to interface the seed laser 2702 and the first amplifier 2703. In particular, a filter can be inserted between the seed laser 2702 and the first amplifier 2703 to filter out laser beams with unacceptably narrow linewidths, preventing such laser beams from reaching and damaging the second amplifier 2704.

[0487] A particularly preferred embodiment of the linewidth filter 2800 suitable for use in the present invention is shown in Figure 28.

[0488] Referring next to Figure 28, the filter structure 2800 appears to be implemented downstream of the seed laser 2702 and upstream of the first amplifier 2703. The laser output from the seed laser 2702 is preferably split into two parts by a divider 2805 at the inlet to the filter 2800 and recombined by a recombiner 2806 before exiting the filter 2800. The first part of the split laser output from the seed laser 2702 preferably travels along the first arm 2807 of the filter 2800 between the divider 2805 and the recombiner 2806. The second part of the split laser output from the seed laser 2702 preferably travels along the second arm 2808 of the filter 2800 between the divider 2805 and the recombiner 2806. As can be seen from a comparison of the first and second arms 2807 and 2808, the first arm 2807 preferably includes an additional portion 2809 compared to the second arm 2808, and is therefore longer than the second arm 2808.

[0489] If the laser output from the seed laser 2702 has an unacceptably narrow linewidth, the laser outputs from the first and second arms 2807 and 2808 interfere with each other due to their relatively high coherence when recombined in the recombiner 2806. The recombined beam is preferably detected by a detector 2810, which is preferably connected to an electronic control module 2811. The electronic control module 2811 is preferably a coherent beam coupling (CBC) card in controlling the operation of a phase modulator 2812 positioned along the second arm 2808. The phase modulator 2812 is preferably operated by the electronic control card 2811 to change the phase of the beam along the second arm 2808 so that substantially all of the beam recombined in the recombiner 2806 is directed toward the detector 2810. Therefore, the recombined beam does not travel toward the first amplifier 2703 and thus does not reach the second amplifier 2704 and cause damage to it. The reception of laser output from the seed laser 2702 by the first amplifier 2703 is thereby stopped, and the first amplifier 2703 generates either amplified spontaneous emission or additional laser output, as described in detail above herein.

[0490] If the seed laser 2702 is functioning properly and the laser output from the seed laser 2702 has an acceptable linewidth, the laser outputs from the first and second arms 2807 and 2808 will not interfere with each other when recombined in the recombiner 2806. This is because the coherence is relatively low and therefore the linewidth is wide enough that little or no mutual interference occurs. In this case, a portion of the laser output in the recombiner 2806 is directed toward the first amplifier 2703, and a portion of the laser output in the recombiner 2806 is delivered to the detector 2810. As outlined above with reference to system 2700, the laser output received by the first amplifier 2703 is preferably subsequently provided by the first amplifier 2703 to the second amplifier 2704.

[0491] It is understood that the damage protection system shown in Figures 27 and 28, including the additional amplifier 2703 and filter structure 2800, may be used alone or in combination with any one of the protection systems shown in Figures 24 to 26.

[0492] Next, referring to Figure 29, which is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to a more preferred embodiment of the present invention.

[0493] As shown in Figure 29, preferably, a laser system 2900 is provided which includes a seed laser 2902 that provides a first laser output 2903 and an amplification subsystem, where, for example, the amplification subsystem is embodied as a power amplifier 2904, which receives the first laser output 2903 from the seed laser 2902 and amplifies the laser output to provide an amplified laser output 2906. The laser system 2900 may be embodied, for example, as a master oscillator power amplifier (MOPA) laser, or as any other laser system including a seed laser and a power amplifier.

[0494] To detect potential defects in the laser output of the seed laser 2902, the system 2900 preferably further includes a detector subsystem that receives the output from the seed laser 2902, which is preferably embodied as a seed sensor 2920. The sensor subsystem 2920 may include one or more sensors for sensing characteristics in the laser output, more specifically for detecting potential faults in the laser output. The sensor subsystem 2920 is preferably operably coupled to a power amplifier 2904. The sensor subsystem 2920 is preferably configured to deactivate the power amplifier 2904 when it detects a fault in the laser output from the seed laser 2902.

[0495] A particular feature of preferred embodiments of the present invention is that the laser system 2900 preferably includes an auxiliary laser subsystem, which is preferably embodied as an auxiliary seed laser 2930. The auxiliary seed laser 2930 preferably provides a second laser output 2932 to the amplifier 2904, the second laser output 2932 preferably having significantly lower power than the first laser output 2903. Simply as an example, the first laser output 2903 may have a first output in the range of 80 to 100 milliwatts, while the second laser output 2932 may have a second output in the range of 50 to 70 milliwatts.

[0496] The auxiliary seed laser 2930 preferably provides a second laser output 2932 to the amplifier 2904 at least when the seed laser 2902 is stopped, thereby providing the first laser output 2903. Particularly preferably, the auxiliary seed laser 2930 operates continuously to provide the second laser output 2932 to the amplifier 2904 at the same time that the seed laser 2902 provides the first laser output 2903 to the amplifier 2904, and at the same time that the seed laser 2902 stops providing the first laser output 2903.

[0497] During proper operation of the seed laser 2902, the amplifier 2904 preferably receives both a first laser output 2903 from the seed laser 2902 and a second laser output 2932 from the auxiliary seed laser 2930. Because the power of the second laser output 2932 is significantly lower than that of the first laser output 2903, the contribution of the second laser output 2903 to the amplified laser output 2906 is preferably negligible. Preferably, although not strictly necessary, the second laser output 2932 has a different wavelength from the first laser output 2903 to further reduce its influence on the amplified laser output 2906. Simply as an example, the first laser output 2903 may have a first wavelength in the range of 1060–1070 nm, while the second laser output 2932 may have a second wavelength in the range of 1070–1080 nm.

[0498] When the laser output from the seed laser 2902 stops, the sensor subsystem 2920, due to a malfunction of the seed laser 2902 detected by the sensor subsystem 2920, preferably operates to deactivate the amplifier 2904. Due to the finite response time of the amplifier 2904 and the detector subsystem 2920, the amplifier 2904 is not deactivated instantaneously but continues to operate for a limited time after the laser output from the seed laser 2902 stops. During this time, it is understood that the amplifier 2904 no longer receives the first laser output 2903 from the seed laser 2902. However, the auxiliary seed laser 2930 preferably continues to provide the amplifier 2904 with a second laser output 2932. Therefore, even when the seed laser 2902 stops providing laser output, it is understood that the amplifier 2904 continues to receive input signals in the form of the second laser output 2932. The second laser output 2932 provided to the amplifier 2904 by the auxiliary seed laser 2930 is sufficient to prevent damage to the amplifier 2904, which would otherwise likely be damaged due to the interruption of signal supply, before the amplifier 2904 is deactivated by the sensor 2920.

[0499] Next, referring to Figure 30, which is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operating according to yet a more preferred embodiment of the present invention.

[0500] As shown in Figure 30, preferably, a laser system 3000 is provided which includes a seed laser 3002 that provides a first laser output 3003 and an amplification subsystem, the amplification subsystem which is hereby embodied as a power amplifier 3004, for example, which receives the first laser output 3003 from the seed laser 3002 and amplifies the laser output to provide an amplified laser output 3006. The laser system 3000 may be embodied as a master oscillator power amplifier (MOPA) laser, for example, or as any other laser system which includes a seed laser and a power amplifier.

[0501] To detect potential defects in the laser output of the seed laser 3002, the system 3000 preferably further includes a detector subsystem 3020 that receives the output from the seed laser 3002. The detector subsystem 3020 may include one or more sensors for sensing characteristics in the laser output, more specifically for detecting potential faults in the laser output. The sensor subsystem 3020 is preferably operably coupled to a power amplifier 3004. The sensor subsystem 3020 is preferably configured to deactivate the power amplifier 3004 when it detects a fault in the laser output from the seed laser 3002.

[0502] A particular feature of a preferred embodiment of the present invention is that the laser system 3000 preferably includes a pair of gratings 3030. The pair of gratings 3030 preferably includes a first reflection grating 3032 positioned at the inlet 3034 of the amplifier 3004, and preferably a second reflection grating 3036 positioned at the outlet 3038 of the amplifier 3004. The pair of gratings 3030 combined with the amplifier 3004 preferably form a preferred embodiment of the auxiliary laser subsystem 3040.

[0503] During proper operation of the seed laser 3002, the amplifier 3004 preferably receives a first laser output 3003 from the seed laser 3002 and amplifies the first laser output 3003 to provide an amplified laser output 3006.

[0504] When the laser output from the seed laser 3002 stops, the sensor subsystem 3020, due to a malfunction of the seed laser 3002 detected by the sensor subsystem 3020, preferably operates to deactivate the amplifier 3004. Due to the finite response time of the amplifier 3004 and the sensor subsystem 3020, the amplifier 3004 is not deactivated instantaneously, but rather, typically, continues to operate for a limited period after the laser output from the seed laser 3002 stops. During this time, it is understood that the amplifier 3004 no longer receives laser output from the seed laser 3002. In this case, the reflection grating 3030 preferably provides signal feedback to the amplifier 3004, and as a result, the amplifier 3004, in combination with the pair of gratings 3030, preferably begins to operate as a laser. The reflection grating 3030 preferably has a relatively low reflectivity such that the signal feedback provided by the reflection grating 3030 has a lower power than the power of the laser output 3003 of the seed laser 3002.

[0505] Particularly preferable, though not strictly necessary, the pair of gratings 3030 are reflective at wavelengths different from the wavelength of the first laser output 3003 of the seed laser 3002, so that during proper operation of the seed laser 3002, the gratings 3030 have only a negligible effect on the amplified output 3006. For example, the first laser output 3003 may have wavelengths in the range of 1060–1070 nm, while the gratings 3030 may be reflective at wavelengths in the range of 1090–1100 nm.

[0506] Therefore, it is understood that even if the seed laser 3002 stops providing laser output, the amplifier 3004 will continue to receive input signals in the form of signal feedback from the grating 3030. As a result, the amplifier 3004, in combination with the grating 3030, will start operating as a laser when the seed laser 3002 stops operating, thereby preventing damage to the amplifier 3004, which would otherwise occur due to the cessation of signal supply to the amplifier.

[0507] As seen in Figures 29 and 30, the laser output from seed lasers 2902 and 3002 may be supplied directly to amplifiers 2904 and 3004, respectively. Alternatively, additional elements can be inserted to interface the seed lasers with the amplifiers, as shown in Figures 31 and 32. In particular, linewidth filters, such as filter 2800 or any other suitable filter, may be inserted between the seed lasers 2902 and 3002 and amplifiers 2904 and 3004, respectively, to filter out laser beams with unacceptably narrow linewidths and prevent such laser beams from reaching the amplifiers 2904 and 3004 and thus damaging them.

[0508] As detailed above in this specification, each laser system described with reference to Figures 24–32 may include detector subsystems such as detector subsystems 2420, 2920, and 3020. The detector subsystems are preferably embodied as at least one sensor for detecting the output from a seed laser. Particularly preferred embodiments of sensors forming part of detector subsystems such as detector subsystems 2420, 2920, and 3020 are shown in Figure 33. However, it should be understood that the sensors shown in Figure 33 are not limited to use in the types of systems described herein and may be incorporated as laser output sensors in any laser system that would benefit from their use.

[0509] As shown in Figure 33, a detector subsystem 3320 is provided. The laser output from the seed laser preferably enters the sensor subsystem 3320 at input point 3330 and proceeds toward a divider 3334. In the divider 3334, a small portion, such as 1%, of the laser output is directed toward a detector 3336, and the remainder of the laser output proceeds toward a sensor amplifier 3340. The sensor amplifier 3340 is preferably a lower power amplifier than power amplifiers 2404, 2704, 2904, or 3004. The sensor amplifier 3340 preferably outputs an amplified laser output, which is preferably delivered to an additional detector 3342 via an elongated optical fiber 3344.

[0510] During the operation of the detector subsystem 3320, if the output from the seed laser stops, the intensity of the amplified laser output detected by the additional detector 3342 decreases. In this case, a control module (not shown) connected to the additional detector 3342 and a power amplifier such as power amplifiers 2404, 2704, 2904, or 3004 may deactivate the power amplifier to prevent damage to it.

[0511] If the output from the seed laser degrades to an unacceptably narrow linewidth, nonlinear effects will begin in fiber 3344. It is understood that fiber 3344 should be advantageously configured to be as sensitive as possible to such nonlinear effects. For this purpose, in order to increase the sensitivity of fiber 3344 to the linewidth of the laser output from the seed laser, fiber 3344 is preferably of considerable length and preferably has a small core diameter. Simply as an example, fiber 3344 may have a length of about 25 m and a core diameter of about 6 microns.

[0512] When the linewidth of the output from the seed laser is narrowed, due to a nonlinear effect initiated in fiber 3344, fiber 3344 begins to act as a mirror, reflecting light backward toward amplifier 3340. As the reflected light returns to amplifier 3340, the amplified signal reaches divider 3334 and is detected by detector 3336. When the amplified signal is detected by detector 3336, the power amplifier is preferably deactivated to prevent damage to the power amplifier.

[0513] Those skilled in the art will understand that the present invention is not limited to what is specifically claimed below. Rather, the scope of the present invention includes various combinations and subcombinations of the features described herein, as well as modifications and variations thereof, which will be conceivable to those skilled in the art by referring to the drawings and reading the foregoing description, and which are not found in the prior art.

Claims

1. It is a laser system, Seed laser and A laser beam splitting and coupling subsystem that receives the output from the seed laser, splits the output from the seed laser into a plurality of subbeams, and provides a coupled laser output including the plurality of subbeams, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output, A plurality of detectors that detect the coupled laser output intermittently during the phase change of the coupled laser output, A plurality of optical paths between the coupled laser output and the plurality of detectors, wherein the plurality of optical paths are for providing the coupled laser output to the plurality of detectors along the plurality of optical paths, and the spatial density of the entrances of the plurality of optical paths is greater than the spatial density of the plurality of detectors, A phase modulation subsystem that groups at least a portion of the plurality of subbeams into a number of subbeam groups, wherein the phase modulation subsystem is as follows: In order to change the phase of each group, the phase of each subbeam within each group is changed in parallel across the entire group of subbeams with respect to the phase of the other subbeams within that group, and A phase modulation subsystem is configured to change the phase of each group relative to other groups of the numerous sub-beam groups, thereby changing the phase of the combined laser output. A laser system equipped with [the following features].

2. The laser system according to claim 1, further comprising a noise cancellation subsystem which operates to provide a noise-canceling phase-corrected output based on the assumption that the combined laser output has noise, and the laser system detects the noise in the combined laser output by the plurality of detectors during the intermittent time during the phase change of the combined laser output.

3. The laser system according to claim 1 or 2, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output during the time interval between the intermittent periods.

4. The laser system according to claim 1 or 2, wherein the laser beam splitting and coupling subsystem changes the phase of the coupled laser output at a phase change rate exceeding a noise-accommodating rate of the coupled laser output, wherein the coupled laser output has noise, and the noise is detected by the plurality of detectors during the intermittent time.

5. The laser system according to any one of claims 1 to 4, wherein the plurality of optical paths include a plurality of optical fibers, and the ends of the optical fibers are arranged at a spatial density greater than the spatial density of the plurality of detectors.

6. The laser system according to any one of claims 1 to 5, wherein some of the multiple optical paths are spaced apart by a distance of 20 to 1000 microns.

7. The laser system according to claim 6, wherein some of the plurality of detectors are spaced apart by a distance of 5 to 50 mm.

8. A method for detecting laser output, The process of receiving output from the seed laser, The process of splitting the output into multiple sub-beams, A step of combining the aforementioned outputs to provide a combined laser output, Here, the step of combining the outputs is: A step of grouping at least a portion of the aforementioned multiple subbeams into a large number of subbeam groups, In order to change the phase of each group, a step is taken to change the phase of each subbeam within each group in parallel across the entire group of subbeams with respect to the phase of other subbeams within the group, A step of changing the phase of each group relative to other groups of the aforementioned number of sub-beams, thereby changing the phase of the combined laser output. Processes including, A step of providing the combined laser output to a plurality of detectors along a plurality of optical paths, wherein the spatial density at the entrance of the plurality of optical paths is greater than the spatial density of the plurality of detectors. Methods that include...

9. The method according to claim 8, wherein the coupled laser output has noise, and the method provides a noise-canceling phase-corrected output based on taking into account the noise in the coupled laser output detected intermittently by the plurality of detectors during the phase change of the coupled laser output.

10. The method according to claim 9, wherein the phase change is performed during the time interval between the intermittent periods.

11. The method according to claim 9 or 10, wherein the phase change of the combined laser output is performed at a phase change rate exceeding the noise-accommodating rate of the combined laser output, at which time the noise is detected by the plurality of detectors during the intermittent period.

12. The method according to any one of claims 8 to 11, wherein the plurality of optical paths include a plurality of optical fibers, and the ends of the optical fibers are arranged at a spatial density greater than the spatial density of the plurality of detectors.

13. The method according to any one of claims 8 to 12, wherein the plurality of optical paths are spaced apart by a distance of 20 to 1000 microns.

14. The method according to claim 12, wherein the plurality of detectors are spaced apart by a distance of 5 to 50 mm.

15. The phase modulation subsystem includes a number of detectors corresponding to the number of groups in order to detect the far-field intensity pattern of each of the number of groups. The laser system according to claim 1.

16. The laser system according to claim 15, wherein each of the plurality of detectors includes the plurality of detectors.

17. The laser system according to claim 16, wherein the plurality of optical paths are provided between each of the plurality of groups of far-field intensity patterns and each of the plurality of detectors, and are for providing the far-field intensity patterns to the plurality of detectors along the plurality of optical paths, and the spatial density of the plurality of optical paths is greater than the spatial density of the plurality of detectors.

18. The laser system according to claim 1, wherein the change in the phase of the coupled laser output provides spatial modulation of the coupled laser output.

19. The laser system according to claim 18, wherein the spatial modulation due to the phase change is provided in combination with mechanical spatial modulation, and the spatial modulation combined with the mechanical spatial modulation is faster than the mechanical spatial modulation in the absence of spatial modulation due to the phase change.

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