Laser system and method for focusing a laser beam in a laser system

Abstract

A laser system includes a seed laser, a laser beam splitting and combining subsystem that receives output from the seed laser and provides a combined laser output with noise, and a noise cancellation subsystem operative to provide a noise cancellation phase correction output based on the noise at intermittent times, the laser beam splitting and combining subsystem changing a phase of the combined laser output during time gaps between the intermittent times. A method for focusing a laser beam in a laser system is also disclosed.

Description

[0001] This application is a divisional application of PCT international invention patent application filed on November 6, 2018, with application number 201880078614.8 and invention title "Dynamic Beamforming of Optical Phased Array with Noise Correction".

[0002] Related applications

[0003] References are made to the following: 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. Provisional Patent Application No. 62 / 594,167, filed December 4, 2017, entitled "Laser Back-Reflection Protection Using an Optical Phased Array Laser"; and Scaled Phase Modification, Phase Calibration, and Seed Laser Protection in an Optical Phased Array, filed April 25, 2018. Israeli patent application No. 258936 entitled “Calibration and Seed Laser Protection in Optical Phased Array Laser”; 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, the disclosures of all patent applications are incorporated herein by reference, and priority of all patent applications is as follows, pursuant to 37 CFR. As required by 1.78(a)(4) and (5)(i).

[0004] Reference is also made to US Patent No. 9,893,494, the disclosure of which is incorporated herein by reference. Technical Field

[0005] The present invention generally relates to laser coherent beam combining, and more specifically, to optical phased arrays. Background Technology

[0006] Various types of optical phased arrays are known in this field. Summary of the Invention

[0007] This invention seeks to provide systems and methods related to noise correction and phase modification in dynamically shaped beams generated by laser optical phased arrays.

[0008] Therefore, according to a preferred embodiment of the present invention, a laser system is provided, comprising: a seed laser; a laser beam splitting and combining subsystem that receives the output from the seed laser and provides a synthesized laser output with noise; and a noise cancellation subsystem that operates to provide a noise cancellation phase-corrected output based on taking into account the noise at the interval, wherein the laser beam splitting and combining subsystem changes the phase of the synthesized laser output during a time gap between the intervals.

[0009] According to another preferred embodiment of the invention, a laser system is further provided, comprising a seed laser; a laser beam splitting and combining subsystem that receives the output from the seed laser and provides a synthesized laser output with noise; and a noise cancellation subsystem that operates to provide a noise cancellation phase-corrected output based on noise taken into account at a noise sampling rate, wherein the laser beam splitting and combining subsystem changes the phase of the synthesized laser output by a phase change rate exceeding the noise sampling rate.

[0010] Preferably, at least one of the noise sampling rate and the phase change rate varies over time.

[0011] Preferably, the noise sampling rate is predetermined.

[0012] According to a preferred embodiment of the present invention, the laser beam splitting and combining subsystem alters the phase of the combined laser output to provide spatial modulation of the combined laser output.

[0013] Preferably, spatial modulation of the synthesized laser output is provided by combining mechanical spatial modulation with the synthesized laser output, and the spatial modulation combined with mechanical spatial modulation is faster than mechanical spatial modulation in the absence of spatial modulation.

[0014] Alternatively, spatial modulation of the synthesized laser output can be provided by combining mechanical spatial modulation with the synthesized laser output. Spatial modulation combined with mechanical spatial modulation is more accurate than mechanical spatial modulation in the absence of spatial modulation.

[0015] Preferably, spatial modulation includes modulation of at least one of the shape and diameter of the synthesized laser output.

[0016] Preferably, the laser beam separation and synthesis subsystem provides laser beam amplification downstream of separation and upstream of synthesis.

[0017] According to another preferred embodiment of the invention, the noise cancellation phase correction output is calculated based on sequentially applying at least two phase changes to at least one constituent beam of the synthesized 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.

[0018] Preferably, the system further includes at least one detector, which is cooperatively coupled to the noise cancellation subsystem for detecting at least a portion of the synthesized laser output.

[0019] Preferably, at least one detector performs detection continuously.

[0020] According to another preferred embodiment of the present invention, the noise cancellation phase correction output eliminates intensity noise in the synthesized laser output.

[0021] Preferably, the system further includes at least one intensity modulator for changing the intensity of the synthesized laser output.

[0022] According to another preferred embodiment of the present invention, the noise cancellation phase correction output eliminates position noise in the synthesized laser output.

[0023] Preferably, the system further includes at least one position modulator for changing the position of the synthesized laser output.

[0024] Preferably, a laser cutting system includes the laser system of the present invention.

[0025] Alternatively, a laser additive manufacturing system may include the laser system of the present invention.

[0026] Alternatively or concurrently, a laser welding system may include the laser system of the present invention.

[0027] Alternatively, a free-space optical communication system may include the laser system of the present invention.

[0028] According to a preferred embodiment of the present invention, a method for performing noise correction on a phase-variant laser output is also provided, the method comprising: receiving an output from a seed laser; separating and synthesizing the output to provide a synthesized laser output with noise; applying a noise-reducing phase-corrected output to the synthesized laser output based on noise at intervals; and changing the phase of the synthesized laser output during time gaps between intervals.

[0029] According to another preferred embodiment of the present invention, a method for performing noise correction on a phase-change laser output is also provided, the method comprising: receiving an output from a seed laser; separating and synthesizing the output to provide a synthesized laser output with noise; applying a noise-cancelling phase-corrected output to the synthesized laser output based on noise taken into account at a noise sampling rate; and changing the phase of the synthesized laser output at a phase change rate exceeding the noise sampling rate.

[0030] Preferably, at least one of the noise sampling rate and the phase change rate varies over time.

[0031] Preferably, the noise sampling rate is predetermined.

[0032] According to a preferred embodiment of the invention, the phase change provides spatial modulation of the synthesized laser output.

[0033] Preferably, spatial modulation of the synthesized laser output is provided by combining mechanical spatial modulation with the synthesized laser output, and the spatial modulation combined with mechanical spatial modulation is faster than mechanical spatial modulation in the absence of spatial modulation.

[0034] Alternatively, spatial modulation of the synthesized laser output can be provided by combining mechanical spatial modulation with the synthesized laser output. Spatial modulation combined with mechanical spatial modulation is more accurate than mechanical spatial modulation in the absence of spatial modulation.

[0035] Preferably, spatial modulation includes modulation of at least one of the shape and diameter of the synthesized laser output.

[0036] Preferably, the method further includes amplifying the output downstream of separation and upstream of synthesis.

[0037] According to another preferred embodiment of the invention, the method further includes calculating a noise-cancelled phase-corrected output based on sequentially applying at least two phase changes to at least one constituent beam of the synthesized laser output and identifying one of the at least two phase changes corresponding to the maximum output intensity of at least one constituent beam.

[0038] Preferably, the method further includes detecting at least a portion of the synthesized laser output.

[0039] Preferably, the detection is performed continuously.

[0040] According to another preferred embodiment of the present invention, the noise cancellation phase correction output eliminates intensity noise in the synthesized laser output.

[0041] Preferably, the method further includes modulating the intensity of the output downstream of separation and upstream of synthesis.

[0042] According to another preferred embodiment of the present invention, the noise cancellation phase correction output eliminates position noise in the synthesized laser output.

[0043] Preferably, the method further includes setting the output at the points of separation downstream and synthesis upstream.

[0044] Preferably, the method for laser cutting includes the method of the present invention.

[0045] Alternatively or concurrently, methods for additive manufacturing include the methods of the present invention.

[0046] Alternatively or concurrently, methods for laser welding include the methods of the present invention.

[0047] Alternatively or concurrently, methods for free-space optical communication include the methods of this invention.

[0048] According to another preferred embodiment of the present invention, a laser system is also provided, comprising: a seed laser; a laser beam splitting and combining subsystem that receives an output from the seed laser and provides a synthesized laser output, the laser beam splitting and combining subsystem altering the phase of the synthesized laser output; a plurality of detectors that detect the synthesized laser output at intervals during phase alterations of the synthesized laser output; and a plurality of optical paths between the synthesized laser output and the plurality of detectors, the plurality of optical paths being used to provide the synthesized laser output to the plurality of detectors along them, the spatial density of the plurality of optical paths being greater than the spatial density of the plurality of detectors.

[0049] Preferably, the synthesized laser output has noise, and the laser system further includes a noise cancellation subsystem that operates to provide a noise-cancelled phase-corrected output based on taking into account the noise of the synthesized laser output detected by multiple detectors at intervals during phase changes in the synthesized laser output.

[0050] Preferably, the plurality of optical paths include a plurality of optical fibers, the ends of which are arranged at a spatial density greater than that of the plurality of detectors.

[0051] Preferably, some of the multiple optical paths are spaced apart by a distance of 20 to 1000 micrometers.

[0052] Preferably, some of the multiple detectors are spaced apart from each other at a distance of 5 to 50 millimeters.

[0053] According to another preferred embodiment of the present invention, a method for detecting laser output is further provided, the method comprising: receiving an output from a seed laser; separating and synthesizing the output to provide a synthesized laser output; changing the phase of the synthesized laser output and providing the synthesized laser output to a plurality of detectors along a plurality of optical paths, the spatial density of the plurality of optical paths being greater than the spatial density of the plurality of detectors.

[0054] Preferably, the synthesized laser output has noise, and the method further includes providing a noise-cancelling phase-corrected output based on taking into account the noise of the synthesized laser output detected by multiple detectors during phase changes of the synthesized laser output.

[0055] Preferably, the plurality of optical paths include a plurality of optical fibers, the ends of which are arranged at a spatial density greater than that of the plurality of detectors.

[0056] Preferably, some of the multiple optical paths are spaced apart by a distance of 20 to 1000 micrometers.

[0057] Preferably, some of the multiple detectors are spaced apart from each other at a distance of 5 to 50 millimeters.

[0058] According to another preferred embodiment of the present invention, a laser system is also provided, comprising: a seed laser; a laser beam splitting and combining subsystem that receives the output from the seed laser and provides a combined laser output, the laser beam splitting and combining subsystem altering the phase of the combined laser output; at least one detector that detects the combined laser output during the phase alteration of the combined laser output; and an optical mask comprising at least one of a transmission region and a reflection region, the transmission region and the reflection region being used to provide the combined laser output passing through and obtained therefrom to the at least one detector, respectively.

[0059] 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 synthesized laser output.

[0060] Preferably, the system further includes a focusing subsystem that interfaces an optical mask with at least one detector for focusing the synthesized laser output onto the at least one detector.

[0061] Preferably, the focusing subsystem includes at least one focusing lens.

[0062] Preferably, at least one detector comprises a single detector.

[0063] According to a preferred embodiment of the invention, the transmission region has non-uniform transparency.

[0064] Preferably, the non-uniform transparency of the transmission region compensates for the non-noise-related non-uniformity in the intensity of the synthesized laser output.

[0065] Preferably, the optical mask includes an electrical modulation device, and at least one of the transmission and reflection regions is electronically modifiable.

[0066] Preferably, the optical mask includes an LCD screen.

[0067] According to another preferred embodiment of the invention, the reflective region has a non-uniform reflectivity.

[0068] Preferably, the non-uniform reflectivity of the reflective region compensates for the non-noise-related non-uniformity in the intensity of the synthesized laser output.

[0069] Preferably, the reflective area includes a DMM.

[0070] Preferably, the synthesized laser output has noise, and the laser system further includes a noise cancellation subsystem that operates to provide a noise-cancelled phase-corrected output based on taking into account the noise of the synthesized laser output detected by at least one detector during a phase change of the synthesized laser output.

[0071] According to another preferred embodiment of the present invention, a method for detecting laser output is also provided, the method comprising: receiving an output from a seed laser; separating and synthesizing the output to provide a synthesized laser output; changing the phase of the synthesized laser output; providing the synthesized laser output to at least one detector through an optical mask, the optical mask including at least one of a transmission region and a reflection region, the transmission region and the reflection region being used to provide the synthesized laser output passing through and obtained therefrom, respectively, to the at least one detector; and detecting the synthesized laser output by the at least one detector during the phase change.

[0072] 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 synthesized laser output.

[0073] Preferably, the method further includes focusing the synthesized laser output onto at least one detector.

[0074] Preferably, the method further includes a focusing lens that interfaces the optical mask with at least one detector for performing focusing.

[0075] Preferably, at least one detector comprises a single detector.

[0076] According to a preferred embodiment of the invention, the transmission region has non-uniform transparency.

[0077] Preferably, the non-uniform transparency of the transmission region compensates for the non-noise-related non-uniformity in the intensity of the synthesized laser output.

[0078] Preferably, the optical mask includes an electrical modulation device, and at least one of the transmission and reflection regions is electronically modifiable.

[0079] Preferably, the optical mask includes an LCD screen.

[0080] According to another preferred embodiment of the invention, the reflective region has a non-uniform reflectivity.

[0081] Preferably, the non-uniform reflectivity of the reflective region compensates for the non-noise-related non-uniformity in the intensity of the synthesized laser output.

[0082] Preferably, the reflective area includes a DMM.

[0083] Preferably, the synthesized laser output has noise, and the method further includes providing a noise-cancelling phase-corrected output based on taking into account the noise of the synthesized laser output detected by at least one detector during a phase change of the synthesized laser output.

[0084] According to another preferred embodiment of the present invention, a laser system is also provided, comprising: a seed laser; a laser separation and synthesis subsystem that receives an output from the seed laser and synthesizes the output to provide a synthesized laser output; a phase modulation subsystem for changing the phase of the synthesized laser output; and a voltage-phase correlation subsystem for correlating a voltage applied to the phase modulation subsystem with the phase modulation output generated by the phase modulation subsystem and for providing a voltage-phase correlation output suitable for calibrating the phase modulation subsystem, the correlation being performed periodically during phase changes.

[0085] Preferably, the phase modulation subsystem includes multiple phase modulators.

[0086] Preferably, the voltage is applied to multiple phase modulators via a phase modulation control module.

[0087] Preferably, the voltage includes a voltage designed to produce a 2π phase shift in the synthetic laser output.

[0088] Preferably, the correlation includes: measuring the intensity change of the far-field intensity pattern of the synthesized laser output after applying a voltage, and deriving the relationship between the voltage and the phase shift corresponding to the intensity change.

[0089] Preferably, the voltage is applied sequentially to some of the multiple phase modulators.

[0090] Preferably, correlation is performed at a rate slower than the phase change.

[0091] Preferably, phase changes are performed at a rate of one million times per second, and correlations are performed at a rate of once per second.

[0092] According to another preferred embodiment of the present invention, a method for performing phase calibration of a laser system is also provided, the method comprising: receiving an output from a seed laser; separating and synthesizing the output to provide a synthesized laser output; periodically changing the phase of the synthesized laser output during a phase change by a phase modulation subsystem; applying a voltage to the phase modulation subsystem and correlating the voltage with the phase modulation output generated by the phase modulation subsystem and providing a voltage-phase correlated output suitable for calibrating the phase modulation subsystem.

[0093] Preferably, the phase modulation subsystem includes multiple phase modulators.

[0094] Preferably, the applied voltage is executed through a phase modulation control module.

[0095] Preferably, the voltage includes a voltage designed to produce a 2π phase shift in the synthetic laser output.

[0096] Preferably, the correlation includes: measuring the intensity change of the far-field intensity pattern of the synthesized laser output after applying a voltage, and deriving the relationship between the voltage and the phase shift corresponding to the intensity change.

[0097] Preferably, the method further includes sequentially applying voltages to some of a plurality of phase modulators.

[0098] Preferably, correlation is performed at a rate slower than the phase change.

[0099] Preferably, phase changes are performed at a rate of one million times per second, and correlations are performed at a rate of once per second.

[0100] According to another preferred embodiment of the present invention, a laser system is also provided, comprising: a seed laser; a laser beam splitting and combining subsystem that receives the output from the seed laser, splits the output into a plurality of sub-beams, and provides a combined laser output comprising the plurality of sub-beams; and

[0101] A phase modulation subsystem that divides at least a portion of a plurality of sub-beams into a plurality of sub-beam groups, the phase modulation subsystem spanning the plurality of sub-beam groups in parallel, thereby changing the phase of each sub-beam within each group relative to the phase of other sub-beams within each group, so as to change the phase of each group, and changing the phase of each group relative to the phase of other groups in the plurality of groups, thereby changing the phase of the synthesized laser output.

[0102] Preferably, the phase modulation subsystem includes at least one cylindrical lens for performing grouping.

[0103] Alternatively, the phase modulation subsystem includes an array of mirrors for performing grouping and a corresponding focusing lens.

[0104] Preferably, the phase modulation subsystem includes multiple phase modulators for changing the phase of the sub-beam.

[0105] Preferably, the phase modulation subsystem includes at least one electronic control module that operates and controls multiple phase modulators.

[0106] Preferably, the phase modulation subsystem includes multiple detectors corresponding to multiple groups for detecting far-field intensity patterns in each of the multiple groups.

[0107] According to a preferred embodiment of the invention, the system further includes a plurality of optical masks that mask corresponding detectors among a plurality of detectors, each optical mask including at least one of a transmission region and a reflection region, the transmission region and the reflection region being used to provide a far-field intensity pattern, respectively, through which and obtained therefrom, to the corresponding detector among the plurality of detectors.

[0108] Preferably, the multiple detectors perform detection at least partially simultaneously with each other.

[0109] Preferably, the phase modulation subsystem includes an additional auxiliary detector for detecting a far-field intensity pattern of a combination of multiple groups.

[0110] Preferably, the phase modulation subsystem includes multiple additional phase modulators, each of which is common to all sub-beams within each group for changing the phase of each group relative to the phase of other groups in the multiple groups.

[0111] Preferably, the phase modulation subsystem includes an additional electronic control module that operates and controls multiple additional phase modulators.

[0112] According to another preferred embodiment of the invention, each of the plurality of detectors includes a plurality of detectors.

[0113] Preferably, the system further includes multiple optical paths between the far-field intensity pattern of each of the multiple groups and each of the multiple detectors, the multiple optical paths being used to provide the far-field intensity pattern to the multiple detectors along them, the spatial density of the multiple optical paths being greater than the spatial density of the multiple detectors.

[0114] Preferably, changing the phase of the synthesized laser output includes maximizing the intensity of the synthesized laser output.

[0115] Preferably, changing the phase of the synthesized laser output provides spatial modulation of the synthesized laser output without involving mechanical spatial modulation of the synthesized laser output.

[0116] Preferably, the laser beam separation and synthesis subsystem provides laser beam amplification downstream of separation and upstream of synthesis.

[0117] According to another preferred embodiment of the invention, a method for performing a phase change of a laser output is also provided, the method comprising receiving a laser output from a seed laser; separating the laser output into a plurality of sub-beams and combining the plurality of sub-beams to provide a combined laser output; dividing at least a portion of some of the plurality of sub-beams into a plurality of groups of sub-beams; altering the phase of each sub-beam within each group relative to the phase of other sub-beams within each group, thereby altering the phase of each group; and altering the phase of other groups within the plurality of groups relative to the phase of each group, thereby altering the phase of the combined laser output.

[0118] Preferably, grouping is performed by at least one cylindrical lens.

[0119] Alternatively, grouping is performed using a mirror array and corresponding focusing lenses.

[0120] Preferably, the phase change of the sub-beam is performed by multiple phase modulators.

[0121] Preferably, the method further includes controlling multiple phase modulators via at least one electronic control module.

[0122] Preferably, the method further includes detecting the far-field intensity pattern of each of the multiple groups using corresponding multiple detectors.

[0123] According to a preferred embodiment of the invention, the method includes providing a far-field intensity pattern to a corresponding detector among a plurality of detectors through a plurality of optical masks, each optical mask including at least one of a transmission region and a reflection region, the transmission region and the reflection region being used to provide the far-field intensity pattern passing through and obtained therefrom to the corresponding detector among the plurality of detectors, respectively.

[0124] Preferably, for multiple groups, the detection is performed simultaneously, at least partially, with each group.

[0125] Preferably, the method further includes detecting a combined far-field intensity pattern of multiple groups using an auxiliary detector.

[0126] Preferably, the phase change of each group relative to the phases of other groups in the multiple groups is performed by multiple additional phase modulators, each additional phase modulator being common to all sub-bundles within each group.

[0127] Preferably, the method further includes controlling multiple additional phase modulators via an additional electronic control module.

[0128] According to another preferred embodiment of the invention, each of the plurality of detectors includes a plurality of detectors.

[0129] Preferably, the method further includes providing a far-field intensity pattern of each of the plurality of groups to each of the 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.

[0130] Preferably, changing the phase of the synthesized laser output includes maximizing the intensity of the synthesized laser output.

[0131] Preferably, changing the phase of the synthesized laser output provides spatial modulation of the synthesized laser output without involving mechanical spatial modulation of the synthesized laser output.

[0132] Preferably, the method further includes amplifying the laser output downstream of separation and upstream of synthesis.

[0133] According to another preferred embodiment of the present invention, a laser system is also provided, comprising an optical phased array laser, the optical phased array laser comprising: a seed laser; and a laser beam splitting and combining subsystem that receives laser output from the seed laser and provides a combined laser output, the laser beam splitting and combining subsystem changing the phase of the combined laser output to focus the combined laser output onto a substrate, the combined laser output not being focused onto the substrate in the absence of a phase change.

[0134] Preferably, the system further includes an optical element that receives the synthesized laser output from the laser beam separation and synthesis subsystem and focuses the synthesized laser output at a focal point that does not coincide with the substrate.

[0135] Preferably, the laser beam backscattered from the substrate is not focused on the optical phased array laser.

[0136] According to another preferred embodiment of the present invention, a method for focusing a laser beam in a laser system is also provided, the method comprising: receiving a laser output from a seed laser; separating 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, wherein the combined laser output is not focused onto the substrate in the absence of a phase change.

[0137] Preferably, the method further includes focusing the synthesized laser output onto a focal point that does not coincide with the substrate using optical elements.

[0138] Preferably, the laser beam backscattered from the substrate is not focused on the laser system.

[0139] According to another preferred embodiment of the present invention, a laser amplifier system is further provided, the laser amplifier system comprising: a seed laser providing a laser output; an amplification subsystem receiving the laser output from the seed laser along a first optical path and providing amplified laser output; and a detector subsystem receiving the laser output from the seed laser along a second optical path, the detector subsystem being operable to deactivate the amplification subsystem upon detecting at least one fault in the laser output by the detector subsystem, wherein a first flight time of the laser output from the seed laser to the amplification subsystem along the first optical path is greater than a combination of a second flight time of the laser output from the seed laser to the detector subsystem along the second optical path and the time taken for the detector subsystem to deactivate the amplification subsystem.

[0140] Preferably, the first optical path includes a coiled optical fiber.

[0141] Preferably, at least one fault includes at least one of a reduction in laser output power and a reduction in laser output linewidth.

[0142] Preferably, the amplification subsystem includes a power amplifier, and the laser amplifier system includes an MOPA.

[0143] According to another preferred embodiment of the present invention, a method for preventing damage to an amplification subsystem in a laser system is also provided, the method comprising: receiving laser output from a seed laser along a first optical path; amplifying the laser output to provide amplified laser output; receiving laser output from the seed laser along a second optical path; detecting at least one fault in the laser output received along the second optical path and stopping amplification when at least one fault in the laser output is detected, wherein a first flight time of the laser output along the first optical path is greater than a combination of a second flight time of the laser output along the second optical path and the time taken to stop amplification.

[0144] Preferably, the first optical path includes a coiled optical fiber.

[0145] Preferably, at least one fault includes at least one of a reduction in laser output power and a reduction in laser output linewidth.

[0146] Preferably, the amplification subsystem includes a power amplifier, and the laser amplifier system includes an MOPA.

[0147] According to another preferred embodiment of the present invention, a laser amplifier system is also provided, comprising: a seed laser that provides a laser output; a first amplifier arranged to receive the laser output from the seed laser, the first amplifier providing a first amplified laser output when receiving the laser output from the seed laser, and providing one of amplified spontaneous emission and additional laser output when ceasing to receive the laser output from the seed laser; and a second amplifier that receives one of the first amplified laser output, amplified spontaneous emission, and additional laser output from the first amplifier and provides a second amplified laser output, wherein the amplification provided by the second amplifier is greater than the amplification provided by the first amplifier.

[0148] Preferably, the system further includes a filter structure downstream of the seed laser and upstream of the first amplifier.

[0149] Preferably, the filter structure includes: a beam splitter that separates laser outputs along first and second optical paths, the first optical path being longer than the second optical path; a detector that detects the combined laser outputs from the first and second optical paths; an electronic control module coupled to the detector for receiving outputs from the detector; and a phase control module positioned along one of the first and second optical paths, the phase control module being operated by the electronic control module to modify the phase of the laser outputs in response to the detector detecting interference in the combined laser outputs.

[0150] According to another preferred embodiment of the present invention, a method for preventing damage to an amplifier in a laser system is also provided, the method comprising: receiving laser output from a seed laser; providing a first amplified laser output via a first amplifier when receiving laser output from the seed laser, and providing one of amplified spontaneous emission and an additional laser output via the first amplifier when receiving laser output from the seed laser ceases; and receiving one of the first amplified laser output, amplified spontaneous emission, and an additional laser output via a second amplifier and providing a second amplified laser output, the second amplified laser output being greater than the first amplified laser output.

[0151] Preferably, the method further includes filtering the laser output downstream of the seed laser and upstream of the first amplifier.

[0152] Preferably, the filtering includes: separating the laser output along first and second optical paths, the first optical path being longer than the second optical path; detecting the combined laser output from the first and second optical paths by a detector; receiving the output from the detector by an electronic control module and modifying the phase of the laser output along one of the first and second optical paths in response to the detector detecting interference in the combined laser output.

[0153] 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 having a second power lower than the first power at least when the first laser output stops.

[0154] Preferably, the auxiliary laser subsystem includes an additional seed laser that provides a second laser output to the amplification subsystem at least while providing a first laser output.

[0155] Alternatively, the amplification subsystem includes an inlet for receiving the first laser output and an outlet for providing amplified laser output, and the laser amplifier system includes a first reflective grating at the inlet and a second reflective grating at the outlet, the first and second reflective gratings being combined with the amplification subsystem including the auxiliary laser subsystem.

[0156] Preferably, the first and second reflective gratings are reflective in the wavelength range of 1090 nm to 1100 nm.

[0157] Preferably, the second laser output has a different wavelength than the first laser output.

[0158] Preferably, the system further includes filters downstream of the seed laser and upstream of the amplification subsystem.

[0159] Preferably, the filter includes: a beam splitter that separates a first laser output along a first optical path and a second optical path, the first optical path being longer than the second optical path; a detector that detects the combined laser output from the first and second optical paths; an electronic control module coupled to the detector for receiving output from the detector; and a phase control module positioned along one of the first and second optical paths, the phase control module being operated by the electronic control module to modify the phase of the laser output in response to the detector detecting interference in the combined laser output.

[0160] Preferably, the system further includes a detector subsystem for detecting the first laser output from the seed laser.

[0161] Preferably, the detector subsystem includes: a beam splitter that separates the first laser output into a first portion and a second portion; an additional amplifier that amplifies the second portion 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.

[0162] Preferably, the fiber is 25 meters long and the core diameter is 6 micrometers.

[0163] According to another preferred embodiment of the present invention, a method for preventing damage to an amplifier in a laser system is also provided, the method comprising: providing a first laser output having a first power; amplifying the first laser output by an amplifier to provide an amplified laser output; and providing a second laser output having a second power lower than the first power at least when the provision of the first laser output ceases.

[0164] Preferably, the provision of the second laser output is performed at least simultaneously with the provision of the first laser output.

[0165] Preferably, the amplifier includes an inlet for receiving a first laser output and an outlet for providing amplified laser output, and further includes positioning a first reflective grating at the inlet and a second reflective grating at the outlet, the first and second reflective gratings being combined with the amplifier to provide a second laser output.

[0166] Preferably, the first and second reflective gratings are reflective in the wavelength range of 1090 nm to 1100 nm.

[0167] Preferably, the second laser output has a different wavelength than the first laser output.

[0168] Preferably, the method further includes filtering the first laser output upstream of the amplified first laser output.

[0169] Preferably, the method includes: separating a first laser output along first and second optical paths, the first optical path being longer than the second optical path; detecting a synthesized laser output from the first and second optical paths using a detector; receiving an output from the detector via an electronic control module and modifying 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 detecting interference in the synthesized laser output.

[0170] Preferably, the method further includes detecting the first laser output.

[0171] Preferably, the detection includes: separating the 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 through an optical fiber configured to exhibit a nonlinear effect when the linewidth of the first laser output becomes unacceptably narrow.

[0172] Preferably, the fiber is 25 meters long and the core diameter is 6 micrometers. Attached Figure Description

[0173] The invention will be more fully understood and appreciated based on the following detailed description taken in conjunction with the accompanying drawings, in which:

[0174] Figure 1A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to a preferred embodiment of the present invention.

[0175] Figure 1B and 1C yes Figure 1A A simplified graphical representation of phase change and noise correction in a system of the type shown;

[0176] Figure 2A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention;

[0177] Figure 2B and 2C yes Figure 2A A simplified graphical representation of phase change and noise correction in a system of the type shown;

[0178] Figure 3A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention;

[0179] Figure 3B and 3C yes Figure 3A A simplified graphical representation of phase change and noise correction in a system of the type shown;

[0180] Figure 4A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention.

[0181] Figure 4B and 4C yes Figure 4A A simplified graphical representation of phase change and noise correction in a system of the type shown;

[0182] Figure 5A to 5G yes Figures 1A to 4C A simplified illustration of possible far-field motions of the output of any type of optical phased array laser system shown;

[0183] Figure 6 This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple closely spaced optical paths constructed and operated according to another preferred embodiment of the present invention.

[0184] Figure 7 This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple closely spaced optical paths, constructed and operated according to another preferred embodiment of the present invention.

[0185] Figure 8 This is a simplified schematic diagram of an optical phased array laser system comprising multiple detectors and corresponding multiple closely spaced optical paths constructed and operated according to another preferred embodiment of the present invention.

[0186] Figure 9 This is a simplified schematic diagram of an optical phased array laser system comprising a detector mask configured according to an exemplary laser beam trajectory, constructed and operated according to a preferred embodiment of the present invention.

[0187] Figure 10 It represents different levels of transparency. Figure 9 A simplified schematic diagram of a detector mask of the type shown;

[0188] Figure 11 This is a simplified schematic diagram of an optical phased array laser system comprising a detector mask configured according to an exemplary laser beam shape, constructed and operated according to another preferred embodiment of the present invention;

[0189] Figure 12 It represents different levels of transparency. Figure 11 A simplified schematic diagram of a detector mask of the type shown;

[0190] Figure 13 This is a simplified schematic diagram of an optical phased array laser system including voltage-phase correlation function constructed and operated according to a preferred embodiment of the present invention.

[0191] Figure 14 It is shown that it is used in Figure 13 A simplified flowchart illustrating the voltage-phase related steps performed in a system of the type shown.

[0192] Figure 15 This is a simplified schematic plan view of an optical phased array laser system comprising dynamic beam scaling phase modification constructed and operated according to an additional preferred embodiment of the present invention;

[0193] Figure 16 This is a simplified schematic plan view of an optical phased array laser system comprising dynamic beam scaling phase modification constructed and operated according to yet another preferred embodiment of the present invention;

[0194] Figure 17A and 17B It includes Figure 15 or Figure 16 Simplified top and perspective views of an optical phased array laser system with scaled phase modification of dynamic beams of the type shown;

[0195] Figure 18This is a simplified schematic plan view of an optical phased array laser system comprising dynamic beam scaling phase modification constructed and operated according to another preferred embodiment of the present invention;

[0196] Figure 19 This is a simplified schematic plan view of an optical phased array laser system comprising dynamic beam scaling phase modification constructed and operated according to another preferred embodiment of the present invention;

[0197] Figure 20A and 20B It includes Figure 18 or Figure 19 Simplified top and perspective views of an optical phased array laser system with scaled phase modification of dynamic beams of the type shown;

[0198] Figure 21 This is a simplified schematic plan view of an optical phased array laser system comprising dynamic beam scaling phase modification constructed and operated according to another preferred embodiment of the present invention;

[0199] Figure 22A and 22B This is a simplified schematic diagram of the corresponding first and second focusing states of an optical phased array laser system constructed and operated according to a preferred embodiment of the present invention;

[0200] Figure 23 yes Figure 22A and 22B A simplified representation of backscattering in an optical phased array laser system of the type shown;

[0201] Figure 24 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to a preferred embodiment of the present invention.

[0202] Figure 25 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0203] Figure 26 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0204] Figure 27 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0205] Figure 28 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0206] Figure 29 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0207] Figure 30 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0208] Figure 31 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to an additional preferred embodiment of the present invention.

[0209] Figure 32 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to yet another preferred embodiment of the present invention; and

[0210] Figure 33 It is applicable Figures 24 to 32 A simplified schematic diagram of a sensor for any type of laser amplification system shown. Detailed Implementation

[0211] Now for reference Figure 1A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming, constructed and operated according to a preferred embodiment of the present invention; and referenced to Figure 1B and 1C , it is Figure 1A A simplified graphical representation of phase change and noise correction in a system of the type shown.

[0212] like Figure 1A As seen herein, an optical phased array (OPA) laser system 100 is provided, which is illustrated herein by way of example as being used within a laser cutting system 102. The laser cutting system 102 may include the OPA laser system 100 mounted at a distance from a multi-axis positioning stage 104, on which, as detailed later, the laser system 100 can be used to cut articles, such as article 106. It should be understood that although the laser cutting system 102 is shown herein in the context of stage 104, as those skilled in the art will appreciate, system 102 can be embodied in any type of laser cutting system.

[0213] Referring preferably to enlarged Figure 110, the OPA laser 100 preferably includes a seed laser 112 and a laser beam splitting and combining subsystem 114. The splitting and combining subsystem 114 preferably receives the output laser beam from the seed laser 112 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 116. Here, by way of example only, the output from the seed laser 112 is illustrated as split into ten sub-beams along ten channels 116, but it should be understood that the splitting and combining subsystem 114 may include fewer or more channels along which the output of the seed laser 112 is split, and typically may include far more channels, such as 32 or more channels.

[0214] The relative phase of each sub-beam can be individually modulated by phase modulators 118 preferably positioned along each of the channels 116. Each phase-modulated sub-beam resulting from the separation and subsequent phase modulation of the output of the seed laser 112 preferably propagates toward the collimating lens 119. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at the focusing lens 120 to form the output beam 122.

[0215] The separation and combining subsystem 114 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 112 is separated into sub-beams and before the sub-beams are combined to form the output beam 122. Here, for example, the separation and combining subsystem 114 is illustrated as including a plurality of optical amplifiers 124 positioned along corresponding channels in channel 116 for amplifying each sub-beam. However, it should be understood that this amplification is optional and can be omitted depending on the power output requirements of the OPA laser 100.

[0216] The phase of the output beam 122, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 122. In various applications, such as... Figure 1A In the laser cutting process shown, it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 100 by dynamically changing the relative phase of the individual sub-beams through the laser separation and synthesis subsystem 114, thereby changing the phase of the synthesized laser output 122, so as to dynamically control the position and shape of its far-field intensity pattern.

[0217] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern for cutting the article 106. Particularly preferably, a variable relative phase is applied by a phase control subsystem 130. The phase control subsystem 130 is preferably part of the control electronics module 132 in the OPA laser 100, and preferably controls each phase modulator 118 to dynamically modulate the relative phase of the sub-beams along the channel 116.

[0218] The output beam 122 is noisy due to the inherent noise in the OPA system 100. In the presence of the optical amplifier 124 in the OPA system 100, the noise in the output beam 122 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. A specific feature of a preferred embodiment of the invention is that the laser system 100 includes a noise cancellation subsystem 140 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 122 in a manner detailed below.

[0219] Particularly preferably, the noise cancellation subsystem 140 employs an algorithm to sense and correct phase noise in the synthesized laser output. The noise-cancelled phase-corrected output is preferably provided by the noise cancellation subsystem 140 to the phase modulator 118 to correct phase noise in the output beam 122, and thus avoids distortion of the shape and position of the far-field intensity pattern of the output beam 122 that would otherwise be caused by noise. The noise cancellation subsystem 140 may be included in the control electronics module 132.

[0220] It should be understood that the output beam 122 may additionally or alternatively be affected by noise types other than phase noise, including intensity noise. In the case of intensity noise in the output beam 122, the noise cancellation subsystem 140 operates to provide a noise-cancelled phase-corrected output to eliminate the intensity noise in the output beam 122. In this case, the OPA laser system 100 may optionally additionally include an intensity modulator 142 along channel 116 for modulating the intensity of each of the sub-beams along channel 116.

[0221] It should be understood that the output beam 122 may additionally or alternatively be affected by mechanical noise, which may affect the relative positions of the sub-beams. In the case of position noise in the output beam 122, the noise cancellation subsystem 140 operates to provide a noise cancellation phase correction output in order to eliminate the position noise in the output beam 122. In this case, the OPA laser system 100 may optionally additionally include a position modulator 144 along channel 116 for modulating the position of each of the sub-beams along channel 116.

[0222] To facilitate the application of phase change and noise correction to the output beam 122, a portion of the output of the OPA laser 100 is preferably extracted and directed to at least one detector, shown herein as a single detector 150. Detector 150 may alternatively be embodied as multiple detectors, as will be referred to below. Figures 6 to 8 As detailed in 15 to 21. The extracted portion of the output beam preferably serves as a reference beam, and based on its characteristics, the required noise correction and / or phase change can be calculated. Figure 1AIn the illustrated embodiment, multiple sub-beams are guided along channel 116 to beam splitter 160. Beam splitter 160 preferably divides each sub-beam into a transmissive portion 162 and a reflective portion 164 according to a predetermined ratio. For example, beam splitter 160 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0223] The transmissive portion 162 of the sub-beam preferably propagates toward the focusing lens 120, where the sub-beam is combined to form an output beam 122 having a far-field intensity pattern 166 incident on the surface of the article 106. The reflective portion 164 of the sub-beam preferably reflects toward an additional focusing lens 168, where the sub-beam is combined to form an output reference beam 170 having a far-field intensity pattern 172 incident on the surface of the detector 150.

[0224] It should be understood that the specific structures and configurations of the beam splitting and recombining elements (including beam splitter 160 and focusing lenses 120 and 168) illustrated herein are exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 100 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0225] As described above, the shape and position of the far-field intensity pattern 166 of the output beam 122 and the corresponding far-field intensity pattern 172 of the reference beam 170 are constantly changing due to the continuous variation in the relative phase of the sub-beams. Therefore, the far-field intensity pattern 172 is not fixed to the detector 150, but rather constantly moves about the detector 150 depending on the relative phase of the composite of the sub-beams. However, in order for the detector 150 to provide the required noise-cancelled phase-corrected output, the far-field intensity pattern 172 must be incident on the detector 150 so that the detector measures the intensity of the far-field intensity pattern 172 and thus applies noise correction accordingly, thereby producing a fixed output beam.

[0226] In this invention, the conflict between the dynamic properties of the far-field intensity pattern 172 due to its phase variation and the fixed properties required by the far-field intensity pattern 172 for deriving and applying its noise correction is advantageously resolved by providing noise cancellation and phase variation at different times and rates.

[0227] A noise-cancelled phase-corrected output is provided based on noise measured by detector 150 at a noise sampling rate. The output beam 122 is controlled such that the shape and position of the output and reference far-field intensity patterns 166, 172 are dynamically changed onto detector 150 at a rate equal to or higher than the desired noise sampling rate. Noise in the reference beam 170 is taken into account during the intervals during which the far-field intensity pattern 172 returns to detector 150.

[0228] During the time interval between the incident on far-field intensity pattern 172 and the incident on detector 150, the phases of the synthesized output beams 122 and 170 change to dynamically alter the shape and position of their far-field intensity patterns as needed to perform laser cutting of article 106. The synthesized laser output changes phase at a rate exceeding the noise sampling rate to rapidly change the phase and thus alter the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be approximately 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0229] For reference Figure 1A The curves seen in Figure 180 and Figure 1B The enlarged version illustrated in the figure best illustrates the different rates and time scales by which noise cancellation and phase change are preferably performed in embodiments of the invention.

[0230] like Figure 1B As most clearly seen, graph 180 includes an upper portion 182 and a lower portion 184, the upper portion 182 showing the change in intensity over time of the far-field intensity pattern 172 as measured at detector 150, and the lower portion 184 showing the change in relative phase of the multiple sub-beams that contribute to the output beam 122 and the reference beam 170 within the same time period. For simplicity, graph 180 shows the relative phase of ten sub-beams, but it should be understood that the OPA system 100, and therefore the explanation provided herein, applies to fewer or more typically far greater numbers of sub-beams.

[0231] As seen in the upper section 182, intensity peak 186 represents the measured intensity of the reference beam 170 as it passes the detector 150 in the far-field intensity pattern 172. As seen in the lower section 184, intensity peak 186 occurs during the interval T when the relative phase of each sub-beam is zero. i The presence of this pattern at a certain point indicates that there is no phase shift between the sub-beams, therefore the position of the synthesized output beam remains unchanged and the far-field intensity pattern 172 is directly incident on detector 150. It should be understood that detector 150 can alternatively be positioned such that the relative phase of the sub-beams there is non-zero. Furthermore, more than one detector can be used to allow measurements of the far-field intensity pattern 172 at more than one location along it, and then referenced. Figures 6 to 8 Details are provided from 15 to 21.

[0232] Between intensity peaks 186, the measured intensity is close to zero because the far-field intensity pattern 172 has shifted to either side of detector 150 and is therefore not directly incident on detector 150. As understood from the upper portion 182, the magnitude of intensity peak 186 is not constant due to noise in the laser output beam, which degrades the far-field intensity pattern 172.

[0233] As seen in Part 184 below, the relative phase of the sub-beams during the interval T i The time interval T between between The phase change function shown in this paper plots the relative phase of the sub-beams as a periodically, regularly repeating pattern with equal phase shifts applied in both the positive and negative directions. It should be understood that this simplified pattern is merely illustrative and the phase change need not be regularly repeating, nor symmetrical in the positive and negative directions. Furthermore, it should be understood that the time interval T... between Preferably, but not necessarily not related to the interval time T i Overlap. Additionally, it should be understood that at least one of the phase change rate and the noise sampling rate may be constant or may vary over time.

[0234] The noise cancellation subsystem 140 takes into account the intermittent time T i Preferred to operate due to noise at the location, and based on the interval time T i The noise sensed at the point provides a noise cancellation phase correction output. The noise cancellation subsystem 140 preferably employs an algorithm to sense noise and correct the sensed noise accordingly.

[0235] According to an exemplary embodiment of the present invention, the noise cancellation subsystem 140 employs an algorithm such that the relative phase of one of the channels varies with a given phase during each cycle of the far-field intensity pattern 172 traveling about the detector 150. The way it is modified changes. After multiple such cycles, different phase changes occur. Applying the algorithm to the selected sub-beam in each cycle, the algorithm determines the maximum output intensity across all cycles and finds the optimal phase change that produces this maximum intensity. The phase change of the selected sub-beam is then fixed at the optimal phase change in subsequent periods. At this point, the algorithm proceeds to optimize another sub-bundle.

[0236] Graph 180 illustrates noise cancellation in three of the total ten sub-bundles, or channels A, B, and C, according to this exemplary algorithm. For clarity, in Figure 1C Sub-bundles A, B, and C are shown separately. It should be understood that, with... Figure 1A and 1B In comparison, Figure 1C The line shapes of the traces representing the phase changes and noise corrections of sub-bundles A, B, and C have been modified to aid in distinguishing between the various sub-bundles for explanatory purposes in the following text.

[0237] As initially observed in the case of channel A, and most clearly understood considering the enlarged view 190, the dashed line represents the pattern of relative phase variation in sub-beam A, as would be applied by the phase control subsystem 130 in the absence of any noise correction. This trace can be referred to as A. uncorrected The dotted line represents the actual relative phase of sub-bundle A after modification by a noise correction algorithm to find the optimal phase noise correction. This trace can be called A. corrected A corrected The modified relative phase is at different times in the first five periods of sub-bundle A. Regarding A uncorrected The unmodified relative phase shift. The intensity 186 measured at detector 150 varies within the first five cycles of sub-beam A optimization due to careful alteration of the relative phase shift.

[0238] After the first five cycles of sub-bundle A, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the second phase shift. The generated IA max Therefore, the phase change of the relative phase change applied to sub-beam A is fixed in the second phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle B.

[0239] It should be understood that during the continuous period of optimization of sub-bundle A, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle A.

[0240] As can be seen further in the case of sub-bundle B, and most clearly understood considering the enlarged figure 192, the coarser trace during the optimization of channel B represents the pattern of relative phase variation of sub-bundle B, as would be applied by the phase control subsystem 130 in the absence of any noise correction. This trace may be referred to as B. uncorrected The finer trace during the optimization of channel B represents the actual relative phase of sub-bundle B, modified by a noise correction algorithm to find the optimal phase noise-corrected phase. This trace can be referred to as B. corrected B corrected The modified relative phase is at different times in the first five periods of the optimized sub-bundle B. Regarding B uncorrectedThe unmodified relative phase shift. The intensity 186 measured at detector 150 varies within the first five cycles of sub-bundle B optimization due to careful alteration of the relative phase shift.

[0241] After the first five cycles of sub-bundle B, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the fourth phase shift. The generated IAB max Therefore, the phase change of the relative phase change applied to sub-beam B is fixed at the fourth phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle C.

[0242] It should be understood that during the five cycles of optimization of sub-bundle B, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle B.

[0243] Preferably, a similar optimization process is performed for sub-bundle C, wherein the phase change The intensity reduction is applied over several cycles to optimize the output beam intensity and to correct the phase noise in the beam C.

[0244] At least one detector 150 can operate continuously to continuously optimize the relative phase of the sub-beams and correct for phase noise therein. However, due to the finite response time of detector 150, detector 150 only considers the noise in the reference beam 170 at the intervals with a relatively slow noise sampling rate. The noise sampling rate is preferably, but not necessarily, predetermined. The noise sampling rate can alternatively be random.

[0245] It should be understood that the specific parameters of the noise correction algorithm depicted in Figure 180 are merely exemplary and can be easily modified, as those skilled in the art will understand. For example, phase shift... Optimization can be performed over a number of periods more or fewer than those shown herein. Each sub-bundle can be fully optimized each time it passes detector 150, or several or all sub-bundles can be optimized during each period in which the far-field intensity pattern passes detector 150. Furthermore, discontinuous noise correction optimization algorithms can be implemented alternatively, including but not limited to stochastic parallel gradient descent optimization algorithms.

[0246] Using dynamically shaped, noise-corrected optical phased array output beams in laser cutting is highly advantageous, enabling rapid beam steering, rapid power modulation, rapid beam focusing, and customized beam shape. Compared to conventional laser cutting methods, using dynamically shaped, noise-corrected optical phased array outputs improves both the speed and quality of the cuttable material. It should be understood that, according to a preferred embodiment of the invention, without noise correction, the shape and position of the optical phased array output beam will deteriorate, thereby reducing the quality, speed, and accuracy of the laser cutting process.

[0247] To maintain output beam intensity as the far-field intensity pattern of the beam shifts, which is advantageous in certain laser cutting applications, the movement of the output beam can be controlled so that the beam spends more time at lower intensity locations to compensate for the reduced power delivery there. Alternatively, an intensity profile mask, such as a neutral density (ND) filter, can be applied to the output beam to modify its intensity.

[0248] Now for reference Figure 2A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention; and referenced to Figure 2B and 2C , it is Figure 2A A simplified graphical representation of phase change and noise correction in a system of the type shown.

[0249] like Figure 2A As seen herein, an optical phased array (OPA) laser system 200 is provided, which is illustrated herein by way of example as being used within an additive manufacturing system 202. The additive manufacturing system 202 may include the OPA laser system 200 mounted at a distance from a scanning mirror 203 and a multi-axis positioning stage 204 on which the laser system 200 can be used to additively manufacture articles, such as article 206. It should be understood that although the additive manufacturing system 202 is shown herein in the context of a scanning mirror 203, as those skilled in the art will appreciate, the system 202 may be embodied in any type of additive manufacturing system.

[0250] Referring preferably to enlarged Figure 210, the OPA laser 200 preferably includes a seed laser 212 and a laser beam splitting and combining subsystem 214. The splitting and combining subsystem 214 preferably receives the output laser beam from the seed laser 212 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 216. Here, by way of example only, the output from the seed laser 212 is illustrated as split into ten sub-beams along ten channels 216, but it should be understood that the splitting and combining subsystem 214 may include fewer or more channels along which the output of the seed laser 212 is split, and typically may include far more channels, such as 32 or more channels.

[0251] The relative phase of each sub-beam can be individually modulated by phase modulators 218 preferably positioned along each of the channels 216. Each phase-modulated sub-beam, generated by the separation and subsequent phase modulation of the output of the seed laser 212, preferably propagates toward collimating lens 219. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at focusing lens 220 to form output beam 222.

[0252] The separation and combining subsystem 214 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 212 is separated into sub-beams and before the sub-beams are combined to form the output beam 222. Here, for example, the separation and combining subsystem 214 is illustrated as including a plurality of optical amplifiers 224 positioned along corresponding channels in channel 216 for amplifying each sub-beam. However, it should be understood that this amplification is optional and can be omitted depending on the power output requirements of the OPA laser 200.

[0253] The phase of the output beam 222, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 222. In many applications, such as... Figure 2A In the laser additive manufacturing process shown, it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 200 by dynamically changing the relative phase of the individual sub-beams through the laser separation and synthesis subsystem 214, thereby changing the phase of the synthesized laser output 222, so as to dynamically control the position and shape of its far-field intensity pattern.

[0254] The relative phase of the sub-beams is preferably predetermined according to the laser output pattern desired for the 3D printing of article 206. Particularly preferably, a varying relative phase is applied via a phase control subsystem 230. The phase control subsystem 230 is preferably part of a control electronics module 232 within the OPA laser 200, and preferably controls each phase modulator 218 to dynamically modulate the relative phase of the sub-beams along channel 216.

[0255] The output beam 222 is noisy due to the inherent noise in the OPA system 200. With the presence of the optical amplifier 224 in the OPA system 200, the noise in the output beam 222 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. A specific feature of a preferred embodiment of the invention is that the laser system 200 includes a noise cancellation subsystem 240 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 222 in a manner detailed below.

[0256] Particularly preferably, the noise cancellation subsystem 240 employs an algorithm to sense and correct phase noise in the synthesized laser output. The noise-cancelled phase-corrected output is preferably provided by the noise cancellation subsystem 240 to the phase modulator 218 to correct phase noise in the output beam 222, and thus avoids distortion of the shape and position of the far-field intensity pattern of the output beam 222 that would otherwise be caused by noise. The noise cancellation subsystem 240 may be included in the control electronics module 232.

[0257] It should be understood that the output beam 222 may additionally or alternatively be affected by noise types other than phase noise, including intensity noise. In the case of intensity noise in the output beam 222, the noise cancellation subsystem 240 operates to provide a noise-cancelled phase-corrected output to eliminate the intensity noise in the output beam 222. In this case, the OPA laser system 200 may optionally additionally include an intensity modulator 242 along channel 216 for modulating the intensity of each of the sub-beams along channel 216.

[0258] It should be understood that the output beam 222 may additionally or alternatively be affected by mechanical noise, which may affect the relative positions of the sub-beams. In the case of position noise in the output beam 222, the noise cancellation subsystem 240 operates to provide a noise cancellation phase correction output to eliminate the position noise in the output beam 222. In this case, the OPA laser system 200 may optionally additionally include a position modulator 244 along channel 216 for modulating the position of each of the sub-beams along channel 216.

[0259] To facilitate the application of phase change and noise correction to the output beam 222, a portion of the output of the OPA laser 200 is preferably extracted and directed to at least one detector, shown herein as a single detector 250. Detector 250 may alternatively be embodied as multiple detectors, as will be referred to below. Figures 6 to 8 As detailed in 15 to 21. The extracted portion of the output beam preferably serves as a reference beam, and based on its characteristics, the required noise correction and / or phase change can be calculated. Figure 2A In the illustrated embodiment, multiple sub-beams are guided along channel 216 to beam splitter 260. Beam splitter 260 preferably divides each sub-beam into a transmissive portion 262 and a reflective portion 264 according to a predetermined ratio. For example, beam splitter 260 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0260] The transmissive 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 incident on the scanning mirror 203. The reflective 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 incident on the surface of the detector 250.

[0261] It should be understood that the specific structures and configurations of the beam splitting and recombining elements (including beam splitter 260 and focusing lenses 220 and 268) illustrated herein are exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 200 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0262] As described above, the shape and position of the far-field intensity pattern 266 of the output beam 222 and the corresponding far-field intensity pattern 272 of the reference beam 270 are constantly changing due to the continuous variation in the relative phase of the sub-beams. Therefore, the far-field intensity pattern 272 is not fixed to the detector 250, but rather constantly moves about the detector 250 depending on the relative phase of the composite of the sub-beams. However, in order for the detector 250 to provide the required noise-cancelled phase-corrected output, the far-field intensity pattern 272 must be incident on the detector 250 so that the detector measures the intensity of the far-field intensity pattern 272 and thus applies noise correction accordingly, thereby producing a fixed output beam.

[0263] In this invention, the conflict between the dynamic properties of the far-field intensity pattern 272 due to its phase variation and the fixed properties required by the far-field intensity pattern 272 for deriving and applying its noise correction is advantageously resolved by providing noise cancellation and phase variation at different times and rates.

[0264] A noise-cancelled phase-corrected output is provided based on noise measured by detector 250 at a noise sampling rate. The output beam 222 is controlled such that the shape and position of the output and reference far-field intensity patterns 266 and 272 are dynamically changed during a process in which they are incident on detector 250 at a rate equal to or higher than the desired noise sampling rate. Noise in the reference beam 270 is taken into account during the intervals during which the far-field intensity pattern 272 returns to detector 250.

[0265] During the time intervals between the incident on far-field intensity pattern 272 and the detector 250, the phase of the synthesized output beams 222 and 270 changes to dynamically alter the shape and position of their far-field intensity patterns as needed to perform additive manufacturing of article 206. The synthesized laser output changes phase at a rate exceeding the noise sampling rate to rapidly change the phase and thus alter the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be approximately 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0266] For reference Figure 2A The curves seen in Figure 280 and Figure 2B The enlarged version illustrated in the figure best illustrates the different rates and time scales by which noise cancellation and phase change are preferably performed in embodiments of the invention.

[0267] like Figure 2B As most clearly seen, graph 280 comprises an upper portion 282 and a lower portion 284, the upper portion 282 showing the change in intensity over time of the far-field intensity pattern 272 as measured at detector 250, and the lower portion 284 showing the change in relative phase of the multiple sub-beams that contribute to the output beam 222 and the reference beam 270 within the same time period. For simplicity, graph 280 shows the relative phase of ten sub-beams, but it should be understood that the OPA system 200, and therefore the explanation provided herein, applies to fewer or more typically far greater numbers of sub-beams.

[0268] As seen in the upper section 282, intensity peak 286 represents the measured intensity of the reference beam 270 as it passes the detector 250 in the far-field intensity pattern 272. As seen in the lower section 284, intensity peak 286 occurs during the interval T when the relative phase of each sub-beam is zero. i The presence of this pattern indicates that there is no phase shift between the sub-beams, therefore the position of the synthesized output beam remains unchanged and the far-field intensity pattern 272 is directly incident on detector 250. It should be understood that detector 250 can alternatively be positioned such that the relative phase of the sub-beams is non-zero. Furthermore, more than one detector can be used to allow measurement of the far-field intensity pattern 272 at more than one location along it, and then referenced. Figures 6 to 8 Details are provided from 15 to 21.

[0269] Between intensity peaks 286, the measured intensity is close to zero because the far-field intensity pattern 272 has shifted to either side of detector 250 and is therefore not directly incident on detector 250. As understood from the upper portion 282, the magnitude of intensity peak 286 is not constant due to noise in the laser output beam, which degrades the far-field intensity pattern 272.

[0270] As seen in Part 284 below, the relative phase of the sub-beams during the interval T i The time interval T between between The phase change function shown in this paper plots the relative phase of the sub-beams as a periodically, regularly repeating pattern with equal phase shifts applied in both the positive and negative directions. It should be understood that this simplified pattern is merely illustrative and the phase change need not be regularly repeating, nor symmetrical in the positive and negative directions. Furthermore, it should be understood that the time interval T... between Preferably, but not necessarily not related to the interval time T i Overlap. Additionally, it should be understood that at least one of the phase change rate and the noise sampling rate may be constant or may vary over time.

[0271] The noise cancellation subsystem 240 takes into account the intermittent time T i Preferred to operate due to noise at the location, and based on the interval time T i The noise sensed at the point provides a noise cancellation phase correction output. The noise cancellation subsystem 240 preferably employs an algorithm to sense noise and correct the sensed noise accordingly.

[0272] According to an exemplary embodiment of the present invention, the noise cancellation subsystem 240 employs an algorithm such that the relative phase of one of the channels varies with a given phase during each cycle of the far-field intensity pattern 272 traveling about the detector 250. The way it is modified changes. After multiple such cycles, different phase changes occur. Applying the algorithm to the selected sub-beam in each cycle, the algorithm determines the maximum output intensity across all cycles and finds the optimal phase change that produces this maximum intensity. The phase change of the selected sub-beam is then fixed at the optimal phase change in subsequent periods. At this point, the algorithm proceeds to optimize another sub-bundle.

[0273] Graph 280 illustrates noise cancellation in three sub-bundles, or channels A, B, and C, out of a total of 10 sub-bundles according to this exemplary algorithm. For clarity, in Figure 2C Sub-bundles A, B, and C are shown separately. It should be understood that, with... Figure 2A and 2B In comparison, Figure 2C The line shapes of the traces representing the phase changes and noise corrections of sub-bundles A, B, and C have been modified to aid in distinguishing between the various sub-bundles for explanatory purposes in the following text.

[0274] As initially observed in the case of channel A, and most clearly understood considering the enlarged diagram 290, the dashed line represents the pattern of relative phase variation in sub-bundle A, as would be applied by the phase control subsystem 230 in the absence of any noise correction. This trace can be referred to as A. uncorrected The dotted line represents the actual relative phase of sub-bundle A after modification by a noise correction algorithm to find the optimal phase noise correction. This trace can be called A. corrected A corrected The modified relative phase is at different times in the first five periods of sub-bundle A. Regarding A uncorrected The unmodified relative phase shift. The intensity 286 measured at detector 250 varies within the first five cycles of sub-beam A optimization due to careful alteration of the relative phase shift.

[0275] After the first five cycles of sub-bundle A, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the second phase shift. The generated IA max Therefore, the phase change of the relative phase change applied to sub-beam A is fixed in the second phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle B.

[0276] It should be understood that during the continuous period of optimization of sub-bundle A, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle A.

[0277] As can be seen further in the case of sub-bundle B, and most clearly understood considering enlarged Figure 292, the coarser trace during the optimization of channel B represents the pattern of relative phase variation of sub-bundle B, as would be applied by phase control subsystem 230 in the absence of any noise correction. This trace may be referred to as B. uncorrected The finer trace during the optimization of channel B represents the actual relative phase of sub-bundle B, modified by a noise correction algorithm to find the optimal phase noise-corrected phase. This trace can be referred to as B. corrected B corrected The modified relative phase is at different times in the first five periods of the optimized sub-bundle B. Regarding B uncorrected The unmodified relative phase shift. The intensity 286 measured at detector 250 varies within the first five cycles of sub-bundle B optimization due to careful alteration of the relative phase shift.

[0278] After the first five cycles of sub-bundle B, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the fourth phase shift. The generated IAB max Therefore, the phase change of the relative phase change applied to sub-beam B is fixed at the fourth phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle C.

[0279] It should be understood that during the five cycles of optimization of sub-bundle B, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle B.

[0280] Preferably, a similar optimization process is performed for sub-bundle C, wherein the phase change The intensity reduction is applied over several cycles to optimize the output beam intensity and to correct the phase noise in the beam C.

[0281] Detector 250 can operate continuously to continuously optimize the relative phase of the sub-beams and correct for phase noise therein. However, due to the limited response time of detector 250, detector 250 only considers noise in the reference beam 270 at relatively slow noise sampling rates during intervals. The noise sampling rate is preferably, but not necessarily, predetermined. The noise sampling rate can alternatively be random.

[0282] It should be understood that the specific parameters of the noise correction algorithm depicted in graph 280 are merely exemplary and can be easily modified, as those skilled in the art will understand. For example, phase shift... Optimization can be performed over a number of periods more or fewer than those shown herein. Each sub-bundle can be fully optimized each time it passes detector 250, or several or all sub-bundles can be optimized during each period in which the far-field intensity pattern passes detector 250. Furthermore, discontinuous noise correction optimization algorithms can be implemented alternatively, including but not limited to stochastic parallel gradient descent optimization algorithms.

[0283] Using dynamically shaped, noise-corrected optical phased array output beams in laser additive manufacturing is highly advantageous, enabling rapid beam steering, rapid power modulation, rapid beam focusing, and customized beam shape. Compared to conventional laser 3D printing methods, using dynamically shaped, noise-corrected optical phased array outputs improves both the speed and quality of the manufactured items. It should be understood that, according to a preferred embodiment of the invention, without noise correction, the shape and position of the optical phased array output beam will deteriorate, thereby reducing the quality, speed, and accuracy of the laser additive manufacturing process.

[0284] To maintain output beam intensity as the far-field intensity pattern of the beam shifts, which is advantageous in certain additive manufacturing applications, the movement of the output beam can be controlled so that the beam spends more time at lower intensity locations to compensate for the reduced power delivery there. Alternatively, an intensity profile mask, such as an ND filter, can be applied to the output beam to modify its intensity.

[0285] Now for reference Figure 3A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention; and referenced to Figure 3B and 3C , it is Figure 3A A simplified graphical representation of phase change and noise correction in a system of the type shown.

[0286] like Figure 3A As seen herein, an optical phased array (OPA) laser system 300 is provided, which is illustrated herein by way of example as being used within a free-space optical communication system 302. The free-space optical communication system 302 may include an OPA laser system 300 installed at an outdoor location (e.g., on a building) spaced apart from a receiver 303 for receiving optical signals originating from the OPA laser 300. It should be understood that although the free-space optical communication system 302 is shown herein in the context of communication between two fixed points, the free-space optical communication system 302 is applicable to communication between two locations moving relative to each other, as those skilled in the art will understand. Further understanding is that although the free-space optical communication system 302 is shown herein in the context of terrestrial communication, the free-space optical communication system 302 is applicable to space communication, as those skilled in the art will understand.

[0287] It should be understood that the free-space optical communication system 302 is in Figure 3A For simplicity, this diagram only shows a single OPA laser 300 and receiver 303, but a greater number of OPA lasers and receivers may be included depending on the communication requirements of system 302. Further understanding suggests that receiver 303 may also be an OPA laser of a type similar to OPA laser 300 but with receiving functionality. Additionally, OPA laser 300 may include receiving functionality to allow full-duplex operation of OPA lasers 300 and 303 for transmitting and receiving optical signals therebetween.

[0288] Referring preferably to enlarged Figure 310, the OPA laser 300 preferably includes a seed laser 312 and a laser beam splitting and combining subsystem 314. The splitting and combining subsystem 314 preferably receives the output laser beam from the seed laser 312 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 316. Here, by way of example only, the output from the seed laser 312 is illustrated as split into ten sub-beams along ten channels 316, but it should be understood that the splitting and combining subsystem 314 may include fewer or more channels along which the output of the seed laser 312 is split, and typically may include far more channels, such as 32 or more channels.

[0289] The relative phase of each sub-beam can be individually modulated by phase modulators 318 preferably positioned along each of the channels 316. Each phase-modulated sub-beam, generated by the separation and subsequent phase modulation of the output of the seed laser 312, preferably propagates toward the collimating lens 319. Subsequently, the individually collimated phase-modulated sub-beams are combined, for example, at the focusing lens 320 to form the output beam 322.

[0290] The separation and combining subsystem 314 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 312 is separated into sub-beams and before the sub-beams are combined to form the output beam 322. Here, for example, the separation and combining subsystem 314 is illustrated as including a plurality of optical amplifiers 324 positioned along corresponding channels in channel 316 for amplifying each sub-beam. However, it should be understood that such amplification is optional and can be omitted depending on the power output requirements of the OPA laser 300.

[0291] The phase of the output beam 322, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 322. In many applications, such as... Figure 3A In the free-space optical communication illustrated, it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 300 by dynamically changing the relative phase of the individual sub-beams through the laser separation and combining subsystem 314, thereby changing the phase of the combined laser output 322, so as to dynamically control the position and shape of its far-field intensity pattern.

[0292] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern for transmission to receiver 303. Particularly preferably, a varying relative phase is applied by a phase control subsystem 330. The phase control subsystem 330 is preferably part of a control electronics module 332 in the OPA laser 300, and preferably controls each phase modulator 318 to dynamically modulate the relative phase of the sub-beams along channel 316.

[0293] The output beam 322 is noisy due to the inherent noise in the OPA system 300. With the presence of the optical amplifier 324 in the OPA system 300, the noise in the output beam 322 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. A specific feature of a preferred embodiment of the invention is that the laser system 300 includes a noise cancellation subsystem 340 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 322 in a manner detailed below.

[0294] Particularly preferably, the noise cancellation subsystem 340 employs an algorithm to sense and correct phase noise in the synthesized laser output. The noise-cancelled phase-corrected output is preferably provided by the noise cancellation subsystem 340 to the phase modulator 318 to correct phase noise in the output beam 322, and thus avoids distortion of the shape and position of the far-field intensity pattern of the output beam 322 that would otherwise be caused by noise. The noise cancellation subsystem 340 may be included in the control electronics module 332.

[0295] It should be understood that the output beam 322 may additionally or alternatively be affected by noise types other than phase noise, including intensity noise. In the case of intensity noise in the output beam 322, the noise cancellation subsystem 340 operates to provide a noise-cancelled phase-corrected output to eliminate the intensity noise in the output beam 322. In this case, the OPA laser system 300 may optionally additionally include an intensity modulator 342 along channel 316 for modulating the intensity of each of the sub-beams along channel 316.

[0296] It should be understood that the output beam 322 may additionally or alternatively be affected by mechanical noise, which may affect the relative positions of the sub-beams. In the case of position noise in the output beam 322, the noise cancellation subsystem 340 operates to provide a noise cancellation phase correction output to eliminate the position noise in the output beam 322. In this case, the OPA laser system 300 may optionally additionally include a position modulator 344 along channel 316 for modulating the position of each of the sub-beams along channel 316.

[0297] To facilitate the application of phase change and noise correction to the output beam 322, a portion of the output of the OPA laser 300 is preferably extracted and directed to at least one detector, shown herein as a single detector 350. Detector 350 may alternatively be embodied as multiple detectors, as will be referred to below. Figures 6 to 8 As detailed in 15 to 21. The extracted portion of the output beam preferably serves as a reference beam, and based on its characteristics, the required noise correction and / or phase change can be calculated. Figure 3AIn the illustrated embodiment, multiple sub-beams are guided along channel 316 to beam splitter 360. Beam splitter 360 preferably divides each sub-beam into a transmissive portion 362 and a reflective portion 364 according to a predetermined ratio. For example, beam splitter 360 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0298] The transmissive portion 362 of the sub-beam preferably propagates toward the focusing lens 320, where the sub-beam is combined to form an output beam 322 having a far-field intensity pattern 366. The reflective portion 364 of the sub-beam preferably reflects toward an additional focusing lens 368, where the sub-beam is combined to form an output reference beam 370 having a far-field intensity pattern 372 incident on the surface of the detector 350.

[0299] It should be understood that the specific structures and configurations of the beam splitting and recombining elements (including beam splitter 360 and focusing lenses 320 and 368) illustrated herein are exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 300 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0300] As described above, the shape and position of the far-field intensity pattern 366 of the output beam 322 and the corresponding far-field intensity pattern 372 of the reference beam 370 are constantly changing due to the continuous variation in the relative phase of the sub-beams. Therefore, the far-field intensity pattern 372 is not fixed to the detector 350, but rather moves continuously about the detector 350 depending on the relative phase of the composite of the sub-beams. However, in order for the detector 350 to provide the required noise-cancelled phase-corrected output, the far-field intensity pattern 372 must be incident on the detector 350 so that the detector measures the intensity of the far-field intensity pattern 372 and thus applies noise correction accordingly, thereby producing a fixed output beam.

[0301] In this invention, the conflict between the dynamic properties of the far-field intensity pattern 372 due to its phase variation and the fixed properties required by the far-field intensity pattern 372 for deriving and applying its noise correction is advantageously resolved by providing noise cancellation and phase variation at different times and rates.

[0302] A noise-cancelled phase-corrected output is provided based on noise measured by detector 350 at a noise sampling rate. The output beam 322 is controlled such that the shape and position of the output and reference far-field intensity patterns 366 and 372 are dynamically changed during a process in which they are incident on detector 350 at a rate equal to or higher than the desired noise sampling rate. Noise in the reference beam 370 is taken into account during the intervals during which the far-field intensity pattern 372 returns to detector 350.

[0303] During the time interval between the incident on the far-field intensity pattern 372 and the detector 350, the phase of the synthesized output beams 322 and 370 changes to dynamically alter the shape and position of their far-field intensity patterns as needed to perform additive manufacturing of article 206. The synthesized laser output changes phase at a rate exceeding the noise sampling rate to rapidly change the phase and thus alter the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be approximately 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0304] For reference Figure 3A The curves seen in graph 380 and Figure 3B The enlarged version illustrated in the figure best illustrates the different rates and time scales by which noise cancellation and phase change are preferably performed in embodiments of the invention.

[0305] like Figure 3B As most clearly seen, graph 380 includes an upper portion 382 and a lower portion 384, whereby the upper portion 382 shows the change in intensity over time of the far-field intensity pattern 372 as measured at detector 350, and the lower portion 384 shows the change in relative phase of the multiple sub-beams that contribute to the output beam 322 and the reference beam 370 within the same time period. For simplicity, graph 380 shows the relative phase of ten sub-beams, but it should be understood that the OPA system 300, and therefore the explanation provided herein, applies to fewer or more typically far greater numbers of sub-beams.

[0306] As seen in the upper section 382, ​​intensity peak 386 represents the measured intensity of the reference beam 370 as it passes the detector 350 in the far-field intensity pattern 372. As seen in the lower section 384, intensity peak 386 occurs during the interval T when the relative phase of each sub-beam is zero. i The presence of this feature indicates that there is no phase shift between the sub-beams, therefore the position of the synthesized output beam remains unchanged and the far-field intensity pattern 372 is directly incident on detector 350. It should be understood that detector 350 can alternatively be positioned such that the relative phase of the sub-beams is non-zero. Furthermore, more than one detector can be used to allow measurement of the far-field intensity pattern 372 at more than one location along it, and then referenced. Figures 6 to 8 Details are provided from 15 to 21.

[0307] Between intensity peaks 386, the measured intensity is close to zero because the far-field intensity pattern 372 has shifted to either side of the detector 350 and is therefore not directly incident on the detector 350. As understood from the upper portion 382, ​​the magnitude of intensity peak 386 is not constant due to noise in the laser output beam, which degrades the far-field intensity pattern 372.

[0308] As seen in section 384 below, the relative phase of the sub-beams during the interval T i The time interval T between between The phase change function shown in this paper plots the relative phase of the sub-beams as a periodically, regularly repeating pattern with equal phase shifts applied in both the positive and negative directions. It should be understood that this simplified pattern is merely illustrative and the phase change need not be regularly repeating, nor symmetrical in the positive and negative directions. Furthermore, it should be understood that the time interval T... between Preferably, but not necessarily not related to the interval time T i Overlap. Additionally, it should be understood that at least one of the phase change rate and the noise sampling rate may be constant or may vary over time.

[0309] The noise cancellation subsystem 340 takes into account the intermittent time T i Preferred to operate due to noise at the location, and based on the interval time T i The noise sensed at the point of detection provides a noise cancellation phase correction output. The noise cancellation subsystem 340 preferably employs an algorithm to sense noise and correct the sensed noise accordingly.

[0310] According to an exemplary embodiment of the present invention, the noise cancellation subsystem 340 employs an algorithm such that the relative phase of one of the channels varies with a given phase during each cycle of the far-field intensity pattern 372 traveling with respect to the detector 350. The way it is modified changes. After multiple such cycles, different phase changes occur. Applying the algorithm to the selected sub-beam in each cycle, the algorithm determines the maximum output intensity across all cycles and finds the optimal phase change that produces this maximum intensity. The phase change of the selected sub-beam is then fixed at the optimal phase change in subsequent periods. At this point, the algorithm proceeds to optimize another sub-bundle.

[0311] Graph 380 illustrates noise cancellation in three sub-bundles, or channels A, B, and C, out of a total of 10 sub-bundles according to this exemplary algorithm. For clarity, in Figure 3C Sub-bundles A, B, and C are displayed separately. It should be understood that, with... Figure 3A and 3B In comparison, Figure 3C The line shapes of the traces representing the phase changes and noise corrections of sub-bundles A, B, and C have been modified to aid in distinguishing between the various sub-bundles for explanatory purposes in the following text.

[0312] As initially observed in the case of channel A, and most clearly understood considering the enlarged view 390, the dashed line represents the pattern of relative phase variation in sub-beam A, as would be applied by the phase control subsystem 330 in the absence of any noise correction. This trace can be referred to as A. uncorrected The dotted line represents the actual relative phase of sub-bundle A after modification by a noise correction algorithm to find the optimal phase noise correction. This trace can be called A. corrected A corrected The modified relative phase is at different times in the first five periods of sub-bundle A. Regarding A uncorrected The unmodified relative phase shift. The intensity 386 measured at detector 350 varies within the first five cycles of sub-beam A optimization due to careful alteration of the relative phase shift.

[0313] After the first five cycles of sub-bundle A, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the second phase shift. The generated IA max Therefore, the phase change of the relative phase change applied to sub-beam A is fixed in the second phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle B.

[0314] It should be understood that during the continuous period of optimization of sub-bundle A, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle A.

[0315] As can be seen further in the case of sub-bundle B, and most clearly understood considering enlarged view 392, the coarser trace during the optimization of channel B represents the pattern of relative phase variation of sub-bundle B, as would be applied by phase control subsystem 330 in the absence of any noise correction. This trace may be referred to as B. uncorrected The finer trace during the optimization of channel B represents the actual relative phase of sub-bundle B, modified by a noise correction algorithm to find the optimal phase noise-corrected phase. This trace can be referred to as B. corrected B corrected The modified relative phase is at different times in the first five periods of the optimized sub-bundle B. Regarding B uncorrected The unmodified relative phase shift. The intensity 386 measured at detector 350 varies within the first five cycles of sub-bundle B optimization due to careful alteration of the relative phase shift.

[0316] After the first five cycles of sub-bundle B, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the fourth phase shift. The generated IAB max Therefore, the phase change of the relative phase change applied to sub-beam B is fixed at the fourth phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle C.

[0317] It should be understood that during the five cycles of optimization of sub-bundle B, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle B.

[0318] Preferably, a similar optimization process is performed for sub-bundle C, wherein the phase change The intensity reduction is applied over several cycles to optimize the output beam intensity and to correct the phase noise in the beam C.

[0319] Detector 350 can operate continuously to continuously optimize the relative phase of the sub-beams and correct for phase noise therein. However, due to the limited response time of detector 350, detector 350 only considers noise in the reference beam 370 at relatively slow noise sampling rates during intervals. The noise sampling rate is preferably, but not necessarily, predetermined. The noise sampling rate can alternatively be random.

[0320] It should be understood that the specific parameters of the noise correction algorithm depicted in graph 380 are merely exemplary and readily modifiable, as those skilled in the art will understand. For example, phase shift... Optimization can be performed over a number of periods more or fewer than those shown herein. Each sub-bundle can be fully optimized whenever the sub-bundle passes through detector 350, or several or all sub-bundles can be optimized during each period in which the far-field intensity pattern passes through detector 350. Furthermore, discontinuous noise correction optimization algorithms can be implemented alternatively, including but not limited to stochastic parallel gradient descent optimization algorithms.

[0321] Using dynamically shaped, noise-corrected optical phased array output beams in free-space optical communication is highly advantageous, enabling rapid beam steering, rapid power modulation, rapid beam focusing, and customized beam shape. Compared to conventional free-space optical communication methods, using dynamically shaped, noise-corrected optical phased array outputs improves both communication speed and quality. It should be understood that, according to a preferred embodiment of the invention, without noise correction, the shape and position of the optical phased array output beam will deteriorate, thereby reducing the quality, speed, and accuracy of the transmitted laser output.

[0322] To maintain output beam intensity as the far-field intensity pattern of the beam shifts, which is advantageous in certain optical communication applications, the movement of the output beam can be controlled so that the beam spends more time at lower intensity locations to compensate for the reduced power delivery there. Alternatively, an intensity profile mask, such as an ND filter, can be applied to the output beam to modify its intensity.

[0323] Now for reference Figure 4A This is a simplified schematic diagram of an optical phased array laser system for noise-corrected dynamic beamforming constructed and operated according to another preferred embodiment of the present invention; and referenced to Figure 4B and 4C , it is Figure 4A A simplified graphical representation of phase change and noise correction in a system of the type shown.

[0324] like Figure 4A As seen herein, an optical phased array (OPA) laser system 400 is provided, which is illustrated herein by way of example as being used within a laser welding system 402. The laser welding system 402 may include the OPA laser system 400 mounted on or within a portion of a laser welding robot 404. For example, an article 406 may be welded by the laser welding robot 404, as detailed below. It should be understood that although the laser welding system 402 is shown herein in the context of a welding robot 404, the system 402 can be adapted to any welding setup, as those skilled in the art will understand.

[0325] Referring preferably to enlarged Figure 410, the OPA laser 400 preferably includes a seed laser 412 and a laser beam splitting and combining subsystem 414. The splitting and combining subsystem 414 preferably receives the output laser beam from the seed laser 412 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 416. Here, by way of example only, the output from the seed laser 412 is illustrated as split into ten sub-beams along ten channels 416, but it should be understood that the splitting and combining subsystem 414 may include fewer or more channels along which the output of the seed laser 412 is split, and typically may include far more channels, such as 32 or more channels.

[0326] The relative phase of each sub-beam can be individually modulated by phase modulators 418 preferably positioned along each of the channels 416. Each phase-modulated sub-beam resulting from the separation and subsequent phase modulation of the output of the seed laser 412 preferably propagates toward collimating lens 419. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at focusing lens 420 to form output beam 422.

[0327] The separation and combining subsystem 414 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 412 is separated into sub-beams and before the sub-beams are combined to form the output beam 422. Here, for example, the separation and combining subsystem 414 is illustrated as including a plurality of optical amplifiers 424 positioned along corresponding channels in channel 416 for amplifying each sub-beam. However, it should be understood that such amplification is optional and can be omitted depending on the power output requirements of the OPA laser 400.

[0328] The phase of the output beam 422, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 422. In many applications, such as... Figure 4A In the laser welding process shown, it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in the laser system 400 by dynamically changing the relative phase of the individual sub-beams through the laser separation and synthesis subsystem 414, thereby changing the phase of the synthesized laser output 422, so as to dynamically control the position and shape of its far-field intensity pattern.

[0329] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern of the article 406 to be welded. Particularly preferably, a variable relative phase is applied by a phase control subsystem 430. The phase control subsystem 430 is preferably part of the control electronics module 432 in the OPA laser 400, and preferably controls each phase modulator 418 to dynamically modulate the relative phase of the sub-beams along the channel 416.

[0330] The output beam 422 has noise due to inherent noise in the OPA system 400. With the presence of the optical amplifier 424 in the OPA system 400, the noise in the output beam 422 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. A specific feature of a preferred embodiment of the invention is that the laser system 400 includes a noise cancellation subsystem 440 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 422 in a manner detailed below.

[0331] Particularly preferably, the noise cancellation subsystem 440 employs an algorithm to sense and correct phase noise in the synthesized laser output. The noise-cancelled phase-corrected output is preferably provided by the noise cancellation subsystem 440 to the phase modulator 418 to correct phase noise in the output beam 422, and thus avoids distortion of the shape and position of the far-field intensity pattern of the output beam 422 that would otherwise be caused by noise. The noise cancellation subsystem 440 may be included in the control electronics module 432.

[0332] It should be understood that the output beam 422 may additionally or alternatively be affected by noise types other than phase noise, including intensity noise. In the case of intensity noise in the output beam 422, the noise cancellation subsystem 440 operates to provide a noise-cancelled phase-corrected output to eliminate the intensity noise in the output beam 422. In this case, the OPA laser system 400 may optionally additionally include an intensity modulator 442 along channel 416 for modulating the intensity of each of the sub-beams along channel 416.

[0333] It should be understood that the output beam 422 may additionally or alternatively be affected by mechanical noise, which may affect the relative positions of the sub-beams. In the case of position noise in the output beam 422, the noise cancellation subsystem 440 operates to provide a noise cancellation phase correction output in order to eliminate the position noise in the output beam 422. In this case, the OPA laser system 400 may optionally additionally include a position modulator 444 along channel 416 for modulating the position of each of the sub-beams along channel 416.

[0334] To facilitate the application of phase change and noise correction to the output beam 422, a portion of the output of the OPA laser 400 is preferably extracted and directed to at least one detector, shown herein as a single detector 450. Detector 450 may alternatively be embodied as multiple detectors, as will be referred to below. Figures 6 to 8 As detailed in 15 to 21. The extracted portion of the output beam preferably serves as a reference beam, and based on its characteristics, the required noise correction and / or phase change can be calculated. Figure 4A In the illustrated embodiment, multiple sub-beams are guided along channel 416 to beam splitter 460. Beam splitter 460 preferably divides each sub-beam into a transmissive portion 462 and a reflective portion 464 according to a predetermined ratio. For example, beam splitter 460 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0335] The transmissive 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 incident on the article 406. The reflective 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 incident on the surface of the detector 450.

[0336] It should be understood that the specific structures and configurations of the beam splitting and recombining elements (including beam splitter 460 and focusing lenses 420 and 468) illustrated herein are exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 400 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0337] As described above, the shape and position of the far-field intensity pattern 466 of the output beam 422 and the corresponding far-field intensity pattern 472 of the reference beam 470 are constantly changing due to the continuous variation in the relative phase of the sub-beams. Therefore, the far-field intensity pattern 472 is not fixed to the detector 450, but rather constantly moves around about the detector 450 depending on the relative phase of the composite of the sub-beams. However, in order for the detector 450 to provide the required noise-cancelled phase-corrected output, the far-field intensity pattern 472 must be incident on the detector 450 so that the detector measures the intensity of the far-field intensity pattern 472 and thus applies noise correction accordingly, thereby producing a fixed output beam.

[0338] In this invention, the conflict between the dynamic properties of the far-field intensity pattern 472 due to its phase changes and the fixed properties required by the far-field intensity pattern 472 for deriving and applying its noise correction is advantageously resolved by providing noise cancellation and phase changes at different times and rates.

[0339] A noise-cancelled phase-corrected output is provided based on noise measured by detector 450 at a noise sampling rate. The output beam 422 is controlled such that the shape and position of the output and reference far-field intensity patterns 466 and 472 are dynamically changed during a process in which they are incident on detector 450 at a rate equal to or higher than the desired noise sampling rate. Noise in the reference beam 470 is taken into account during the interval during which the far-field intensity pattern 472 returns to detector 450.

[0340] During the time interval between the incident on far-field intensity pattern 472 and the detector 450, the phase of the synthesized output beams 422 and 470 changes to dynamically alter the shape and position of their far-field intensity patterns as needed to perform laser welding on article 406. The synthesized laser output changes phase at a rate exceeding the noise sampling rate to rapidly change the phase and thus alter the shape and position of the far-field intensity pattern. For example, the noise sampling rate may be approximately 10 to 1000 Hz, while the phase change rate may be greater than 10,000 Hz.

[0341] For reference Figure 4A The curves seen in graph 480 and Figure 4BThe enlarged version illustrated in the figure best illustrates the different rates and time scales by which noise cancellation and phase change are preferably performed in embodiments of the invention.

[0342] like Figure 4B As most clearly seen, graph 480 includes an upper portion 482 and a lower portion 484, whereby the upper portion 482 shows the change in intensity over time of the far-field intensity pattern 472 as measured at detector 450, and the lower portion 484 shows the change in relative phase of the multiple sub-beams that contribute to the output beam 422 and the reference beam 470 within the same time period. For simplicity, graph 480 shows the relative phase of ten sub-beams, but it should be understood that the OPA system 400, and therefore the explanation provided herein, applies to fewer or more typically far greater numbers of sub-beams.

[0343] As seen in the upper section 482, intensity peak 486 represents the measured intensity of the reference beam 470 as it passes the detector 450 in the far-field intensity pattern 472. As seen in the lower section 484, intensity peak 486 occurs during the interval T when the relative phase of each sub-beam is zero. i The presence of this pattern indicates that there is no phase shift between the sub-beams, therefore the position of the synthesized output beam remains unchanged and the far-field intensity pattern 472 is directly incident on detector 450. It should be understood that detector 450 can alternatively be positioned such that the relative phase of the sub-beams is non-zero. Furthermore, more than one detector can be used to allow measurements of the far-field intensity pattern 472 at more than one location along it, and then referenced. Figures 6 to 8 Details are provided from 15 to 21.

[0344] Between intensity peaks 486, the measured intensity is close to zero because the far-field intensity pattern 472 has shifted to either side of detector 450 and is therefore not directly incident on detector 450. As understood from the upper portion 482, the magnitude of intensity peak 486 is not constant due to noise in the laser output beam, which degrades the far-field intensity pattern 472.

[0345] As seen in section 484 below, the relative phase of the sub-beams during the interval T i The time interval T between between The phase change function shown in this paper plots the relative phase of the sub-beams as a periodically, regularly repeating pattern with equal phase shifts applied in both the positive and negative directions. It should be understood that this simplified pattern is merely illustrative and the phase change need not be regularly repeating, nor symmetrical in the positive and negative directions. Furthermore, it should be understood that the time interval T... between Preferably, but not necessarily not related to the interval time T iOverlap. Additionally, it should be understood that at least one of the phase change rate and the noise sampling rate may be constant or may vary over time.

[0346] The noise cancellation subsystem 440 takes into account the intermittent time T i Preferred to operate due to noise at the location, and based on the interval time T i The noise sensed at the noise level provides a noise cancellation phase correction output. The noise cancellation subsystem 440 preferably employs an algorithm to sense noise and correct the sensed noise accordingly.

[0347] According to an exemplary embodiment of the present invention, the noise cancellation subsystem 440 employs an algorithm such that the relative phase of one of the channels varies with a given phase during each cycle of the far-field intensity pattern 472 traveling with respect to the detector 150. The way it is modified changes. After multiple such cycles, different phase changes occur. Applying the algorithm to the selected sub-beam in each cycle, the algorithm determines the maximum output intensity across all cycles and finds the optimal phase change that produces this maximum intensity. The phase change of the selected sub-beam is then fixed at the optimal phase change in subsequent periods. At this point, the algorithm proceeds to optimize another sub-bundle.

[0348] Graph 480 illustrates noise cancellation in three of the total ten sub-bundles, or channels A, B, and C, according to this exemplary algorithm. For clarity, in Figure 4C Sub-bundles A, B, and C are displayed separately. It should be understood that, with... Figure 4A and 4B In comparison, Figure 4C The line shapes of the traces representing the phase changes and noise corrections of sub-bundles A, B, and C have been modified to aid in distinguishing between the various sub-bundles for explanatory purposes in the following text.

[0349] As initially observed in the case of channel A, and most clearly understood considering the enlarged view 490, the dashed line represents the pattern of relative phase variation in sub-beam A, as would be applied by the phase control subsystem 430 in the absence of any noise correction. This trace can be referred to as A. uncorrected The dotted line represents the actual relative phase of sub-bundle A after modification by a noise correction algorithm to find the optimal phase noise correction. This trace can be called A. corrected A corrected The modified relative phase is at different times in the first five periods of sub-bundle A. Regarding A uncorrected The unmodified relative phase shift. The intensity 486 measured at detector 450 varies within the first five cycles of sub-beam A optimization due to careful alteration of the relative phase shift.

[0350] After the first five cycles of sub-bundle A, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the second phase shift. The generated IA max Therefore, the phase change of the relative phase change applied to sub-beam A is fixed in the second phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle B.

[0351] It should be understood that during the continuous period of optimization of sub-bundle A, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle A.

[0352] As can be seen further in the case of sub-bundle B, and most clearly understood considering enlarged Figure 492, the coarser trace during the optimization of channel B represents the pattern of relative phase variation of sub-bundle B, as would be applied by the phase control subsystem 430 in the absence of any noise correction. This trace may be referred to as B. uncorrected The finer trace during the optimization of channel B represents the actual relative phase of sub-bundle B, modified by a noise correction algorithm to find the optimal phase noise-corrected phase. This trace can be referred to as B. corrected B corrected The modified relative phase is at different times in the first five periods of the optimized sub-bundle B. Regarding B uncorrected The unmodified relative phase shift. The intensity 486 measured at detector 450 varies within the first five cycles of sub-bundle B optimization due to careful alteration of the relative phase shift.

[0353] After the first five cycles of sub-bundle B, the algorithm determines the maximum intensity and identifies the phase change that produces the maximum intensity. In this case, the maximum intensity is considered to be due to the fourth phase shift. The generated IAB max Therefore, the phase change of the relative phase change applied to sub-beam B is fixed at the fourth phase shift in subsequent periods. At this point, the algorithm proceeds to optimize sub-bundle C.

[0354] It should be understood that during the five cycles of optimization of sub-bundle B, the relative phase of the rest of the sub-bundle changes as usual, each at a phase change rate that is far greater than the noise sampling rate taking into account the noise in sub-bundle B.

[0355] Preferably, a similar optimization process is performed for sub-bundle C, wherein the phase change The intensity reduction is applied over several cycles to optimize the output beam intensity and to correct the phase noise in the beam C.

[0356] Detector 450 can operate continuously to continuously optimize the relative phase of the sub-beams and correct for phase noise therein. However, due to the limited response time of detector 450, detector 450 only considers noise in the reference beam 470 at relatively slow noise sampling rates during intervals. The noise sampling rate is preferably, but not necessarily, predetermined. The noise sampling rate can alternatively be random.

[0357] It should be understood that the specific parameters of the noise correction algorithm depicted in graph 480 are merely exemplary and can be easily modified, as those skilled in the art will understand. For example, phase shift... Optimization can be performed over a number of periods more or fewer than those shown herein. Each sub-bundle can be fully optimized whenever the sub-bundle passes through detector 450, or several or all sub-bundles can be optimized during each period in which the far-field intensity pattern passes through detector 450. Furthermore, discontinuous noise correction optimization algorithms can be implemented alternatively, including but not limited to stochastic parallel gradient descent optimization algorithms.

[0358] Using dynamically shaped, noise-corrected optical phased array output beams in laser welding is highly advantageous, enabling rapid beam steering, rapid power modulation, rapid beam focusing, and customized beam shape. Compared to conventional laser cutting methods, using dynamically shaped, noise-corrected optical phased array outputs improves both the speed and quality of the cuttable material. It should be understood that, according to a preferred embodiment of the invention, without noise correction, the shape and position of the optical phased array output beam will deteriorate, thereby reducing the quality, speed, and accuracy of the laser cutting process.

[0359] To maintain output beam intensity as the far-field intensity pattern of the beam shifts, which is advantageous in certain laser cutting applications, the movement of the output beam can be controlled so that the beam spends more time at lower intensity locations to compensate for the reduced power delivery there. Alternatively, an intensity profile mask, such as an ND filter, can be applied to the output beam to modify its intensity.

[0360] Now for reference Figure 5A to 5G , it is Figures 1A to 4C A simplified illustration of possible far-field motions of the output of an optical phased array laser system of the type shown.

[0361] As detailed above, the use of dynamically shaped noise-corrected optical phased array output beams in various laser applications (including but not limited to laser cutting, laser additive manufacturing, laser welding, and laser free-space optical communication) is highly advantageous, enabling rapid beam steering, rapid power modulation, rapid beam focusing, and customized beam shape. Figure 5A and 5BThe diagram illustrates exemplary far-field patterns of rapid beam steering according to embodiments of the present invention. These beam steering patterns can be provided in conjunction with and to complement mechanical spatial modulation of the beam (e.g., mechanical beam steering). Mechanical beam steering can be attributed to... Figure 1A The motion provided by the positioning stage 104 illustrated in the figure is attributed to mirror scanning, for example in... Figure 2A In additive manufacturing systems of the type shown; attributed to Figure 3A The mechanical movement between the laser system 300 and the receiver 303 is illustrated in the figure; attributed to the mechanical movement between the laser system 300 and the receiver 303. Figure 4A The motion provided by the robot 404 illustrated in the figure; or attributable to any other source of mechanical motion.

[0362] The mechanical motion can be desired or undesired. Preferably, the far-field rapid beam steering provided by embodiments of the invention supplements the mechanical motion to achieve the desired composite beam motion. The desired composite motion can be faster and / or more precise than motion produced solely as a result of mechanical beam modulation.

[0363] like Figure 5A As seen, the output beam of the dynamically shaped noise-corrected optical phased array can exhibit rapid multi-point hopping, as shown in the first beam path 502, which is attributed to the mechanical scanning represented by the second beam path 504, and the rapid multi-point hopping complements the beam motion.

[0364] For example, this type of multi-point hopping can be advantageous in materials processing, where time is spent absorbing energy at each point in the material to be processed. Multi-point hopping allows the beam to hop between points and return to each point multiple times, thus facilitating parallel processing of multiple points. As a further example, this type of multi-point hopping can be advantageous in communication systems by allowing parallel transmission to multiple locations.

[0365] like Figure 5B As seen, the use of dynamically shaped, noise-corrected optical phased array output beams also facilitates rapid scanning, as shown in the third beam path 506, attributed to a mechanical scan represented by the fourth beam path 508, which complements the beam motion. This rapid scanning contributes to continuous, smooth mechanical beam motion, which, according to embodiments of the invention, can be provided with fine features through far-field dynamic shaping. Furthermore, dynamic noise-corrected far-field modulation can be provided in conjunction with the mechanical beam motion to correct for any inaccuracies that may exist in the mechanically modulated beam pattern.

[0366] Figure 5C The diagram illustrates an exemplary far-field beam pattern of electro-optic beam oscillation according to a preferred embodiment of the present invention. Figure 5CAs seen, the output beam of the dynamically shaped, noise-corrected optical phased array is controlled to exhibit rapid beam oscillation 510 along the beam motion direction 512, for example in... Figure 4A The laser welding system shown is particularly useful.

[0367] Figures 5D to 5F The diagram illustrates an exemplary far-field beam pattern with dynamic modification of the focusing depth according to a preferred embodiment of the present invention. Figures 5D to 5F As seen in the invention, the depth of beam focusing can be dynamically varied by the system of the present invention, thereby allowing for variable beam focal length for scanning. Figure 5E And used for deep cutting ( Figure 5D and 5F ), for example in Figure 1A , 2A It is particularly useful in cutting, additive manufacturing, and welding systems of the type shown in 4A.

[0368] Figure 5G The diagram illustrates an exemplary far-field beam pattern of dynamic beamforming according to a preferred embodiment of the present invention. Figure 5G As seen in the diagram, the shape of the beam can be dynamically changed to produce the desired beam shape output. This is, for example, in... Figure 1A , 2A This invention may be particularly useful in cutting, additive manufacturing, and welding systems of the type shown in 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 laser beam. This invention allows the beam to be dynamically adapted to an optimal shape at any point.

[0369] It should be understood that Figure 5A to 5G The various far-field beam motion patterns shown are all preferably generated by the system of the present invention using digital electronic controls without requiring any moving parts.

[0370] Now for reference Figure 6 This is a simplified schematic diagram of an optical phased array laser system constructed and operated according to a preferred embodiment of the present invention, comprising multiple detectors and corresponding multiple closely spaced optical paths.

[0371] like Figure 6 As seen herein, an optical phased array (OPA) laser 600 is provided. The OPA laser 600 can typically be... Figures 1A to 4CThe laser beam splitting and combining subsystem 614 is of the type shown in any of the examples, and preferably includes a seed laser 612 and a laser beam splitting and combining subsystem 614. The splitting and combining subsystem 614 preferably receives the output laser beam from the seed laser 612 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 616. Here, by way of example only, the output from the seed laser 612 is illustrated as split into four sub-beams along ten channels 616, but it should be understood that the splitting and combining subsystem 614 may include fewer or more channels along which the output of the seed laser 612 is split, and typically may include far more channels, such as 32 or more channels.

[0372] The relative phase of each sub-beam can be individually modulated by phase modulators 618 preferably positioned along each of the channels 616. Each phase-modulated sub-beam, generated by the separation and subsequent phase modulation of the output of the seed laser 612, preferably propagates toward the collimating lens 619. Subsequently, the individually collimated phase-modulated sub-beams are combined, for example, at the focusing lens 620 to form the output beam 622.

[0373] The separation and combining subsystem 614 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 612 is separated into sub-beams and before the sub-beams are combined to form the output beam 622. Here, for example, the separation and combining subsystem 614 is illustrated as including a plurality of optical amplifiers 624 positioned along corresponding channels in channel 616 for amplifying each sub-beam. However, it should be understood that, depending on the power output specifications of the OPA laser 600, this amplification is optional and can be omitted.

[0374] The phase of the output beam 622, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 622. (Refer to the above text) Figure 1A to 5G As described, in various applications (such as laser cutting, laser welding, laser additive manufacturing, and optical free-space communication), it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. This can be achieved in laser system 600 by dynamically changing the relative phase of individual sub-beams through laser separation and combining subsystem 614, thereby changing the phase of the combined laser output 622, in order to dynamically control the position and shape of its far-field intensity pattern.

[0375] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern. Particularly preferably, a varying relative phase is applied via a phase control subsystem 630. The phase control subsystem 630 is preferably part of the control electronics module 632 in the OPA laser 600 and preferably controls each phase modulator 618 to dynamically modulate the relative phase of the sub-beams along the channel 616, as referred to above respectively. Figure 1A , 2AThe phase control subsystems 130, 230, 330, and 430 of 3A and 4A are described.

[0376] The output beam 622 is noisy due to inherent noise in the OPA system 600. With the presence of the optical amplifier 624 in the OPA system 600, the noise in the output beam 622 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. The OPA system 600 preferably includes a noise cancellation subsystem 640 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 622 in a manner detailed below.

[0377] Particularly preferably, the noise cancellation subsystem 640 employs an algorithm to sense and correct phase noise in the synthesized laser output, which preferably, but not necessarily, belongs to the category mentioned above. Figures 1A to 4C The type described. The noise cancellation phase correction output is preferably provided by the noise cancellation subsystem 640 to the phase modulator 618 to correct 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 noise. The noise cancellation subsystem 640 may be included in the control electronics module 632.

[0378] To facilitate the application of phase changes and noise corrections to the output beam 622, a portion of the output of the OPA laser 600 is preferably extracted and directed to multiple detectors 650. The extracted portion of the output beam preferably serves as a reference beam, based on which the required noise corrections and / or phase changes can be calculated.

[0379] According to a preferred embodiment of the invention, a plurality of sub-beams are guided along channel 616 to beam splitter 660. Beam splitter 660 preferably divides each sub-beam into a transmissive portion 662 and a reflective portion 664 according to a predetermined ratio. For example, beam splitter 660 can separate each sub-beam with a 99.9% transmittance: 0.01% reflectance ratio.

[0380] The transmissive portion 662 of the sub-beam preferably propagates toward the focusing lens 620, where the sub-beams are combined to form an output beam 622 having a far-field intensity pattern 666. The reflective portion 664 of the sub-beam preferably reflects toward an additional focusing lens 668, where the sub-beams are combined to form an output reference beam 670 having a far-field intensity pattern 672 incident on one or more surfaces of a plurality of detectors 650.

[0381] As referenced above Figures 1A to 4CAs described, the noise-cancelled phase-corrected output is preferably provided based on noise measured by detector 650 at a noise sampling rate. The output beam 622 is controlled such that the shape and position of the output and reference far-field intensity patterns 666, 672 are dynamically changed during a process in which they are incident on detector 650 at a rate equal to or higher than the desired noise sampling rate. Noise in the reference beam 670 is taken into account during the interval during which the far-field intensity pattern 672 returns to detector 650.

[0382] During the time interval between the incident on far-field intensity pattern 672 and the incident on detector 650, the phase of the synthesized output beams 622 and 670 occurs to dynamically change the shape and position of their far-field intensity patterns. The synthesized laser output changes phase at a rate exceeding the noise sampling rate to rapidly change the phase and thus the shape and position of the far-field intensity patterns. Therefore, noise cancellation and phase change are preferably provided at different times and rates than each other.

[0383] It has been found that using multiple detectors 650 instead of a single detector in certain embodiments of the invention is highly advantageous, resulting in various advantages detailed below. However, given the relatively short focal length of the additional focusing lens 668, some of the multiple detectors 650 will preferably need to be positioned very close to each other, as desired in forming the system 600 in a compact manner. The required inter-detector spacing can be several micrometers. This high spatial density arrangement of the detectors 650 is generally impractical, especially when the size of conventional detectors is much larger than the preferred inter-detector spacing.

[0384] To allow high spatial density sampling of the far-field intensity pattern 672 by multiple detectors 650, the OPA system 600 preferably includes multiple optical paths, exemplified herein by way of example as multiple optical fibers 680 correspondingly coupled to the multiple detectors 650. A reference beam 670 preferably enters one or more of the multiple open ends 682 of the optical fiber 680 and propagates along the optical fiber 680 to a corresponding detector in the detector 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 in the optical fiber 680 is smaller than the spacing between corresponding adjacent detectors in the detector 650. This allows the detectors 650 to detect the far-field intensity pattern 672 at close intervals without requiring the detectors 650 themselves to be physically located at a small-pitch position for sampling the far-field intensity pattern 672.

[0385] For example, the ends 682 of the optical fiber 680 may be spaced several micrometers apart, while the detectors 650 of the corresponding optical fibers coupled into the optical fiber 680 may be spaced several millimeters apart. It should be understood that this arrangement allows the use of conventional detectors in the system 600 and avoids the need for expensive and complex miniaturized detection systems.

[0386] It has been found that, in a preferred embodiment of the invention, it is highly advantageous to include a plurality of detectors 650 that are effectively closely spaced, such as those facilitated by the actual physical close spacing of the ends 682 of the optical fiber 680. Specifically, as Figure 1A , 2A As shown in Figures 3A and 4A, using multiple detectors 650 instead of a single detector 150 allows the far-field intensity pattern 672 to be sampled at multiple locations rather than just a single location. This facilitates more efficient and / or more frequent noise correction during dynamic changes in the output beam 622.

[0387] It should be understood that multiple closely spaced optical paths are not limited to multiple optical fibers 680 having very closely spaced ends 682, wherein the end-to-end spacing between the optical fibers is less than the inter-detector spacing of the detectors 650. In fact, the scope of the invention extends to include any suitable multiple optical paths that can deliver a far-field intensity reference pattern 672 to multiple detectors 650 and can be arranged with a sufficiently high spatial density.

[0388] For example, multiple closely spaced optical paths can be represented as follows: Figure 7 The multiple lenses 780 shown are illustrated. These lenses 780 can be very closely spaced to focus portions of the far-field intensity reference pattern 672 toward multiple, less closely spaced detectors 650. Further, for example, multiple closely spaced optical paths can be embodied as... Figure 8 The diagram shows multiple mirrors 880 that cooperate with the multiple lenses 882. The multiple mirrors 880 can be spaced very closely so that portions of the far-field intensity reference pattern 672 are reflected toward multiple less closely spaced detectors 650.

[0389] It should be understood that multiple detectors can be included. Figures 6 to 8 Any of the OPA laser systems of the type shown in the examples are incorporated into Figure 1A , 2A In any of the OPA laser systems of the type shown in 3A and 4A, to provide more efficient and / or more frequent noise correction to their phase-change output.

[0390] Now for reference Figure 9This is a simplified schematic diagram of an optical phased array laser system comprising a detector mask configured according to an exemplary laser beam trajectory, constructed and operated according to a preferred embodiment of the present invention.

[0391] like Figure 9 As seen herein, an optical phased array (OPA) laser 900 is provided. Except for the use of a detector arrangement therein, the OPA laser 900 is generally similar in its relevant aspects to... Figure 6 The OPA laser 600. Although the OPA laser 600 preferably employs multiple detectors that receive the output beam by means of corresponding multiple closely spaced optical paths, the OPA laser 900 need not employ more than one detector.

[0392] Figure 9 A specific feature of the preferred embodiment of the invention shown is that the OPA laser 900 preferably includes an optical mask 980 having at least one transmission region 982 for providing an output reference beam 670 passing through it to at least one detector 650, shown herein as including a single detector 650. The optical mask 980 is preferably an optically opaque element that transmits the beam 670 only in the transmission region 982. Here, for example, the transmission region 982 is illustrated as being formed as a star-shaped transmission path, constructed according to the star-shaped trajectory of the output and reference far-field intensity patterns 666, 672.

[0393] The output reference beam 670 is preferably transmitted through the transmission region 982 and focused onto the detector 650 (here exemplified by the focusing lens 990) by means of a focusing subsystem. Preferably, a noise-cancelled phase-corrected output is provided by a noise cancellation subsystem 630 based on the intensity of the far-field intensity pattern 672, which takes into account the focusing and the intensity incident on the detector 650.

[0394] 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 pass through predetermined trajectories, such as star-shaped trajectories corresponding to the shape of the star-shaped transmission region 982. In the absence of noise in the OPA laser 900, the trajectories traversed by the output and reference beams 622 and 670 will at least almost perfectly correspond to the shape of the transmission region 982, such that the intensity of the far-field intensity pattern 672, as detected by the detector 650, will be at its maximum, non-degraded intensity. However, due to the presence of noise in the output and reference beams 622 and 670, the trajectory and shape of the far-field intensity pattern 672 may deviate slightly from the shape of the transmission region 982, such that a portion of the reference beam 670 is incident on the opaque area of ​​the mask 980 instead of the transmission region 982, and therefore does not pass through the transmission region 982 to the detector 650. In this case, the intensity of the far-field intensity pattern 672, as detected by the detector 650, is lower than the maximum intensity that would be detected in the absence of noise.

[0395] Therefore, a decrease in the intensity of the far-field intensity pattern 672, as measured by detector 650, preferably indicates noise-induced distortion of the trajectories of the output and reference beams 622, 670, and can thus be used to derive the desired noise-cancelled phase-corrected output to be applied by noise cancellation subsystem 640.

[0396] It should be understood that the above arrangement of the detector 650 positioned behind the mask 980 only allows for a single detector 650 to sense the output intensity of the reference beam 670 along its trajectory, and the noise cancellation phase correction output can be applied based on said output intensity. This contrasts with alternative detector arrangements that do not include the mask 980, such as those mentioned above. Figures 6 to 8 The described detector arrangement includes multiple detectors to provide sufficiently effective and / or frequent noise correction during dynamic changes in the output beam 622.

[0397] In addition to the intensity variation of the reference beam 670 due to noise-induced distortion of the beam trajectory, as measured by detector 650, the intensity of the reference beam 670 can typically vary along its trajectory due to inherent intensity variations in the far-field intensity pattern 672. Since the intensity variation of the reference beam 670 can be attributed to noise or inherent intensity variations unrelated to noise, this can complicate the noise correction feedback provided by detector 650.

[0398] 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 a region of varying transparency, and its transparency level may be set to compensate for the inherent intensity variation in the reference beam 670 along its trajectory.

[0399] Figure 10The image shows a simplified representation of the height of the transmission area 982 of a mask 980 with uneven transparency. (See image for details.) Figure 10 As seen, the first portion of the transmission region 982, defined between its first point P1 and second point P2, may have a first transparency T1; the second portion of the transmission region 982, defined between its second point P2 and third point P3, may have a second transparency T2 different from the first transparency T1; the third portion of the transmission region 982, defined between its third point P3 and fourth point P4, may have a first transparency T1; the fourth portion of the transmission region 982, defined between its fourth point P4 and fifth point P5, may have a third transparency T3 different from the first and second transparencys T1 and T2; and the fifth point of the transmission region 982, defined between its fifth point P5 and its first point P1, may have a second transparency T2.

[0400] It should be understood that, according to the intensity compensation requirements of the far-field intensity pattern 672, each part of the transmission area 982 may have discretely different transparency values, or the transparency of the transmission area 982 may gradually change in a gradient manner across its various parts.

[0401] Preferably, although not strictly necessary, the mask 980 is an electronically modulated device, such as an LCD screen or similar device. The properties of the transmissive region 982 can therefore be easily modified electronically according to the output characteristics of the reference beam 670.

[0402] It should be understood that Figure 9 and 10 The specific shape of the transmission region 982 shown is merely exemplary and can be configured according to any trajectory of the output and reference far-field intensity patterns 666 and 672. Furthermore, it should be understood that the transmission region 982 may include more than one transmission region. In this case, a single detector 650 may be used to receive light from all transmission regions, or a corresponding number of detectors may be positioned with respect to each transmission region.

[0403] Furthermore, it should be understood that the transmission region 982 may be configured, alternatively or otherwise, according to the shape of the output and reference far-field intensity patterns 666 and 672 rather than their trajectories, as in the reference... Figure 11 and 12 Detailed explanation.

[0404] Now for reference Figure 11 This is a simplified schematic diagram of an optical phased array laser system comprising a detector mask configured according to an exemplary laser beam shape, constructed and operated according to another preferred embodiment of the present invention.

[0405] like Figure 11 What is seen here, replacing Figure 9 and 10The optical mask 980, generally similar in its relevant respects to system 900, may include an optical mask 1180 having at least one transmission region 1182. Except that the transmission region 1182 is constructed according to the shape of the reference beam 670 rather than its trajectory, the optical mask 1180 may be similar to the optical mask 980 in all relevant respects. Here, for example, the transmission region 1182 is depicted as a bowtie-shaped transmission region, constructed according to bowtie-shaped output and reference far-field intensity patterns 666 and 672.

[0406] Transmitting region 1182 may have non-uniform transparency, and its highly simplified representation is shown in Figure 12 In the middle. For example Figure 12 As seen above, the first portion of the transmission region 1182 may have a first transparency T1, and the second portion of the transmission region 1182 may have a second transparency T2 that is different from the first transparency T1. (See above reference...) Figure 10 In detail, various levels of transparency of the transmission region 1182 can be used to compensate for inherent intensity variations in the output beam 670, and thus improve the noise-corrected output based on the intensity detected at detector 650.

[0407] It should be understood that the transmission regions 982 and 1182 of masks 980 and 1180 can, alternatively or otherwise, be embodied as reflection regions, which will reflect the output reference beam 670 obtained therefrom toward detector 650. In this arrangement, appropriate modifications and / or additions will be needed to the focusing subsystem (embodied herein by way of example as focusing lens 990) to guide the output reference beam 670 from the reflection regions 982, 1182 onto the surface of detector 650. The reflection regions of masks 980 and 1180 may have uniform reflectivity. Alternatively, the reflection regions of masks 980 and 1180 may have non-uniform reflectivity to compensate for inherent intensity variations in the output reference beam 670, as described above.

[0408] When masks 980 and 1180 include reflective areas, masks 980 and 1180 may be embodied as electrical modulation devices, such as digital micromirror devices (DMDs) or other similar devices.

[0409] It should be understood that it can be Figures 9 to 12 An OPA laser system of any of the types shown in the diagram (including at least one detector that receives the output reference beam via a transmission or reflection optical mask) is incorporated into Figure 1A , 2A In any of the OPA laser systems of the type shown in 3A and 4A, to provide more efficient noise correction to its phase-change output.

[0410] Now for reference Figure 13This is a simplified schematic diagram of an optical phased array laser system including voltage-phase correlation function constructed and operated according to a preferred embodiment of the present invention.

[0411] like Figure 13 As seen in the above reference, an OPA laser system 1300 is provided. The OPA laser 1300 may belong to a category generally similar to the one described above. Figures 1A to 4C The OPA lasers described are of types 100, 200, 300, and 400. OPA laser 1300 preferably includes a seed laser 1312 and a laser beam splitting and combining subsystem 1314. The splitting and combining subsystem 1314 preferably receives the output laser beam from the seed laser 1312 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 1316.

[0412] The relative phase of each sub-beam can be individually modulated by phase modulators 1318 preferably positioned along each of the channels 1316. Each phase-modulated sub-beam resulting from the separation and subsequent phase modulation of the output of the seed laser 1312 preferably propagates toward collimating lens 1319. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at the focal plane of lens 1320 to form output beam 1322.

[0413] The separation and combining subsystem 1314 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 1312 is separated into sub-beams and before the sub-beams are combined to form the output beam 1322. Here, for example, the separation and combining subsystem 1314 is illustrated as including a plurality of optical amplifiers 1324 positioned along corresponding channels in channel 1316 for amplifying each sub-beam. However, it should be understood that, depending on the power output specifications of the OPA laser 1300, this amplification is optional and can be omitted.

[0414] The phase of the output beam 1322, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 1322. In many applications (such as laser cutting, laser welding, optical free-space communication, and laser additive manufacturing described above), it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. (Refer to above...) Figures 1A to 4C As described, the parameters of the output beam can be dynamically varied by dynamically changing the relative phase of the individual sub-beams along channel 1316 and thereby changing the phase of the synthesized laser output 1322, so as to dynamically control the position and shape of its far-field intensity pattern.

[0415] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern. Particularly preferably, a varying relative phase 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 the desired phase modulation of the sub-beams along the channel 1316. It should be understood that a particularly preferred embodiment of the phase modulation control module 1330 combined with the phase modulator 1318 forms a phase modulation subsystem 1332, which preferably operates to change the phase of the synthesized laser output 1322.

[0416] To facilitate the application of a phase change to the output beam 1322, a portion of the output of the OPA laser 1300 is preferably extracted and directed to at least one detector 1350. The extracted portion of the output beam preferably serves as a reference beam, based on which the desired phase change can be calculated. Figure 13 In the illustrated embodiment, multiple sub-beams are guided along channel 1316 to beam splitter 1360. Beam splitter 1360 preferably divides each sub-beam into a transmissive portion 1362 and a reflective portion 1364 according to a predetermined ratio. For example, beam splitter 1360 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0417] The transmissive portion 1362 of the sub-beam preferably propagates toward the focusing lens 1320, where the sub-beams are combined to form an output beam 1322 having a far-field intensity pattern 1366. The reflective portion 1364 of the sub-beam preferably propagates toward an additional focusing lens 1368, where the sub-beams are combined to form an additional reference beam 1370 having a far-field intensity pattern 1372 incident on the surface of the detector 1350.

[0418] Detector 1350 preferably samples the far-field intensity pattern 1372 incident upon it. It should be understood that although detector 1350... Figure 13 The image shows a single detector that directly receives the far-field intensity pattern 1372, but according to... Figures 6 to 8 Any of the multiple detector arrangements shown in any of the examples may alternatively employ multiple detectors. Alternatively, according to Figures 9 to 12 Any of the configurations shown in any of the examples can be combined with an optical mask to employ a single detector, such as detector 1350.

[0419] In cooperation with the phase modulation subsystem 1332, the detector 1350 then preferably optimizes the relative phase of the sub-beams to obtain the 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 those referenced above. Figures 1A to 4CThe phase optimization scheme is described.

[0420] 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 modulators 1318 thus produce a phase modulation output corresponding to the applied voltage. It should be understood that in order for the phase modulators 1318 to produce the desired phase shift in order to dynamically shape the far-field intensity pattern 1366 according to a predetermined pattern, the phase modulation control module 1330 must accurately apply a voltage to each phase modulator 1318 corresponding to the specific phase modulation output required to be produced by each phase modulator 1318.

[0421] To ensure that the voltage applied to the phase modulator 1318 via the phase modulation control module 1330 produces the desired and expected phase modulation output through the phase modulator 1318, the OPA laser 1300 preferably includes a voltage-phase correlation subsystem 1380. The voltage-phase correlation subsystem 1380 is preferably operated such that the voltage applied to the phase modulation subsystem 1332 is correlated with the phase modulation output produced by the phase modulation subsystem 1332 (and more precisely by its phase modulator 1318).

[0422] Furthermore, the voltage-phase correlation subsystem 1380 preferably operates to provide a voltage-phase correlation output suitable for calibrating the phase modulation subsystem 1332. Preferably, the voltage-phase correlation subsystem periodically performs a correlation between the voltage and the phase modulation output during the process of phase change of the synthesized laser output 1322.

[0423] It should be understood that including correlation and calibration subsystems (e.g., voltage-phase correlation subsystem 1380 in OPA laser 1300) is highly advantageous because it ensures that the voltage applied to phase modulator 1318 is actually those required to generate the desired phase shift of output beam 1322 and thus the shape of far-field intensity pattern 1366. It is particularly important that the phase modulators suitable for the preferred embodiments of the invention are typically highly sensitive devices, where different devices exhibit different voltage-phase relationships. Furthermore, the voltage-phase relationship of an individual phase modulator is not constant but can vary over time and in response to operating conditions.

[0424] It should be understood that when the output of laser 1300 is noisy, it is preferable, but not necessary, that the phase modulation and calibration, along with the noise correction, provided by phase modulation control module 1330 and voltage-phase correlation control module 1380 respectively, are applied to the output of OPA laser 1300 in a coordinated manner. In this case, phase modulation control module 1330 and voltage-phase correlation control module 1380 can be considered as a combined phase control subsystem (e.g., phase control subsystem 130...). Figure 1A ), 230 Figure 2A ), 330 Figure 3A ) and 430 Figure 4A A particularly preferred embodiment of )).

[0425] Figure 14 Flowchart 1400 illustrates an exemplary voltage-phase correlation and calibration scheme applicable to the present invention. However, it should be understood that the specific steps of flowchart 1400 are merely exemplary, and the voltage-phase correlation subsystem 1380 can be implemented as any suitable subsystem within the OPA laser 1300 capable of periodically calibrating the phase modulation subsystem 1332 during phase changes of the output beam 1322. Furthermore, it should be understood that the various steps shown in flowchart 1400 need not be performed in the order illustrated and described, and many steps may be omitted or supplemented by additional or alternative steps, as will be apparent to those skilled in the art.

[0426] As seen in the first step 1402, the phase modulation control module 1330 preferably applies a voltage to the phase modulator 1318 to generate the desired phase shift of the sub-beam along the channel 1316. The far-field intensity pattern of the reference output beam 1372 is then measured at the detector 1350, as seen in the second step 1404. The desired phase shift of the sub-beam is then determined, and the voltage is again applied to the phase modulator 1318. The application of voltage at the first step 1402 and the measurement of the reference output beam 1372 at the second step 1404 can be repeated periodically multiple times at a given repetition rate. For example, the first and second steps can be repeated 20 times at a rate of one million times per second.

[0427] After the first step 1402 and the second step 1404 are repeated a predetermined number of times (e.g., 20 times), the voltage-phase correlation subsystem 1380 can be activated. As seen in the third step 1406, a voltage intended to generate a 2π phase shift is preferably applied to a phase modulator 1318. As seen in the fourth step 1408, the intensity of the far-field intensity pattern 1372 is then preferably measured at the detector 1350.

[0428] Next, at step 1410, the phase shift of the far-field intensity pattern 1372 is checked to determine if the phase shift is zero. It should be understood that if the voltage applied at step 1406 is actually the voltage that produces a 2π phase shift, the phase shift of beam 1322 will be zero, and the intensity of the far-field intensity pattern 1372 will therefore not change in response to the applied voltage. In this case, it is found that the phase modulator 1318 to which the 2π phase shift was applied in step 1406 is correctly calibrated, and no additional calibration of the specific phase modulator 1318 is required.

[0429] It should also be understood that if the voltage applied at step 1406 does not produce a 2π phase shift, the phase shift of beam 1322 will be non-zero, and the intensity of the far-field intensity pattern 1372 will therefore change in response to the applied voltage, as observed at step 1414. In this case, it is preferable to derive the relationship between the applied voltage and the resulting phase shift at step 1414. Then, it is preferable to calibrate the phase modulator 1318 based on the voltage-phase relationship derived at step 1414, as seen at step 1416.

[0430] As seen at inquiry 1418, after calibrating a specific phase modulator 1318 at the eighth calibration step 1416 or determining that a specific phase modulator 1318 has been properly calibrated at the fifth step 1410, the voltage-phase correlation subsystem 1380 preferably checks whether a predetermined number of phase modulators 1318 have been calibrated and, if necessary, proceeds to calibrate the next phase modulator, as seen at the ninth step 1420. The voltage-phase correlation subsystem 1380 can continuously calibrate all phase modulators 1318 included in the system 1300, or it can continuously calibrate a predetermined number of phase modulators 1318, for example, N phase modulators 1318. Once the predetermined number of phase modulators 1318 has been calibrated, the subsystem 1380 preferably deactivates, and at step 1402, the phase change of the output beam 1322 is restored.

[0431] It should be understood that the voltage-phase correlation subsystem 1380 is preferably activated at a frequency significantly lower than the frequency at which the phase change of the output beam 1322 is performed. For example, the phase change of the output beam 1322 can be performed one million times per second, while the voltage-phase correlation can be activated once per second.

[0432] Furthermore, it should be understood that although flowchart 1400 does not include a step for noise correction, such noise correction can be applied during the phase shifting process of the sub-beams that contribute to the output beam 1322, as referenced above. Figures 1A to 4C As described.

[0433] Now for reference Figure 15 This is a simplified schematic plan view of an optical phased array laser system comprising scaling phase modification of a dynamic beam, constructed and operated according to an additional preferred embodiment of the invention.

[0434] like Figure 15 As seen in the above reference, an optical phased array (OPA) laser system 1500 is provided, the OPA laser 1500 being related to the above reference. Figures 1A to 4CThe OPA laser 1500 preferably includes a seed laser 1512 and a laser beam splitting and combining subsystem 1514. The splitting and combining subsystem 1514 preferably receives the output laser beam from the seed laser 1512 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 1516. Here, by way of example only, the output from the seed laser 1512 can be divided into a 4×4 matrix of 16 sub-beams along 16 corresponding channels 1516, four of which are combined with the channel 1516 in... Figure 15 The OPA laser 1500 is visible in a top view. However, it should be understood that the separation and synthesis subsystem 1514 may include fewer or more channels along the output of the separation seed laser 1512, and typically may include far more channels, such as 32 or more channels.

[0435] The relative phase of each sub-beam can be individually modulated by phase modulators 1518 preferably positioned along each of the channels 1516. Each phase-modulated sub-beam resulting from the separation and subsequent phase modulation of the output of the seed laser 1512 is preferably propagated toward collimating lens 1519. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at the focal plane of lens 1520 to form output beam 1522.

[0436] The separation and combining subsystem 1514 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 1512 is separated into sub-beams and before the sub-beams are combined to form the output beam 1522. Here, for example, the separation and combining subsystem 1514 is illustrated as including a plurality of optical amplifiers 1524 positioned along corresponding channels in channel 1516 for amplifying each sub-beam. However, it should be understood that, depending on the power output specifications of the OPA laser 1500, this amplification is optional and can be omitted.

[0437] The phase of the output beam 1522, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 1522. In many applications (such as laser cutting, laser welding, optical free-space communication, and laser additive manufacturing as described above), it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. (Refer to above...) Figures 1A to 4C As described, the parameters of the output beam can be dynamically varied by dynamically changing the relative phase of the individual sub-beams along channel 1516 and thereby changing the phase of the synthesized laser output 1522, so as to dynamically control the position and shape of its far-field intensity pattern.

[0438] In the case of an OPA laser 1500 comprising a large number of individual sub-beams, the phase measurement and corresponding phase modification of each sub-beam relative to all other sub-beams within that sub-beam is challenging due to the large number of individual sub-beams involved. Specifically, due to the large number of individual sub-beams contributing to the synthesized output 1522, the time required to measure and modify the phase of each individual sub-beam relative to the other sub-beams in order to dynamically control the phase of the synthesized laser output 1522 may be unacceptably long. Furthermore, the signal-to-noise ratio may be unacceptably low.

[0439] A specific feature of a preferred embodiment of the invention is that the OPA laser 1500 preferably includes a phase modulation subsystem 1530 for phase modulation of the synthesized laser output in a scaling manner. More specifically, the phase modulation subsystem 1530 preferably groups at least a portion of the sub-beams provided by the laser separation and synthesis subsystem 1514 into multiple groups, and then performs phase modulation only relative to other sub-beams within each group. This group phase modulation is preferably performed in parallel across multiple individual groups of sub-beams. Next, the phase modulation subsystem 1530 preferably optimizes the phase of each group of sub-beams relative to the phase of other sub-beams in the group of sub-beams to change the phase of the synthesized laser output 1522 in a manner detailed later.

[0440] The phase modulation subsystem 1530 preferably includes a phase control electronics module 1532 that operates and controls the phase modulators 1518. The phase control electronics module 1532 preferably controls each phase modulator 1518 to dynamically modulate the relative phase of the sub-beams along the channel 1516 according to the desired far-field intensity pattern of the output beam 1522, as determined by the phase modulation subsystem 1530.

[0441] To facilitate the application of a phase change to the output beam 1522, a portion of the output of the OPA laser 1500 is preferably extracted and directed to multiple detectors 1550. The extracted portion of the output beam preferably serves as a reference beam, based on which the desired phase change can be calculated. Figure 15 In the illustrated embodiment, multiple sub-beams are guided along channel 1516 to beam splitter 1560. Beam splitter 1560 preferably divides each sub-beam into a transmissive portion 1562 and a reflective portion 1564 according to a predetermined ratio. For example, beam splitter 1560 can separate each sub-beam with a 99.9% transmittance:0.01% reflectance ratio.

[0442] The transmissive 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 reflective portion 1564 of the sub-beam preferably propagates toward the cylindrical lens 1568. The cylindrical lens 1568 is preferably operated to receive the reflective portion 1564 of the sub-beam and to group the sub-beams into multiple groups by converging them along the curvature direction of the lens 1568. Here, for example, the sub-beams are depicted as converging into four groups 1570, each group 1570 consisting of four sub-beams.

[0443] Preferably, each sub-beam group 1570, grouped by cylindrical lenses 1568, forms a beam having a far-field intensity pattern 1572 incident on a surface of a corresponding one of the plurality of detectors 1550. Each detector 1550 preferably samples the group of far-field intensity patterns 1572 incident thereon. In cooperation with a corresponding control electronics sub-module 1574 included in control module 1532, each detector 1550 then preferably optimizes the relative phase of the sub-beams within the group 1570 with respect to the phase of the other sub-beams within the group 1570 thus sampled. Preferably, such sampling and optimization are performed in parallel and preferably simultaneously for some of the far-field intensity patterns 1572 on all detectors 1550. Various algorithms suitable for phase optimization include sequential or non-sequential optimization algorithms, including, for example, those referenced above. Figures 1A to 4C The noise correction algorithm is described.

[0444] To optimize the relative phase of each of groups 1570 relative to the other groups in group 1570, a portion of group 1570 is preferably guided by an auxiliary cylindrical lens 1582 via an auxiliary beam splitter 1580. It should be understood that the curvature of the auxiliary cylindrical lens 1582 is preferably orthogonal to the curvature of the cylindrical lens 1568 to focus the sub-beams. The auxiliary cylindrical lens 1582 preferably converges the sub-beam group 1570 into a single beam 1584 having a far-field intensity pattern 1586 incident on an auxiliary detector 1588. The auxiliary detector 1588 preferably receives the single beam with the far-field intensity pattern 1586, which corresponds to the far-field intensity pattern of the combination of all sub-beam groups 1570. In cooperation with an additional phase control electronics submodule 1590 included in the electronic control module 1532, the auxiliary detector 1588 preferably samples the phase of group 1570 and optimizes the phase relative to each other. Particularly preferred is that one function of the phase control electronics module 1532 is to control each phase modulator 1518 to apply a phase shift on the auxiliary detector 1588 that maximizes the total power.

[0445] It should be understood that phase modulation in the scaling manner described above is much faster and less complex than phase optimization of each individual sub-beam relative to all other sub-beams in the OPA 1500, where the phase of each sub-beam is optimized relative to the phases of the other sub-beam members in its group 1570, and the phases of the group 1570 are optimized relative to each other to change the phase of the synthesized laser output 1522. Furthermore, this allows for phase optimization by individual sets of control electronics in each control electronics submodule 1574, each coupled to each detector 1550 (rather than a single set of control electronics), and improves the signal-to-noise ratio.

[0446] It should be understood that the function of optimizing the relative phase of each of groups 1570 relative to the other groups in group 1570 can alternatively be performed by operating an additional group phase modulator to modulate the collective phase of each of groups 1570, rather than by operating an individual phase modulator 1518 to modulate the individual phase of each sub-bundle member of each of groups 1570. An exemplary embodiment of this arrangement is described in... Figure 16 The phase modulation arrangement shown herein and generally similar in some respects to that described in US Patent No. 9,893,494, the disclosure of which is incorporated herein by reference.

[0447] like Figure 16 As seen, system 1500 can be modified by adding a series of group phase modulators corresponding to the number of groups 1570. For example, system 1500 includes 16 sub-beams, four of which are included in each of the four groups 1570, such that a total of four additional group phase modulators 1618 can be included in system 1500, as... Figure 16 As seen in the diagram. Each group phase modulator 1618 is preferably common to the four channels 1516 forming the portion of each group 1570, and provides phase shift of the collective group phase of the sub-bundle along the four channels 1516 connected thereto.

[0448] Preferably, some of the group phase modulators 1618 are controlled by an additional control submodule 1690 preferably included in the control module 1532. The auxiliary detector 1588 is preferably coupled to the additional control submodule 1690. It should be understood that optimizing the relative phase of the group 1570 with respect to each other via the group phase modulators 1618, rather than via individual sub-beam phase modulators 1518, may be more efficient and simplify the phase modulation process, but requires additional phase modulation and circuitry, thus increasing the cost and complexity of the system 1500.

[0449] The phase change of the synthesized laser output 1522 preferably provides spatial modulation of the output 1522. It should be understood that, due to the scaling nature of the phase modulation performed via the phase modulation subsystem 1530, the phase of the synthesized laser output 1522 can change very rapidly at a rate greater than that achievable via mechanical spatial modulation mechanisms. The spatial modulation provided by the OPA laser 1500 may optionally be enhanced by additional mechanical spatial modulation mechanisms, as known in the art, or may not involve mechanical spatial modulation.

[0450] It should be understood that the specific structures and configurations of the optical elements (including beam splitter 1560, focusing lens 1520, cylindrical lens 1568, auxiliary beam splitter 1580, and auxiliary cylindrical lens 1582) illustrated herein are exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 1500 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0451] Furthermore, it should be understood that the cylindrical lens 1568 may have the optical property of dividing individual sub-bundles into groups that are similar or identical to each other and contain an equal number of sub-bundles. Alternatively, the cylindrical lens 1568 may have the optical property of dividing individual sub-bundles into groups that are different from each other and contain different numbers of sub-bundles.

[0452] exist Figure 17A and 17B The middle shows Figure 15 or Figure 16 An exemplary implementation of an OPA laser system of the type shown. Now turn to... Figure 17A and 17B An OPA laser system 1700 is provided, wherein the output laser beam from a seed laser (not shown), such as seed laser 1512, is split into multiple sub-beams along corresponding multiple channels 1716. For example, the laser output can be split into a 10×10 matrix of 100 sub-beams along 100 corresponding channels 1716. It should be understood that, for clarity, Figure 17B Only selected sub-beams are shown in the diagram. The sub-beams along channel 1716 can then be collimated and focused by collimating and focusing elements (not shown), such as collimating lens 1519 and focusing lens 1520, to produce a composite output beam.

[0453] To facilitate the application of a phase change to the output beam, a portion of the output of the OPA laser 1700 is preferably extracted and directed to multiple detectors 1750. The extracted portion of the output beam preferably serves as a reference beam, based on which the desired phase change can be calculated. Figure 17A and 17BIn the illustrated embodiment, multiple sub-beams are guided along channel 1716 to beam splitter 1760. Beam splitter 1760 preferably divides each sub-beam into a transmission portion 1762 and a reflection portion 1764 according to a predetermined ratio.

[0454] Preferably, the transmissive portion 1762 of the synthesized sub-beams forms the output beam. The reflective portion 1764 of the sub-beams preferably reflects toward the cylindrical lens 1768, a particularly preferred embodiment of the cylindrical lens 1568. The cylindrical lens 1768 is preferably operated to receive the reflective portion 1764 of the sub-beams and to converge the sub-beams into multiple groups along the curvature direction of the cylindrical lens 1768. For example, in the case of 100 sub-beams, the cylindrical lens 1768 can converge the sub-beams into ten groups 1770 of ten sub-beams each.

[0455] Preferably, each sub-beam group 1770, grouped by cylindrical lenses 1768, forms a beam having a far-field intensity pattern incident on the surface of a corresponding one of the plurality of detectors 1750. For example, the plurality of detectors 1750 may include ten detectors 1750, each of which samples a group of beams comprising ten individual sub-beams. In cooperation with a corresponding control electronics module (not shown), such as control module 1532, each detector 1750 then preferably optimizes the phase of the sub-beams included in the sub-beam group 1770 thus sampled, preferably in parallel and preferably simultaneously across all detectors 1750.

[0456] To optimize the relative phase of each of groups 1770 with respect to the other groups in group 1770, a portion of group 1770 is preferably guided by an auxiliary cylindrical lens 1782 via an auxiliary beam splitter 1780. It should be understood that the auxiliary cylindrical lens 1782 is a particularly preferred embodiment of the auxiliary cylindrical lens 1582. It should be understood that the curvature of the auxiliary cylindrical lens 1782 is preferably orthogonal to the curvature of the cylindrical lens 1768 to focus the sub-beams. The auxiliary cylindrical lens 1782 preferably focuses the sub-beam group 1770 into a single composite beam 1784 incident on the auxiliary detector 1788.

[0457] In cooperation with phase control electronics (not shown), auxiliary detector 1788 preferably receives a far-field intensity pattern corresponding to the combined far-field intensity pattern of all sub-beam groups 1770, and samples the phase of group 1770 and optimizes the phase relative to each other. It should be understood that the optimization of the phase of group 1770 relative to each other may be achieved by phase modulation of the phase of individual sub-beams using phase modulator 1518, as referenced above. Figure 15 The described, or possibly intended, method involves phase modulation of the sub-beam group phase using a group phase modulator 1618, as referenced above. Figure 16 As described.

[0458] Now for reference Figure 18 This is a simplified schematic plan view of an optical phased array laser system comprising scaling phase modification of a dynamic beam, constructed and operated according to another preferred embodiment of the present invention.

[0459] like Figure 18 As seen in the above reference, an optical phased array (OPA) laser system 1800 is provided, the OPA laser 1800 being related to the above reference. Figures 1A to 4C The OPA laser 800 preferably includes a seed laser 1812 and a laser beam splitting and combining subsystem 1814. The splitting and combining subsystem 1814 preferably receives the output laser beam from the seed laser 1812 and splits the output laser beam into multiple sub-beams along corresponding multiple channels 1816. Here, by way of example only, the output from the seed laser 1812 can be divided into a 4×4 matrix of 16 sub-beams along 16 corresponding channels 1816, four of which are combined with the channel 1816 in... Figure 18 The OPA laser 1800 is visible in a top view. However, it should be understood that the separation and synthesis subsystem 1814 may include fewer or more channels along the output of the separation seed laser 1812, and typically may include far more channels, such as 32 or more channels.

[0460] The relative phase of each sub-beam can be individually modulated by phase modulators 1818 preferably positioned along each of the channels 1816. Each phase-modulated sub-beam resulting from the separation and subsequent phase modulation of the output of the seed laser 402 preferably propagates toward the collimating lens 1819. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at the focal plane of the lens 1820 to form the output beam 1822.

[0461] The separation and combining subsystem 1814 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 1812 is separated into sub-beams and before the sub-beams are combined to form the output beam 1822. Here, for example, the separation and combining subsystem 1814 is illustrated as including a plurality of optical amplifiers 1824 positioned along corresponding channels in channel 1816 for amplifying each sub-beam. However, it should be understood that such amplification is optional and can be omitted depending on the power output requirements of the OPA laser 1800.

[0462] The phase of the output beam 1822, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 1822. In many applications (such as laser cutting, laser welding, optical free-space communication, and laser additive manufacturing as described above), it is necessary to dynamically move and shape the far-field intensity pattern of the output beam. (See reference above.) Figures 1A to 4C As described, the parameters of the output beam can be dynamically varied by dynamically changing the relative phase of the individual sub-beams along channel 1816 and thereby changing the phase of the synthesized laser output 1822, so as to dynamically control the position and shape of its far-field intensity pattern.

[0463] In the case of an OPA laser 1800 comprising a large number of individual sub-beams, phase measurement of each sub-beam and corresponding phase modification relative to all other sub-beams within that sub-beam are challenging due to the sheer number of individual sub-beams involved. Specifically, the time required to measure and modify the phase of each individual sub-beam relative to the other sub-beams in order to dynamically control the phase of the synthesized laser output 1822, given the large number of individual sub-beams contributing to the synthesized output 1822, can be unacceptably long. Furthermore, the signal-to-noise ratio can become unacceptably low.

[0464] A specific feature of a preferred embodiment of the invention is that the OPA laser 1800 preferably includes a phase modulation subsystem 1830 for phase modulation of the synthesized laser output in a scaling manner. More specifically, the phase modulation subsystem 1830 preferably groups at least a portion of the sub-beams provided by the laser separation and synthesis subsystem into multiple groups, and then performs phase modulation within each group only relative to the phase of the other sub-beams within that group. Preferably, this group phase modulation is performed in parallel across multiple individual groups. The phase modulation subsystem 1830 then preferably optimizes the phase of each group of sub-beams relative to the phase of the other sub-beams in the group to change the phase of the synthesized laser output 1822 in a manner detailed later.

[0465] The phase modulation subsystem 1830 preferably includes a phase control electronics module 1832 that operates and controls the phase modulators 1818. The phase control electronics module 1832 preferably controls each phase modulator 1818 to dynamically modulate the relative phase of the sub-beams along the channel 1816 according to the desired far-field intensity pattern of the output beam 1822 and as determined by the phase modulation subsystem 1830.

[0466] To facilitate the application of a phase change to the output beam 1822, a portion of the output of the OPA laser 1800 is preferably extracted and directed to multiple detectors 1850. The extracted portion of the output beam preferably serves as a reference beam, based on which the desired phase change can be calculated. Figure 18In the illustrated embodiment, multiple sub-beams are guided along channel 1816 to beam splitter 1860. Beam splitter 1860 preferably divides each sub-beam into a transmissive portion 1862 and a reflective portion 1864 according to a predetermined ratio. For example, beam splitter 1860 can separate each sub-beam with a 99.9% transmittance: 0.01% reflectance ratio.

[0467] The transmission portion 1862 of the sub-beam preferably propagates toward the focusing lens 1820, where the sub-beams are combined to form an output beam 1822 having a far-field intensity pattern 1866. The reflection portion 1864 of the sub-beam preferably reflects toward an array of mirrors 1868, each mirror 1868 being positioned at intervals with a corresponding focusing lens 1869. For example, the array of mirrors 1868 may comprise four mirrors 1868 positioned at intervals with four focusing lenses 1869, two of which are visible in the focusing lens. Figure 18 In the top view of System 1800.

[0468] The reflector 1868 is preferably angled to operate so as to reflect the incident sub-beams toward the corresponding focusing lens 1869, thereby dividing the reflected portion 1864 of the sub-beams into multiple groups, for example, here embodied as four groups 1870, each group 1870 comprising four sub-beams, two of which are in… Figure 18 It can be seen in the top view of System 18100.

[0469] Preferably, each set of sub-beams reflected at each of the reflectors 1868 is focused by a corresponding focusing lens 1869 to form a single beam, the single beam comprising a sub-beam group 1870 and having a far-field intensity pattern 1872 incident on the surface of a corresponding one of the plurality of detectors 1850. In cooperation with a corresponding control electronics sub-module 1874 included in the control module 1832, each detector 1850 then preferably optimizes the relative phase of the sub-beams within the group 1870 with respect to the phase of the other sub-beams within the sampled sub-beam group 1870. Preferably, such sampling and optimization are performed in parallel and preferably simultaneously for some of the far-field intensity patterns 1872 on all detectors 1850. Various algorithms suitable for phase optimization include sequential or non-sequential optimization algorithms, including those referenced above. Figures 1A to 4C The noise correction algorithm is described.

[0470] To optimize the relative phase of each of groups 1870 relative to the other groups in group 1870, a portion of the reflecting portion 1864 is preferably guided by an auxiliary lens 1882 via an auxiliary beam splitter 1880. The auxiliary lens 1882 preferably converges the sub-beams incident upon it into a single beam 1884 having a far-field intensity pattern 1886 incident on an auxiliary detector 1888. The auxiliary detector 1888 preferably receives the single beam with the far-field intensity pattern 1886 therein, which corresponds to the far-field intensity pattern of the combination of all sub-beam groups 1870. Cooperating with an additional phase control electronics submodule 1890 included in the electronic control module 1832, the auxiliary detector 1888 preferably samples the phase of groups 1870 and optimizes the phases relative to each other. Particularly preferably, a function of the phase control electronics module 1832 is to control each phase modulator 1818 to apply a phase shift on the auxiliary detector 1888 that maximizes the total power.

[0471] It should be understood that phase modulation in the scaling manner described above is much faster and less complex than phase optimization of each individual sub-beam relative to all other sub-beams in OP 1800, where the phase of each sub-beam is optimized relative to the phases of other sub-beam members in its group 1870, and the phases of the group 1870 are optimized relative to each other to change the phase of the synthesized laser output 1822. Furthermore, this allows for phase optimization by individual sets of control electronics in each control electronics submodule 1874, each coupled to each detector 1850 (rather than a single set of control electronics), and improves the signal-to-noise ratio.

[0472] It should be understood that the function of optimizing the relative phase of each of groups 1870 relative to the other groups in group 1870 can alternatively be performed by operating an additional group phase modulator to modulate the collective phase of each of groups 1870, rather than by operating an individual phase modulator 1818 to modulate the individual phase of each sub-bundle member of each of groups 1870. An exemplary embodiment of this arrangement is shown in Figure 19 It is also generally similar in some respects to the phase modulation arrangement described in US Patent No. 9,893,494.

[0473] like Figure 19 As seen, system 1800 can be modified by adding a series of group phase modulators corresponding to the number of groups 1870. For example, system 1800 includes 16 sub-beams, four of which are included in each of the four groups 1870, such that a total of four additional group phase modulators 1918 can be included in system 1800, as... Figure 19As seen in the diagram. Each group phase modulator 1918 is preferably common to the four channels 1816 forming the portion of each group 1870, and provides phase shift of the collective group phase of the sub-bundles optimized along the four channels 1816.

[0474] Preferably, some of 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. It should be understood that optimizing the relative phase of the group 1870 with respect to each other via the group phase modulators 1918, rather than via individual sub-beam phase modulators 1818, may be more efficient and simplify the phase modulation process, but requires additional phase modulation and circuitry, thus increasing the cost and complexity of the system 1800.

[0475] The phase change of the synthesized laser output 1822 preferably provides spatial modulation of the output 1822. It should be understood that, due to the scaling nature of the phase modulation performed via the phase modulation subsystem 1830, the phase of the synthesized laser output 1822 can change very rapidly at a rate greater than that achievable via mechanical spatial modulation mechanisms. The spatial modulation provided by the OPA laser 1800 may optionally be enhanced by additional mechanical spatial modulation mechanisms, as known in the art, or may not involve mechanical spatial modulation.

[0476] It should be understood that the specific structures and configurations of the optical elements (including the beam splitter 1860, the focusing lens 1820, the array of mirrors 1868, and the corresponding focusing lens 1869) illustrated herein are merely exemplary and depicted in a highly simplified form. It should be understood that the OPA laser system 1800 may include a variety of such elements, as well as additional optical elements, including, by way of example only, additional or alternative lenses, optical fibers, and coherent free-space far-field synthesizers.

[0477] Furthermore, it should be understood that the mirror 1868 and the corresponding focusing lens 1869 may have similar or identical optical properties to group individual sub-beams into similar or identical groups containing an equal number of sub-beams. Alternatively, the mirror 1868 and the corresponding focusing lens 1869 may have different optical properties to group individual sub-beams into different groups containing different numbers of sub-beams.

[0478] exist Figure 20A and 20B The middle shows Figure 18 or Figure 19 An exemplary implementation of an OPA laser system of the type shown. Now turn to... Figure 20A and 20BAn OPA laser system 2000 is provided, wherein the output laser beam from a seed laser (not shown), such as seed laser 1812, is split into multiple sub-beams along corresponding multiple channels 2016. Here, by way of example only, the laser output can be split into a 10×10 matrix of 100 sub-beams along 100 corresponding channels 2016, for clarity... Figure 20B Only selected sub-beams of the sub-beams are shown in the diagram. The sub-beams along channel 2016 can then be collimated and focused by collimating and focusing elements (not shown), such as collimating lens 1819 and focusing lens 1820, to produce a composite output beam.

[0479] To facilitate the application of a phase change to the output beam, a portion of the output of the OPA laser 2000 is preferably extracted and directed to multiple detectors 2050. The extracted portion of the output beam preferably serves as a reference beam, and the desired phase change can be calculated based on its characteristics. Figure 20A and 20B In the illustrated embodiment, multiple sub-beams are guided along channel 2016 to beam splitter 2060. Beam splitter 2060 preferably divides each sub-beam into a transmission portion 2062 and a reflection portion 2064 according to a predetermined ratio.

[0480] Preferably, the transmission portion 2062 of the synthesized sub-beam forms the output beam. The reflection portion 2064 of the sub-beam preferably reflects toward an array of mirrors 2068, each mirror 2068 being positioned at intervals with a corresponding focusing lens 2069. It should be understood that the array of mirrors 2068 and the lenses 2069 are particularly preferred embodiments of the array of mirrors 1868 and the focusing lens 1869.

[0481] The reflector 2068 is preferably angled to orient the incident sub-beams toward a corresponding focusing lens 2069, thereby dividing the reflected portions 2064 of the sub-beams into multiple groups, for example, four groups here, each group 2070 comprising 25 sub-beams. Preferably, each group of sub-beams reflected at each of the reflectors 2068 is focused by the corresponding focusing lens 2069 to form a single beam comprising a group 2070 of 25 sub-beams. Each group 2070 of sub-beams is incident on the surface of a corresponding one of a plurality of detectors 2050. Each detector 2050 preferably samples the group of far-field intensity patterns incident thereon. In cooperation with a corresponding control electronics submodule (not shown), for example, included in the control electronics submodule 1874 in the control module 1832, each detector 2050 then preferably optimizes the phase of the sub-beams included in the sampled group 2070 of sub-beams so that the synthesized phase produces the desired group of far-field intensity patterns. Preferably, such sampling and optimization are performed in parallel and preferably simultaneously on some of the far-field intensity patterns on all detectors 2050.

[0482] To optimize the relative phase of each of groups 2070 relative to the other groups in group 2070, a portion of the reflecting portion 2064 is preferably guided by an auxiliary lens 2082 via an auxiliary beam splitter 2080. The auxiliary lens 2082 preferably converges a portion of the reflecting portion 2064 into a single beam 2084 incident on an auxiliary detector 2088. The auxiliary detector 2088 preferably receives the single beam at its location having a far-field intensity pattern corresponding to the far-field intensity pattern of the combination of all sub-beams. In cooperation with phase control electronics included in the electronic control module 1832, the auxiliary detector 2088 preferably samples the phase of groups 2070 and optimizes the phase relative to each other.

[0483] It should be understood that the phase optimization of group 2070 relative to each other may be achieved by phase modulation of the individual sub-beams using phase modulator 1818, as referenced above. Figure 18 The described, or possibly intended, description involves phase modulation of the sub-beam group phase using a group phase modulator 1918, as referenced above. Figure 19 As described.

[0484] It should be understood that, Figures 15 to 20B In the above embodiments of the OPA lasers 1500, 1700, 1800 and 2000, phase modulation is preferably performed in a scaling manner, wherein multiple detectors, such as detectors 1550, 1750, 1850 and 2050, are used to simultaneously perform phase measurements of sub-beams within multiple groups, and a single detector, such as auxiliary detectors 1586, 1786, 1886 and 2086, is used to perform phase measurements of a single beam comprising multiple groups.

[0485] However, it should be understood that the system constructed and operated according to the preferred embodiment of the invention can be further extended to include additional hierarchical structures of detectors and corresponding optical elements, depending on the number of sub-beams involved.

[0486] For example, such as Figure 21 As shown, the OPA laser system 1500 can be modified to include an additional focusing lens 2102 for focusing the sub-beam group 1570 into an intermediate group 2104, which is incident on an intermediate detector 2106. The intermediate group 2104 is then further combined and incident on a single detector 2108, where the intermediate group 2104 is preferably phase-modified relative to each other.

[0487] It should also be understood that, based on the above references Figures 6 to 8 The embodiments of the present invention described herein can be modified by replacing one or more of the individual detectors with a plurality of detectors and corresponding plurality of closely spaced optical paths. Figures 15 to 21Any of the described OPA laser systems, in order to improve the sampling of the output beam. Furthermore, according to the above reference... Figures 9 to 12 The embodiments of the present invention described above are referenced. Figures 15 to 21 Any of the described OPA laser systems may be alternatively modified to include a mask that masks one or more of the multiple detectors employed therein, either a transmission or a reflection detector, in order to further improve the sampling of the output beam.

[0488] It should also be understood that, based on the above references Figure 13 and 14 The preferred embodiments of the present invention described above are referenced. Figures 15 to 21 Any of the described OPA laser systems can be modified to include a voltage-phase calibration function to ensure proper calibration of the phase modulator used therein.

[0489] Now for reference Figure 22A and 22B This is a simplified schematic diagram of the corresponding first and second focusing states of an optical phased array laser system constructed and operated according to a preferred embodiment of the present invention.

[0490] like Figure 22A and 22B As seen above, a laser system 2200 is provided, preferably comprising an optical phased array (OPA) laser 2202. The OPA laser system 2200 may be of the type commonly described in US Patent No. 9,584,224, assigned to the same assignee as this invention, or in US Patent Application No. 15 / 406,032, the contents of which are incorporated herein by reference. Alternatively, the OPA laser system 2200 may be as described above. Figures 1A to 21 Laser systems of any one or a combination thereof that describe the type of laser system.

[0491] Referring preferably to enlarged Figure 2210, the OPA laser 2202 preferably includes a seed laser 2212 and a laser beam splitting and combining subsystem 2214, which receives laser output from the seed laser 2212 and provides a combined laser output. The laser beam splitting and combining subsystem 2214 preferably includes a plurality of phase modulators 2218 for changing the phase of the combined laser output, preferably after splitting the laser output from the seed laser 2212 and before performing combining via the splitting and combining subsystem 2214.

[0492] Each phase-modulated sub-beam generated by the separation and subsequent phase modulation of the output of the seed laser 2212 preferably propagates toward the collimating lens 2219. Subsequently, for example, the individually collimated phase-modulated sub-beams are combined at the focusing lens 2220 to form the output beam 2222.

[0493] The separation and combining subsystem 2214 can also provide laser amplification of the sub-beams, preferably after the output beam of the seed laser 2212 is separated into sub-beams and before the sub-beams are combined to form the output beam 2222. Here, for example, the separation and combining subsystem 2214 is illustrated as including a plurality of optical amplifiers 2224 for amplifying each sub-beam. However, it should be understood that, depending on the power output specifications of the OPA laser 2200, this amplification is optional and can be omitted.

[0494] The phase of the output beam 2222, and therefore the position and shape of its far-field intensity pattern, are at least partially controlled by the relative phase of the constituent sub-beams synthesized to form the output beam 2222. (Refer to the above text) Figure 1A to 5G As described, in various applications (such as laser cutting, laser welding, laser additive manufacturing, and optical free-space communication), it is necessary 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 dynamically changing the relative phase of the individual sub-beams through the laser separation and combining subsystem 2214, thereby changing the phase of the combined laser output 2222 to dynamically control the position and shape of its far-field intensity pattern.

[0495] The relative phase of the sub-beams is preferably predetermined according to the desired laser output pattern. Particularly preferably, a varying relative phase is applied by a phase control subsystem 2230. The phase control subsystem 2230 is preferably part of the control electronics module 2232 in the OPA laser system 2200, and preferably controls each phase modulator 2218 to dynamically modulate the relative phase of the sub-beams, preferably as described above. Figure 1A , 2A The phase control subsystems 130, 230, 330, and 430 of 3A and 4A are described.

[0496] The output beam 2222 may be noisy due to inherent noise in the OPA system 2200. In the presence of the optical amplifier 2224 in the OPA system 2200, the noise in the output beam 2222 is typically phase noise generated by thermal or mechanical effects and / or by the amplification process. In the case of noise in the output beam 2222, the OPA system 2200 may include a noise cancellation subsystem 2240 that operates to provide a noise-cancelled phase-corrected output to eliminate the noise in the output beam 2222 in a manner detailed below.

[0497] Particularly preferably, the noise cancellation subsystem 2240 employs an algorithm to sense and correct phase noise in the synthesized laser output, which preferably, but not necessarily, belongs to the category mentioned above. Figures 1A to 4CThe type described. The noise cancellation phase correction output is preferably provided by the noise cancellation subsystem 2240 to the phase modulator 2218 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 noise. The noise cancellation subsystem 2240 may be included in the control electronics module 2232.

[0498] Alternatively, if the noise in the output beam 2222 is not significant, the noise cancellation subsystem 2240 can be avoided from the OPA system 2200, and noise correction is not performed accordingly.

[0499] To facilitate the application of phase changes and noise corrections in relation to the output beam 2222, a portion of the output of the OPA laser 2202 is preferably extracted and directed to at least one detector 2250. Here, for example, at least one detector 2250 is illustrated as a single detector 2250. However, it should be understood that at least one detector 2250 may be embodied as multiple detectors receiving a portion of the output of the OPA laser 2202 through closely spaced optical paths, as referenced above. Figures 6 to 8 The described, or may be embodied, is at least one detector that receives a portion of the output of the OPA laser 2202 via a transmission or reflection optical mask, as referenced above. Figures 9 to 12 As described. The extracted portion of the output beam preferably serves as a reference beam, and based on its characteristics, the required noise correction and / or phase change can be calculated.

[0500] According to a preferred embodiment of the invention, a plurality of sub-beams are guided along channel 2216 to beam splitter 2260. Beam splitter 2260 preferably divides each sub-beam into a transmissive portion 2262 and a reflective portion 2264 according to a predetermined ratio. For example, beam splitter 2260 can separate each sub-beam with a 99.9% transmittance: 0.01% reflectance ratio.

[0501] The transmissive 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 reflective 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 incident on one or more of the surfaces of the plurality of detectors 2250.

[0502] In some applications, the output beam 2222 is preferably directed onto a substrate 2280, and the far-field intensity pattern 2266 is preferably incident on the substrate 2280. The substrate 2280 may be a workpiece processed by the OPA laser 2202. For example, the OPA laser 2202 may be operable to fabricate, cut, weld, sinter, or otherwise process the workpiece 2280 in a superimposed manner. The phase control subsystem 2230 preferably alters the phase of the output beam 2222 to focus the output beam 2222 onto the substrate 2280. It should be understood that without such a phase change applied by the phase control subsystem 2230, the output beam 2222 will not be focused onto the substrate 2280.

[0503] A specific feature of a preferred embodiment of the invention is that the focusing lens 2220 is preferably designed such that the output beam 2222 of the OPA laser 2202 will be focused onto the surface of the substrate 2280 without passing through the lens 2220, in the absence of any phase change applied thereto. For example, consider Figure 22A As is understood, it shows the configuration of the output beam 2222 in the absence of a phase change applied to it, and the focusing lens 2220 can be optically designed to focus the non-phase-changing collimated wavefront 2282 containing the output beam 2222 at a focal point 2284 above the surface of the substrate 2280.

[0504] As considered Figure 22B As is understood, it illustrates the configuration of the output beam 2222 with a phase change applied thereto, the phase change of the output beam 2222 preferably used to modify the shape of the wavefront 2282 and thus its focus, as seen in the representative case of the phase-modified wavefront 2286, which is preferably focused on the substrate 2280 by means of a focusing lens 2220. It should be understood that, therefore, the focusing of the output beam 2222 on the substrate 2280 is achieved by combining the phase change of the focusing lens 2220, as... Figure 22B As shown in the diagram, this is achieved not only through the focusing lens 2220.

[0505] As a result of focusing the output beam 2222 onto the substrate 2280 via its phase change, the backscattering caused by the substrate 2280 is correspondingly not focused onto the OPA laser 2202 by the focusing lens 2220. As is well known in the art, backscattering from surfaces processed by the laser beam typically returns to the laser and can potentially damage it, especially in laser amplification systems. In this invention, since the focusing lens 2220 does not focus the backscattering onto the OPA laser 2202, the backscattering does not reach and damage the OPA laser 2202, thus avoiding such damage.

[0506] Figure 23An exemplary return path of backscattering from substrate 2280 toward OPA laser 2202 is shown. Figure 23 As seen, the backscattered laser beam 2300 emanating from substrate 2280 preferably reaches focusing lens 2220. However, the backscattered laser beam 2300 is preferably not focused onto OPA laser 2202 by focusing lens 2220, thereby preventing damage to it. It should be understood that focusing lens 2220 is designed to focus the non-phase-modified laser output from OPA laser 2202 onto substrate 2280, which is typically the case in conventional laser systems, where the path of backscattered beam 2300 would correspondingly be focused onto OPA laser 2202 by focusing lens 2220, potentially causing damage to it.

[0507] It should be understood that, in some embodiments of the present invention, the focus of the output of the OPA laser 2202 on the substrate 2280 can be performed solely by means of an appropriate phase change of the output beam 2222, thereby avoiding the need for the focusing lens 2220.

[0508] As referenced above Figures 1A to 23 As described, the output from a seed laser can be directed to an amplification system for amplification. As is well known to those skilled in the art, defects in the laser output supplied to the amplification system by the seed laser can cause damage to the amplification system. Typical defects in the laser output of the seed laser that can cause damage to the amplification system connected thereto may include a reduction in the power of the seed laser output and a decrease in the laser linewidth. The resulting damage to the amplification system can occur extremely rapidly, within a few nanoseconds, and before the response time of internal sensing mechanisms that may be included in the amplification system.

[0509] For reference Figures 24 to 33 This section describes a preferred embodiment of the invention for preventing damage to the amplification system in the event of a seed laser failure connected to the amplification system. It should be understood that the seed laser failure protection system described below is incorporated herein by reference. Figures 1A to 23 This applies to any type of OPA laser described, or to any other laser system including a seed laser and amplifier connected to it.

[0510] Turn now Figure 24 ,like Figure 24As seen herein, a laser system 2400 is provided, preferably comprising: a seed laser 2402 providing laser output; and an amplification subsystem, exemplified herein by way of example 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. For example, the laser system 2400 may be embodied as a master oscillator power amplifier (MOPA) laser, or may be any other laser system including 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, which is exemplified herein, for example, as comprising a coiled optical fiber 2410.

[0511] To detect potential defects in the laser output of the seed laser 2402, system 2400 further preferably includes a detector subsystem for receiving the output from the seed laser 2402, 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 the nature of the laser output, and more specifically, for detecting potential faults in the laser output. The sensor subsystem 2420 is preferably operatively coupled to a power amplifier 2404. The sensor subsystem 2420 is preferably configured to deactivate the power amplifier 2404 upon detecting a fault in the laser output from the seed laser 2402.

[0512] A specific feature of the preferred embodiment of the invention is that the first flight time (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 flight time (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 spent by the sensor subsystem 2420 deactivating the power amplifier 2404.

[0513] Since the flight time of the laser output from the seed laser 2402 to the power amplifier 2404 is relatively long, the sensor subsystem 2420 is preferably able to detect a fault in the laser output received at its location and deactivate the power amplifier 2404 before the power amplifier 2404 receives the faulty laser output, thereby preventing damage to the power amplifier 2404.

[0514] Figure 24The embodiment of the invention shown in the diagram extends the flight time of the laser output from the seed laser 2402 to the power amplifier 2404 by including an optical fiber coil 2410 along a first optical path. This allows the sensor 2420 time to sense faults in the laser output and, if necessary, to deactivate the power amplifier 2404 before it receives the faulty laser output. For example, the optical fiber coil 2410 may have a physical length of 10 kilometers, and the flight time of the laser output along it may be approximately 50 microseconds. In the event of a fault in the output from the seed laser 2402, the power amplifier 2404 will therefore continue to receive fault-free input signals for 50 microseconds after the faulty output signal from the seed laser 2402 begins.

[0515] The optical path between the seed laser 2402 and the sensor subsystem 2420 does not include the coil 2410 and can be straight and therefore shorter. Therefore, the flight time of the laser output from the seed laser 2402 to the sensor subsystem 2420 is preferably much shorter than 50 microseconds, for example, about 30 microseconds or less. In the event of a fault in the output from the seed laser 2402, the sensor subsystem 2420 can therefore receive the laser output rapidly, detect the fault, and shut down the power amplifier 2404 before the time delay between the seed laser 2402 and the power amplifier 2404 expires. Therefore, the power amplifier 2404 is preferably shut down 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.

[0516] It should be understood that the extension of the optical path between the seed laser 2402 and the power amplifier 2404, and therefore the increase in flight time, compared to the optical path time and length between the seed laser 2402 and the sensor subsystem 2420, is not limited to being achieved by including an optical fiber coil along the optical path between the seed laser 2402 and the power amplifier 2404. In fact, the optical path between the seed laser 2402 and the power amplifier 2404 can be extended in any suitable manner, including, for example, including an optical delay line 2500 along it, such as... Figure 25 As shown in the diagram. Furthermore, the optical path between the seed laser 2402 and the power amplifier 2404 can be a free-space optical path 2600, such as... Figure 26 As shown, in this case, the flight time along it can be extended by using optical elements such as mirrors. However, it should be understood that including a coiled fiber 2410 in the first optical path 2408 may be particularly advantageous, due to its compact configuration and because the coiled fiber 2410 maintains the optical mode of the seed laser output.

[0517] It should be understood that Figure 24 The specific configuration of the coiled fiber 2410 shown is merely representative and exemplary. The coiled fiber 2410 can be embodied in any suitable form and can be adapted to allow the laser output to travel along it in a single direction or in a reciprocating manner, in order to further increase the effective length of the optical path provided by the coiled fiber 2410.

[0518] Now for reference Figure 27 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system constructed and operated according to another preferred embodiment of the present invention.

[0519] like Figure 27 As seen herein, a laser system 2700 is provided, which preferably includes a seed laser 2702 providing a laser output. The seed laser 2702 is preferably connected to a first amplifier 2703, which is preferably subsequently connected to a second amplifier 2704, exemplified herein as a power amplifier 2704, thereby providing an amplified laser output 2706. For example, the laser system 2700 may be embodied as a master oscillator power amplifier (MOPA) laser, or may be any other laser system including a seed laser and a power amplifier.

[0520] As is well known to those skilled in the art, and as detailed above, defects in the laser output from the seed laser 2702 can cause 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 stopping or reducing the power output of the seed laser and reducing the laser linewidth. Such damage to the power amplifier can occur extremely rapidly, within a few nanoseconds, and before the response time of the internal sensing mechanisms that may be included in the power amplifier 2704.

[0521] To prevent damage to the power amplifier 2704 due to defects in the output of the seed laser 2702, a specific feature of a preferred embodiment of the invention is that the laser system 2700 includes an additional amplifier 2703. Preferably, the additional amplifier 2703 provides a much lower amplification than the power amplifier 2704 and is included in the system 2700 for the purpose of preventing damage to the power amplifier 2704 in the event of degradation of the laser output from the seed laser 2702, rather than for the purpose of amplifying the laser output from the seed laser 2702 itself.

[0522] In the operation of system 2700, the laser output from seed laser 2702 is preferably received by first amplifier 2703. First amplifier 2703 preferably provides a first amplified laser output, which is preferably received and amplified by second amplifier 2704.

[0523] When laser output from seed laser 2702 ceases due to a malfunction, first amplifier 2703 no longer receives laser output from seed laser 2702. In this case, first amplifier 2703 generates amplified spontaneous emission, which is received by second amplifier 2704. Alternatively, first amplifier 2703 may be configured such that when laser output from seed laser 2702 ceases, first amplifier 2703 begins to operate as a laser and generates additional laser output.

[0524] It should be understood that even when the seed laser 2702 has stopped providing laser output, the second amplifier 2704 continues to receive input signals in the form of amplified spontaneous emissions or additional laser output from the first amplifier 2703. The amplified spontaneous emissions provided by the first amplifier 2703 to the second amplifier 2704 are sufficient to prevent damage to the second amplifier 2704, damage that would otherwise likely have occurred due to the cessation of signal supply to it. It should be understood that the system 2700 may additionally include a sensor connected to the seed laser 2702 to sense faults in the laser output from the seed laser 2702 and deactivate the second amplifier 2704 accordingly.

[0525] It should be understood that during proper operation of the seed laser 2702, the first amplification provided by the first amplifier 2703 is preferably negligible compared to the second major amplification provided by the second amplifier 2704.

[0526] like Figure 27 As seen, the laser output from seed laser 2702 can be directly supplied to first amplifier 2703. Alternatively, as Figure 28 As shown, additional components may be inserted between the seed laser 2702 and the first amplifier 2703. Specifically, a filter may be inserted between the seed laser 2702 and the first amplifier 2703 to filter out laser beams with unacceptably narrow linewidths, and thus prevent such laser beams from reaching and damaging the second amplifier 2704.

[0527] Figure 28 A particularly preferred embodiment of the linewidth filter 2800 suitable for use with the present invention is shown.

[0528] Turn now Figure 28The filter structure 2800 is configured 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 at a beam splitter 2805 upon entering the filter 2800, and reassembled at a reassembler 2806 before exiting the filter 2800. The first part of the split laser output from the seed laser 2702 preferably travels along a first arm 2807 of the filter 2800 between the beam splitter 2805 and the reassembler 2806. The second part of the split laser output from the seed laser 2702 preferably travels along a second arm 2808 of the filter 2800 between the beam splitter 2805 and the reassembler 2806. As can be understood by comparing the first arm 2807 and the second arm 2808, the first arm 2807 preferably includes an additional portion 2809 and is therefore longer than the second arm 2808.

[0529] When the laser output from seed laser 2702 has an unacceptably narrow linewidth, the laser outputs from the first arm 2807 and the second arm 2808 will interfere with each other due to their relatively high coherence when recombined at recombination unit 2806. The recombined beam is preferably detected by detector 2810, which is preferably connected to electronic control module 2811. Electronic control module 2811 is preferably a coherent beam combining (CBC) card that operates and controls phase modulator 2812 positioned along the second arm 2808. Phase modulator 2812 is preferably operated by electronic control card 2811 to change the phase of the beam along the second arm 2808 such that substantially all of the recombined beam at recombination unit 2806 is directed to detector 2810. The recombined beam therefore does not travel toward the first amplifier 2703, and therefore does not reach the second amplifier 2704 and damage it. Thus, receiving laser output from seed laser 2702 via first amplifier 2703 is stopped, and first amplifier 2703 generates either amplified spontaneous emission or additional laser output, as detailed above.

[0530] Provided that the seed laser 2702 operates properly and the laser output from the seed laser 2702 has an acceptablely wide linewidth, the laser outputs from the first arm 2807 and the second arm 2808 will not interfere with each other during recombination at the recombination unit 2806. This is because the linewidth is wide enough that the coherence is relatively low and therefore little or no interference occurs. In this case, a portion of the laser output at the recombination unit 2806 will continue toward the first amplifier 2703, and a portion of the laser output at the recombination unit 2806 will be delivered to the detector 2810. The laser output received by the first amplifier 2703 is preferably then provided by the first amplifier 2703 to the second amplifier 2704, as outlined in the reference system 2700 above.

[0531] It should be understood that Figure 27 and 28 The damage protection system shown, including the additional amplifier 2703 and the filter structure 2800, can be used alone or in conjunction with... Figures 24 to 26 Any combination of the protection systems shown is used.

[0532] Now for reference Figure 29 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system, constructed and operated according to another preferred embodiment of the present invention.

[0533] like Figure 29 As seen herein, a laser system 2900 is provided, which preferably includes: a seed laser 2902 providing a first laser output 2903; and an amplification subsystem, exemplified herein by way of example 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. For example, the laser system 2900 may be embodied as a master oscillator power amplifier (MOPA) laser, or may be any other laser system including a seed laser and a power amplifier.

[0534] To detect potential defects in the laser output of the seed laser 2902, system 2900 further preferably includes a detector subsystem for receiving the output from the seed laser 2902, preferably embodied as a seed sensor 2920. Sensor subsystem 2920 may include one or more sensors for sensing the nature of the laser output, and more specifically, for detecting potential faults in the laser output. Sensor subsystem 2920 is preferably operatively coupled to power amplifier 2904. Sensor subsystem 2920 is preferably configured to deactivate power amplifier 2904 upon detecting a fault in the laser output from seed laser 2902.

[0535] A specific feature of a preferred embodiment of the invention is that the laser system 2900 preferably includes an auxiliary laser subsystem, preferably embodied herein 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 a significantly lower power than the first laser output 2903. For example only, the first laser output 2903 may have a first power in the range of 80 to 100 milliwatts, while the second laser output 2932 may have a second power in the range of 50 to 70 milliwatts.

[0536] The auxiliary seed laser 2930 preferably provides a second laser output 2932 to the amplifier 2904 at least when the seed laser 2902 stops providing the first laser output 2903. Particularly preferably, the auxiliary seed laser 2930 preferably operates continuously so as to provide the second laser output 2932 to the amplifier 2904 simultaneously with the seed laser 2902 providing the first laser output 2903 and when the seed laser 2902 stops providing the first laser output 2903.

[0537] During proper operation of the seed laser 2902, the amplifier 2904 preferably receives simultaneously a first laser output 2903 from the seed laser 2902 and a second laser output 2932 from the auxiliary seed laser 2930. Since 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, but not necessarily, the second laser output 2932 has a different wavelength than the first laser output 2903 to further reduce the influence of the second laser output 2932 on the amplified laser output 2906. For example, the first laser output 2903 may have a first wavelength in the range of 1060 to 1070 nanometers, while the second laser output 2932 may have a second wavelength in the range of 1070 to 1080 nanometers.

[0538] When laser output from seed laser 2902 ceases, sensor subsystem 2920 preferably operates to deactivate amplifier 2904 due to a malfunction of seed laser 2902 as sensed by sensor subsystem 2920. Because of the limited response time of amplifier 2904 and detector subsystem 2920, amplifier 2904 does not immediately deactivate, but continues to operate for a limited period after laser output from seed laser 2902 ceases. It should be understood that during this period, amplifier 2904 no longer receives the first laser output 2903 from seed laser 2902. However, auxiliary seed laser 2930 preferably continues to provide a second laser output 2932 to amplifier 2904. It should be understood that even when seed laser 2902 has stopped providing laser output, amplifier 2904 therefore continues to receive an input signal 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 most likely have occurred due to the cessation of signaling to the amplifier 2904 before it is deactivated by the sensor 2920.

[0539] Now for reference Figure 30 This is a simplified schematic diagram of a laser amplification system including a seed laser fault protection system constructed and operated according to another preferred embodiment of the present invention.

[0540] like Figure 30 As seen herein, a laser system 3000 is provided, preferably comprising: a seed laser 3002 providing a first laser output 3003; and an amplification subsystem, exemplified herein by way of example as a power amplifier 3004, which receives the first laser output 3003 from the seed laser 3002 and amplifies the laser output to provide an amplified laser output 3006. For example, the laser system 3000 may be embodied as a master oscillator power amplifier (MOPA) laser, or may be any other laser system including a seed laser and a power amplifier.

[0541] To detect potential defects in the laser output of the seed laser 3002, the system 3000 further preferably includes a detector subsystem 3020 for receiving the output from the seed laser 3002. The detector subsystem 3020 may include one or more sensors for sensing the nature of the laser output, and more specifically, for detecting potential faults in the laser output. The sensor subsystem 3020 is preferably operatively coupled to the power amplifier 3004. The sensor subsystem 3020 is preferably configured to deactivate the power amplifier 3004 upon detecting a fault in the laser output from the seed laser 3002.

[0542] A specific 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 reflective grating 3032 preferably positioned at the inlet 3034 of the amplifier 3004 and a second reflective grating 3036 preferably 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 an auxiliary laser subsystem 3040.

[0543] 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.

[0544] When laser output from seed laser 3002 ceases, sensor subsystem 3020 preferably operates to deactivate amplifier 3004 due to a malfunction of seed laser 3002 as sensed by sensor subsystem 3020. Because amplifier 3004 and sensor subsystem 3020 have finite response times, amplifier 3004 does not immediately deactivate, but continues to operate for a limited period after laser output from seed laser 3002 ceases. It should be understood that during this period, amplifier 3004 no longer receives laser output from seed laser 3002. In this case, reflective grating 3030 preferably provides signal feedback to amplifier 3004, such that amplifier 3004, combined with a pair of gratings 3030, preferably begins to operate as a laser. Reflective grating 3030 preferably has a relatively low reflectivity, such that the signal feedback provided by reflective grating 3030 has a lower power than the laser output 3003 of seed laser 3002.

[0545] Particularly preferred, but not necessarily, is that the pair of gratings 3030 are reflective at a wavelength different from the wavelength of the first laser output 3003 of the seed laser 3002, such that the effect of the gratings 3030 on the amplified output 3006 is negligible during proper operation of the seed laser 3002. For example only, the first laser output 3003 may have a wavelength in the range of 1060 to 1070 nanometers, while the gratings 3030 may be reflective at wavelengths in the range of 1090 to 1100 nanometers.

[0546] It should be understood that even when the seed laser 3002 has stopped providing laser output, the amplifier 3004 continues to receive input signals in the form of signal feedback from the grating 3030. Therefore, when the seed laser 3002 stops operating, the amplifier 3004, combined with the grating 3030, begins to operate as a laser, thereby preventing damage to the amplifier 3004 that would otherwise likely have occurred due to the cessation of signal supply to it.

[0547] like Figure 29 and 30 As seen, the laser output from seed lasers 2902 and 3002 can be directly supplied to amplifiers 2904 and 3004, respectively. Alternatively, as Figure 31 and 32 As shown, additional components can be inserted between the seed laser and the amplifier. Specifically, linewidth filters, such as filter 2800 or any other suitable filter, can be inserted between the seed lasers 2902, 3002 and the amplifiers 2904, 3004, respectively, to filter out laser beams with unacceptably narrow linewidths and thus prevent such laser beams from reaching and damaging the amplifiers 2904, 3004.

[0548] As detailed above, see reference Figures 24 to 32 Each of the described laser systems may include a detector subsystem, such as detector subsystems 2420, 2920, and 3020. The detector subsystem is preferably embodied as at least one sensor for sensing the output from the seed laser. Figure 33 Particularly preferred embodiments of sensors forming part of detector subsystems such as detector subsystems 2420, 2920, and 3020 are shown. However, it should be understood that... Figure 33 The sensor shown is not limited to use in systems of the type described herein, and can be incorporated as a laser output sensor into any laser system that benefits from its use.

[0549] like Figure 33 As seen, a detector subsystem 3320 is provided. The laser output from the seed laser preferably enters the sensor subsystem 3320 at input point 3330 and travels toward a beam splitter 3334. At the beam splitter 3334, a small portion, for example 1% of the laser output, is directed to detector 3336, and the remainder of the laser output continues toward sensor amplifier 3340. Sensor amplifier 3340 is preferably a power amplifier with a lower power than power amplifiers 2404, 2704, 2904, or 3004. Sensor amplifier 3340 preferably outputs an amplified laser output, which is preferably delivered to an additional detector 3342 via an elongated optical fiber 3344.

[0550] In the operation of detector subsystem 3320, when the output from the seed laser stops, the intensity of the amplified laser output detected at additional detector 3342 decreases. In this case, a control module (not shown) connected to additional detector 3342 and to power amplifiers such as power amplifiers 2404, 2704, 2904, or 3004 can deactivate the power amplifiers to prevent damage.

[0551] When the output from the seed laser deteriorates to an unacceptably narrow linewidth, nonlinear effects will be induced in the fiber 3344. It should be understood that the fiber 3344 is advantageously configured to be as sensitive as possible to such nonlinear effects. For this purpose, the fiber 3344 preferably has a considerably long length and preferably a small core diameter to increase its sensitivity to the linewidth of the laser output from the seed laser. For example, the fiber 3344 may have a length of approximately 25 meters and a core diameter of approximately 6 micrometers.

[0552] Due to the nonlinear effect induced in fiber 3344 as the linewidth of the output from the seed laser narrows, fiber 3344 preferably begins to operate as a mirror, reflecting light backward toward amplifier 3340. As the reflected light returns to amplifier 3340, the enhanced signal reaches beam splitter 3334 and is detected by detector 3336. Upon detection of the enhanced signal at detector 3336, the power amplifier is preferably deactivated to prevent damage.

[0553] Those skilled in the art will understand that this invention is not limited to the contents specifically claimed below. In fact, the scope of this invention includes various combinations and sub-combinations of the features described above, as well as modifications and variations of the invention that would occur to those skilled in the art upon reading the foregoing description with reference to the drawings and that are not found in the prior art.

Claims

1. A laser system, characterized in that, The laser system includes: An optical phased array laser, comprising: Seed laser; and A laser beam separation and combining subsystem receives the laser output from the seed laser and provides the combined laser output. The laser beam separation and combining subsystem alters the phase of the combined laser output to provide a phase-changing combined laser output focused on the substrate, the phase-changing combined laser output being focused on the substrate by a focusing lens; The focusing lens operates as follows: The synthesized laser output with the phase change is received and focused onto the substrate, wherein the synthesized laser output is not focused onto the substrate by the focusing lens when the phase change is not present. and The laser beam backscattered from the substrate is received but not focused onto the optical phased array laser, thereby preventing the backscattered laser beam from damaging the optical phased array laser.

2. A method for focusing a laser beam in a laser system, characterized in that, The method includes: Receives laser output from a seed laser, which is contained in the optical phased array laser of the laser system; The laser outputs are separated and synthesized to provide a synthesized laser output; The phase of the synthesized laser output is changed to provide a phase-varying synthesized laser output that is focused onto the substrate by a focusing lens; The phase-changing synthesized laser output is focused onto the substrate by the focusing lens, and the synthesized laser output is not focused onto the substrate by the focusing lens when the phase change is not present. and The laser beam backscattered from the substrate is received by the focusing lens, and the laser beam backscattered from the substrate is not focused onto the optical phased array laser by the focusing lens, thereby preventing the backscattered laser beam from damaging the optical phased array laser.

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