Multi-aperture beam coherent synthesis device and method for off-axis parabolic reflector

Abstract

The present invention discloses a multi-aperture beam coherent synthesis device and method of an off-axis parabolic reflector, and relates to the technical field of beam coherent synthesis. The present invention carries out a simplified optical path design: the distributed design reduces the complexity of the optical path design, simplifies the optical path of the system, and improves the overall efficiency of the system. The design of the parabolic shape enables the array beam to complete focusing while sampling, further simplifying the complexity of the sampling optical path; low beam power loss: the distributed off-axis parabolic reflector effectively reduces the sampling power loss of the beam, reduces the optical power loss, and has a high light energy utilization rate for the transmitted beam. Different from the traditional structure of a beam splitter plus a focusing lens, which requires all beams to be split and focused, the present invention uses a reflector that only needs to reflect a small part of the beam to complete the sampling and focusing of the array beam, and the overall reflector area is small and the processing price is cheap.

Description

Technical Field

[0001] The invention relates to the technical field of coherent light beam synthesis, in particular to a multi-aperture light beam coherent synthesis device of an off-axis parabolic reflector and a method thereof. Background Art

[0002] The existing beam coherent combination system usually uses a beam splitter to split the array beam in the near field and focuses it with a lens. Then the control system uses the beam quality of the focal spot as an evaluation function to control the phase modulator in the laser phased array system, so that the phase of all beams is kept at an integer multiple of 2π, and the outgoing array beam is coherently combined in the far field. Common configurations include:

[0003] (1) Beam splitter: All sub-beams are split using a beam splitter. This type of device is bulky and heavy.

[0004] (2) Focusing lens: The function of this device is to focus all the light beams separated by the beam splitter in the near field in order to obtain the focal spot required for subsequent phase-locked control.

[0005] The prior art has the following technical problems:

[0006] (1) Complex and bulky structure: When the existing coherent synthesis phase-locked system based on a beam splitter and a focusing lens is expanded in scale, the sub-beam sampling equipment is heavy. It is difficult to reduce the weight of the optical path system structure to improve system accuracy when applied to target tracking, adaptive optics and other systems. The number and arrangement complexity of sub-beams have increased significantly, making the alignment of optical components extremely difficult.

[0007] (2) Power loss of the sampling system: Most current coherent combining systems use a spectroscope for beam sampling. This device causes a large loss in beam power and is not conducive to the formation of a high-power beam in the coherent light combining system.

[0008] Therefore, a new solution to the above problems needs to be proposed. Summary of the invention

[0009] The purpose of the present invention is to provide a multi-aperture beam coherent synthesis device and method of an off-axis parabolic reflector. The device innovatively utilizes distributed off-axis parabolic reflectors in combination with a phase modulation module to achieve efficient and stable beam coherent synthesis, thereby solving the technical problems raised in the background technology.

[0010] To achieve the above-mentioned object, the present invention provides the following technical solution: a multi-aperture beam coherent synthesis device of an off-axis parabolic reflector, comprising a laser seed source, a beam splitter, a phase modulator array, a collimator array, a distributed off-axis parabolic reflector, a PC control terminal and a focusing lens;

[0011] A beam splitter is provided at the output end of the laser seed source, a phase modulator array is provided at one end of the beam splitter away from the laser seed source, a collimator array is provided at one end of the phase modulator array away from the beam splitter, a distributed off-axis parabolic reflector is provided at one end of the collimator array away from the phase modulator array, a focusing lens is provided at one end of the distributed off-axis parabolic reflector away from the collimator array, and a collection device is provided on one side of the distributed off-axis parabolic reflector.

[0012] Furthermore, the acquisition device includes a CCD camera, which is an industrial area array camera for collecting light beam information collected by a distributed off-axis parabolic reflector, wherein the light beam information includes power, spot distribution and beam quality of the detected synthetic light beam.

[0013] Furthermore, the laser seed source is a narrow linewidth laser, and the narrow linewidth laser is a fiber laser or a solid laser.

[0014] Furthermore, the phase modulator array is used to split the light beam output by the beam splitter into N beams, and the beam splitter used is a fiber beam splitter.

[0015] Furthermore, the phase modulator array controls the phase difference between the light beams according to the phase modulation signal applied by the PC control terminal, and the phase modulator array is a LiNbO or piezoelectric ceramic phase modulator;

[0016] Furthermore, the collimator array drives the optical fiber end face to move in the focal plane of the collimating lens through the dual piezoelectric ceramic sheets, thereby changing the direction of the optical axis of the outgoing light beam;

[0017] Furthermore, the distributed off-axis parabolic reflector is composed of a plurality of metal mirror arrays with customized shapes and special arrangements, and the mirrors are discretely distributed at different positions relative to the optical axis, presenting a parabolic shape as a whole;

[0018] Furthermore, the PC control end processes the light spot information provided by the CCD camera, converts it into a control signal of the phase modulator array, and uses an optimization algorithm to perform phase-locked control, and the optimization algorithm at least includes an SPGD method.

[0019] Furthermore, the focusing lens is a transmission lens, which is used to achieve coherent superposition of sub-beams in the far field.

[0020] The method for using the multi-aperture beam coherent synthesis device of the off-axis parabolic reflector comprises at least the following steps:

[0021] S1: The light output by the laser seed source enters the beam splitter and is divided into N beams;

[0022] S2: The light coming out of the beam splitter passes through the phase modulator and enters the collimation direction of the collimator array, and then propagates in its own independent sub-beams;

[0023] S3: The beam array is reflected and sampled by a distributed off-axis parabolic reflector, and the CCD camera completes the near-field information acquisition;

[0024] S4: The PC control end processes the spot information collected by the CCD camera and transmits the phase control signal to the phase modulator array to modulate the phase of each sub-beam to achieve closed-loop control of the entire system. Since the phases of the transmitted composite beam and the reflected composite beam in each sub-beam are consistent, the transmitted composite beam can also achieve coherent synthesis at the intersection.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Simplified optical path design: Distributed design reduces the complexity of optical path design, simplifies the optical path of the system, and improves the overall efficiency of the system. The parabolic shape design enables the array beam to be focused while sampling, further simplifying the complexity of the sampling optical path;

[0027] 2. Low beam power loss: Distributed off-axis parabolic reflectors effectively reduce the sampling power loss of the beam, reduce the optical power loss, and have a high light energy utilization rate for the transmitted beam. Unlike the traditional structure of a beam splitter plus a focusing lens, which requires all beams to be split and focused, the present invention uses a reflector that only needs to reflect a small part of the beam to complete the sampling and focusing of the array beam. The overall reflector area is small and the processing price is cheap;

[0028] 3. Flexible system scalability: By adjusting the number and position of distributed off-axis parabolic reflectors, the scale of the optical path sampling system can be easily expanded by splicing to meet the needs of coherent synthesis sampling applications with a large number of units. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0030] Figure 1 This is a design diagram of the system of the present invention;

[0031] Figure 2 This is a diagram showing the overlapping effect of the light beam array and the distributed off-axis parabolic reflector of the present invention;

[0032] Figure 3A comparison diagram of the transmitted light beam and the reflected light beam of the present invention;

[0033] Figure 3 (a) is the transmitted beam array, Figure 3 (b) is the reflected beam array;

[0034] Figure 4 It is the SPGD iterative PIB curve diagram of the present invention;

[0035] Figure 5 This is a system effect diagram of the present invention;

[0036] Figure 5 (a) is an open loop, Figure 5 (b) is a closed loop;

[0037] Figure 6 This is a comparison diagram of sampling power loss of the present invention;

[0038] Figure 6 (a) Traditional spectroscopic sampling, Figure 6 (b) Distributed off-axis parabolic sampling.

[0039] In the figure: 1. Laser seed source; 2. Beam splitter; 3. Phase modulator array; 4. Collimator array; 5. Distributed off-axis parabolic reflector; 6. PC control terminal; 7. Focusing lens. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] Embodiment 1:

[0042] See also Figure 1 , a multi-aperture beam coherent synthesis device of an off-axis parabolic reflector, comprising a laser seed source 1, a beam splitter 2, a phase modulator array 3, a collimator array 4, a distributed off-axis parabolic reflector 5, a PC control terminal 6 and a focusing lens 7;

[0043] A beam splitter 2 is provided at the output end of the laser seed source 1, a phase modulator array 3 is provided at the end of the beam splitter 2 away from the laser seed source 1, a collimator array 4 is provided at the end of the phase modulator array 3 away from the beam splitter 2, a distributed off-axis parabolic reflector 5 is provided at the end of the collimator array 4 away from the phase modulator array 3, a focusing lens 7 is provided at the end of the distributed off-axis parabolic reflector 5 away from the collimator array 4, and a collection device is provided on one side of the distributed off-axis parabolic reflector 5.

[0044] The acquisition device includes a CCD camera, which is an industrial array camera and is used to collect the beam information collected by the distributed off-axis parabolic reflector 5. The beam information includes the power, spot distribution and beam quality of the detected synthetic beam.

[0045] The laser seed source 1 is a narrow linewidth laser, and the narrow linewidth laser is a fiber laser or a solid laser.

[0046] The phase modulator array 3 is used to split the light beam output by the beam splitter 2 into N beams, and the beam splitter 2 used is a fiber beam splitter.

[0047] The phase modulator array 3 controls the phase difference between the light beams according to the phase modulation signal applied by the PC control terminal 6. The phase modulator array 3 is a LiNbO3 or piezoelectric ceramic phase modulator;

[0048] The collimator array 4 uses a dual piezoelectric ceramic plate to push the end face of the optical fiber to move in the focal plane of the collimating lens, thereby changing the direction of the optical axis of the outgoing light beam;

[0049] The distributed off-axis parabolic reflector 5 is composed of a plurality of metal mirror arrays with customized shapes and special arrangements. The mirrors are discretely distributed at different positions relative to the optical axis, and present a parabolic shape as a whole.

[0050] The PC control terminal 6 processes the light spot information provided by the CCD camera, converts it into a control signal for the phase modulator array 3, and uses an optimization algorithm to perform phase-locked control. The optimization algorithm at least includes the SPGD method.

[0051] The focusing lens 7 is a transmission lens, which is used to achieve coherent superposition of sub-beams in the far field.

[0052] It should be emphasized that the distributed off-axis parabolic reflector is used in the present invention in order to achieve reflection and sampling focusing of the sub-beams while intercepting a small amount of array beam energy through the distributed off-axis parabolic reflector.

[0053] The technical feature is that the distributed design is used to reduce beam power loss, and the parabolic design completes beam focusing while sampling.

[0054] The advantages of the present invention are that the optical path design is simplified, the light beam power loss is low, Figure 6 The sampling light power loss and spot comparison of the traditional spectroscope sampling scheme and the distributed off-axis parabola sampling scheme with the same number of arrays and array arrangement, as well as the flexible system scalability.

[0055] Embodiment 2:

[0056] Based on the above embodiments, this embodiment proposes a method for using a multi-aperture beam coherent synthesis device of an off-axis parabolic reflector;

[0057] The method for using the multi-aperture beam coherent synthesis device of the off-axis parabolic reflector comprises at least the following steps:

[0058] S1: The light output by laser seed source 1 enters the beam splitter and is divided into N beams;

[0059] S2: The light coming out of beam splitter 2 passes through phase modulator 3 and enters the collimation direction of the collimator array, and then propagates in its own independent sub-beams;

[0060] S3: The beam array is reflected and sampled by a distributed off-axis parabolic reflector, and the CCD camera completes the near-field information acquisition;

[0061] S4: The PC control terminal 6 processes the light spot information collected by the CCD camera and transmits the phase control signal to the phase modulator array 3 to modulate the phase of each sub-beam to achieve closed-loop control of the entire system. Since the phases of the transmitted synthetic beam and the reflected synthetic beam in each sub-beam are consistent, the transmitted synthetic beam can also achieve coherent synthesis at the intersection.

[0062] Embodiment three:

[0063] This embodiment proposes a specific implementation application based on the above embodiment, taking the coherent synthesis process of a 16-channel light beam array as an example to illustrate the implementation process of the entire solution. The entire system can be expanded to multiple channels;

[0064] The light output from the laser seed source 1 enters the beam splitter and is divided into N beams; the light from the beam splitter 2 passes through the phase modulator 3 and enters the collimation direction of the collimator array, adjusts the position of the fiber end face, aligns the beam with the lens optical axis, and then propagates in each independent sub-beam. The beam array is sampled by reflection through a distributed off-axis parabolic reflector. Figure 2 The figure shows the overlapping effect of the beam array and the distributed off-axis parabolic reflector. The green part is a 16-unit square beam array. The sub-beams are numbered 1 to 16 from left to right and from top to bottom. The gray part is the layout of the distributed off-axis parabolic reflector. Each reflector is numbered R1 to R4. Four sub-beams and a distributed off-axis parabolic reflector form a basic unit to ensure that each sub-beam can be sampled. The sub-beams numbered 1, 2, 5, and 6 are reflected by the distributed off-axis parabolic reflector numbered R1; the sub-beams numbered 3, 4, 7, and 8 are reflected by the distributed off-axis parabolic reflector numbered R2; the sub-beams numbered 9, 10, 13, and 14 are reflected by the distributed off-axis parabolic reflector numbered R3; the sub-beams numbered 11, 12, 15, and 16 are reflected by the distributed off-axis parabolic reflector numbered R4. Figure 3The figure shows the comparison of the transmitted light beam and the reflected light beam. The distributed off-axis parabolic reflector presents a parabolic shape as a whole. When each unit completes the collection of sub-beam information, it also completes the focusing of the collection beam array. The CCD camera collects the spot information transmitted by the distributed off-axis parabolic reflector, and the PC control terminal 6 processes the spot information collected by the CCD camera. Through the control algorithm SPGD, the phase control signal is transmitted to the phase modulator array 3 to modulate the phase of each sub-beam, thereby realizing the closed-loop control of the entire system. Figure 4 The phase iteration optimization curve of the SPGD algorithm is based on the power ratio PIB of the reflected sampling spot in the barrel. Since the phases of the transmitted composite beam and the reflected composite beam in each sub-beam are consistent, the transmitted composite beam can also achieve coherent synthesis at the intersection. Figure 5 The figure shows the beam quality comparison of the far-field spot formed by the transmitted light beam when the system is open-loop and closed-loop, with PIB as the evaluation index of the light beam.

[0065] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A multi-aperture beam coherent synthesis device using an off-axis parabolic reflector, characterized in that: It includes a laser seed source (1), a beam splitter (2), a phase modulator array (3), a collimator array (4), a distributed off-axis parabolic reflector (5), a PC control terminal (6) and a focusing lens (7); The output end of the laser seed source (1) is provided with a beam splitter (2); the end of the beam splitter (2) away from the laser seed source (1) is provided with a phase modulator array (3); the end of the phase modulator array (3) away from the beam splitter (2) is provided with a collimator array (4); the end of the collimator array (4) away from the phase modulator array (3) is provided with a distributed off-axis parabolic reflector (5); the end of the distributed off-axis parabolic reflector (5) away from the collimator array (4) is provided with a focusing lens (7); and a collection device is provided on one side of the distributed off-axis parabolic reflector (5); The distributed off-axis parabolic reflector (5) is composed of a plurality of metal mirror arrays with customized shapes and special arrangements. The mirrors are discretely distributed at different positions relative to the optical axis and present a parabolic shape as a whole.

2. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The acquisition device comprises a CCD camera, which is an industrial array camera and is used to acquire light beam information acquired by a distributed off-axis parabolic reflector (5), wherein the light beam information comprises power, light spot distribution and light beam quality of a detected synthetic light beam.

3. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The laser seed source (1) is a narrow line width laser, and the narrow line width laser is a fiber laser or a solid laser.

4. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The phase modulator array (3) is used to split the light beam output by the beam splitter (2) into N beams, and the beam splitter (2) used is a fiber beam splitter.

5. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The phase modulator array (3) controls the phase difference between the light beams according to the phase modulation signal applied by the PC control terminal (6), and the phase modulator array (3) is a LiNbO3 or piezoelectric ceramic phase modulator.

6. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The collimator array (4) drives the optical fiber end face to move on the focal plane of the collimating lens through the dual piezoelectric ceramic sheets, thereby changing the direction of the optical axis of the outgoing light beam.

7. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 2, characterized in that: The PC control terminal (6) processes the light spot information provided by the CCD camera, converts it into a control signal for the phase modulator array (3), and uses an optimization algorithm to perform phase-locked control, wherein the optimization algorithm at least includes an SPGD method.

8. The multi-aperture beam coherent synthesis device of the off-axis parabolic reflector according to claim 1, characterized in that: The focusing lens (7) is a transmission lens, and is used to achieve coherent superposition of sub-beams in the far field.

9. A method for using a multi-aperture beam coherent synthesis device of an off-axis parabolic reflector, used for the multi-aperture beam coherent synthesis device of an off-axis parabolic reflector according to claim 1, characterized in that: At least the following steps are included: S1: The light output by the laser seed source (1) enters the beam splitter and is divided into N beams; S2: The light coming out of the beam splitter (2) passes through the phase modulator array (3) and then enters the collimation direction of the collimator array, and then propagates in each independent sub-beam; S3: The beam array is reflected and sampled by a distributed off-axis parabolic reflector, and the CCD camera completes the near-field information acquisition; S4: The PC control terminal (6) processes the light spot information collected by the CCD camera and transmits the phase control signal to the phase modulator array (3) to modulate the phase of each sub-beam, thereby realizing closed-loop control of the entire system. Since the phases of the transmitted composite beam and the reflected composite beam in each sub-beam are consistent, the transmitted composite beam can also achieve coherent synthesis at the intersection.

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