Multiple coherent beam combining systems sharing a common receiver.

Abstract

The targeting receiver operates in conjunction with the beam emitters. Each emitter generates a coherent beam that is directed toward the target as a composite beam having an associated signature. For each composite beam, the target reflects a portion of the radiation intensity as a reflected radiation component. The receiving telescope collects the radiation reflected from the target and directs the radiation to a spatial filter. The reflected radiation includes radiation components, at least some of which are combined as a composite radiation comprised of the reflected radiation components. The intensity of the combined radiation indicates the intensity of the composite beam incident on the target. The spatial filter filters the reflected radiation by selectively passing the combined radiation. Each component of the combined radiation is identifiable by a signature associated with the composite beam corresponding to the combined radiation component. In some embodiments, an identification module is coupled to the receiver and identifies the components based on the signature.

Description

[Technical field]

[0001] The present invention relates to a coherent beam combining (CBC) system. [Background technology]

[0002] To achieve power scaling of laser sources, it is known to utilize CBC systems in which multiple coherent laser beams are combined to form an output beam. To provide system flexibility in terms of number and distribution of beam sources, it has been considered to direct the output beams from multiple CBC systems to combine at a target as a combined beam. Coherent combining of output beams from multiple CBC systems has been a technical challenge without any notable benefits. In particular, due to the coherence between the output beams of the CBC system, the resulting interference pattern of the combined beam (typically used for beam intensity optimization in combination with target imaging) consists of tight lines, which makes stabilization of the combined beam on the target very difficult. Furthermore, coherent combining of output beams on a target requires separate measurements of each of the sub-beams of the CBC system to achieve intensity optimization of the individual output beams. Similar challenges exist when the output beams from multiple CBC systems are combined incoherently. Summary of the Invention

[0003] The present invention is a system and method for receiving radiation reflected from a target in response to illumination of the target by multiple beam emitters using a common receiver.

[0004] In accordance with the teachings of an embodiment of the present invention, a system is provided that includes a plurality of beam-emitting subsystems, each configured to generate a plurality of coherent beams for directing towards a region of a target to combine as a composite output beam at or in front of the target, and for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, the plurality of radiation components being coupled to each other; The system includes a telescope array, at least some of which combine as a combined radiation made up of reflected radiation components, and the intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on the target, a spatial filtering arrangement disposed at the focal plane and configured to filter the reflected radiation by selectively passing the combined radiation, and a radiation discrimination module for receiving the combined radiation passed by the spatial filtering arrangement and, for each reflected radiation component, discriminating an intensity parameter of the reflected radiation component from an intensity parameter of the combined radiation of all remaining reflected radiation components.

[0005] According to further features of embodiments of the present invention, each beam delivery subsystem includes a beam generating array for generating a respective one of the composite output beams, and a beam directing array for directing the composite output beam towards a target.

[0006] According to further features of embodiments of the invention, each reflected radiation component has a different wavelength than all the rest of the reflected radiation components, and the radiation discrimination module includes an optical system array including at least one dispersive optical component for splitting the combined radiation into a plurality of constituent wavelengths corresponding to the wavelengths of the reflected radiation components, and a detector array for receiving the radiation split by the at least one dispersive optical component, the detector array configured to measure radiation of each of the constituent wavelengths separately.

[0007] According to further features in embodiments of the present invention, the at least one dispersive optical component includes a prism.

[0008] According to further features in embodiments of the present invention, the at least one dispersive optical component includes a diffraction grating.

[0009] According to further features of embodiments of the present invention, the optical system arrangement further includes a collimating element disposed in an optical path between the spatial filtering arrangement and the at least one dispersive optical component, the collimating element configured to collimate the combined radiation to produce collimated radiation and to direct the collimated radiation to the at least one dispersive optical component.

[0010] According to further features of embodiments of the present invention, the detector arrangement includes an array of detectors, each individual detector of the array of detectors configured to measure radiation at a different individual one of the constituent wavelengths.

[0011] According to further features of embodiments of the present invention, each beam emission subsystem includes an array of beam sources configured to generate a plurality of coherent beams for directing towards a target to combine as a composite output beam at or in front of the target, a plurality of adjustable phase modulators coupled to the beam sources to enable adjustment of relative phase offsets of the plurality of coherent beams, and an encoding module for encoding the phase of each of the plurality of coherent beams with a code locally unique to the beam emission subsystem.

[0012] According to further features of embodiments of the present invention, the radiation discrimination module includes a detector arranged to receive the combined radiation and monitor an intensity parameter of the combined radiation, and a decoding module configured to decode, for each mixed output beam, the intensity parameter of the combined radiation in accordance with a locally unique code of the beam emission subsystem that generated that mixed output beam to isolate an intensity parameter of a reflected radiation component corresponding to that mixed output beam.

[0013] According to further features of an embodiment of the present invention, the encoding module includes a modulator, and the code includes modulation frequencies such that each composite output beam is assigned at least one unique modulation frequency, and the encoding module is configured to encode the phase of each coherent beam for each beam emission subsystem by modulating the current phase of the coherent beam at the assigned at least one modulation frequency, and the decoding module includes a plurality of demodulators, each demodulator configured to demodulate a signal at one or more selected demodulation frequencies selected from the assigned unique modulation frequencies.

[0014] According to further features of embodiments of the present invention, there is also provided a control subsystem coupled to the radiation discrimination module and each of the multiple beam emission subsystems, each beam emission subsystem including an array of beam sources configured to generate multiple coherent beams for directing towards a target to combine as a composite output beam at or in front of the target, and a plurality of adjustable phase modulators coupled to the beam sources to enable adjustment of the relative phase offset of the coherent beams, and for each reflected radiation component, the control subsystem is configured to receive intensity parameters of the radiation component from the radiation discrimination module, and to adjust beam parameters of one or more coherent beams of the composite output beam corresponding to the reflected radiation component based on the received intensity parameters.

[0015] According to further features of embodiments of the present invention, there is also provided an imaging system for generating an image of a target, the imaging system including a wavefront sensor, a deformable mirror for receiving radiation from a spatial filtering arrangement, a beam splitter for receiving radiation from the deformable mirror and providing a portion of the received radiation to the wavefront sensor and providing another portion of the received radiation to a radiation discrimination module, and an adaptive optics controller associated with the wavefront sensor operative to control the deformable mirror to reduce optical distortions in reflected radiation collected by a telescope array.

[0016] According to the teachings of an embodiment of the present invention, there is also provided a system including: a plurality of beam-emitting subsystems, each beam-emitting subsystem configured to generate a plurality of coherent beams for directing towards a region of a target to combine as a composite output beam at or in front of the target, the composite output beams being generated by the beam-emitting subsystems having different respective wavelengths, and for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; and a receiver, a telescope arrangement for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflecting beam being reflected by the target. The receiver includes a telescope array, where the emitted radiation includes a plurality of radiation components, at least some of the radiation components combining into a combined radiation comprised of reflected radiation components; a spatial filtering arrangement disposed at the focal plane, configured to filter the reflected radiation by selectively passing the combined radiation; an optical system array for receiving the combined radiation from the spatial filtering arrangement, the optical system array including at least one dispersive optical component for splitting the combined radiation into a plurality of constituent wavelengths corresponding to wavelengths of the composite output beam; and a detector array for receiving the radiation split by the at least one dispersive optical component, the detector array configured to separately measure radiation at each of the constituent wavelengths.

[0017] According to further features in embodiments of the present invention, the at least one dispersive optical component includes a prism.

[0018] According to further features in embodiments of the present invention, the at least one dispersive optical component includes a diffraction grating.

[0019] According to further features of embodiments of the present invention, the optical arrangement further includes a collimating element disposed in an optical path between the spatial filtering arrangement and the at least one optical component, the collimating element configured to collimate the combined radiation to produce collimated radiation and to direct the collimated radiation to the at least one optical element.

[0020] According to a further feature of an embodiment of the present invention, a control subsystem is also provided that is coupled to the detector array and to each of the plurality of beam emission subsystems, and for each beam emission subsystem, the control subsystem is configured to adjust beam parameters of one or more coherent beams of the composite output beam generated by the beam emission subsystem based on radiation measured by the detector array.

[0021] According to further features of embodiments of the present invention, the detector arrangement includes an array of detectors, each individual detector of the array of detectors configured to measure radiation at a different individual one of the constituent wavelengths.

[0022] In accordance with the teachings of embodiments of the present invention, there is also provided a system comprising an array of beam sources, each beam emission subsystem configured to generate a plurality of coherent beams for directing toward a region of a target to combine as a composite output beam at or in front of the target, a portion of the radiation intensity of the composite output beam that is reflected by the target as a reflected radiation component, a plurality of adjustable phase modulators coupled to the beam sources to enable adjustment of a relative phase offset of the coherent beams, and an encoding module for encoding a phase of each of the coherent beams with a code that is local to the beam emission subsystem. the combined radiation being combined with a signal representative of the intensity of the combined radiation; and a receiver including a telescope array for collecting radiation reflected from a target and directing the reflected radiation onto a focal plane, the reflected radiation including a plurality of radiation components, at least some of the radiation components combining as a combined radiation made up of reflected radiation components; a spatial filtering arrangement disposed at the focal plane and configured to filter the reflected radiation by selectively passing the combined radiation; a detector disposed to receive the combined radiation from the spatial filtering arrangement and generate a signal representative of the intensity of the combined radiation; and a decoding module for deciphering the signal according to a code locally unique for each beam-emitting subsystem.

[0023] According to further features of embodiments of the present invention, the encoding module includes a modulator, and each composite output beam is assigned a locally unique modulation frequency, and for each beam emission subsystem, the modulator is configured to modulate a current phase of the coherent beam at the assigned modulation frequency, and the decoding module includes a plurality of demodulators, each demodulator configured to demodulate a signal at one or more selected demodulation frequencies selected from the assigned unique modulation frequencies.

[0024] According to further features of the present embodiment, for each beam emission subsystem, the encoding module includes a sequence generator for generating a code sequence and the encoding module is configured to encode the phase of each coherent beam by modulating a current phase of the coherent beam with a waveform linked to the code sequence, and the decoding module includes a signal generator for generating the waveform linked to the code sequence and the decoding module is configured to demodulate the signal using each of the waveforms.

[0025] According to the teachings of the present invention, there is also provided a system, comprising: a plurality of beam-emitting subsystems, each configured to generate a plurality of coherent beams for directing toward a region of a target to combine as a composite output beam at or in front of the target, for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a plurality of receivers, each of which collects radiation reflected from the target and directs the reflected radiation onto a focal plane, the reflected radiation including a plurality of radiation components, at least some of the radiation components being reflected by the target; the reflected radiation being combined into a combined radiation comprised of line components, where an intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on the target; spatially filtering the reflected radiation at a focal plane by selectively passing the combined radiation; and configured to receive the spatially filtered combined radiation and, for each reflected radiation component, discriminate an intensity parameter of that reflected radiation component from an intensity parameter of a combined radiation of all remaining reflected radiation components; and a control subsystem coupled to the receivers and configured to select the selected receiver based on an estimate of the effective resolution of the target provided by each of the receivers.

[0026] According to a further feature of an embodiment of the present invention, the control subsystem is further configured to operate each of the beam emission subsystems to adjust one or more beam parameters of the coherent beam based on the intensity parameter discriminated by the selected receiver.

[0027] According to the teachings of an embodiment of the present invention, a method is also provided, the method including the steps of transmitting a plurality of composite output beams by generating a plurality of coherent beams for directing towards a region of a target to combine as a composite output beam at or in front of the target, and for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining as a combined radiation made up of the reflected radiation components, where the intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on the target; spatially filtering the reflected radiation by selectively passing the combined radiation; and receiving the combined radiation passed through the spatial filtering arrangement and, for each reflected radiation component, discriminating an intensity parameter of the reflected radiation component from an intensity parameter of a combined radiation of all remaining reflected radiation components.

[0028] According to the teachings of an embodiment of the present invention, there is also provided a method for detecting a radiation intensity of a target by a plurality of beam emission subsystems, each of which is configured to generate a plurality of coherent beams for directing toward a region of a target to combine as a composite output beam at or in front of the target, wherein each composite output beam has an associated locally unique signature, and wherein for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, wherein the reflected radiation is reflected by a plurality of beam emission subsystems; wherein at least some of the radiation components combine as a combined radiation made up of the reflected radiation components, where an intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on the target, and a spatial filtering arrangement disposed at the focal plane configured to filter the reflected radiation by selectively passing the combined radiation, where each component of the combined radiation is distinguishable by a locally unique signature associated with a composite output beam corresponding to the component of the combined radiation.

[0029] According to further features of embodiments of the present invention, there is also provided at least one radiation discrimination module for receiving the combined radiation passed by the spatial filtering arrangement and for discriminating, for at least one of the reflected radiation components, at least one intensity parameter of the reflected radiation component from intensity parameters of a combined radiation of all remaining reflected radiation components based on at least one of the locally unique signature constants associated with the composite output beam corresponding to a component of the combined radiation.

[0030] According to further features in embodiments of the present invention, the at least one radiation discrimination module includes exactly one module.

[0031] According to further features of embodiments of the present invention, the at least one radiation discrimination module includes a plurality of radiation discrimination modules, each radiation discrimination module being associated with a respective one of said beam emission subsystems, and for each radiation discrimination module, said radiation discrimination module is configured to discriminate an intensity parameter of one of said reflected radiation components from an intensity parameter of a combined radiation of all remaining reflected radiation components, corresponding to a composite output beam generated by said beam emission subsystem associated with said radiation discrimination module.

[0032] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as understood by those skilled in the art to which this invention belongs.Although methods and materials similar or equivalent to those described herein can be carried out or used to test the embodiments of this invention, exemplary methods and / or materials are described below.In case of conflict, this patent specification, including definitions, controls.In addition, materials, methods, and examples are merely illustrative and are not necessarily intended to be limiting. [Brief description of the drawings]

[0033] Some embodiments of the present invention are herein described, by way of example only, with reference to the accompanying drawings. With detailed reference to certain drawings, it is stressed that the details are shown by way of example and for purposes of illustrative illustration of embodiments of the invention. In this regard, the description made with respect to the drawings will make apparent to those skilled in the art how to practice embodiments of the present invention.

[0034] Turning now to the drawings, like reference numbers or letters indicate corresponding or similar elements.

[0035] [Figure 1]1 is a diagrammatic representation of a system constructed and operative in accordance with an embodiment of the present invention, the system having multiple beam delivery subsystems for transmitting beams of radiation toward a target, and a single receiver shared among the beam delivery subsystems, having a telescope for collecting corresponding reflected radiation from the target, and a radiation discrimination module for discriminating components of the reflected radiation from other reflected radiation components. [Diagram 2] 2 is a diagrammatic representation of a beam delivery subsystem for transmitting a beam that may be implemented in the system of FIG. 1 in accordance with an embodiment of the present invention. [Diagram 3] 2 is a diagrammatic representation of the receiver of FIG. 1 , in which the radiation discrimination module includes dispersive optics and a detector array for discriminating components of the reflected radiation from other reflected radiation, in accordance with an embodiment of the present invention; [Figure 4] 2 is a diagrammatic representation of the receiver of FIG. 1 , according to an embodiment of the present invention, where the radiation discrimination module includes a photodetector and a decoding module that decodes information in the collected reflected radiation to discriminate between the reflected radiation component and other reflected radiation components; [Diagram 5] 2 diagrammatically illustrates a telescope array, such as the receiver telescope of FIG. 1, including adaptive optics for correcting wavefront distortions and images received by the telescope array. [Figure 6] FIG. 2 is a schematic representation of a system integrating a telescope with adaptive optics into the receiver of FIG. 1. [Figure 7] 2 is a diagrammatic representation of a system having multiple beam emission subsystems for transmitting beams and multiple receivers, each corresponding to the receiver configuration of FIG. 1, in accordance with an embodiment of the present invention. [Figure 8] 2 is a diagrammatic representation of a system constructed and operative in accordance with an embodiment of the present invention, generally similar to the system of FIG. 1, but in which the radiation discrimination module is separated from the receiver. [Figure 9]FIG. 9 is a schematic representation of a system constructed and operable in accordance with an embodiment of the present invention, generally similar to the system of FIG. 8, but where there are multiple radiation discrimination modules, and each of the beam emission subsystems is associated with a respective one of the radiation discrimination modules. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The present invention is a system and method that uses a common receiver to receive radiation reflected from a target in response to illumination of the target by multiple beam emitters.

[0037] The beam emitters are configured such that each beam emitter transmits a coherent beam that combines coherently at or before reaching the target to illuminate a common spot on the target. The receiver is positioned and directed at the target in certain embodiments to view the spot and capture radiation reflected from the spot corresponding to radiation illumination from all of the beam emitters, and to image the spot. The receiver is typically smaller in size and lower in cost compared to the beam emitters, and can be positioned independently of the beam emitters. The size, cost-effectiveness, and placement options of the receiver compared to the beam emitters provide the system of the present disclosure with significant advantages over conventional systems that utilize dedicated receivers for each CBC system. One particular advantage of using a single receiver with multiple beam emitters (including hundreds of beam emitters) is the ability, according to embodiments of the present disclosure, to aim the receiver at a target spot common to the beam emitters, capture radiation reflected from the target from a corresponding number of coherently combined beams, and then process the captured radiation to form an image of the target spot and / or use it as input for other purposes, such as feedback to the beam emitter for beam intensity optimization. In an embodiment, the reflected radiation is processed by a control subsystem and provided to the beam emitter as feedback to adjust beam delivery parameters for beam intensity optimization. To improve the effectiveness of the beam emitter in performing intensity optimization, embodiments of the present disclosure process the reflected radiation to isolate radiation components in the reflected radiation that correspond to the beam transmitted by a particular beam emitter. Radiation processing may be performed by the receiver itself or by one or more modules separate from the receiver.

[0038] The principles and operation of the systems and methods according to the present invention may be better understood with reference to the drawings accompanying this specification.

[0039] Systems and methods according to the present invention are particularly valuable when applied in the context of high energy laser or directed energy weapon systems.

[0040] Before describing at least one embodiment of the invention in detail, it is to be understood that the invention, in its application, is not necessarily limited to the details of construction and the arrangement of components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples, as the invention may be practiced or carried out in other embodiments or in various ways.

[0041] Referring now to the drawings, Figure 1 illustrates an implementation of a multiple coherent beam combining (CBC) system (hereinafter referred to as the "system"), generally designated (10), constructed and operable in accordance with certain non-limiting embodiments of the present disclosure. Broadly speaking, the system (10) includes a series (i.e., collection or group) of beam delivery subsystems (12a, 12b, and 12c) configured to generate and transmit (direct) respective composite output beams (14a, 14b, and 14c) toward a region of a target (26) (typically a remote target), and a receiver (16) (also referred to as a targeted receiver) that is common (i.e., shared between) all of the beam delivery subsystems (12a, 12b, and 12c) is positioned to receive radiation reflected from the target (26).

[0042] The beam delivery subsystems (12a, 12b, and 12c) transmit their respective output beams such that the composite output beams (14a, 14b, and 14c) are incoherently combined at or before reaching the target (26). The composite output beams (14a, 14b, and 14c) (interchangeably referred to as the "output beams", "composite beams", or "output composite beams") are transmitted along optical paths that pass through an optically inhomogeneous and / or momentarily varying medium (28), such as air, toward the target (26). It is desirable for each of the composite output beams (14a, 14b, and 14c) to be incident on the same region of the target (26) so that effective power scaling of the individual beam delivery subsystems (12a, 12b, and 12c) can be achieved.

[0043] Various approaches have been shown to directing beams from different (or the same) sources to combine with high precision onto a common spot on a target. One approach uses a master-slave-beam emitter configuration, in which a master unit emits (transmits) a low-power guide beam onto an intended spot on the target, where the guide beam forms a local coordinate system on the target. The slave unit tracks the guide beam's spot on the target, calculates a direction vector from the slave unit to the target spot (e.g., using the formed local coordinate system), and then transmits one or more high-power beams along the vector to combine on the intended target spot. Further details of a system providing for combining beams (of generally lower power than the output beams (14a, 14b, and 14c)) onto a target spot can be found in commonly owned U.S. Patent No. 9,003,942 B2, the entirety of which is incorporated herein by reference. Although this prior approach is directed to low-power beams combining onto a target, the general concept of such a system may be applicable in the context of the present invention. In this regard, a master unit may be arranged to transmit a low power guide beam, and the beam emission subsystems (12a, 12b, and 12c) may function as synchronized slave units that transmit high power output beams (14a, 14b, and 14c) based on a calculated direction vector, where synchronization may be provided by a control subsystem linked to the beam emission subsystems (12a, 12b, and 12c) and the master unit. The calculation of the direction vector may be performed by such a control subsystem, or may be performed by hardware / software processing installed locally on the beam emission subsystems (12a, 12b, and 12c).

[0044] The beam-emitting subsystems (12a, 12b, and 12c) can be arranged in a variety of configurations depending on the particular application for which the system (10) is to be used. In one non-limiting example configuration, the beam-emitting subsystems (12a, 12b, and 12c) are arranged in close proximity to one another, preferably within a single modular housing. In another example configuration, the beam-emitting subsystems (12a, 12b, and 12c) are arranged in an array with equal or uneven spacing between adjacent beam-emitting subsystems, and adjacent beam-emitting subsystems may be approximately 5 to 50 meters apart. In other configurations, the beam-emitting subsystems (12a, 12b, and 12c) are arranged in a strategically separated (non-array) configuration, and adjacent beam-emitting subsystems may be separated by distances ranging up to several kilometers, so long as the beam-emitting subsystems (12a, 12b, and 12c) can each be directed to the same point on the target (26).

[0045] Although three beam emission subsystems are illustrated here for simplicity of explanation, embodiments of the present disclosure may be practiced with arrays including anywhere from two to hundreds of such subsystems.

[0046] As discussed below, each of the composite output beams (14a, 14b, and 14c) is formed from a plurality of respective coherent beams produced by beam sources associated with the respective beam emission subsystems (12a, 12b, and 12c). FIG. 2 diagrammatically illustrates a non-limiting example of a beam emission subsystem (30) that can be used to implement each of the beam emission subsystems (12a, 12b, and 12c). Generally speaking, the beam emission subsystem (30) includes an array of beam sources (32a, 32b, and 32c) configured to generate a plurality of coherent beams (40a, 40b, and 40c) (also referred to as "sub-beams") for directing toward the target (26). A plurality of adjustable phase modulators (34a, 34b, and 34c) are associated with the respective beam sources (32a, 32b, and 32c) to enable adjustment of the relative phase offset of the beams. 2 for simplicity of explanation, embodiments of the present disclosure are most preferably implemented with arrays containing anywhere from two to hundreds of beams, and most typically with a range of 15-40 beam sources, with at least 10 beam sources in some particularly preferred cases. Although phase modulators are typically provided one per beam source, it will be understood that one of the sources may be implemented as a constant reference phase with no adjustment, and the remaining beams and phase offsets may be measured and / or adjusted relative to that reference phase.

[0047] It will be appreciated that various details of the implementation of the system (10) and beam delivery subsystem (30) will vary considerably depending on the intended application of the device. The various applications may range from low energy research tools for measuring fast variations in optical properties in turbulent media through various communication applications (energy media) to high energy directed energy weapon systems. Although the beam delivery subsystem (30), and thus the system (10), support a wide variety of applications, the beam delivery subsystem (30) and system (10) are particularly valuable when used as part of a high energy laser or directed energy weapon system. In each case, the array of beam sources (32a, 32b, and 32c) is most preferably an array of fiber lasers seeded by a common seeder oscillator (36). For high energy applications, each fiber laser is preferably rated for at least 100 W of power output. The principles of the present embodiment can be used in devices operating at a variety of different wavelengths, but are typically implemented in the near infrared (NIR) region. Seeder oscillators and fiber lasers suitable for operating in these regions are well known in the art and are readily commercially available. The phase modulators (34a, 34b, and 34c) may be any type of phase modulator with suitable response time and low attenuation. The phase modulators are placed after splitting the seeder (36), but preferably before the fiber laser to operate with relatively low power signals. Suitable phase modulators are commercially available. One suitable non-limiting example is a 10 GHz titanium diffused Z-Cut LiNbO3 phase modulator identified by model number LN53S-FC, commercially available from Thorlabs, NJ (USA). The combination of the beam sources (32a, 32b, and 32c), the phase modulators (34a, 34b, and 34c), and the seeder (36) constitute a "beam generating array."

[0048] In one embodiment, a coding module (44) is linked to each of the phase modulators (34a, 34b, and 34c). As will be discussed, the coding module (44) operates to code (or "tag") the phase of the coherent beam with a code (or "signature") that is unique to a particular beam-emitting subsystem (and the output beam transmitted by that beam-emitting subsystem).

[0049] The beam directing array (schematically represented in FIG. 2 by lenses 38) directs the beams 40a, 40b, and 40c toward a particular area of ​​the target 26 such that the beams 40a, 40b, and 40c combine (constructively interfere) at or before reaching the target 26 to form a composite output beam 42. The composite output beam 42, which is made up of the sub-beams 40a, 40b, and 40c, is representative of any one of the composite output beams 14a, 14b, and 14c illustrated in FIG. 1. The beam directing array 38, which is only shown diagrammatically in FIG. 2, typically includes separate collimators for each beam and common large aperture focusing optics for collectively directing the beams toward the target 26 such that they combine at or before reaching the target 26. Separate focusing optics may also be provided for each beam. In the context of this specification, coherent sub-beams that are combined at or before reaching the target generally refer to coherent sub-beams that are coherently combined at the target or that are coherently combined in front of the target and remain coherently combined over the remaining distance to the target. The term "target" is used broadly here to refer to the object on which the beams (40a, 40b, and 40c) (as well as the composite output beams (14a, 14a, and 14c)) are incident, and in certain preferred applications is a target in the military sense for weapons applications, but may also be a receiver (detector) for communications applications. Indeed, the system (10) is particularly valuable in situations where the target (26) is a remote, uncooperative target (in the military sense). However, the system (10) can also be used in situations where the target (26) is a cooperative target, for example, where the system (10) is used as a diagnostic or research tool, or as a measurement tool to assist other devices / systems. In such circumstances, a detector may be attached to the target (26) to provide feedback to the system (10) via a communications link.

[0050] The sub-beams (i.e., coherent beams (40a, 40b, and 40c)) for each of the respective composite output beams (14a, 14b, and 14c) are coherent so as to constructively interfere, but the composite output beams (14a, 14b, and 14c) themselves are mutually incoherent. In other words, while the sub-beams of a particular composite output beam have the same effective wavelength and phase, the composite output beams (14a, 14b, and 14c) have different respective effective wavelengths and / or phases.

[0051] It should be noted that the number of sub-beams generated by the beam-emitting subsystems need not necessarily be uniform across the beam-emitting subsystems. In other words, each of the composite output beams (14a, 14b, and 14c) may be composed of a different respective number of sub-beams. For example, one of the beam-emitting subsystems may generate (i.e., include) on the order of 10 sub-beams, another of the beam-emitting subsystems may generate (i.e., include) on the order of 15-40 sub-beams, and yet another of the beam-emitting subsystems may generate (i.e., include) on the order of 100 beam sources.

[0052] A portion of the radiation incident on the target (26) is reflected (typically backscattered) by the target (26) toward a targeting receiver (16) associated with the beam delivery subsystem (12a, 12b, and 12c). In general, in response to illumination of the target (26) by each of the composite output beams (14a, 14b, and 14c), a percentage of the radiation intensity of each of the composite output beams (14a, 14b, and 14c) is reflected from the target (26) as a corresponding reflected radiation component designated by the thin dashed arrow (15a, 15b, and 15c). The intensity of the reflected radiation (corresponding to the reflected radiation components (15a, 15b, and 15c)) varies as a function of the intensity of the radiation (from the composite output beams (14a, 14b, and 14c)) that impinges on an area of ​​the target (26). In FIG. 2, the reflected radiation from the single composite beam (42) is generally designated (43). It should be noted that the reflected radiation (43) includes radiation components corresponding to the reflection of each of the sub-beams (40a, 40b, and 40c) from the target (26).

[0053] The receiver (16) is positioned and configured to receive radiation (i.e., light) reflected from the target (26), including radiation received from the reflected radiation components (15a, 15b, and 15c). The receiver (16) may be co-located with one or more of the beam delivery subsystems (12a, 12b, and 12c). Alternatively, the receiver (16) may be located remotely from some or all of the beam delivery subsystems (12a, 12b, and 12c). Additionally, the major components of the receiver (16) may be located at the same location or distributed at different geographic locations. Regardless of the specific location configuration of the receiver (16) and its major components described above, the receiver (16) is preferably located independently of the beam delivery subsystems (12a, 12b, and 12c), and the receiver (16) should be located such that radiation corresponding to all reflected radiation components (15a, 15b, and 15c) reaches a particular major component of the receiver (16).

[0054] Typically, the radiation reflected from the target (i.e., the reflected radiation) includes multiple radiation components, some of which correspond to the reflected radiation components (15a, 15b, and 15c) and some of which correspond to other radiation sources including, for example, atmospheric noise. The reflected radiation components (15a, 15b, and 15c) are combined (i.e., the radiation intensities of the reflected radiation components (15a, 15b, and 15c) are summed) before reaching the receiver to form the "combined radiation." The intensity of the combined radiation (composed of the reflected radiation components (15a, 15b, and 15c)) is a measure of the intensity of the radiation incident on that region of the target (26) by each of the composite output beams (14a, 14b, and 14c). In a preferred embodiment, the receiver (16) is coupled to a radiation discrimination module (22) configured to separate the combined radiation intensity parameters (combined radiation intensity signals) to discriminate the intensity parameters of the reflected radiation components corresponding to each of the combined radiation components from the combined radiation intensity parameters of all other reflected radiation components. In other words, in such an embodiment, the radiation discrimination module (22) coupled to the receiver (16) is configured to discriminate the reflected intensity signals resulting from each one of the beam emission subsystems (12a, 12b, and 12c) from the received reflected intensity signals of the combined reflected radiation. As described below, in some embodiments, the radiation discrimination module (22) is functionally part of the receiver (16) (i.e., the radiation discrimination module (22) is a component of the receiver (16)), while in other implementations, the radiation discrimination module (22) is a separate component of the receiver (16) and may be located independently of the receiver (16).

[0055] It is noted that for each of the composite output beams (14a, 14b, and 14c), a certain intensity percentage of a sub-beam (e.g., beams (40a, 40b, and 40c)) is reflected from the target (26). When referring to the reflected radiation components (15a, 15b, and 15c), it is noted that these components represent combinations of the reflected radiation sub-components of the associated composite output beams (14a, 14b, and 14c). In other words, the reflected radiation component (15a) represents a combination of the reflected radiation sub-components of the composite output beam (14a), and the reflected radiation component (15b) represents a combination of the reflected radiation sub-components of the composite output beam (14b). Thus, the combined radiation formed from the combination of radiation corresponding to the reflected radiation components (15a, 15b, and 15c) actually includes radiation corresponding to all of the reflected radiation sub-components of all associated composite output beams (14a, 14b, and 14c). Thus, for a particular beam-emitting subsystem, the receiver (16) is configured to split the received combined radiation in order to identify a subset of the reflected radiation sub-components that correspond to a particular composite output beam generated by this beam-emitting subsystem. In other words, for a particular beam-emitting subsystem, the receiver (16) is configured to split the received combined radiation in order to discriminate the combined radiation components that correspond to the composite output beam generated by this beam-emitting subsystem.

[0056] To ensure that the receiver (16) receives the correct radiation, an optics array, typically in the form of a targeting telescope, is positioned to define a field of view corresponding to the area from which the reflected radiation comes so that it is collected by the optics array (at least the combined radiation reaches the entrance aperture of the optics array). The optics array is represented diagrammatically in FIG. 1 by lens (18), but is typically an assembly of lenses, which may be refractive or reflective, or any combination thereof, as is well known in the art. The telescope (18) defines an optical path from the target (26) to the receiver (16).

[0057] Incidentally, coarse alignment of the output beams (14a, 14b, and 14c) is applied by individual tracking subsystems for each of the beam delivery subsystems (12a, 12b, and 12c) to the point where the extended lobes (i.e., side lobes) of the radiation patterns of the output beams (14a, 14b, and 14c) overlap, in order to direct the output beams (14a, 14b, and 14c) to the same region (also referred to as the same "spot") of the target (26). Alignment of the central lobes of the output beams (14a, 14b, and 14c) is achieved by closing the loop through the receiver (16) and feeding back to the beam delivery subsystems (12a, 12b, and 12c). In one embodiment, the optical arrangement (i.e., telescope (18)) also preferably forms part of or is integrated with an imaging system that can be used to target each of the beam delivery subsystems (12a, 12b, and 12c). The imaging system creates an image of the target (26) and an image of a desired area (or "spot") on the target (26) on which the composite output beams (14a, 14b, and 14c) are incident. By forming the image of the target (26) and the spot, the composite output beams (14a, 14b, and 14c) can be targeted at the target (26) (such that the side lobes of the composite output beams (14a, 14b, and 14c) overlap) and the intensities of the composite output beams (14a, 14b, and 14c) can be optimized (by a control system). An imaging system is not illustrated herein, but a non-limiting example of a telescope integrated into an imaging system will be described later in this disclosure with reference to FIGS.

[0058] The reflected radiation, collected at the entrance aperture of the telescope 18, is focused by the telescope 18 into a focal plane. A spatial filtering arrangement 20, associated with the telescope 18, is disposed at the focal plane. The spatial filtering arrangement (20) is configured to spatially filter the reflected radiation collected by the telescope (18) to generate "filtered radiation" by passing only reflected radiation components originating from a spot on the target (26) (these reflected radiation components are referred to as "combined radiation" as described above), such that only radiation resulting from the illumination of the target (26) by the composite output beams (14a, 14b, and 14c) (i.e., reflected radiation components (15a, 15b, and 15c)) can pass through the spatial filtering arrangement. A narrow-band filter (not shown) can be positioned in the optical path between the telescope (18) and the spatial filtering arrangement (20) to filter out ambient background radiation emanating from the illuminated area of ​​the target (26), thereby improving the signal-to-noise ratio in the illumination sensing component of the system (10).

[0059] The spatial filtering arrangement (20) may be implemented in a variety of ways. In one non-limiting example, the spatial filtering arrangement (20) is implemented as a pinhole that acts as a spatial frequency low-pass filter at the image plane of the telescope (18). Similarly, the spatial filtering arrangement (20) may be implemented using an optical fiber, with the end of the optical fiber located at the image plane of the telescope (20). Here, only light having the desired spatial frequency is coupled into the core of the optical fiber. Alternatively, the spatial filtering arrangement (20) may be implemented using a small detector located at the exit aperture of the telescope (18). After the intensity of the composite output beams (14a, 14b, and 14c) has been optimized (e.g., by the imaging and control systems described above), the size of the spatial filtering arrangement (20), e.g., the size of the pinhole, may be used to determine the size and location of the central lobe of the composite output beams (14a, 14b, and 14c) relative to the desired spot on the target (26).

[0060] The placement of the receiver (16) with the spatial filtering arrangement (20) allows the receiver (16) to "see" a common spot on the target (26) illuminated by the beam emission subsystems (12a, 12b, and 12c). Thus, the receiver (16) can provide a feedback signal, or feedback information, to the beam emission subsystems (12a, 12b, and 12c) based on reflected radiation from the captured target spot.

[0061] One particular method for generating such feedback according to an embodiment of the present disclosure is based on discriminating a particular component of the combined radiation (provided by the spatial filtering arrangement (20)) from the remaining components of the combined radiation. The discrimination of the radiation is performed by a radiation discrimination module (22), which is coupled to the telescope (18) and the spatial filtering arrangement (20) and is arranged to receive the combined radiation from the spatial filtering arrangement (20). In the non-limiting example illustrated in FIG. 1, the radiation discrimination module (22) is part of the receiver (16), although as described below, all or some of the components of the radiation discrimination module may be separate from the receiver (16). In an embodiment, multiple radiation discrimination modules are arranged such that each is coupled to (or is part of) a respective one of the beam emission subsystems. For clarity in illustrating the functionality and operation of the radiation discrimination module (22), the radiation discrimination module will be described in the context of being part of the receiver (16) unless expressly indicated otherwise.

[0062] Preferably, the radiation discrimination module (22) receives the filtered radiation from the spatial filtering arrangement (20) such that substantially only the combined radiation is received by the radiation discrimination module (22). The radiation discrimination module (22) is further configured to split the combined radiation such that for each reflected radiation component, an intensity parameter (intensity-bearing signal) of the reflected radiation component (corresponding to one of the combined radiation components, not just one of the composite output beams) can be differentiated from an intensity parameter (intensity-bearing signal) of the combined radiation of all other reflected radiation components. In particular, the radiation discrimination module (22) is configured to receive reflected radiation from the reflected radiation components having intensity parameters representative of the combined radiation, and (for each of the reflected radiation components) to differentiate the intensity parameter of the particular component of the reflected radiation corresponding to the reflected radiation component.

[0063] A control subsystem (23) having at least one control device (24) including logic circuitry is linked to the radiation discrimination module (22) and the beam emission subsystems (12a, 12b, and 12c) by one or more communication and / or data links, and the control subsystem (23) is configured to receive output signals generated by the radiation discrimination module (22), process the received signals, and provide processed signals to the beam emission subsystem, thereby enabling adjustment of the composite beams (14a, 14b, and 14c), including adjustment of beam parameters of the coherent sub-beams generated by each of the beam emission subsystems (12a, 12b, and 12c). The logic circuitry of the controller (24) may be implemented as suitably configured hardware using digital and / or analog processing, including, but not limited to, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more digital signal processors (DSPs), as a general purpose computing system configured by software operating under a suitable operating system, or by any combination of hardware / software / firmware configured to perform the functions described herein at a suitable rate. The controller (24) also typically includes data storage and suitable input / output interfaces to control (directly or indirectly) the beam delivery subsystems (12a, 12b, and 12c) and to receive input from the radiation discrimination module (22), as will be apparent to one skilled in the art.

[0064] The controller (24) may be linked to the receiver (16) by a data link, which may be, for example, a data bus or a wired or wireless data link. In an embodiment, the data link is embodied as a communication link of a communication network (including, for example, a wired network, a wireless network, a cellular network, a satellite communication network, a private network such as an intranet, and the like). In such an embodiment, the controller (24) preferably includes communication hardware and / or software components to transmit data to / receive data from the receiver (16) by the communication interface of the controller (24). The controller (24) is also linked to the beam delivery subsystems (12a, 12b, and 12c), preferably by a data bus or data link. Preferably, the receiver (16) and the beam delivery subsystems (12a, 12b, and 12c) are arranged in an arrangement that supports low latency data transmission (by the control subsystem (23)) between the receiver (16) and the beam delivery subsystems (12a, 12b, and 12c).

[0065] A control subsystem (23) may further be associated with the master unit that transmits low power guide beams, as described previously in this disclosure, and performs direction vector calculations to enable highly accurate combination of the output beams (14a, 14b, and 14c) onto a common target spot.

[0066] Generally speaking, the present disclosure proposes two main approaches for performing signal separation by the radiation discrimination module (22), which utilize two different implementation architectures. Both architectures rely on each of the beam emission subsystems (12a, 12b, and 12c) having an assigned locally unique signature associated with the respective composite beam (14a, 14b, and 14c). The unique signature is assigned such that each of the components (15a, 15b, and 15c) making up the combined radiation is uniquely identifiable (i.e., uniquely identifiable) in the combined radiation according to the signature associated with the composite beam due to the radiation component. In the context of this specification, a combined radiation component is identifiable in the combined radiation (or separable from the combined radiation) if the intensity signal of the component can be accurately separated from the intensity signal of the combined radiation. Preferably, the intensity of the combined radiation contains information about the locally unique signatures of all constituent components (15a, 15b, and 15c) so as to make it possible to extract the intensity of each component from the intensity of the combined radiation.

[0067] In the context of this document, the term locally unique signature generally refers to a signature assigned to a particular beam-emitting subsystem of system (10) that is unique to that beam-emitting subsystem such that there is a one-to-one relationship between the signature and the beam-emitting subsystem (i.e., a signature assigned to one beam-emitting subsystem of system (10) is not assigned to any other beam-emitting subsystem of system (10). It is noted that some or all of the signatures of system (10) may be used as signatures of beam-emitting subsystems of other systems that are generally similar to system (10) but located at different locations from each other and from system (10), so long as the reflected radiation components of each beam-emitting subsystem of the system can be accurately distinguished from the received reflected radiation.

[0068] According to a first non-limiting implementation, the radiation discrimination module (22) can perform the desired signal separation using dispersive optics to achieve spectral separation of the received radiation. In this first non-limiting implementation, the signatures of the beam emission subsystems (12a, 12b, and 12c) and the corresponding output hybrid beams (14a, 14b, and 14c) are wavelengths or wavelength ranges (spectral sub-bands, or sub-regions) of transmission. According to a second non-limiting implementation, the radiation discrimination module (22) performs the desired signal separation by decoding information encoded in the phases of the sub-beams of the output hybrid beams (14a, 14b, and 14c). In this second non-limiting implementation, the signatures of the beam emission subsystems (12a, 12b, and 12c) and the corresponding output hybrid beams (14a, 14b, and 14c) are codes (e.g., modulation frequencies, or sequences / waveforms). It is noted that in embodiments where the spatial filtering arrangement (20) is implemented using a small detector placed at the exit aperture of the telescope, the loss of spectral information at the detector may make the discrimination of radiation by spectral separation ineffective, and therefore in such embodiments it is preferred to implement the radiation discrimination module (22) according to the second non-limiting implementation.

[0069] The following paragraphs, with reference to FIG. 3, describe a receiver (16) having a radiation discrimination module (100) according to a first non-limiting implementation. By way of preamble, in order for the radiation discrimination module (100) to achieve effective spectral separation of the filtered and collimated radiation according to the first non-limiting implementation, the output beams (14a, 14b, and 14c) should occupy respective different spectral sub-bands or sub-regions of the electromagnetic spectrum (i.e., the spectral sub-bands or sub-regions in which each beam-emitting subsystem is configured to transmit beams) according to the signature of the beam-emitting subsystem. As mentioned above, the principles of the embodiments of the present disclosure may be used in devices operating at a variety of different wavelengths, but are generally implemented in the NIR range, which generally refers to light having wavelengths generally within the range of 800 to 2500 nanometers (nm). Thus, in such an exemplary implementation, the beam emission subsystems (12a, 12b, and 12c) are configured to generate output beams (14a, 14b, and 14c) that occupy different sub-bands or sub-regions in the NIR range. For example, the beam emission subsystem (12a) may be configured to generate an output beam (14a) at a wavelength λ1 of about 1060 nm, the beam emission subsystem (12b) may be configured to generate an output beam (14b) at a wavelength λ2 of about 1065 nm, and the beam emission subsystem (12c) may be configured to generate an output beam (14c) at a wavelength λ3 of about 1070 nm. Here, the signature of the beam emission subsystem (12a) is radiation at wavelength λ1, the signature of the beam emission subsystem (12b) is radiation at wavelength λ2, and the signature of the beam emission subsystem (12c) is radiation at wavelength λ3.

[0070] Referring now more specifically to the structural details of the radiation discrimination module (100) of Figure 3, the radiation discrimination module (100) comprises a detector array (108) and an optics array (102) disposed in an optical path from the target (26) to the detector array (108). The optics array (102) may comprise a collimating optic, represented diagrammatically in Figure 3 by a lens (104), but may be an assembly of lenses, and a dispersive optic (106). The dispersive optic (106) is represented diagrammatically in Figure 3 by a prism, but may alternatively be implemented as one or more diffraction gratings.

[0071] The collimating optics (104) receives the filtered radiation from the spatial filtering arrangement (20) and collimates the radiation to generate filtered and collimated radiation. The collimated radiation is incident on the dispersive optics (106) which splits the filtered and collimated radiation into constituent wavelengths corresponding to the output beams (14a, 14b, and 14c) (i.e., according to the spectral signature of each beam delivery subsystem). For each constituent wavelength, the split radiation of that wavelength is deflected in a specific direction according to the deflection angle for that wavelength applied to the collimated radiation by the dispersive optics (106). The resulting spectrally separated radiation is incident on the detector array (108), which is configured to separately measure radiation at each of the constituent wavelengths. The radiation of each constituent wavelength is incident on a different region of the detector array (108) according to the deflection direction of the radiation. In an embodiment in which the detector arrangement (108) is implemented as an array of photodetectors, the array of photodetectors preferably comprises one photodetector for each constituent wavelength, arranged at the required positions dictated by the deflection angles so as to be able to measure the radiation intensity of the radiation at the constituent wavelengths. This is illustrated in FIG. 3, which shows three such photodetectors (110a, 110b, and 110c). The photodetectors (110a, 110b, and 110c) are configured to measure the radiation intensity of the reflected radiation components (15a, 15b, and 15c) in parallel, so as to separate (discriminate) the radiation intensity of each of the reflected radiation components (15a, 15b, and 15c) from the combined radiation intensity. Each photodetector is sensitive to radiation in a different specific sub-band or sub-region of the electromagnetic spectrum, corresponding to the wavelengths at which the output beams (14a, 14b, and 14c) are transmitted by the beam emission subsystems (12a, 12b, and 12c).For example, continuing with the above example in which the output beams (14a, 14b, and 14c) have wavelengths of approximately 1060 nm, 1065 nm, and 1070 nm, respectively, the photodetectors (110a, 110b, and 110c) may be configured to be sensitive to radiation in the ranges of 1059-1061 nm, 1064-1066 nm, and 1069-1071 nm, respectively.

[0072] The detector array (108) is configured to generate a signal ("intensity parameter") indicative of the intensity of radiation incident on an area of ​​the target (26) by each output beam (14a, 14b, and 14c) at each constituent wavelength. In an embodiment in which the detector array (108) is implemented as an array of photodetectors, each of the photodetectors (110a, 110b, and 110c) generates such a signal. In other words, the photodetector (110a) generates a first signal indicative of the intensity of radiation incident on an area of ​​the target (26) by the output beam (14a), the photodetector (110b) generates a second signal indicative of the intensity of radiation incident on an area of ​​the target (26) by the output beam (14b), and so on. Each of the generated signals varies as a function of the intensity of radiation (from the corresponding composite output beam) incident on an area of ​​the target (26).

[0073] The controller (24) receives signals (i.e., intensity parameters) from the detector array (108). These received signals can then be processed to enable the beam emission subsystems (12a, 12b, and 12c) to perform additional functions, including adjusting beam parameters of the respective sub-beams. In a specific, non-limiting implementation, the control subsystem (23) includes a dedicated control / processing unit for each of the beam emission subsystems (12a, 12b, and 12c), thereby allowing further processing of the signals received from the detector array (108). In such an implementation, for example, the controller (24) provides a first signal to the control / processing unit of the beam emission subsystem (12a), a second signal to the control / processing unit of the beam emission subsystem (12b), and so on.

[0074] In one non-limiting implementation, the signals received by the controller (24) from the detector array (108) are used to adjust beam parameters of one or more of the sub-beams of the beam emission subsystems (12a, 12b, and 12c) by performing phase corrections on the phases of the sub-beams to achieve effective coherent combining of the sub-beams into each of the output beams (14a, 14b, and 14c). Generally, in each of the beam emission subsystems (12a, 12b, and 12c), the associated signals (i.e., intensity parameters) are monitored (by the controller (24) or a control / processing unit dedicated to that beam emission subsystem) while each phase modulator of the beam emission subsystem is operated to modulate the current phase of the correspondingly transmitted sub-beam between at least three phase states (typically an initial "unmodified" phase state and two "modified" phase states). Monitoring the signals includes analyzing the signals (by the controller (24), or a control / processing unit of that beam delivery subsystem) to identify variations in the measured intensity parameter resulting from modulation of the current phase of each transmit sub-beam relative to the sum of all other sub-beams. The controller (24), or a control / processing unit of that beam delivery subsystem, then calculates (based on the identified variations) a phase offset of the current phase for each sub-beam relative to a phase representing the sum of all other sub-beams emitted by that particular beam delivery subsystem.

[0075] This process of modulating the phase of the sub-beams, identifying corresponding variations in the measured intensity parameters, calculating the phase offset of the sub-beams, and correcting the phase offset is preferably repeated in rapid cycles, thereby correcting in real time for dynamic variations in operating conditions that may result from variations in the beam generation hardware or from variations in atmospheric conditions caused by atmospheric turbulence. Further details of this process can be found in WO 2020 / 016824 A1, which is incorporated herein by reference in its entirety.

[0076] Note that the current phase of each sub-beam is modulated at a particular modulation frequency. In one non-limiting example, the phase of each sub-beam is modulated with a phase variation modulation amplitude Φ at a modulation frequency ω. m The phase of each sub-beam is sinusoidally varied (by the control device (24) or the control / processing unit of its beam delivery subsystem) about a central phase state by . Preferably, modulation frequencies anywhere in the MHz to GHz range are used. In particular, a range of modulation frequencies between 100 kHz and 20 MHz has been found to be suitable. In another non-limiting example, the phase of each sub-beam is modulated stepwise between a current base value and two discrete modulated values. Regardless of the modulation approach (i.e., continuous / sinusoidal or discrete), an additional layer of modulation or coding can be applied on top of this low level modulation. This additional layer of modulation / coding is particularly useful in situations where a different approach to signal separation than the spectrum separation approach described above is adopted. This may be the case, for example, in situations where spectral separation of the filtered and collimated radiation cannot be achieved, such as scenarios where the constituent beams transmitted by the beam emission subsystems (12a, 12b, and 12c) have densely packed spatial frequencies and the physical limitations of the dispersive optical component (106) may not allow for unambiguous separation of the received radiation into the appropriate constituent radiation components. In such scenarios, a different approach to signal separation is taken, and the radiation discrimination module (22) is implemented according to a second non-limiting implementation to achieve signal separation by decoding information (i.e., codes, or signatures) that are encoded in the phases of the sub-beams of the output beams (14a, 14b, and 14c) by this additional layer of modulation / coding.

[0077] The following paragraphs, with reference to FIG. 4, describe a receiver (16) having a radiation discrimination module (200) according to a second non-limiting implementation. By way of introduction, in order for the radiation discrimination module (200) to achieve the aforementioned signal separation, the current phase of each sub-beam (for a particular beam-emitting subsystem) is coded with a code (signature) that is unique to the particular beam-emitting subsystem by the coding module (44) (FIG. 2). This coding is applied on top of a continuous / sinusoidal or discrete low-level modulation of the phase of each of the aforementioned sub-beams. It should be noted that the term "coding" as used herein encompasses both conventional analog and digital modulation used in analog and digital communication systems, as well as conventional information coding techniques, including those used in spread spectrum communications. The "code" used to code the phase can be, for example, a specific frequency, a specific sequence / waveform, or any other suitable type of code that can be used to uniquely code information. It should be noted that the code used to code the phase information is locally unique to the system (10) and its associated corresponding components (i.e., beam-emitting subsystems).

[0078] With this in mind, various types of encoding by the encoding module (44) are within the scope of this disclosure. In one non-limiting example, the encoding module (44) is configured to apply an additional layer of analog frequency modulation on top of the continuous / sinusoidal or discrete low-level modulation of the phase of each sub-beam. In this example, the encoding module (44) applies a (code) modulation frequency ω m The analog frequency modulator includes one or more analog frequency modulators configured to modulate the phase of the low-level modulated current of each sub-beam at a modulation frequency ω. The analog frequency modulator is implemented as a waveform / signal generator (46) for generating a carrier signal at a modulation frequency and for modulating the phase with the carrier signal. In one particularly preferred implementation, the modulation frequency ω m is higher than the modulation frequency ω0, and in a more preferred implementation, m is significantly higher (e.g., an order of magnitude higher) than the modulation frequency ω (i.e., ωm >>ω0). As previously mentioned, the low level modulation frequency ω0 is preferably selected from a range of frequencies between 100 kHz and 20 MHz. Thus, in such a preferred implementation, the highest level modulation frequency ω m can be selected from a frequency range between 1 MHz and 100 MHz. For example, if the low frequency modulation is in the range between 1 MHz and 2 MHz, the high frequency modulation can be in the range between 10 MHz and 20 MHz.

[0079] Each composite output beam has at least one such modulation frequency ω m In some cases, all of the modulation phases of the sub-beams are assigned the same unique modulation frequency ω m In such a case, a single such waveform / signal generator (46) may be coupled to all of the phase modulators of a beam delivery subsystem to modulate the phase for all of the sub-beams generated by that beam delivery subsystem. Alternatively, a waveform / signal generator may be provided, one for each phase modulator, such that the phase of each sub-beam is modulated by its respective waveform / signal generator. In other cases, the modulation phase of each sub-beam is modulated at a different unique modulation frequency, which may be higher or lower than the low-level modulation frequency ω0. For example, for a beam delivery subsystem that delivers a composite output beam made up of three sub-beams, the modulation phase of the first sub-beam may be modulated at a first modulation frequency ω0. m1 and the modulation phase of the first sub-beam may be modulated using a first modulation frequency ω m2 and the modulation phase of the first sub-beam may be modulated using a first modulation frequency ω m2In such a case, each phase modulator of a particular beam-emitting subsystem has an associated waveform / signal generator configured to modulate the phase of the respective sub-beam. It is noted that since the system (10) typically includes a series of beam-emitting subsystems, each having tens or hundreds of beam sources, assigning a unique modulation frequency to each individual beam source may present problems in terms of bandwidth and spectral efficiency. Furthermore, modulating each of the low-level modulation phases with a unique modulation frequency requires corresponding demodulation hardware in the receiver, resulting in a bank of demodulators (one for each modulation frequency). Therefore, it may be preferable to modulate the low-level modulation phases of all sub-beams of a single beam-emitting subsystem with a common modulation frequency that is unique to that beam-emitting subsystem. Alternatively, the modulation of the low-level modulation phases of different sub-beams of a particular beam-emitting subsystem may be performed sequentially.

[0080] In another non-limiting example, the encoding module (44) is configured to encode the low-level modulation current phase with a distinct code sequence that is unique to the beam-emitting subsystem and the output beam generated by the beam-emitting subsystem. The code sequence may be any code sequence (e.g., binary) that can be suitably used to discriminate between reflected radiation components (and thus the corresponding output beams that generate the reflected radiation components). In one non-limiting example, the code sequences may be selected from a set of mutually orthogonal pseudo-random sequences such that each sequence has high autocorrelation and low cross-correlation with other sequences, as is routinely used in certain spread spectrum communication techniques such as code division multiple access (CDMA), as is well known in the art. In this non-limiting exemplary implementation, the encoding module (44) may include a sequence generator (e.g., a pseudo-random number generator, as is well known in the art and readily commercially available) for generating the code sequences, and a waveform generator (i.e., a signal generator) for generating waveforms associated with each of the code sequences. In terms of binary sequences, a simple example of a waveform (signal) that can be generated by the waveform generator is a rectangular pulse amplitude modulated waveform that outputs a "high" voltage for a binary "1" and a "low" voltage for a binary "0". The sequence generator and the waveform generator may be combined as a single functional element that generates a waveform based on a pseudorandom binary sequence (commonly referred to as a PN sequence). In this context, the signal generator (46) operates to perform the functions of sequence generation and signal / waveform generation. Furthermore, the signal generator (46) is operable to modulate the low-level modulation current phase of each sub-beam with the generated waveform (although this modulation may be accomplished by another modulator / multiplier component of the encoding module (44)). In a preferred implementation, the phases of all sub-beams generated by a particular beam-emitting subsystem are modulated by the same generated waveform. In other words, for each beam-emitting subsystem, a single unique code sequence is used to encode all phase information of the sub-beams generated by that beam-emitting subsystem.A single signal generator may be coupled to all of the phase modulators of the beam emission subsystem to modulate the phase of each of the sub-beams with a common signal generator. Alternatively, each beam source of a beam emission subsystem may have an associated signal generator that modulates the phase of the sub-beam generated by the beam source. Additionally, similar to that described in the frequency modulator example above, the low-level modulation phase of each sub-beam of a particular beam emission subsystem may be provided with a unique coding such that all of the sub-beams throughout the system 10 each have a unique code. Again, however, performance issues may arise because the receiver 16 would need to cycle through multiple demodulation waveforms (code sequences) to receive the modulation phases of all the sub-beams generated by all the beam emission subsystems.

[0081] Although the phase encoding process has been described within the context of a particular example of top-level frequency modulation and (binary) sequence (waveform) encoding, the scope of the embodiments of the present disclosure should not be limited to the particular example of frequency modulation and encoding sequence mentioned above. As will be apparent to those skilled in the art, a wide variety of techniques are available for encoding the low-level modulation phase of the sub-beams, including techniques commonly used in spread spectrum communication systems and free space optical communications, including multiplexing and / or multiple access techniques such as orthogonal / optical frequency division multiplexing (OFDM) and frequency division multiple access (FDMA).

[0082] Now, to explain the structure of the radiation discrimination module (200) of FIG. 4 in more detail, the radiation discrimination module (200) includes a photodetector (202) and a decoding module (204). The photodetector (202) is configured to receive the filtered radiation from the spatial filtering arrangement (20) such that substantially only the combined radiation is sensed by the photodetector (202). The photodetector (202) converts the sensed radiation into a received signal (i.e., the photodetector (202) generates a signal ("intensity parameter") from the received combined radiation). Preferably, the photodetector (202) is AC-coupled (e.g., by a DC blocking capacitor) to remove a DC offset from the signal and prevent saturation of the detector. The signal generated by the photodetector (202) represents the combined (i.e., sum) radiation intensity of the reflected radiation components (15a, 15b, and 15c) and is indicative of the intensity of the combined radiation incident on the area of ​​the target (26). In particular, the generated signal varies as a function of the intensity of the combined (i.e., total) radiation (corresponding to the composite output beams (14a, 14b, and 14c)) incident on the target (26) area. The signal includes a plurality of signal components, each corresponding to the radiation intensity associated with a respective one of the composite output beams (14a, 14b, and 14c). Because the phase of each sub-beam of the composite output beams (14a, 14b, and 14c) is encoded with a code unique to the beam delivery subsystem that transmitted the composite output beam, the signal components corresponding to the individual composite output beams (and individual beam delivery subsystems) can be isolated, i.e., separated from other signal components of the overall received signal.

[0083] The decoding module (204) is configured to perform the aforementioned signal separation by applying decoding techniques to isolate individual signal components from the received signal. The decoding module (204) may include a bank of decoders (206), preferably one decoder for each unique code used to encode information by the encoding module of the beam emission subsystem. For example, in a non-limiting example where the encoding module (44) for each beam emission subsystem is implemented as one or more analog frequency modulators, the decoding module (204) includes a corresponding number of demodulators (decoders) implemented as signal generators (208). The encoding module (44) of each beam emission subsystem modulates the low-level modulation phase of all sub-beams generated by that beam emission subsystem to the same modulation frequency ω m If the decoder (206) is configured to modulate the received signal with a 10 MHz bin, the decoding module (204) will include one decoder (e.g., implemented as a signal generator performing frequency demodulation to generate a demodulated signal) for each beam emission subsystem. The decoders are preferably configured to operate in parallel such that the received signal is decoded by each of the decoders simultaneously. If the decoder (206) is implemented as a bank of demodulators, the decoding module (204) may include a low pass filter associated with each demodulator to remove residual signal effects and noise from the demodulated signal.

[0084] In a non-limiting example, where the encoding module (44) for each beam emission subsystem is configured to encode the low-level modulation current phase of the sub-beam with a separate code sequence specific to the beam emission subsystem, a bank of decoders (206) is configured with components for decoding signals based on the sequences to separate relevant signal components from the received signal. Again, the decoders (206) may be arranged one for each sequence, and each decoder may be assigned a specific one of the sequences. In this context, each of the signal generators (208) operates to perform the functions of sequence generation and waveform generation to generate the code sequence assigned to that decoder, and to generate a waveform associated with the assigned code sequence (sequence generation and waveform generation may be combined as a single functional element). The signal generators are also preferably configured to perform demodulation by demodulating the received signal with the generated waveform (i.e., applying the generated waveform to the received signal). Additional logic implemented as part of the decoder (206) is configured to identify correlation peaks in the demodulated signal in order to separate signal components corresponding to associated composite output beams (and associated beam delivery subsystems) from the overall received signal.

[0085] Each decoder (206) provides a separate component of the received signal as an output signal such that the decoding module (204) outputs multiple output signals (one output signal per decoder). In a non-limiting exemplary implementation illustrated in FIG. 4, the controller (24) receives output signals from the bank of decoders (206) that are indicative of the intensity of radiation incident on an area of ​​the target (26) by each composite output beam (14a, 14b, and 14c). The output signals received by the controller (24) can be subsequently processed to enable the beam delivery subsystems (12a, 12b, and 12c) to perform additional functions, such as adjusting beam parameters of the generated sub-beams by performing phase corrections of the phases of the sub-beams generated by the beam delivery subsystems (12a, 12b, and 12c) (as previously described with reference to FIG. 3). In other non-limiting implementations, the decoding module (204) can be implemented as part of the control subsystem (23).

[0086] As shown and described herein, the encoding module (44) includes a signal generator (46) to perform a number of functions, including functions for sequence generation, signal generation / waveform generation, and modulation, although it is noted that each of those functions may be performed by a dedicated separate component (e.g., a sequence generator, a signal generator, and a modulator). Similarly, as shown and described herein, the decoding module (204) includes a signal generator (208) to perform a number of functions, including functions for sequence generation, signal generation / waveform generation, and demodulation, although each of those functions may be performed by a dedicated separate component (e.g., a sequence generator, a signal generator, and a demodulator).

[0087] As mentioned above, in one embodiment, the optical system arrangement (i.e., telescope (18)) is integrated with an imaging system that can be used to direct each of the beam delivery subsystems (12a, 12b, and 12c) to a target spot. FIG. 5 illustrates a schematic of an optical system arrangement adapted to correct distortions in an image received by the telescope. Light (i.e., radiation) collected by the telescope (not shown, but which may be the telescope (18)) is reflected from an adapted optical element, such as a deformable mirror (50), which generally has a reflective surface that can be selectively deformed by a number of actuators. The deformable mirror (50) can be implemented using any suitable deformable mirror technology, including, but not limited to, MEMS actuated mirrors, electrostatically actuated mirror membranes, piezoelectrically actuated mirrors, and magnetically actuated mirrors. The light reflected by the deformable mirror is split by a beam splitter (52), and a portion of the light emerging from the beam splitter (52) passes to a wavefront sensor (54), such as a Shack-Hartmann wavefront sensor, which measures the distortion of the wavefront. A control system (56) analyzes the distortion of the wavefront reaching the wavefront sensor (54) and dynamically adjusts the deformable mirror (50) to reduce the wavefront distortion. The remainder of the light emerging from the beam splitter (52) is directed to an imaging system (60) (and / or other sensors). The components described with reference to Figure 5, as well as the processes required to provide wavefront correction, are well known and can be readily implemented by those skilled in the art.

[0088] FIG. 6 illustrates a specific implementation of an adapted optics arrangement, such as the arrangement illustrated in FIG. 5, in the context of a multi-coherent beam combining (CBC) system, where the adapted optics arrangement is integrated as part of the target receiver described with reference to FIG. 1, FIG. 3, and FIG. 4. The telescope arrangement (18) receives reflected light (i.e., radiation) from a target (26) that has passed through a medium (28) that introduces optical distortion. The light collected by the telescope (18) is spatially filtered by a spatial filtering arrangement (20) and directed from the deformable mirror (40) through a beam splitter (52) to a wavefront sensor (54), the output of which is processed by an adapted optical control system (56) to provide closed-loop feedback for adjusting the deformable mirror (50), as previously described with reference to FIG. 5. The remainder of the light emerging from the beam splitter (52) passes through a second beam splitter (58), which directs a portion of the light to an imaging sensor (camera (60)) and a portion of the light to a radiation discrimination module (22), which discriminates the radiation intensity of each reflected radiation component. An overall control system (62) receives the images produced by the camera (60) and controls the operation of the system, such as target selection, aim correction, etc.

[0089] It should be noted that the subdivision of the control system into separate elements (24, 56, and 62) is shown here according to functional subdivision. However, it should be noted that these functions may be performed by processing systems or other logic circuitry hardware that may be subdivision in any desired manner, with one or more functions being performed by a single processing system or a single function being performed by separate distributed processing systems. In some cases, certain processing and control functions may be performed remotely.

[0090] It is noted that the two non-limiting implementations of the radiation discrimination module (22) according to the embodiments presented herein have independent utility such that the beam emission subsystem and the control subsystem are not limited to use with a particular one of the radiation discrimination modules (100), (200). It is further noted that each of the radiation discrimination modules (100), (200) is most preferably implemented in combination with a series of beam emission subsystems including 10 to 30. In situations where it is desirable to use a series of beam emission subsystems including more than 30 and up to several hundred, the receiver (16) may be implemented to utilize the radiation discrimination module (100) and the radiation discrimination module (200) in parallel. In such an embodiment, the light collected by the telescope (18) may be routed separately to the radiation discrimination module (100) and the radiation discrimination module (200), and parallel radiation discrimination is performed by the modules (100) and (200). Routing may be achieved, for example, by a beam splitter (not shown) placed in the optical path of the telescope (18) after the spatial filtering arrangement (20).

[0091] As previously mentioned, the receivers (16) may be deployed in a variety of configurations, so long as the receivers have a line of sight with the target (i.e., can receive radiation reflected from the target (26)) and can support a low latency data link to the beam emission subsystems (12a, 12b, and 12c). The receivers (16) are also generally small in size and low in cost compared to the beam emission subsystems, and therefore it may be advantageous to deploy multiple such receivers (16) at various discrete locations (i.e., geographic locations). One advantage in deploying multiple receivers is that the output from the receiver that provides the best effective resolution of the target can be utilized to perform additional functions, such as adjusting the beam parameters of the beam emission subsystems (12a, 12b, and 12c).

[0092] There are several contributing factors that can be used alone or in combination in determining the receiver-to-target effective resolution. Such factors include, but are not limited to, the (straight line) distance between the target and the receiver, the level of turbulence along the optical path from the target to the receiver, the aperture size of the optical receiver (telescope), and the stability of the line of sight between the receiver and the target. An estimation of the effective resolution can be performed based on an image of the target generated by the receiver (e.g., generated by the camera (60)) and / or from known mission parameters and turbulence models, all as known in the art. Determining which receiver produces the "best" effective resolution can be performed by comparing the estimates and identifying the receiver that produces the highest estimated effective resolution.

[0093] FIG. 7 illustrates a non-limiting example of a receiver arrangement in a system with three receivers (160a, 160b, and 160c), each corresponding to the structure and operation of receiver (16). In this non-limiting example arrangement, receivers (160a, 160b, and 160c) are located at different positions relative to a series of beam delivery subsystems (12a, 12b, and 12c) (120) and two targets (26a and 26b). Here, the composite output beams directed to the targets by each of the beam delivery subsystems (12a, 12b, and 12c) are generally designated by thick arrows, and radiation reflected by the targets is generally designated by thin dashed arrows. Although only three receivers are illustrated, the present embodiment can be implemented with anywhere from two to several tens of receivers, most preferably between two and ten receivers.

[0094] For each target illuminated by the beam emission subsystems (12a, 12b, and 12c), a control subsystem (23) associated with each of the receivers (160a, 160b, and 160c) is preferably configured to estimate an effective resolution for each receiver and select the receiver that provides the best effective resolution (based on the effective resolution estimates). The control subsystem (23) is further configured to select the output signal(s) resulting from the radiation separation performed by the radiation discrimination module (22) of the selected receiver for subsequent processing to enable the series of beam emission subsystems (120) to perform additional functions (e.g., adjusting beam parameters of the generated sub-beams by performing phase corrections of the phases of the sub-beams generated by the beam emission subsystems).

[0095] When / if the series of beam delivery subsystems (120) are directed to a different target (e.g., switching from target (26a) to target (26b)), the control subsystem (23) re-estimates the effective resolution of each receiver and then again selects the signal output from the receiver that provides the best effective resolution for the new target. In this way, the control subsystem (23) can dynamically switch between receivers to select the output from the receiver that provides the best effective resolution for a particular target. It may be advantageous to switch between receivers during the engagement time for a single target if the selected receiver suffers a degradation in effective resolution. Such degradation in resolution may occur sporadically depending on the mission situation, since the engagement time for one target may extend to several seconds. To effectively switch receivers during the engagement time, the effective resolution for all receivers is preferably recalculated in a rapid cycle (e.g., 10 or more times per second incident) during the engagement time for the target. If the effective resolution of the selected target falls below a usability threshold, the control subsystem (23) may switch to a different receiver having a higher effective resolution than the previously selected receiver.

[0096] It should be noted that the radiation discrimination modules of the receivers (160a, 160b, and 160c) do not necessarily have to be implemented according to the same implementation, for example, the radiation discrimination modules of some of the receivers may be implemented as radiation discrimination modules (100), while the radiation discrimination modules of the remaining receivers may be implemented as radiation discrimination modules (200).

[0097] Additionally, the control subsystem (23) may be configured to receive output signal(s) from receivers other than the selected receiver and combine the output signal(s) provided by the selected receiver with the output signal(s) provided by the additional receivers to form an overall (combined) output signal. This overall output signal may then be processed to enable the series of beam delivery subsystems (120) to perform additional functions. The signals may be combined using various signal combining techniques, including, for example, weighted averaging techniques, in which the signal from the receiver providing the best effective resolution on the target is given the highest weight, and the signal from the receiver providing the second best effective resolution is given the second highest weight. Preferably, the receivers contributing to the aggregate signal are aimed at the same spot on the target with high accuracy, which may require a dedicated target tracking and aiming subsystem linked to the receivers and the control subsystem (23).

[0098] Although the radiation discrimination module (22) has been described primarily in the context of an embodiment in which the radiation discrimination module (22) is part of the receiver (16), as previously mentioned, other embodiments are possible in which the radiation discrimination module (22) is associated with the receiver (16) but separate from the receiver (16). FIG. 8 illustrates one such embodiment in which the radiation discrimination module (22) is disposed between the receiver (16) and the control subsystem (23). In an embodiment, the radiation discrimination module (22) may be implemented as a module of the control subsystem (23) disposed between the controller (24) and the receiver (16). Different configurations of coupling between the radiation discrimination module (22) and the receiver (16) are possible. For example, optical fibers may be used to provide the coupling (connection) between the receiver telescope (20) and the radiation discrimination module (22). The optical fiber may further be used to perform spatial filtering of the radiation received by the telescope (18) (thereby functioning as the spatial filtering arrangement (20)), such that the radiation discrimination module (22) receives the spatially filtered radiation directly from the telescope 20 by the (spatial filtering) optical fiber. In implementations in which the radiation discrimination module (22) is implemented using decoding (as in the case of the radiation discrimination module (200)), a low-latency broadband data link may provide the coupling between the receiver (16) (including a photodetector (202) for generating an encoded signal from the received radiation) and the radiation discrimination module (22). In such implementations, the generated signal is transmitted from the receiver (16) to the radiation discrimination module (22) by a low-latency link.

[0099] The configuration of the control subsystem (23) and radiation discrimination module (22) illustrated in Fig. 8 can be extrapolated to include a configuration in which each beam emission subsystem is linked to a respective control and radiation discrimination subsystem. A non-limiting example of such a configuration is illustrated diagrammatically in Fig. 9, in which three radiation discrimination modules (22a, 22b, and 22c) are arranged as part of each of the three control subsystems (23a, 23b, and 23c) (having controllers (24a, 24b, and 24c)) and linked to each of the beam emission subsystems (12a, 12b, and 12c). Although not shown in Fig. 9, the control subsystems (23a, 23b, and 23c) are preferably linked by low latency links, either directly or indirectly, to form the overall control subsystem of the system.

[0100] The description of various embodiments of the present disclosure is presented for illustrative purposes, without intending to be exhaustive or limiting to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles, practical applications, or technical improvements over the art found in the marketplace of the embodiments, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0101] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0102] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments, and / or does not exclude the incorporation of features from other embodiments.

[0103] It will be understood that certain features of the invention that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination, or as appropriate, in any other described embodiment of the invention. Certain features that are described in the context of various embodiments are not considered essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0104] The appended claims have been drafted without multiple dependent claims only to address formality requirements in jurisdictions that do not recognize such multiple dependent claims. It should be noted that all possible combinations of features implied by making the claims multiple dependent are expressly contemplated and should be considered part of the present invention.

[0105] While the present invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. a plurality of beam emission subsystems, each configured to generate a plurality of coherent beams for directing toward a region of the target to combine as a composite output beam at or in front of the target, where for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining as a combined radiation made up of reflected radiation components, where an intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on a target; a spatial filtering arrangement disposed at the focal plane and configured to filter the reflected radiation by selectively passing the combined radiation; and a radiation discrimination module for receiving the combined radiation passed by the spatial filtering arrangement and for each reflected radiation component, for discriminating an intensity parameter of the reflected radiation component from an intensity parameter of a combined radiation of all remaining reflected radiation components. system.

2. Each beam delivery subsystem includes: a beam forming array for generating a respective one of said composite output beams; and a beam directing array for directing the composite output beam towards the target.

3. Each reflected radiation component has a different wavelength than all the remainder of the reflected radiation components, and wherein the radiation discrimination module comprises: an optical system arrangement including at least one dispersive optical component for splitting the combined radiation into a plurality of constituent wavelengths corresponding to the wavelengths of the reflected radiation components; and 2. The system of claim 1, comprising a detector array for receiving radiation split by the at least one dispersive optical component, the detector array configured to separately measure radiation at each of the constituent wavelengths.

4. The system of claim 3 , wherein the at least one dispersive optical component comprises a prism.

5. The system of claim 3 , wherein the at least one dispersive optical component comprises a diffraction grating.

6. 4. The system of claim 3, wherein the optical arrangement further comprises a collimating element disposed in an optical path between the spatial filtering arrangement and the at least one dispersive optical component, the collimating element configured to collimate the combined radiation to produce collimated radiation and to direct the collimated radiation to the at least one dispersive optical component.

7. The system of claim 3 , wherein the detector arrangement includes an array of detectors, each detector in the array of detectors configured to measure radiation at a different individual one of the constituent wavelengths.

8. Each beam delivery subsystem includes: an array of beam sources configured to generate a plurality of coherent beams for directing towards the target to combine as the composite output beam at or in front of the target; a plurality of adjustable phase modulators coupled to the beam source to enable adjustment of a relative phase offset of the coherent beams; and an encoding module for encoding a phase of each of the plurality of coherent beams with a code that is local to the beam delivery subsystem. The system of claim 1 .

9. The radiation discrimination module includes: a detector positioned to receive the combined radiation and monitor an intensity parameter of the combined radiation; and a decoding module configured to decode, for each composite output beam, an intensity parameter of the combined radiation in accordance with the locally unique code of the beam delivery subsystem that produced the composite output beam to isolate an intensity parameter of the reflected radiation component corresponding to the composite output beam; The system of claim 8.

10. 10. The system of claim 9, wherein the encoding module includes a modulator, wherein the code includes a modulation frequency such that each composite output beam is assigned at least one unique modulation frequency, wherein the encoding module is configured to encode the phase of each coherent beam for each beam emission subsystem by modulating the current phase of the coherent beam at the assigned at least one modulation frequency, and wherein the decoding module includes a plurality of demodulators, each demodulator configured to demodulate a signal at one or more selected demodulation frequencies selected from the assigned unique modulation frequencies.

11. a control subsystem coupled to the radiation discrimination module and to each of the plurality of beam delivery subsystems, wherein each beam delivery subsystem comprises: an array of beam sources configured to generate a plurality of coherent beams for directing towards the target to combine as a composite output beam at or in front of the target; a phase modulator coupled to the beam source to enable adjustment of a relative phase offset of the coherent beams; and wherein for each reflected radiation component, the control subsystem determines: receiving intensity parameters of the reflected radiation components from the radiation discrimination module; and and configured to adjust beam parameters of one or more coherent beams of the composite output beam corresponding to the reflected radiation components based on the received intensity parameters. The system of claim 1 .

12. and an imaging system for generating an image of the target, the imaging system comprising: Wavefront sensor, a deformable mirror for receiving radiation from the spatial filtering arrangement; a beam splitter for receiving radiation from the deformable mirror and providing a portion of the received radiation to the wavefront sensor and providing another portion of the received radiation to the radiation discrimination module; and an adaptive optics controller in communication with the wavefront sensor, the adaptive optics controller operable to control the deformable mirror to reduce optical distortions in reflected radiation collected by the telescope array. The system of claim 1 .

13. a plurality of beam emission subsystems, each beam emission subsystem including an array of beam sources configured to generate a plurality of coherent beams for directing toward a region of the target to combine as a composite output beam at or in front of the target, wherein the composite output beams generated by the beam emission subsystems have different respective wavelengths, and wherein for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; and A receiver, a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining into a combined radiation made up of the reflected radiation components; a spatial filtering arrangement disposed at a focal plane and configured to filter the reflected radiation by selectively passing the combined radiation; an optics array for receiving the combined radiation from the spatial filtering arrangement, the optics array including at least one dispersive optical component for splitting the combined radiation into a plurality of constituent wavelengths corresponding to wavelengths of the composite output beam; and a detector array for receiving radiation split by the at least one dispersive optical component, the detector array configured to separately measure radiation at each of the constituent wavelengths. Including a receiver, system.

14. The system of claim 13 , wherein the at least one dispersive optical component comprises a prism.

15. The system of claim 13 , wherein the at least one dispersive optical component comprises a diffraction grating.

16. 14. The system of claim 13, wherein the optical arrangement further comprises a collimating element disposed in an optical path between the spatial filtering arrangement and the at least one optical component, the collimating element configured to collimate the combined radiation to produce collimated radiation and to direct the collimated radiation to at least one optical element.

17. 14. The system of claim 13, further comprising a control subsystem coupled to the detector array and each of the plurality of beam emission subsystems, wherein for each beam emission subsystem, the control subsystem is configured to adjust beam parameters of one or more coherent beams of the composite output beam generated by the beam emission subsystem based on radiation measured by the detector array.

18. The system of claim 13 , wherein the detector arrangement includes an array of detectors, each detector in the array of detectors configured to measure radiation at a different individual one of the constituent wavelengths.

19. A plurality of beam delivery subsystems, each beam delivery subsystem comprising: an array of beam sources configured to generate a plurality of coherent beams for directing toward a region of the target to combine as a composite output beam at or in front of the target, wherein a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a plurality of adjustable phase modulators coupled to the beam source to enable adjustment of a relative phase offset of the coherent beams; and a plurality of beam subsystems, each including an encoding module for encoding a phase of each of the coherent beams with a code that is local to the beam delivery subsystem; and A receiver, a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining into a combined radiation made up of the reflected radiation components; a spatial filtering arrangement disposed at the focal plane and configured to filter the reflected radiation by selectively passing the combined radiation; a detector positioned to receive the combined radiation from the spatial filtering arrangement and to generate a signal representative of an intensity of the combined radiation; and a decoding module for decoding said signal according to a locally unique code for each beam delivery subsystem; Including a receiver, system.

20. 20. The system of claim 19, wherein the encoding module includes a modulator, where each composite output beam is assigned a locally unique modulation frequency, where for each beam emission subsystem, the modulator is configured to modulate a current phase of the coherent beam at the assigned modulation frequency, and where the decoding module includes a plurality of demodulators, where each demodulator is configured to demodulate a signal at one or more selected demodulation frequencies selected from the assigned unique modulation frequencies.

21. 20. The system of claim 19, wherein, for each beam emission subsystem, the encoding module includes a sequence generator for generating a code sequence, where the encoding module is configured to encode a phase of each of the coherent beams by modulating a current phase of the coherent beam with a waveform linked to the code sequence, where the decoding module includes a signal generator for generating the waveform linked to the code sequence, and where the decoding module is configured to demodulate the signal using each of the waveforms.

22. a plurality of beam emission subsystems, each configured to generate a plurality of coherent beams for directing toward a region of the target to combine as a composite output beam at or in front of the target, where for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; A plurality of receivers, each of the receivers having: collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining into a combined radiation made up of the reflected radiation components, where an intensity of the combined radiation is a measure of a radiation intensity of the composite output beam incident on the target; spatially filtering the reflected radiation at a focal plane by selectively passing the combined radiation; and receiving said spatially filtered combined radiation and for each reflected radiation component discriminating an intensity parameter of that reflected radiation component from an intensity parameter of the combined radiation of all remaining reflected radiation components; A plurality of receivers, a control subsystem coupled to the receivers and configured to select a receiver based on an estimate of an effective resolution of the target provided by each of the receivers; system.

23. 23. The system of claim 22, wherein the control subsystem is further configured to operate each of the beam emission subsystems to adjust one or more beam parameters of the coherent beam based on the intensity parameter discriminated by the selected receiver.

24. transmitting a plurality of composite output beams, wherein each output beam is transmitted by generating and directing a plurality of coherent beams toward a region of a target, thereby combining as a composite output beam at or in front of the target, wherein for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation comprising a plurality of radiation components, at least some of the radiation components combining as a combined radiation made up of reflected radiation components, where an intensity of the combined radiation is an indication of the radiation intensity of the composite output beam incident on the target; spatially filtering the reflected radiation by selectively passing the combined radiation with a spatial filtering arrangement disposed at the focal plane; and receiving the combined radiation that has been passed through the spatial filtering arrangement and, for each reflected radiation component, discriminating an intensity parameter of that reflected radiation component from an intensity parameter of a combined radiation of all remaining reflected radiation components; method.

25. a plurality of beam emission subsystems, each configured to generate a plurality of coherent beams for directing toward a region of the target to combine as a composite output beam at or in front of the target, each composite output beam having an associated locally unique signature, and wherein for each composite output beam, a portion of the radiation intensity of the composite output beam is reflected by the target as a reflected radiation component; a telescope array for collecting radiation reflected from the target and directing the reflected radiation onto a focal plane, the reflected radiation including a plurality of radiation components, at least some of the radiation components combining as a combined radiation made up of the reflected radiation components, where an intensity of the combined radiation is an indication of a radiation intensity of the composite output beam incident on the target; and a spatial filtering arrangement disposed at the focal plane configured to filter the reflected radiation by selectively passing the combined radiation, wherein each component of the combined radiation is distinguishable by a locally unique signature associated with a composite output beam corresponding to the component of the combined radiation; system.

26. 26. The system of claim 25, further comprising at least one radiation discrimination module for receiving the combined radiation passed by the spatial filtering arrangement and for discriminating, for at least one of the reflected radiation components, at least one intensity parameter of the reflected radiation component from intensity parameters of a combined radiation of all remaining reflected radiation components based on at least one of the locally unique signature constants associated with the composite output beam corresponding to a component of the combined radiation.

27. 27. The system of claim 26, wherein the at least one radiation discrimination module includes exactly one radiation discrimination module.

28. 27. The system of claim 26, wherein the at least one radiation discrimination module includes a plurality of radiation discrimination modules, each radiation discrimination module coupled to a respective one of the beam emission subsystems, and wherein, for each radiation discrimination module, the radiation discrimination module is configured to discriminate an intensity parameter of one of the reflected radiation components from an intensity parameter of a combined radiation of all remaining reflected radiation components corresponding to a composite output beam generated by the beam emission subsystem coupled to the radiation discrimination module.

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