System and Method for a Gradient Interference Locked Laser Source

Abstract

A system and method are achieved for forming a coherent optical phased array laser source from an array of spatially combined output beams without using any external measurement device or wavefront sensor. A master oscillator laser is split into a plurality of optical beam transport and amplifier channels, creating a plurality of optical output beams that are spatially combined into an array format. The spatial phase states of the plurality of output beams are measured at the output of a spatial combiner without using an external measurement device or sensor. The phases of the plurality of optical output beams are controlled to create a coherent and spatially phased laser beam at the output of the laser source, or to create a phased laser beam with a defined phase state at each output beam, compensating for both aberrations introduced by the optical beam transport and amplifier paths.

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 336,915, filed on April 29, 2022, entitled "SYSTEM AND METHOD FOR GRADIENT INTERFEROMETRICALLY LOCKED LASER SOURCE", the entire content of which is incorporated herein by reference.

[0002]

[0002] The present disclosure relates to methods and some system implementations for creating a coherent optical phased - array laser source from a spatially combined array of output beams to form a coherent optical beam.

Background Art

[0003]

[0003] There are a number of approaches to forming a coherent laser beam. A particular method for forming a coherent high - energy laser beam or HEL involves using an optical phase - array with a master oscillator laser, an optical beam splitter that divides the output of the master oscillator laser into a plurality of optical channels, phase - modulation devices in the low - power beam paths of the plurality of optical channels, followed by a plurality of amplifiers to form a high - power combined beam. The outputs of the plurality of output channels are typically arranged in a linear or hexagonal pattern, with possible variations, to maximize the fill - factor of the beam output. This method is typically referred to as an optical phased - array laser. When the beam transport between the above - mentioned elements is a single - mode optical fiber, this method can be referred to as a fiber optical phased - laser array. However, conventional methods of forming an optical phased - array laser generally do not provide a way to phase - lock the elements without using some measurement external to the spatial beam - combining assembly.

[0004]

[0004] The depiction of a classical science fiction of an optical phased array laser system is similar to an electronically steerable array similar to a phased array radio frequency antenna or a microwave frequency antenna that can be arbitrarily controlled to form a focused beam. The actual optical phased array is quite different. Conventional approaches use some form of external measurement method to phase-lock multiple beams to each other in a spatial combiner assembly. In some methods, attempts are made to phase-lock multiple beams to each other, but those methods only do so for any random spatial reference and will not phase-align the beams coherently when focused. Known conventional methods can be calibrated with respect to the errors introduced by this arbitrary random spatial reference, but often those methods suffer from and are degraded by random drift caused by thermal and / or mechanical drift over time and will also be sensitive to drift on the scale of tens of nanometers (nm) of drift in the optical path that is not directly measured. Another possible method for phase-locking an optical phased array can rely on measurements strictly internal to the spatial combining assembly. However, this approach has historically been subject to requirements for alignment uniformity and mechanical stability in the tens of nanometer class and is therefore not effective. Thermal and vibration drift exceed those requirements, making the possible methods infeasible and ineffective with respect to the phase control of the optical phased array. The general theme of known methods and conventional attempts for phase-locking an optical phased array is that all of the methods developed to date require some kind of external measurement or external calibration, which is highly sensitive to drift and prevents those methods from being able to provide a truly coherent and programmable output laser source.

[0005]

[0005] There is a need for a robust method for measuring the phase of output beams relative to each other that does not require external sensors. These and other features and advantages will become apparent to those skilled in the relevant art by reference to the following description and the accompanying drawings.

SUMMARY OF THE INVENTION

[0006]

[0006] A robust method for measuring the phase of output beams relative to each other that does not require external sensors has been an invention and development that has long been avoided, because the problem requires a virtual measurement of the laser beam in a measurement plane that is not easily accessible in the absence of an external measurement sample optical system and sensor. The embodiments described herein have the following features: (a) a minimally invasive beam sampling approach that includes information about the relative phase information between the beams and can remain strictly within the spatial beam combiner assembly that arranges the output beams; (b) the non-invasive beam samples are detected in a form that has no non-common path errors and results in a thermally stable and mechanically robust configuration that can withstand high levels of random manufacturing errors and / or thermal or vibrational drift; and (c) a processor configured to process the measurement data to control the array and enable an accurate measurement of the phase difference between the beams, thereby enabling an accurate reconstruction of the spatial phase state of the array of beams at the output of the spatial combiner element of the optical phased array. By providing a configuration that combines one or more of these, this need is met.

[0007]

[0007] According to some embodiments, a method for generating a phase difference measurement value between adjacent output beams includes irradiating a plurality of output beams, each output beam being emitted from an associated output laser source; collimating the plurality of output beams with a plurality of lenses of a lens array; forming a plurality of sampling regions in an output window; directing samples of pairs of adjacent beams to return through the plurality of lenses by the sampling regions; and forming a focused pair of beams in an optical capture configuration such as a detector or a single-mode waveguide or fiber that directs light to the detector.

[0008]

[0008] The method can further include providing a pinhole or hole at the focus of the focused pair of beams. In some cases, the optical path from the sampling region to the detector or optical capture configuration such as a single-mode waveguide or fiber is of the same optical path length.

[0009]

[0009] According to some embodiments, a method for measuring the phase difference between adjacent output beams includes measuring an optical sample using a detector; demodulating a time series of subsequent optical samples to determine a phase difference measurement value; unwrapping the phase difference measurement value to generate a phase estimate; adding the phase estimate to an offset of beam steering or beam pattern phase to generate an error signal; and generating a phase command signal configured to modulate the phase of the beam sample in channel control by passing the error signal through an actuator filter and a control block.

[0010]

[0010] In some examples, the demodulating step includes a timing control signal. In some cases, the modulating and demodulating approximate a phase gradient by two-point temporal modulation. The demodulating step can optionally include full circle reconstruction of the phase difference measurement values.

[0011]

[0011] In some cases, the method includes adjusting the phase offset by a calibration error offset. Optionally, the actuator filter and control block add the phase command signal to a control output according to a timing signal, and the actuator filter and control block can include one or more of a pure integrator, a proportional-integral controller, a leaky integrator controller, and a proportional-integral-derivative controller.

[0012]

[0012] The method can include combining the adjacent output beams into a spatially combined illumination beam.

[0013]

[0013] According to some embodiments, a gradient interference locking laser source includes a laser source configured to produce an optical beam, a beam splitter configured to split the optical beam into a plurality of output beams, a detector configured to receive the plurality of output beams, a demodulator configured to demodulate the plurality of output beams and further configured to determine a phase difference measurement value associated with the plurality of output beams, a phase unwrapper configured to receive the phase difference measurement value and at least partially determine a phase estimate based on the phase difference measurement value, an actuator filter and control block configured to receive the phase estimate and one or more of a beam steering offset, a beam pattern phase offset, and a calibration error offset and further configured to create a phase command signal to adjust one or more parameters of the plurality of output beams, and a combiner configured to spatially combine the output beams of the array to form an irradiation laser beam.

[0014]

[0014] The gradient interference locking laser source can further include a housing, and the laser source, the beam splitter, the detector, the demodulator, the phase unwrapper, and the actuator and filter control block are located within the housing.

[0015] The specific advantages of the embodiments described herein are that all or almost all sensing and measurements can be included in a spatial combiner that can be disposed within the housing and do not require external measurements or phase sensors. A further advantage of the disclosed embodiments is that they do not require a phase correction device in the high-power segment of the illumination laser beam path to compensate for both the transport of multiple optical beams and the aberrations in the amplifier channels. Further, in some embodiments, a highly accurate high-speed null-seeking feedback control loop that is inside the laser source and does not require feedback from external devices of an assembly that holds and supports the optical elements that enable illumination of the spatial combiner or phased array laser source is used for phase correction, thus providing a robust method for compensation. Further, the phase correction does not exhibit the round-trip time of the flight data latency in the control loop. Some embodiments can control the combined output beam using electronically commanded offset values for electronically steering the beam. Further, some embodiments can control the combined output beam using electronically commanded offset values to form any desired focused beam pattern up to the limits of the spatial bandwidth of the array. Some embodiments can control the combined output beam using electronically commanded offset values to pre-compensate for aberrations in a beam transport or beam delivery system that directs or focuses the beam as long as the aberrations are measured or determined or known or confirmed by some other means. Some embodiments can control the combined output beam using electronically commanded offset values to pre-compensate for aberrations introduced by propagation through a rough medium as long as the aberrations are measured or determined or known or confirmed by some other means.Similarly, embodiments can control the composite output beam using electronically commanded offset values to pre-compensate for aberrations in a beam transport or beam delivery system that directs or focuses a beam that combines aberrations introduced by propagation through a rough medium, as long as or to the extent that the aberrations are measured or known by some other means. Some embodiments can combine the above-described functionality for pre-compensating for aberrations in beam transport, beam delivery, or from a rough medium, using beam steering or beam forming offsets.

[0016]

[0016] Many of the methods in the literature can be used to measure the optical path in a beam transport or beam delivery system. Many of the methods in the literature can be used to measure aberrations introduced by propagation through a rough medium. However, the embodiments described herein have additional advantages and functionality not achievable with known structures and methods. In particular, some of the disclosed embodiments are configured to create a coherent optical beam phase-matched to an arbitrary desired phase measurement pattern without the need for external measurement devices or sensors.

[0017]

[0017] Thus, according to some examples, the embodiments described herein provide a structure and method for forming a coherent optical phased array laser source from an array of spatially combined output beams without using an external measurement device or a wavefront sensor. According to some embodiments, all the measurements necessary to form a coherent optical beam are internal to the device. In some cases, the exemplary embodiments include one or more features, which are: (a) a minimally invasive beam sampling approach that includes information about the relative phase information between the beams and can remain strictly within the spatial beam combiner assembly that arranges the output beams, (b) the non-invasive beam samples are detected in a form that has no non-common path errors and results in a thermally stable and mechanically robust configuration that can withstand high levels of random manufacturing errors and / or thermal or vibrational drift, and (c) a processor configured to process the measurement data to control the array, enabling an accurate measurement of the phase difference between the beams and thereby enabling an accurate reconstruction of the spatial phase state of the array of beams at the output of the spatial combiner element of the optical phased array. In some cases, all three of these features may be included in combination with these or other features.

[0018]

[0018] The summary of the features included in various embodiments is included herein. In some examples, the method is designed to use a master oscillator laser source, which creates a plurality of optical output beams that are spatially combined by a spatial combiner in an array format and are separated into a plurality of optical beam transport and amplifier channels. The method can provide a method for measuring the spatial phase state of the plurality of output beams at the output of the spatial combiner without using an external measurement device or sensor. Thereby, the method can control the plurality of optical output beam phases to compensate for both aberrations introduced by the optical beam transport and amplifier paths in order to create a coherent and spatially phased laser beam at the output of the laser source or to create a phased laser beam with a defined phase state at each output beam. In some cases, the advantage is that all sensing and measurement can be included in the spatial combiner and no external measurement or phase sensor is required. A further advantage can be that no phase correction device is required in the high-power segment of the illumination laser beam path to compensate for both aberrations in the plurality of optical beam transport and amplifier channels. Further, a strictly fast null-seeking feedback control loop that is inside the laser source and does not require feedback from external devices of an assembly that holds and supports the optical elements that enable illumination of the spatial combiner or phased array laser source can be used to perform phase correction, thus providing a robust method for compensation. According to some embodiments, the phase correction does not have or exhibit a round-trip time of flight data latency in the control loop. Some embodiments can control the combined output beam using an electronically commanded offset value for electronically steering the beam. Some embodiments can be configured to control the combined output beam using an electronically commanded offset value to form any desired focused beam pattern up to the limit of the spatial bandwidth of the array.Similarly, some embodiments can control the combined output beam using electronically commanded offset values to pre-compensate for aberrations in a beam transport or beam delivery system that directs or focuses the beam, as long as the aberration is measured, determined, or known by some other means. Some embodiments can control the combined output beam using electronically commanded offset values to pre-compensate for aberrations introduced by propagation through a rough medium, as long as the aberration is measured or known by some other means. Similarly, the embodiments disclosed herein can be configured to control the combined output beam using electronically commanded offset values to pre-compensate for aberrations in a beam transport or beam delivery system that directs or focuses a combined beam having aberrations introduced by propagation through a rough medium, as long as the aberration is measured, determined, or known by some other means. Some of the embodiments described herein can combine the above-described functions for pre-compensating for aberrations in beam transport, beam transport, or from a rough medium, using beam-steering or beam-forming offsets.

[0019]

[0019] According to some embodiments, a method of generating a measurement signal related to a plurality of phase differences between adjacent output beams includes irradiating a plurality of output beams, each output beam being emitted from a related output beam source; adapting the collimation state of the plurality of output beams by a plurality of lenses of a lens array; forming a plurality of sampling regions in an output window; directing samples of pairs of adjacent beams through the plurality of lenses back to the sampling regions to form pairs of focused beams; and creating an optical sample signal related to the pairs of focused beams by a detector. Here, adapting the collimation state refers to adjusting the convergence or divergence of the plurality of output beams. In some cases, adapting the collimation state causes two or more beams to become more convergent, more divergent, or more parallel.

[0020]

[0020] In some cases, the optical path lengths from the sampling region to the detector are substantially the same between pairs of respective beams. That is, the optical path lengths are the same within a predetermined standard deviation tolerance distance. In some cases, the tolerance distance is within about 1% to about 10% of the optical wavelength. Thus, as used herein, when the optical path lengths are substantially the same between pairs of respective beams, the optical path lengths are within about 10% of the optical wavelength of the irradiation beam, but the numbers are illustrative only and not limiting, and the specific requirements will depend on the application in question.

[0021]

[0021] The method can further include providing an aperture at the focus of the pair of focused beams so as to form a sample of the pair of focused beams. The detector can be disposed after the aperture and can measure the sample of the pair of focused beams.

[0022]

[0022] In some embodiments, an optical capture device is located at the focus of the pair of focused beams and directs the sample of the pair of focused beams to the detector. The optical capture device can be a single-mode waveguide. In some cases, the optical capture device is an optical fiber.

[0023]

[0023] The method can further include combining the pair of adjacent beams into a spatially combined irradiation beam.

[0024]

[0024] According to some embodiments, a method of measuring phase values of a plurality of beams includes measuring, using a detector, an optical sample signal related to a phase difference between adjacent beams, demodulating a time series of subsequent optical sample signals to determine a phase difference measurement value, and unwrapping the phase difference measurement value to generate a phase estimate. The demodulating step can include a timing control signal.

[0025]

[0025] In some cases, the modulation and demodulation steps estimate the phase gradient by, for example, two-point time modulation. The demodulation step may include a full-circle reconstruction of the phase difference measurement value.

[0026]

[0026] The method may further include the step of adjusting the phase estimation by a calibration error offset.

[0027]

[0027] According to some embodiments, a method for coherently combining a plurality of beams includes irradiating a plurality of output beams, each output beam being emitted from a related output beam source; adapting the collimation state of the plurality of output beams by a plurality of lenses of a lens array; forming a plurality of sampling regions in an output window; directing samples of pairs of adjacent beams through the plurality of lenses back to the sampling regions so as to form pairs of focused beams; generating an optical sample signal of the pairs of focused beams by a detector; demodulating a time series of subsequent optical sample signals to determine a phase difference measurement value; unwrapping the phase difference measurement value to generate a phase estimate; adding the phase estimate to an offset of beam steering or beam pattern phase to generate an error signal; and generating a phase command signal configured to modulate the phase of beam samples in channel control by passing the error signal through an actuator filter and a control block. In some cases, the optical path lengths from the sampling regions to the detector are substantially the same between each pair of beams.

[0028]

[0028] In some cases, the method can include providing an aperture at the foci of the pair of focused beams so as to form a sample of the pair of focused beams. The detector can be disposed after the aperture, and the method can further include measuring, by the detector, the sample of the pair of focused beams.

[0029]

[0029] In some cases, an optical trapping device is located at the foci of the pair of focused beams, and the method can include directing, by the optical trapping device, the sample of the pair of focused beams toward the detector. In some examples, the optical trapping device is one or more of a single-mode waveguide or an optical fiber.

[0030]

[0030] The method can include combining the plurality of output beams into a spatially combined irradiation beam. In some examples, the actuator filter and the control block are configured to add the phase command signal to a control output according to a timing signal. The actuator filter and the control block can include one or more of a pure integrator, a proportional-integral controller, a leaky integrator controller, and a proportional-integral-derivative controller.

[0031]

[0031] According to some embodiments, a method of generating a measurement signal related to a plurality of phase differences between adjacent output beams of an optical beam generator includes irradiating a plurality of output beams, each output beam being emitted from a related output beam source; adapting a collimation state of the plurality of output beams by a plurality of lenses of a lens array; forming a plurality of sampling regions in an output window; and generating an optical sample signal related to the plurality of output beams toward a detector by the sampling regions. In some cases, an optical path length from the sampling regions to the detector is substantially the same between pairs of respective beams.

[0032]

[0032] According to some embodiments, a gradient interference locking laser source includes a laser source configured to produce an optical beam, a beam splitter configured to split the optical beam into a plurality of output beams, a plurality of channel control devices configured to control the phase of the plurality of output beams, apply a modulation pattern, and enable measurement of the phase difference between the plurality of output beams, a beam combiner configured using a plurality of lenses to spatially combine the plurality of output beams of the array to form an irradiation laser beam, an output window having a plurality of sampling regions configured to direct samples of pairs of adjacent beams back through the plurality of lenses to form a plurality of pairs of focused beams, a plurality of detectors configured to produce a plurality of optical sample signals associated with the plurality of pairs of focused beams, a demodulator configured to demodulate the plurality of output beams and further configured to determine a phase difference measurement value associated with the plurality of output beams, a phase unwrapper configured to receive the phase difference measurement value and at least partially determine a phase estimate based on the phase difference measurement value, and an actuator filter and control block configured to receive the phase estimate and one or more of a beam steering offset, a beam pattern phase offset, and a calibration error offset, and further configured to produce a phase command signal for adjusting one or more parameters of the plurality of output beams. The optical path lengths extend from the plurality of sampling regions to the plurality of detectors and can be substantially the same for each of the plurality of pairs of focused beams.

[0033]

[0033] The gradient interference locking laser source can include a plurality of apertures, and individual ones of the plurality of apertures are located at the respective foci of the plurality of pairs of focused beams. The plurality of detectors can be located downstream of the plurality of apertures.

[0034]

[0034] In some cases, the system includes a plurality of optical capture devices, and each of the plurality of optical capture devices is configured to direct a sample of a pair of the focused beams to the plurality of detectors. The plurality of optical capture devices can be single-mode waveguides.

[0035]

[0035] In some embodiments, the housing surrounds the beam splitter, the plurality of channel control devices, the beam combiner, the output window, and the plurality of detectors. In other words, a system and method are provided for robust measurement of the phase of an output beam relative to each other without the need for any external source.

[0036]

[0036] The features, advantages, and principles of the present disclosure will be better understood by referring to the following detailed description and the accompanying drawings that describe exemplary embodiments.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0038]

[0046] The following detailed description is provided to better understand the features and advantages of the invention described in this disclosure in accordance with the embodiments disclosed herein. The detailed description includes many specific embodiments, which are provided merely as examples and should not be considered as limiting the scope of the invention disclosed herein.

[0039]

[0047] FIG. 1 is a schematic diagram of a general optical phased array laser source that illustrates the general class of laser sources suitable for use in the embodiments described herein. The optical phased array laser source of interest can include a master oscillator laser source, a beam splitter and associated optical transport for creating a plurality of optical output channels each having a channel controller and an amplifier, and a spatial beam combiner having a plurality of optional integrated tip / tilt devices and / or optional integrated focus control devices.

[0040]

[0048] The channel controller can include a phase modulator and, optionally, a polarity controller and / or a path length controller. The optical phased array laser source produces an output projected laser beam. The optical phased array laser source can also include an input for control of the plurality of channel controllers and an optional input for control of the plurality of optional integrated tip / tilt devices and / or optional integrated focus control devices. FIG. 1 is shown by way of example and not limitation. There are alternative ways to control and / or display the laser path(s) (one or more) recognized by those skilled in the art.

[0041]

[0049] FIG. 1 shows a laser source master oscillator 100. In some embodiments, the laser source master oscillator 100 functions to create a master oscillator beam 101. The master oscillator beam 101 may encounter a beam splitter 102 configured to create a plurality of low-power beam samples 103. For example, the beam splitter 102 can be configured to divide the master oscillator beam 101 into two, three, four, or more low-power beam samples 103. The plurality of low-power beam samples 103 can be modulated by a plurality of channel controllers 104, and in some cases, each of the low-power beam samples 103 is supplied via a unique channel controller 104. The channel controllers 104 can be configured to create a plurality of modulated low-power beam samples 105. The plurality of channel controllers 104 can be implemented by any of a number of channel controllers known to those skilled in the art to control the individual low-power beam samples 103 coming from the beam splitter 102. By way of non-limiting example, these methods include modulation of the current to an electro-optic phase modulator, an acousto-optic modulator, an in-line fiber electro-optic phase modulator, an in-line fiber acousto-optic modulator, and / or an optical amplifier 106. Of course, various combinations of channel controllers can be implemented simultaneously and arranged in series or in parallel. In addition to the phase modulator, each channel of the channel controller 104 can optionally include a polarity control and / or a path length controller. The plurality of modulated low-power beam samples 105 can then be amplified by a plurality of optical amplifiers 106 that can function to create a plurality of high-power beam samples 107. The plurality of high-power beam samples 107 can be combined using a spatial beam combiner 108 that can function to package the output beams as closely as possible or realistically achievable.The beam is typically packaged in a linear output pattern or a hexagonal output pattern, but it need not be these specific packaging patterns, and the pattern can be optimized for the intended application through any suitable geometric or spatial packing pattern.

[0042]

[0050] There are numerous methods known to those skilled in the art for implementing the spatial beam combiner 108, which include, but are not limited to, an array of optical fibers, which is configured using a corresponding array of collimating lenses, diffractive optical elements, and / or beam splitter elements. Each channel of the spatial beam combiner 108 can optionally include an integrated device for controlling the tip / tilt of each channel to provide improved compensation. Further, each channel of the spatial beam combiner 108 can optionally include an integrated device for controlling the focus of each channel to provide improved compensation. In some cases, the output of the spatial beam combiner 108 is the laser source beam 109 to be irradiated. In some cases, the laser source beam 109 to be irradiated consists of a plurality of spatially arranged irradiation laser beams. The beam transport pathway from the laser source master oscillator 100 to the spatial beam combiner 108 can be implemented by one of several means well known to those skilled in the art. In some embodiments, a single-mode optical fiber connects each element of the optical chain from the laser source master oscillator 100 to the spatial beam combiner 108, which can optionally maintain polarization.

[0043]

[0051] Of course, those skilled in the art will recognize that any other suitable optical beam transport means can be used. For example, an optical beam transport means having a limited number of optical modes and all correctable by phase piston modulation, tip / tilt modulation, and / or focus modulation can be used.

[0044]

[0052] In addition to the phase modulator for the channel controller 104, there are several other components that may be beneficial in the channel controller 104. They are not limited to devices such as polarity control, but among others, include a path length adjuster and a line expander device.

[0045]

[0053] For example, when a non-polarization-maintaining fiber or any other non-polarization-maintaining beam transport device is used, the plurality of channel controllers 104 can further include a plurality of polarization controls that function to stabilize the polarities of each channel of the channels relative to each other to ensure that a common polarization state is maintained. Typically, a gradient optimization method can be used to ensure that the common polarization state is maintained.

[0046]

[0054] When the coherence length of the master oscillator 100 is small compared to the total path length tolerance, the channel controller 104 can further include one or more path length adjustment devices that function to adjust the path length as desired to facilitate the coincidence of the irradiation laser source beam 109 with the path length within a portion of the coherence length.

[0047]

[0055] If multiple optical amplifiers 106 require a short coherence length (i.e., a wide linewidth) of multiple modulated low-power beam samples 105 to provide effective amplification, the beam transport means can include one or more line broadening devices that function to broaden the linewidth of the multiple modulated low-power beam samples 105. Typically, this is achieved using one line broadening device installed immediately behind the master oscillator 100, but it can also be achieved using multiple line broadening devices appropriately installed in the beam transport path. If a line broadening device is incorporated, for example, to shorten the coherence length, a path length adjustment device can be provided accordingly.

[0048]

[0056] In some cases, the entire element including the laser source master oscillator 100, beam splitter 102, multiple channel controllers 104, multiple amplifiers 106, and spatial combiner 108 can be considered an irradiation laser source 120. The irradiation laser source 120 can have the multiple output beams already described as the irradiation laser source beam 109. In some cases, the irradiation laser source 120 can have two additional input sources, which are an input channel control signal 130 (which can include a phase modulator control signal, an optional polarity control signal, and / or an optional path length controller configured to modulate the control signal) and an optional input chip / tilt / focus control signal 140. The irradiation laser source 120 can include a housing containing the described components illustrated in FIG. 1.

[0049]

[0057] Figures 2A and 2B are schematic diagrams showing exemplary patterns of a plurality of output beams with respect to a rectilinear array according to some embodiments. In some cases, each beam passes through a collimating lens 201 arranged in a lens array. Alternating beams are labeled with unmodulated beams 202 (open circles) and modulated beams 203 (filled circles). The modulation can be used to obtain X-direction phase difference measurement values 204 and Y-direction phase difference measurement values 205. The "arrows" are shown by way of example and not limitation and are for providing a conceptual coordinate system.

[0050]

[0058] The selection of alternating modulated and unmodulated beams 202, 203 is shown by way of example and not limitation, and there are many other modulation schemes that will be apparent to those skilled in the art. X sampling regions 206 and Y sampling regions 207 between the beam output lenses conceptually show areas where phase difference measurements can be made according to the method shown in detail in FIG. 4. The size of the sampling regions can be balanced with respect to minimizing a sufficient contrast ratio, signal-to-noise ratio, and / or throughput loss. The X and Y sampling regions are shown by way of example and not limitation. FIG. 2 is shown by way of example and not limitation. There are alternative ways of arranging the output beams (other than hexagonal arrays or rectilinear arrays) and alternative ways of selecting modulation patterns that will be recognized by those skilled in the art in view of the present disclosure.

[0051]

[0059] FIG. 3 is a schematic diagram showing the pattern of a plurality of output beams with respect to a hexagonal array. Each beam can pass through a collimating lens 301 arranged in the lens array. Alternate beams are labeled with an unmodulated beam 302 (open circles) and a modulated beam 303 (filled circles). The modulation can be used to obtain phase difference measurement values over sampling regions 304 in three different directions defined by the array. The definition of the directional arrows can be selected by the system designer as will be recognized by those skilled in the art, and thus the directional arrows are not shown in the figure. The selection of alternate modulated and unmodulated beams is shown by way of example and not limitation, and there are many other modulation schemes apparent to those skilled in the art. The X sampling region 304 between the beam output lenses conceptually shows an area where phase difference measurements can be made according to the method detailed in FIG. 4. The sampling region is shown by way of example and not limitation. In some cases, the size of the sampling region can be balanced with respect to minimizing or at least reducing a sufficient contrast ratio, signal-to-noise ratio, and throughput loss. FIG. 3 is shown by way of example and not limitation. There are alternative ways of arranging the output beams (among others than hexagonal arrays and linear arrays) and alternative ways of selecting the modulation pattern that will be recognized by those skilled in the art.

[0052]

[0060] FIG. 4 is a schematic diagram illustrating a cross-section of a sampling scheme for generating a phase difference measurement between adjacent output beams when combined with a suitable phase modulation scheme for alternating beams, according to some embodiments. In some cases, the components and methods described in connection with FIG. 4 are located in and performed at the spatial beam combiner 108. A plurality of output beam sources 210 may be irradiated to form a plurality of output beams 211. The output beams 211 are shown as diverging, for purposes of illustration and not limitation, and there are many configurations apparent to those skilled in the art, such as converging, parallel, collinear, intersecting, non-planar, etc. For purposes of efficiently describing the system, the output beam sources 210 are shown as point sources (i.e., consisting of a single mode fiber or waveguide of some kind, etc.), but there are many configurations of laser sources apparent to those skilled in the art.

[0053]

[0061] When the plurality of beams 211 are diverging, they can be collimated by one or more lenses 212 arranged as a lens array. A plurality of sampling regions 214 can be formed in the output window 213. A plurality of uncollimated beams can be irradiated through the output window 213 and sampled at the sampling regions 214. In some embodiments, the output window 213 is a flat optical system made of a glass with sufficiently low absorption, such that the output window 213 does not overheat and does not lead to unmeasured wavefront errors in non-common paths. The manufacture of such windows is low risk and does not affect the overall performance of the optical phased array laser source, in order to reach sufficiently strict tolerances and to use low absorption glass. As is known to those skilled in the art, windows are generally required for environmental protection of laser sources when used in industrial, defense, or any other outdoor or space-based applications. The sampling regions 214 can be attached in any suitable manner, but in some cases, the sampling regions 214 are attached directly to the output window by epoxy (low absorption and index matching) or etching.

[0054]

[0062] The sampling region 214 can be a partial reflector or a reflector. In some examples, the sampling region can be manufactured as a flat surface or a grating. The sampling region 214 can be manufactured and integrated using a range of options and methods, and as long as they are locally substantially flat with respect to the sampling region (within reasonable manufacturing tolerances), they do not introduce non-common path errors into the measurement. The tilt accuracy of the sampling region 214 can be determined, and generally, it depends on the engineering configuration. In some cases, the tolerance of the tilt accuracy has some impact on the quality of the wavefront achieved in the closed-loop operation in the steady state, but the research to date indicates that the tolerance is on the order of a root mean square (RMS) error of 0.1 to 0.5 waves with respect to a reasonable beam pitch. The sampling region 214 can be configured to direct samples of pairs of adjacent beams 215 back through a plurality of collimating lenses 212 to form a focused beam pair 216 at the detector 217.

[0055]

[0063] One or more lenses 212 can be supported by a structure that determines the position and orientation of the one or more lenses 212 to direct the beam as described herein. The structure can further be configured to support an output window 213 having a sampling region at a certain distance from the one or more lenses 212. Further, the structure can further support the detector 217 at a fixed distance from the one or more lenses 212. In some cases, the distance between the one or more lenses 212 and the detector 217 defines a first space 222, and the distance between the one or more lenses 212 and the output window 213 defines a second space 224.

[0056]

[0064] In some cases, the detector 217 uses a small pinhole at the focus to ensure that the interference measured by the detector 217 approximately measures the average of the complex field over the sampling region. If the complex field is not averaged by some means, there is no interference, and thus it is difficult to measure the phase difference. In some cases, the optical path is the same path length from the sampling region to the detector pinhole. The common path length can help avoid non-common path errors in phase difference measurement that can degrade performance.

[0057]

[0065] According to some embodiments, the plurality of collimating lenses 212 provide a convenient way to focus the beam, which eliminates non-common path errors to the pinhole in the focal plane if the collimating lenses are properly designed. The pinhole can be implemented in various ways well known to those skilled in the art. For example, a single-mode fiber or waveguide can be used, and the fiber or waveguide can be looped into a separate detector. Alternatively, a physical pinhole of approximately the size of the diffraction-limited spot can be used. The size of the pinhole (or the equivalent numerical aperture) is an engineering trade-off to balance the sensitivity to tilts of the sampling region 214 and the signal-to-noise ratio. Generally, there is a large amount of light available for use, and the trade-off can be based on the sensitivity to the accuracy of tilts of the sampling region. In some examples, the exit beam 220 is a collimated beam that exits from the output window 213.

[0058]

[0066] In some cases, the beam 211 is emitted from the beam source 210 and passes through the first space 222 between the beam source 210 and the lens 212. Next, the beam 211 passes through one or more lenses 212 and enters the second space 224 between the lens 212 and the output window 213. In some embodiments, the beam 211 or a portion of the beam 211 is reflected at the sampling region 214, passes through the second space 224, through the lens 212, through the first space 222, and is returned to the detector 217. FIG. 4 is shown by way of example and not limitation. There are various alternative configurations for FIG. 4 that will be recognized by those skilled in the art. According to some embodiments, the optical configuration provides a sampling of the substantially complex field across the sampling region that includes samples of adjacent beams, which, when combined with a certain modulation and demodulation scheme as described in FIG. 5, provides a phase difference measurement between adjacent beams and enables the phase of the output beam to be controlled to uniform conditions. For example, additional geometries are conceivable and possible while considering the advantages of the features described herein. For example, each of a plurality of beam pairs can be directed to a common detector. The system can use a hexagonal geometry where the optical path length at the vertices can be made to coincide with a group of three beams and the sampling region is positioned at the corners. In such cases, the modulation pattern can be configured or adjusted to account for the particular geometry. Similarly, a rectangular geometry can be used where a group of four beams is directed to the sampling region at the corners.

[0059]

[0067] FIG. 5 is a schematic diagram of signal processing used to modulate samples of a plurality of output beams using a small amplitude modulation that enables measurement of the phase difference between adjacent output beams, according to some embodiments. In some embodiments, the phase difference can be unwrapped or "reconstructed" to form a phase error estimate. In some cases, the phase difference is processed by a component referred to as an "unwrapper" that can be any device, circuit, or software configured to determine the phase difference to form a phase error estimate. The phase error estimate can be added to the optical beam steering or beam pattern offset, and can be used to (a) steer the beam, (b) apply a phase to form a pattern when focused, and / or (c) pre-compensate the beam with respect to other aberrations in the system and / or with respect to propagation through a rough medium (or any combination of the above). In some cases, the resulting sum of the error phase estimate and the offset pattern is then converted to a command output (typically via a leaky integrator or a pure integrator controller), and a small amplitude modulation command output that enables measurement of the phase difference is added to the command signal before sending the command to the phase modulator.

[0060]

[0068] Each optical sample 230 from a pair of adjacent beams can be measured using a detector sampling device 231, such as one of the detectors 217 shown in FIG. 4. The time series of detector measurements can be demodulated via signal processing in a demodulator 232 to produce a phase difference measurement 240. In some embodiments, a timing controller 235 ensures that a timing signal 236 is sent to the detector sampling device 231, the demodulator 232, and the modulation command device 237, which can operate in 2-D alternating channels at an appropriate timing to enable effective modulation and demodulation of the phase difference between adjacent beams to produce the phase difference measurement 240. There are a number of possible modulation and demodulation schemes well known to those skilled in the art. By way of example, one more effective approach is to estimate the phase gradient by 2-point temporal modulation using a small amplitude to estimate a value approximately proportional to the phase difference between adjacent beams with a small amplitude error signal. Demodulation can, in this case, be the calculation of the gradient and can be performed by any suitable demodulator, which can be an electronic circuit and, in some cases, can be a computer program stored in memory and executed by one or more processors.

[0061]

[0069] Alternative approaches can use the classical Carre method, or modified or hybrid methods. These methods enable full unit circle reconstruction of the phase difference using small amplitude 4- or 5-point time modulation patterns. In some cases, this approach preserves full unit circle phase difference information and avoids possible minima and convergence errors associated with gradient-based hill climbing or other gradient-based methods. The phase difference measurement 240 can be processed by a phase unwrapping scheme 241 to produce a phase estimate 242. There are a number of options for the phase unwrapping 241, but an easy approach for implementation and implementation is the Complex Exponential Reconstructor or CER. If the desired output beam array is to form a steered beam when focused or to form a specific pattern when focused, the phase estimate 242 can be added to an optional beam steering or beam pattern phase offset 243. The phase offset 243 can also include a calibration error offset. It is expected that there are some small calibration errors that can be optimized for the performance of the focused beam. The resulting sum of the phase estimate 242 and the phase offset 243 can be processed using an actuator filter and control block 244. The actuator filter and control block 244 is configured to process the error signal via several means and convert the error signal into a phase command signal 250 (e.g., an input channel control signal 130) that modulates the phase modulator of the channel controller 104. Also, the actuator filter and control block 244 adds a modulation command to the control output according to the timing signal 236.Although not limiting, the actuator filter and control block 244 can be implemented via any suitable method such as a pure integrator, a proportional-integral controller, a leaky integrator controller, or a proportional-integral-derivative controller. The selection of the controller can be based on the engineering details of the implementation, and the design of the controller is well known to those skilled in the art.

[0062]

[0070] FIG. 6 illustrates a sample processing flow 600 for generating a measurement signal related to the phase difference between adjacent output beams. This process can be substantially described with reference to any of the embodiments herein. The process includes, at block 602, irradiating a plurality of output beams from an output beam source. At block 604, the collimation state of the plurality of output beams is adapted by a plurality of lenses of a lens array. In some cases, each output beam passes through an individual lens.

[0063]

[0071] At block 606, a plurality of sampling regions are formed in the output window. The sampling regions can indicate the areas where the phase difference measurements are made. At block 608, a beam or a portion of the beam can be reflected in the sampling regions, pass back through the lens, and a pair of focused beams can be formed.

[0064]

[0072] At block 610, the detector creates an optical sample signal related to the pair of focused beams.

[0065]

[0073] Figure 7 is a sample processing flow 700 for measuring the phase value of an optical beam. In block 702, an optical sample signal related to the phase difference between adjacent beams is measured using a detector. In block 704, a phase difference measurement value is determined by demodulating the time series of subsequent optical sample signals. In block 706, the phase difference measurement value is unwrapped to generate a phase estimate. A phase estimate can be added, and the resulting sum of the error phase estimate and the offset pattern can be converted into a command output. A small amplitude modulation command for enabling the measurement of the phase difference can be added to the command signal before sending the command to the phase modulator.

[0066]

[0074] Figure 8 illustrates a sample processing flow 800 for coherently combining a plurality of optical beams. In block 802, the system irradiates a plurality of output beams, and each output beam is emitted from an output beam source. In block 804, the system adapts the collimation state of the plurality of output beams using a plurality of lenses of a lens array. In block 806, as substantially disclosed in any of the embodiments herein, the system forms a plurality of sampling regions in the output window. In block 808, the system forms a pair of focused beams by directing samples of pairs of adjacent beams through the plurality of lenses back to the sampling regions.

[0067]

[0075] In block 810, an optical sample signal related to the pair of focused beams is created using a detector. In block 812, the system demodulates the time series of subsequent optical sample signals to determine a phase difference measurement value. In block 814, the system unwraps the phase difference measurement value to generate a phase estimate.

[0068]

[0076] In block 816, the system adds a phase estimate to an offset of beam steering or beam pattern phase to generate an error signal. In block 818, the system generates a phase command signal configured to modulate the phase of beam samples in channel control based at least in part on the error signal passing through an actuator filter and a control block. The resulting beam can be combined into a spatially combined illumination beam.

[0069]

[0077] FIG. 9 illustrates a sample processing flow 900 for generating a measurement signal associated with a plurality of phase differences between output beams. In block 902, a plurality of output beams are irradiated from a beam source. In block 904, the collimation of the output beams is adapted by a plurality of lenses of a lens array. The lens array can be positioned at a first distance from the beam source. In block 906, a plurality of sampling regions are formed in an output window. In block 908, the sampling regions direct the plurality of output beams to a detector, which creates an optical sample signal associated with the plurality of output beams.

[0070]

[0078] This disclosure describes embodiments by way of example and is not intended to limit the scope of the embodiments of this disclosure and the appended claims in any way. Above, functional building blocks have been used to aid in the description of embodiments by way of example of the implementation of specific components, functions, and their relationships. The boundaries of those functional building blocks have been arbitrarily defined here for the convenience of the description. Alternative boundaries can be defined within the scope in which the specific functions and their relationships are properly made.

[0071]

[0079] The foregoing description of the specific embodiments fully discloses the general features of the embodiments of this disclosure. Without departing from the general concept of the embodiments of this disclosure, others can easily make various applications and / or modifications by applying the knowledge of an ordinary person skilled in the art to such specific embodiments. Therefore, such applications and modifications are intended to be within the meaning and scope of the equivalents of the disclosed embodiments based on the teachings and guidance shown herein. The expressions and terminology used herein are for the purpose of explanation rather than limitation, and the expressions and terminology used in this specification are made to be understood by an ordinary person skilled in the relevant art in consideration of the teachings and guidance shown herein.

[0072]

[0080] An ordinary person skilled in the art will recognize that any of the processes and methods described herein can be changed in many ways. The process parameters and sequence of steps described and / or exemplified herein are shown as mere examples and can be varied as desired. For example, although the steps exemplified and / or described herein may be shown or described in a particular order, those steps do not necessarily have to be performed in the order exemplified or described.

[0073]

[0081] Also, the various example methods described and / or exemplified herein can omit one or more of the steps described or exemplified herein, and can include additional steps in addition to the disclosed steps. Furthermore, any step of any method disclosed herein can be combined with one or more steps of any other method disclosed herein.

[0074]

[0082] Unless otherwise expressly stated, the terms "connected" and "coupled" (and their derivatives) used in the specification and claims are to be construed as allowing both direct connection and indirect connection (i.e., via other elements or components). Further, the terms "a" and "an" used in the specification and claims are to be construed as meaning "at least one".

[0075]

[0083] For ease of use, the terms "comprising" and "having" (and their derivatives) used in the specification and claims are replaceable with the word "including" and have the same meaning. The terms "about" and "substantially" used herein may, in some instances, indicate a variability of up to ±5% of the relevant numerical value, for example, up to ±2% or up to ±1%.

[0076]

[0084] Throughout the specification, the term "substantially" with respect to a given parameter, characteristic, or condition is meant to and may include the degree to which a normal person skilled in the art would understand that the given parameter, characteristic, or condition meets the requirement that it lies within a small degree of variance, such as within an acceptable manufacturing tolerance. By way of example, depending on the particular parameter, characteristic, or condition being substantially met, the parameter, characteristic, or condition may be one that meets at least approximately 90%, at least approximately 95%, or even at least approximately 99%.

[0077]

[0085] The processor can be configured by instructions for performing one or more steps of any of the methods described herein.

[0078]

[0086] In particular, hypothetical language such as "can", "could", "would", "might", etc. generally does not, unless specifically stated or understood within the context in which it is used, intend to convey that a particular implementation can include particular features, elements, and / or operations not included in other implementations. Thus, such hypothetical language generally does not imply that features, elements, and / or operations are required in any way for one or more implementations, or that one or more implementations include logic for determining whether those features, elements, and / or operations are included or performed in any particular implementation, with or without user input or prompting.

[0079]

[0087] Here, the term "or" is used inclusively to refer to items in alternative and combination. Characters such as numbers used herein refer to like elements.

[0080]

[0088] According to some exemplary embodiments, the systems and / or methods described herein may be controlled by one or more processors. The one or more processors can access a computer-readable storage medium ("CRSM"), which can be any usable physical medium accessible by the processor(s) to execute instructions stored on the CRSM. In one basic implementation, the CRSM can include random access memory (RAM) and flash memory. In another implementation, without limitation, the CRSM can include read only memory (ROM), electrically erasable programmable read only memory (EEPROM), or any other medium that can be used to store desired information and is accessible by the processor(s).

[0081]

[0089] The embodiments of the present disclosure have been shown and described herein by way of illustration and are provided as examples only. Those of ordinary skill in the art will recognize many modifications, changes, variations, and alternatives without departing from the scope of the present disclosure. Some alternatives and combinations of the embodiments disclosed herein can be used without departing from the scope of the present disclosure and the invention described herein. Accordingly, the scope of the invention disclosed herein is defined only by the scope of the appended claims and their equivalents.

[0082]

[0090] The following clauses are part of the present disclosure.

[0083]

[0091] Clause 1: A method for generating a phase difference measurement value between adjacent beams is

[0093] irradiating a plurality of output beams, each output beam being emitted from a related output beam source

[0094] collimating or adapting the divergence of the plurality of output beams with a plurality of lenses of a lens array;

[0095] forming a plurality of sampling regions on an output window or other suitable surface;

[0096] directing samples of pairs of adjacent beams through the plurality of lenses to return through the plurality of lenses;

[0097] forming a focused pair of beams at a detector. In some cases, adapting the plurality of output beams includes collimating the plurality of output beams.

[0084]

[0098] Item 2: The method of item 1 further includes providing a pin or other suitable aperture at the focus of the focused pair of beams. The aperture can be a pinhole aperture.

[0085]

[0099] Item 3: In the method of item 1, the optical path lengths from the sampling regions associated with the plurality of output beams to the aperture are the same.

[0086]

[0100] Item 4: In the method of item 1, there is a detector or a light trapping device at or behind the aperture.

[0087]

[0101] Item 5: In the method of item 1, the detector or the light trapping device is a single-mode waveguide.

[0088]

[0102] Item 6: In the method of item 1, the detector or the light trapping device is an optical fiber.

[0089]

[0103] Item 7: A method of measuring a phase difference between adjacent output beams is

[0104] measuring an optical sample using a detector or a light trapping device;

[0105] To determine the phase difference measurement value, demodulating the time series of subsequent optical samples,

[0106] To generate a phase estimate, unwrapping the phase difference measurement value,

[0107] To generate an error signal, adding the phase estimate to an offset of beam steering or beam pattern phase,

[0108] Generating a phase command signal configured to modulate the phase of the beam sample in channel control by passing the error signal through an actuator filter and a control block including.

[0090]

[0109] Item 8: In the method of item 7, the step of demodulating includes a timing control signal.

[0091]

[0110] Item 9: In the method of item 7, the modulating and demodulating estimate the phase gradient by two-point time modulation.

[0092]

[0111] Item 10: In the method of any one of items 7-9, the step of demodulating includes full circle reconstruction of the phase difference measurement value.

[0093]

[0112] Item 11: The method of any one of items 7-10 further includes adjusting the phase offset by a calibration error offset.

[0094]

[0113] Item 12: In the method of any one of items 7-11, the actuator filter and the control block add a phase command signal to a control output according to a timing signal.

[0095]

[0114] Item 13: In the method of any one of Items 7 - 12, the actuator filter and the control block include one or more of a pure integrator, a proportional - integral controller, a leaky integrator controller, and a proportional - integral - derivative controller.

[0096]

[0115] Item 14: The method of Item 7 further includes combining the adjacent output beams into a spatially combined irradiation beam.

[0097]

[0116] Item 15: A gradient - interference - method lock - laser source

[0117] a laser source configured to produce an optical beam,

[0118] a beam splitter configured to split the optical beam into a plurality of output beams,

[0119] a provision for realizing one or more sampling regions, wherein the pair of focused beams and / or the optical paths from the plurality of beams have the same optical path length,

[0120] a detector configured to receive the plurality of output beams,

[0121] a demodulator configured to demodulate the plurality of output beams and further configured to determine a phase - difference measurement value associated with the plurality of output beams,

[0122] a phase unwrapper configured to receive the phase - difference measurement value and to determine a phase estimate at least in part based on the phase - difference measurement value,

[0123] an actuator filter and a control block configured to receive the phase estimate and one or more of a beam - steering offset, a beam - pattern phase offset, and a calibration - error offset, and further configured to generate a phase - command signal for adjusting one or more parameters of the plurality of output beams.

[0124] A beam combiner configured to spatially combine the output beams of the array to form an illumination laser beam is included.

[0098]

[0125] Clause 16: The gradient interference method lock laser source of clause 15 further includes a housing, and the laser source, the beam splitter, the detector, the demodulator, the phase unwrapper, and the actuator filter and control block are located within the housing.

[0099]

[0126] Clause 17: A spatial combiner for a coherent optical phased array laser

[0127] A laser source configured to irradiate a beam from the laser source

[0128] One or more lenses separated from the laser source by a first distance

[0129] An output window separated from the one or more lenses by a second distance

[0130] A sampling region located on a first surface of the output window

[0131] A detector arranged near the laser source is included,

[0132] The spatial combiner

[0133] To irradiate the beam from the laser source in a first direction through a first space between the laser source and the one or more lenses, through the one or more lenses, through a second space between the one or more lenses and the sampling region, to the sampling region where two or more beams overlap, and

[0134] To reflect the beam from the sampling region through the second space, through the one or more lenses, through the first space, to the detector arranged near the laser source is configured such that the optical path lengths of two or more beams are equal.

[0100]

[0135] Item 18: The spatial combiner of Item 17 further includes a housing, and the one or more lenses, the output window, the sampling region, and the detector are located within the housing.

[0101]

[0136] Item 19: In the spatial combiner of Item 17 or 18, the sampling region is at least a partial reflector.

[0102]

[0137] Item 20: In the spatial combiner of any of Items 17 - 19, the sampling region defines a plane.

Claims

1. A method for generating multiple phase differences between adjacent output beams and associated measurement signals, The steps include: each output beam irradiating multiple output beams emitted from an associated output beam source; The steps include: adapting the collimation state of the multiple output beams using multiple lenses of a lens array; The steps include forming multiple sampling regions in the output window, The steps of directing a sample of an adjacent beam pair through the sampling area so that it returns through the plurality of lenses, so as to form a focused beam pair, The steps include: generating an optical sample signal associated with the focused beam pair using a detector; Methods that include...

2. A method according to claim 1, wherein the optical path length from the sampling region to the detector is substantially the same between each pair of beams.

3. A method according to claim 1, further comprising the step of providing an aperture at the focal point of the pair of focused beams to form a sample of the pair of focused beams.

4. A method according to claim 3, wherein the detector is positioned after the aperture and measures the pair of samples of the focused beam.

5. A method according to claim 1, wherein the optical capturing device is positioned at the focal point of the pair of focused beams, and directs the sample of the pair of focused beams towards the detector.

6. The method according to claim 5, wherein the optical capturing device is a single-mode waveguide.

7. The method according to claim 5, wherein the optical capturing device is an optical fiber.

8. A method according to claim 1, further comprising the step of combining the adjacent pairs of beams into a spatially combined irradiation beam.

9. A method according to claim 1, wherein the step of directing by the sampling area further includes the step of directing a plurality of beam pairs, each of the plurality of beam pairs being directed to one of a plurality of detectors.

10. A method for measuring the phase values ​​of multiple beams, The steps include using a detector to measure the phase difference between adjacent beams and the associated optical sample signal, To determine the phase difference measurement, the process involves demodulating the time series of the subsequent optical sample signal, To generate a phase estimate, the steps include unwrapping the phase difference measurement values, Methods that include...

11. A method according to claim 10, wherein the demodulation step includes a timing control signal.

12. A method according to claim 10, wherein the modulation step and the demodulation step approximate a phase gradient by two-point time modulation.

13. A method according to claim 10, wherein the demodulation step includes full-circle reconstruction of the phase difference measurement value.

14. A method according to claim 10, further comprising the step of adjusting the phase approximation by calibration error offset.

15. A method for coherently combining multiple beams, The steps include: each output beam irradiating multiple output beams emitted from an associated output beam source; The steps include: adapting the collimation state of the multiple output beams using multiple lenses of a lens array; The steps include forming multiple sampling regions in the output window, The steps include directing a sample of an adjacent beam pair through the sampling area so that it returns through the plurality of lenses, so as to form a focused beam pair, The steps include generating a pair of optical sample signals of the focused beam using a detector, To determine the phase difference measurement, the process involves demodulating the time series of the subsequent optical sample signal, To generate a phase estimate, the steps include unwrapping the phase difference measurement values, To generate an error signal, the steps include adding the phase estimate to the offset of the beam steering or beam pattern phase, The error signal passes through the actuator filter and control block to generate a phase command signal configured to modulate the phase of the beam sample in channel control; Methods that include...

16. A method according to claim 15, wherein the optical path length from the sampling region to the detector is substantially the same between each pair of beams.

17. A method according to claim 15, further comprising the step of providing an aperture at the focal point of the pair of focused beams to form a sample of the pair of focused beams.

18. A method according to claim 17, further comprising the step of measuring the sample of the pair of focused beams by the detector, wherein the detector is positioned after the aperture.

19. A method according to claim 15, further comprising the step of a light-capturing device being positioned at the focal point of the pair of focused beams, and the light-capturing device directing the pair of focused beams of the sample towards the detector.

20. The method according to claim 19, wherein the optical capturing device is a single-mode waveguide.

21. The method according to claim 19, wherein the optical capturing device is an optical fiber.

22. A method according to claim 15, further comprising the step of combining the plurality of output beams into a spatially combined irradiation beam.

23. A method according to claim 15, wherein the actuator filter and control block add the phase command signal to the control output in accordance with the timing signal.

24. The method according to claim 15, wherein the actuator filter and control block include one or more of a pure integrator, a proportional-integral controller, a leaky integrator controller, and a proportional-integral-derivative controller.

25. A method for generating measurement signals associated with multiple phase differences between adjacent output beams of a light beam generator, The steps include: each output beam irradiating multiple output beams emitted from an associated output beam source; The steps include: adapting the collimation state of the multiple output beams using multiple lenses of a lens array; The steps include forming multiple sampling regions in the output window, The sampling region is used to direct the plurality of output beams toward a detector and generate an optical sample signal associated with the plurality of output beams. Methods that include...

26. A method according to claim 25, wherein the optical path length from the sampling region to the detector is substantially the same between each pair of beams.

27. A gradient interferometry-locked laser source, A laser source configured to generate a light beam, A beam splitter configured to divide the aforementioned light beam into multiple output beams, Multiple channel control devices configured to control the phases of the multiple output beams and apply modulation patterns to enable measurement of the phase difference between the multiple output beams, A beam combiner, configured with multiple lenses to spatially combine the multiple output beams of the array to form an irradiation laser beam, An output window having multiple sampling regions configured to direct samples of adjacent beam pairs back through the multiple lenses in order to form multiple pairs of focused beams, Multiple detectors configured to generate multiple optical sample signals associated with the multiple pairs of focused beams, A demodulator configured to demodulate the plurality of output beams, and further configured to determine the phase difference measurements associated with the plurality of output beams, A phase unwrapper configured to receive the phase difference measurement and to determine a phase approximation based at least partially on the phase difference measurement, An actuator filter and control block configured to receive the aforementioned phase estimate and one or more of the beam steering offset, beam pattern phase offset, and calibration error offset, and further configured to generate phase command signals for adjusting one or more parameters of the plurality of output beams, A gradient interferometry-locked laser source equipped with [specific feature].

28. A gradient interferometric lock laser source according to claim 27, wherein the optical path length extends from the plurality of sampling regions to the plurality of detectors, and the optical path length is substantially the same with respect to each of the plurality of pairs of focused beams.

29. A gradient interferometry-locked laser source according to claim 27, further comprising a plurality of apertures, each of which is located at the focal point of each of the plurality of focused beam pairs.

30. A gradient interferometry-locked laser source according to claim 29, wherein the plurality of detectors are located downstream of the plurality of apertures.

31. A gradient interferometry-locked laser source according to claim 27, further comprising a plurality of optical trapping devices, each of which is configured to direct a pair of samples of the focused beam to the plurality of detectors.

32. A gradient interferometry-locked laser source according to claim 31, wherein the plurality of optical trapping devices are single-mode waveguides.

33. A gradient interferometry-locked laser source according to claim 27, further comprising a housing, wherein the beam splitter, the plurality of channel control devices, the beam combiner, the output window, and the plurality of detectors are located within the housing.

Images