阅读说明：本技术 一种活塞相位控制系统及方法 (Piston phase control system and method ) 是由 粟荣涛 龙金虎 马阎星 周朴 常洪祥 常琦 马鹏飞 吴坚 李�灿 姜曼 司磊 于 2019-10-22 设计创作，主要内容包括：本发明公开一种活塞相位控制系统及方法,该方法包括：种子激光经相位调制、放大、准直后出射；出射激光阵列经分光后一部分激光经大气湍流传输到目标靶面经散射、汇聚后被探测以供形成第一反馈信号以控制准直器对大气湍流引起的倾斜相差进行校正；出射激光阵列经分光后另一部分激光经空间调相以模拟大气湍流、聚焦后经探测形成第二反馈信号以控制相位调制器对放大过程引起的活塞相差进行校正；二级活塞相位控制装置,连接在第一探测器与空间调相器件阵列之间。解决现有技术中当激光传输距离较远时,活塞相位的控制速率难以满足大数目激光阵列要求的问题,实现活塞相位控制速率满足大数目激光阵列要求,且激光传输距离不受限制。(The invention discloses a piston phase control system and a method, wherein the method comprises the following steps: the seed laser is emitted after phase modulation, amplification and collimation; after the outgoing laser array is subjected to light splitting, a part of laser is transmitted to a target surface through atmospheric turbulence, is scattered and converged and is detected so as to form a first feedback signal for controlling a collimator to correct the inclination phase difference caused by the atmospheric turbulence; after the outgoing laser array is subjected to light splitting, the other part of laser is subjected to spatial phase modulation to simulate atmospheric turbulence, and after the outgoing laser array is focused, a second feedback signal is formed by detection to control a phase modulator to correct the piston phase difference caused in the amplification process; and the secondary piston phase control device is connected between the first detector and the space phase modulation device array. The problem of in the prior art when laser transmission distance is far away, the control rate of piston phase is difficult to satisfy the requirement of large number laser array is solved, realize that piston phase control rate satisfies the requirement of large number laser array, and laser transmission distance is unrestricted.)

1. A piston phase control system comprises a seed laser, a laser beam splitter, a phase modulator array, a laser amplifier array and an adaptive stress light collimator array which are connected in sequence, wherein emergent laser of each collimator in the adaptive stress light collimator array reaches a target surface after being transmitted through atmospheric turbulence, and on a scattering light path of the target surface, the target scattering light is incident to a first detector after being received by a telescope, and the first detector is connected with each collimator through an inclination control circuit; it is characterized by also comprising:

the spectroscope is arranged on a light path between the emergent laser of each collimator and the atmospheric turbulence and is used for splitting the emergent laser energy of the collimator, one part of the split laser energy is transmitted to a target surface, and the other part of the split laser energy is incident on the spatial phase modulation device array;

the space phase modulation device array is used for changing the phase of a piston emitting laser;

the focusing device is used for focusing the emergent laser which changes the phase of the piston;

the input end of the second detector receives the focused laser, and the output end of the second detector is connected with the phase modulator array through the primary piston phase control device;

and the secondary piston phase control device is connected between the first detector and the space phase modulation device array.

2. The piston phase control system of claim 1 wherein said beam splitter comprises a high or low mirror; the reflectivity of the high reflection mirror is greater than or equal to 99%, or

The low reflection mirror has a transmittance of greater than or equal to 99%.

3. The piston phase control system of claim 1 wherein said beam splitter comprises a single beam splitter or an array of beam splitters, said array of beam splitters optically matching said array of adaptive stress light collimators, and said array of spatial phase modulation devices.

4. The piston phase control system of claim 1 wherein said focusing assembly comprises:

the convex lens is used for focusing the laser array passing through the spatial phase modulation device array;

a small aperture diaphragm; and the small hole is arranged at the focus position of the convex lens and is used for enabling the central energy of the far-field light spot of the laser array to pass through.

5. The piston phase control system of claim 4 wherein said aperture has a diameter of between 1.22 λ f/D and 2.44 λ f/D, where λ laser wavelength, f is the focal length of the convex lens, and D is the diameter of the circumscribed circle of the laser array exiting the adaptive stress optical collimator array.

6. A piston phase control method, comprising the steps of:

the seed laser is emitted after phase modulation, amplification and collimation;

after the outgoing laser array is subjected to light splitting, part of laser is transmitted to a target surface through atmospheric turbulence, and is detected and extracted after being scattered and converged so as to form a first feedback signal, so that a collimator is controlled to correct the inclination phase difference caused by the atmospheric turbulence;

after the outgoing laser array is subjected to light splitting, the other part of laser is subjected to space phase modulation and focusing and then is detected so as to form a second feedback signal for controlling the phase modulator to correct the piston phase difference caused in the amplification process;

the first feedback signal is also used for controlling the spatial phase modulator to correct the piston phase difference caused by simulating atmospheric turbulence in the spatial phase modulation process.

Technical Field

The invention relates to the technical field of optical coherent synthesis, in particular to a hierarchical piston phase control system.

Background

The laser array can be widely applied to the fields of laser communication, laser radar, directional energy technology and the like. The laser coherent array based on Master Oscillator Power Amplifier (MOPA for short) can realize synthetic aperture emission, increase the emission aperture of the system and reduce the transmission divergence angle of laser. Compensation for atmospheric turbulence can also be achieved by tilt phase and piston phase control using target-based in-circuit (see patent 1: CN104037606B, see document 1: T Weyrauch, et al. Deep turbulence effects Transmission with coherent combining of 21laser beams over 7km [ J ]. Optics Letters,2016,41(4): 840-.

Fig. 1 is a block diagram showing a structure of a prior art target-in-loop laser coherent array. The system mainly comprises a seed laser 101, a laser beam splitter 102, a plurality of phase modulators 103, a plurality of laser amplifiers 104, a plurality of adaptive stress light collimators 105, a receiving telescope 106, a photoelectric detector 107, a tilt control circuit 108 and a piston phase control circuit 113. After the laser light emitted from the seed laser 101 is split by the laser beam splitter 102, the laser light beams enter the phase modulator 103, respectively. Each phase modulator 103 is optically connected to each corresponding laser amplifier 104. Each laser amplifier 104 is optically connected to an adaptive stress optical collimator 105. The laser light emitted from the respective adaptive optical collimator 105 reaches the target surface 116 after being transmitted by the atmospheric turbulence 115. The receiving telescope 106 receives scattered light scattered back from the target, and the scattered light is incident on the photodetector 107. The photodetector 107 converts the detected optical signal into an electrical signal, and transmits the electrical signal to the tilt control circuit 108 and the piston phase control circuit 113. The tilt control circuit 108 runs a control algorithm, based on the input signal as a feedback signal, and generates an output signal based on the algorithm, which controls the respective adaptive stress light collimators 105 to correct for tilt phase differences caused by atmospheric turbulence 115. The piston phase control circuit 113 runs a control algorithm, generates an output signal based on the algorithm based on the input signal as a feedback signal, and applies control to each phase modulator 103 to correct for piston phase differences caused by the laser amplifier 104 and the atmospheric turbulence 115. By correcting the inclination phase difference and the piston phase difference, coherent combination of the laser array at a target can be realized, and the laser energy at the target is maximized.

However, since scattered light of a far-field target and the like are used as feedback signals, after control parameters such as the phase and the inclination of the laser array are changed, a new laser array needs to reach the target through transmission at a certain distance, the scattered laser signals return to a laser emission position to obtain the feedback signals, and finally the control parameters are corrected according to the change of the feedback signals. Thus, the single iteration time of the adaptive control is greater than the round trip time of the laser at the reflection and at the target. The frequency of piston phase noise in the laser amplifier 104 is typically high, and the rate of piston phase control is difficult to meet with the requirements of a large number of laser arrays when the laser transmission distance is long.

Disclosure of Invention

The invention provides a piston phase control system and a method, which are used for overcoming the defects that the frequency of piston phase noise in a laser amplifier is higher, and when the laser transmission distance is longer, the control speed of the piston phase is difficult to meet the requirement of a large number of laser arrays and the like in the prior art, so that the single iteration time of a feedback signal is reduced, the piston phase control speed meets the requirement of the large number of laser arrays, and the laser transmission distance is not limited.

In order to achieve the purpose, the invention provides a piston phase control system, which comprises a seed laser, a laser beam splitter, a phase modulator array, a laser amplifier array and an adaptive stress light collimator array which are connected in sequence, wherein emergent laser of each collimator in the adaptive stress light collimator array reaches a target surface after being transmitted by atmospheric turbulence, and is incident to a first detector after being received by a telescope on a scattering light path of the target surface, and the first detector is connected with each collimator through an inclination control circuit; further comprising:

the spectroscope is arranged on a light path between the emergent laser of each collimator and the atmospheric turbulence and is used for splitting the emergent laser energy of the collimator, one part of the split laser energy is transmitted to a target surface, and the other part of the split laser energy is incident on the spatial phase modulation device array;

the space phase modulation device array is used for changing the phase of a piston emitting laser;

the focusing device is used for focusing the emergent laser which changes the phase of the piston;

and the input end of the second detector receives the focused laser, and the output end of the second detector is connected with the phase modulator array through the primary piston phase control device.

In order to achieve the above object, the present invention further provides a piston phase control method, comprising the steps of:

the seed laser is emitted after phase modulation, amplification and collimation;

after the outgoing laser array is subjected to light splitting, part of laser is transmitted to a target surface through atmospheric turbulence, and is detected and extracted after being scattered and converged so as to form a first feedback signal, so that a collimator is controlled to correct the inclination phase difference caused by the atmospheric turbulence;

after the outgoing laser array is subjected to light splitting, the other part of laser is subjected to spatial phase modulation and focusing and then is detected to form a second feedback signal so as to control the phase modulator to correct the piston phase difference caused in the amplification process;

the first feedback signal is also used for controlling the spatial phase modulator to correct the piston phase difference caused by simulating atmospheric turbulence in the spatial phase modulation process.

The piston phase control system and the method provided by the invention have the advantages that light splitting is carried out on an optical path of an incident atmospheric turbulence of a laser array, a part of laser is split, phase modulation is carried out on the split laser through a space phase modulation array, the split laser is focused and then is collected by a second detector, an optical signal is converted into an electric signal and then is output, the electric signal is calculated by a primary piston phase control device to obtain the phase difference of a piston of an amplifier array, a phase modulation signal is formed according to the phase modulation signal, the electric signal is fed back to a phase modulator array to correct the piston phase noise in a laser amplifier, namely, the primary piston phase control device obtains an evaluation function from the output end of the laser array, the evaluation function can be obtained from a near field, the evaluation function does not need to; the other part of the light original path enters atmospheric turbulence to a target, then returns to the telescope after being scattered by the target, the scattered light is collected by the first detector after being output by the telescope, and the light signal is converted and then is calculated by the tilt control circuit to obtain the tilt phase difference caused by the atmospheric turbulence for correction; in addition, the piston phase difference caused by the atmospheric turbulence can be calculated by acquiring a signal from the output end of the first detector through the secondary piston phase control device to serve as an evaluation function, the piston phase difference caused by the atmospheric turbulence is obtained, a phase modulation signal is formed according to the piston phase difference, and the phase modulation signal is fed back to the spatial phase modulation device array to correct the piston phase noise caused by the atmospheric turbulence. Compared with the prior art, the primary piston phase control device has faster control rate due to the fact that the feedback signals are obtained from the near field, so that the requirement of a large number of laser arrays is met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a block diagram showing a prior art structure of a target-in-loop laser coherent array;

fig. 2 is a schematic block diagram of a target-in-loop laser coherent array for stepped piston phase control according to an embodiment of the present invention.

The reference numbers illustrate:

the device comprises a seed laser 201, a laser beam splitter 202, a phase modulator 203, a laser amplifier 204, an adaptive stress light collimator 205, a receiving telescope 206, a photoelectric detector 207, a tilt control circuit 208, a beam splitter 209, a spatial phase modulation device 210, a convex lens 211, an aperture diaphragm 212, a primary piston phase control circuit 213, a secondary piston phase control circuit 214, an atmospheric turbulence 215 and a target surface 216.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; the connection can be mechanical connection, electrical connection, physical connection or wireless communication connection; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.