A multi-wavelength laser tracking and sighting light detection method and system

Abstract

The application discloses a kind of multi-wavelength laser follow sighting light detection method and system, the method utilizes the wavelength separation of multilayer volume grating module to the received incident laser beam, obtains multiple corresponding different wavelength exit laser beams;The angle deviation information of different wavelength of the exit laser beam is obtained, and the multi-wavelength signal information in the incident laser beam is determined according to angle deviation information.The method and system proposed by the application, by designing multilayer volume grating module, utilize the efficient separation and high-precision detection of multi-wavelength laser signal by the volume grating of different grating parameters in multilayer volume grating module.The method and system of the application are compact in structure, robust, and suitable for tracking and aiming light detection in inter-satellite, star-ground and other dynamic laser communication scenarios.

Description

Technical Field

[0001] This application relates to the fields of laser communication and photoelectric detection technology, and in particular to a multi-wavelength laser tracking and detection method and system based on a volume grating. Background Technology

[0002] Laser tracking and aiming detection technology is a core supporting technology in the field of space laser communication. Its performance directly determines the aiming accuracy, response speed, and anti-interference capability of the space laser communication system. With the continuous upgrading of the requirements in the field of space laser communication, laser tracking and aiming systems are iteratively developing towards higher precision, higher sensitivity, miniaturization, and resistance to strong background light interference, which puts forward higher requirements for the detection performance of laser signals.

[0003] Existing multi-wavelength laser tracking and detection technologies generally employ a multi-wavelength parallel detection method. This method is not only limited in capability and difficult to coordinate with wavelength separation and angle detection, but also lacks adaptability to dynamic link adjustment. Therefore, it cannot achieve efficient separation and high-precision detection of multi-wavelength laser signals.

[0004] Therefore, existing technologies need to be improved. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a multi-wavelength laser tracking and detection method and system based on a volume grating, overcoming the shortcomings of the existing multi-wavelength laser detection technology in achieving efficient separation and high-precision detection of multi-wavelength laser signals.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows: In a first aspect, the present invention discloses a multi-wavelength laser tracking and aiming detection method, which is applied to a multi-wavelength laser tracking and aiming detection system. The detection system includes: a collimation module, a multi-level series-connected multilayer volume grating module, and a focusing detection module arranged sequentially. The multilayer volume grating module includes a wavelength splitting unit and an angular amplification unit. The wavelength splitting unit includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength. The detection method includes: The multi-wavelength beam input to the detection system is collimated by the collimation module to obtain a parallel laser beam. The parallel laser beam is input to the wavelength splitting unit, and wavelength separation is performed by each volume grating in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths; The split laser beam is input to the angle amplification unit, and the angle amplification unit amplifies the beam to obtain laser beams with different wavelengths and different emission angles. The focusing detection module collects the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and determines the multi-wavelength signal information in the multi-wavelength beam based on the angle deviation information and pose information.

[0007] Optionally, the collimation module includes multiple collimation elements, each corresponding to a different wavelength beam. The step of collimating the multi-wavelength beams input to the detection system through the collimation module to obtain a parallel laser beam includes: The multi-wavelength optical signals contained in the multi-wavelength beam pass through various collimating elements. After collimation processing by each collimating element, a parallel beam of multi-wavelength optical signals is obtained.

[0008] Optionally, the step of inputting the parallel laser beam into the wavelength splitting unit and performing wavelength separation through each volume grating in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths includes: The parallel laser beam is input to each volume grating of the wavelength splitting unit. Each volume grating performs beam splitting modulation on the optical signals of different wavelengths received in the parallel beam, so that the split beams corresponding to the optical signals of different wavelengths are transmitted independently, resulting in multiple split laser beams.

[0009] Optionally, the angular amplification unit includes multiple volume gratings with different tilt angles and multiple diffraction angles and different gain coefficients; the step of inputting the split laser beam into the angular amplification unit and performing angular amplification to obtain emitted laser beams with different wavelengths and different emission angles includes: The angle amplification unit amplifies and modulates the angle of each received split laser beam, converting the angular offset of the incident angle of each split laser beam into the spatial angle and / or energy distribution difference of the output beam, thereby obtaining output laser beams with different wavelengths and different output angles.

[0010] Optionally, the focusing detection module includes an imaging lens, a photodetector, and a signal processor; the step of the focusing detection module acquiring angular deviation information and pose information of different wavelength light signals in the emitted laser beam, and determining the multi-wavelength signal information in the multi-wavelength beam based on the angular deviation information and pose information includes: The imaging lens receives the emitted laser beam and focuses the emitted laser beam to obtain a focused beam; The photodetector detects the focused beam, converts the optical signal of the focused beam into an electrical signal, and transmits the electrical signal to the signal processor; The signal processor processes the received electrical signal to obtain angular deviation information and pose information relative to the emitted laser beam; Based on the grating parameters, angle deviation information, and pose information of the multi-layer volume grating module, the multi-wavelength signal information in the multi-wavelength beam is obtained.

[0011] Optionally, the step of obtaining the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters, angle deviation information, and pose information of the multi-layer volume grating module includes: Based on the change in the emission angle in the detection data, the minimum angle sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angle amplification unit, the gain weight coefficient of each volume beam in the angle amplification unit, and the angle sensitivity coefficient of each volume grating, the grating parameters of each layer of volume grating in the multilayer volume grating module are designed. The multi-wavelength signal information in the multi-wavelength beam is calculated based on the grating parameters, angle deviation information, and pose information of each volume grating in the multi-layer volume grating module.

[0012] Optionally, each volume grating in the wavelength splitting unit corresponds to a wavelength splitting layer, and each wavelength splitting layer corresponds to a communication sub-wavelength channel; before the step of the signal processor processing the received electrical signal and obtaining the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the following steps are included: The grating parameters of each volume grating in the wavelength splitting unit are set; the steps of setting the grating parameters include: Determine the grating period of each volume grating based on Bragg first-order diffraction conditions; Based on the fact that the optical paths of each split laser beam are parallel and coaxial, the grating tilt angle of each volume grating is determined. The thickness of each volume grating is determined based on its effective diffraction bandwidth. Furthermore, based on the unchanged light field distribution corresponding to the incident angle, the angle sensitivity coefficient is set, and the channel crosstalk suppression ratio is determined based on the target channel diffraction efficiency and the crosstalk diffraction efficiency of adjacent bands.

[0013] Optionally, the angular magnification unit includes a multi-layer cascaded grating; Before the step of processing the received electrical signal by the signal processor and obtaining the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the method further includes: The grating parameters of each volume grating in the angular magnification unit are set; the steps of setting the grating parameters include: The grating period is determined based on the fact that the target laser communication operating wavelength range meets the Bragg diffraction condition. The tilt angle of each volume grating is determined based on the angular sensitivity coefficient of a single volume grating, the minute offset of the incident angle of the split laser beam, and the offset of the exit angle. The grating thickness of each volume grating is determined based on the diffraction modulation efficiency and refractive index modulation amount under angular offset.

[0014] Secondly, the present invention also provides a multi-wavelength laser tracking and aiming detection system, comprising: a collimation module, a multi-level series-connected multi-layer volume grating module, and a focusing detection module arranged in sequence, wherein the multi-layer volume grating module includes a wavelength splitting unit and an angular amplification unit; the wavelength splitting unit includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength. The collimation module is used to collimate the multi-wavelength beams input to the detection system to obtain a parallel laser beam; The wavelength splitting unit is disposed in the optical path of the parallel laser beam and is used to perform wavelength separation on the parallel laser beam to obtain multiple split laser beams corresponding to different wavelengths. The angle amplification unit is disposed in the optical path of the split laser beam and is used to amplify the angle of the split laser beam to obtain outgoing laser beams with different wavelengths and different emission angles. The focusing detection module is used to collect the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and to determine the multi-wavelength signal information in the multi-wavelength beam based on the angle deviation information and pose information.

[0015] Optionally, the system further includes: a parameter setting module for the multilayer volume grating module; The parameter setting module of the multilayer volume grating module is used to design the grating parameters of each layer of volume grating in the multilayer volume grating module based on the change in the emission angle in the detection data, the minimum angle sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angle amplification unit, the gain weight coefficient of each volume beam in the angle amplification unit, and the angle sensitivity coefficient of each volume grating.

[0016] Beneficial effects: This invention discloses a multi-wavelength laser tracking and aiming detection method and system. The method utilizes a multi-layer volume grating module to separate the wavelengths of a received incident laser beam, obtaining multiple outgoing laser beams corresponding to different wavelengths. It acquires the angular deviation information of the outgoing laser beams of different wavelengths and determines the multi-wavelength signal information within the incident laser beam based on this angular deviation information. The proposed method and system, through the design of a multi-layer volume grating module, utilizes volume gratings with different grating parameters within the module to achieve efficient separation and high-precision detection of multi-wavelength laser signals. The system of this invention has a compact structure and strong robustness, making it suitable for tracking and aiming detection in dynamic laser communication scenarios such as inter-satellite and satellite-to-ground communication. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the multi-wavelength laser tracking and aiming detection system in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the steps of the multi-wavelength laser tracking and detection method in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] Existing multi-wavelength laser detection systems typically use prisms, filters, or beam splitters to separate signals of different wavelengths and allocate optical paths. However, prisms have limited dispersion capabilities, and filters have fixed passband widths, typically on the order of tens of nanometers, resulting in poor multi-wavelength scalability and insufficient crosstalk suppression between channels. Filtering methods based on mechanical switching have slow response speeds and low reliability, making them unsuitable for the application requirements of high-speed dynamic laser links.

[0020] In angle detection, methods based on focal plane imaging or Fourier lens arrays typically share the same detection link for different wavelengths, which easily leads to energy aliasing and a decrease in signal-to-noise ratio under strong background light conditions, making it difficult to achieve independent angle measurement of multi-wavelength signals. Although spectral separation methods based on surface gratings or thin-film gratings have been applied to some detector front-end structures, surface gratings generally suffer from insufficient high-order diffraction and stray light suppression capabilities, and are prone to introducing crosstalk under conditions of simultaneous operation of multiple wavelengths. Thin-film gratings are limited by their effective working thickness, making it difficult to simultaneously achieve both diffraction efficiency and angle selectivity. They typically exhibit a wide bandwidth but limited angle resolution, making it difficult to simultaneously meet the requirements of narrowband filtering and high diffraction efficiency.

[0021] Therefore, existing multi-wavelength laser tracking and detection technologies still generally suffer from problems such as limited multi-wavelength parallel detection capabilities, difficulty in coordinating wavelength separation and angle detection design, and insufficient adaptability to dynamic link conditions.

[0022] To overcome the aforementioned problems in the prior art, this application provides a multi-wavelength laser tracking and detection method and system. By systematically designing the angle response of a multi-layer volume grating module, it achieves narrowband efficient separation of multi-wavelength laser signals and synchronously outputs independent angle information of different wavelength laser signals under a unified detection framework. It has the advantages of compact structure, easy integration, and high tolerance to changes in incident angle, and is suitable for the detection front end of high-speed dynamic laser communication links.

[0023] The following description, in conjunction with the accompanying drawings, provides a more detailed account of the multi-wavelength laser tracking and aiming detection method and system provided by the present invention.

[0024] Firstly, this application discloses a multi-wavelength laser tracking and aiming detection method, applied to a multi-wavelength laser tracking and aiming detection system, such as... Figure 1 As shown, the detection system includes: a collimation module 10 arranged in sequence, a multi-level series-connected multi-layer volume grating module 20, and a focusing detection module 30. The multi-layer volume grating module 20 includes a wavelength splitting unit 210 and an angular amplification unit 220. The wavelength splitting unit 210 includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength.

[0025] The core function of the collimation module is beam shaping, which transforms the incident multi-wavelength beams (wavelengths λ1, λ2, ..., λn) into a parallel beam. This ensures that the incident beam fully meets the parallel light incident conditions of the volume Bragg grating, while simultaneously preserving the minute miss angle information carried by the beam, providing a fundamental optical path guarantee for the multi-layer volume grating module. In this embodiment, the collimation module in the detection system includes multiple collimation units, each corresponding to a collimating mirror, and each collimating mirror corresponding to a beam of one wavelength. This allows for the collimation of beams of different wavelengths within the multi-wavelength beam, resulting in a parallel laser beam.

[0026] The multilayer volume grating module consists of multiple volume gratings, including wavelength splitting units and angular amplification units. The wavelength splitting units are axially stacked along the same optical axis, forming a coaxial integrated unit fixed to the same optical substrate. The incident beam passes through each layer sequentially without deflection. Each grating layer strictly adheres to the Bragg diffraction condition and is designed differently for different wavelengths. This allows for precise splitting of the pre-processed multi-wavelength parallel laser beam, enabling independent transmission of each wavelength and avoiding interference from beam superposition. This achieves parallel demodulation of multi-wavelength laser signals; therefore, the number of wavelength splitting units corresponds to the number of wavelengths, n.

[0027] The angular magnification unit utilizes the angle-sensitive diffraction characteristics of a volume grating to amplify the angle of a split single-wavelength laser beam, converting minute angular offsets in the incident laser light into differences in the spatial angle and energy distribution of the outgoing light. It exhibits high sensitivity to changes in the incident angle, amplifying angular deviations. After focusing by the imaging lens, these minute changes in the incident angle are transformed into significant spatial displacements of the detector plane.

[0028] The overall multi-layer volume grating module completes the beam splitting and angle modulation of multi-wavelength laser beams through the coordinated operation of two-level units: wavelength splitting unit and angle amplification unit. It converts key tracking information such as the incident angle and offset attitude of the laser into a light field distribution signal that can be recognized by the back-end detection module.

[0029] The focusing detection module focuses and converges the differentiated light field beam encoded by the multi-layer volume grating module, accurately mapping the differences in spatial angular and energy distributions onto the focal plane. Then, the photoelectric detection component converts the optical signal into an electrical signal, collects optical signal data at different positions and with different energies, and calculates detection data such as the laser beam's offset angle and attitude position, providing core data support for the tracking, aiming, and closed-loop stable control of the laser communication system.

[0030] like Figure 2 As shown, this wavelength laser tracking and aiming detection method includes: Step S1: The multi-wavelength beam input to the detection system is collimated by the collimation module to obtain a parallel laser beam.

[0031] The multi-wavelength beams input to the detection system are first input to the collimation module, which then collimates the multi-wavelength beams to obtain parallel laser beams containing optical signals of different wavelengths.

[0032] Combination Figure 1 As shown, the collimation module includes multiple collimation elements, each corresponding to a different wavelength beam, and each collimation unit corresponds to a light signal of one wavelength. The step of collimating the multi-wavelength beams input to the detection system through the collimation module to obtain a parallel laser beam includes: The multi-wavelength optical signals contained in the multi-wavelength beam pass through various collimating elements. After collimation processing by each collimating element, a parallel beam of multi-wavelength optical signals is obtained.

[0033] Step S2: The parallel laser beam is input to the wavelength splitting unit, and wavelength separation is performed by each volume grating in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths.

[0034] The wavelength splitting unit is located on the transmission optical path of the parallel laser beam and receives the parallel laser beam containing optical signals of different wavelengths. The useful wavelength splitting unit contains multiple volume gratings, thereby realizing the wavelength separation of the parallel laser beam by multiple cascaded volume beams to obtain split laser beams corresponding to different wavelengths.

[0035] In detail, the steps of inputting the parallel laser beam into the wavelength splitting unit, and performing wavelength separation through the volume gratings in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths include: The parallel beam is input to each volume grating of the wavelength splitting unit. Under the premise of satisfying the volume grating Bragg diffraction condition, each volume grating performs beam splitting modulation on the optical signals of different wavelengths in the received parallel beam, so that the split beams corresponding to the optical signals of different wavelengths are transmitted independently, resulting in multiple split laser beams.

[0036] In this step, for the number of laser wavelengths reused by the system, a corresponding number of volume grating stacking structures are matched. A single wavelength corresponds to a single-layer dedicated beam splitter grating, while multiple wavelengths adopt a multi-layer stacked multiplexing structure. Through differentiated grating period design, different wavelength lasers undergo first-order Bragg diffraction, realizing spatial separation of different wavelength beams and ensuring that the optical paths of each diffracted beam are parallel and the energy is uniform.

[0037] Step S3: The split laser beam is input to the angle amplification unit, and the angle amplification unit amplifies the beam to obtain laser beams with different wavelengths and different emission angles.

[0038] In this step, an angular amplification unit is used to amplify the output angle of the input split laser beam. This angular amplification unit is a multi-layer volume grating structure with high angular sensitivity. By optimizing the grating tilt angle and diffraction angle gain coefficient, and setting the angular amplification factor according to the system's aiming accuracy requirements, it linearly amplifies the minute angular deviation of the incident laser. Through the cascading and stacking of multi-layer volume gratings, the linearity of the angular amplification is further improved, ensuring a strict linear correspondence between the laser incident angle and the output light field distribution and energy distribution, thus achieving accurate encoding of angular information.

[0039] Specifically, the angular amplification unit includes multiple volume gratings with different tilt angles and multiple diffraction angles and different gain coefficients; the step of inputting the split laser beam into the angular amplification unit, and having it amplified by the angular amplification unit to obtain emitted laser beams of different wavelengths and different emission angles includes: The angle amplification unit amplifies and modulates the angle of each received split laser beam, converting the angular offset of the incident angle of each split laser beam into the spatial angle and / or energy distribution difference of the output beam, thereby obtaining output laser beams with different wavelengths and different output angles.

[0040] Based on the phase-matching sensitivity of the volume grating to changes in the incident angle, this angle magnification unit constructs an angle magnification mechanism at the optical front end, so that small incident angle deviations are mapped into detectable spatial displacements or changes in energy distribution, thereby significantly improving the sensitivity of angle measurement.

[0041] In this step, all volume gratings in the wavelength splitting unit and the angular amplification unit adopt a coaxial precision stacking structure, and high-precision spacers are set between adjacent gratings to ensure the accuracy of grating spacing and coaxiality. The overall multilayer volume grating module adopts a sealed dustproof structure to ensure the long-term stability of grating diffraction performance and adapt to the field working environment of laser communication.

[0042] Step S4: The focusing detection module collects the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and determines the multi-wavelength signal information in the multi-wavelength beam based on the angle deviation information and pose information.

[0043] The focusing and detection module includes focusing the input outgoing laser beam and using a photodetector to acquire the angle deviation information and pose information of different wavelength light signals in the focused outgoing laser beam, thereby detecting multi-wavelength signal information in the multi-wavelength beam based on the acquired angle deviation information and pose information.

[0044] Further, the focusing detection module includes an imaging lens, a photodetector, and a signal processor; the step of the focusing detection module acquiring angular deviation information and pose information of different wavelength light signals in the emitted laser beam, and determining the multi-wavelength signal information in the incident laser beam based on the angular deviation information and pose information includes: The imaging lens receives the emitted laser beam and focuses the emitted laser beam to obtain a focused beam; The photodetector detects the focused beam, converts the optical signal of the focused beam into an electrical signal, and transmits the electrical signal to the signal processor; The signal processor processes the received electrical signal to obtain angular deviation information and pose information relative to the emitted laser beam; Based on the grating parameters, angular deviation information, and pose information of the multilayer volume grating module, the multi-wavelength signal information in the incident laser beam is obtained.

[0045] This invention, starting from system-level requirements, introduces the diffraction response of a volume grating to changes in incident angle into the system design, proposing a design concept centered on the volume grating's angle response. Utilizing the significant response of the volume grating to minute changes in incident angle under high diffraction efficiency, the angle information is transformed into measurable spatial displacement or energy distribution changes. An equivalent angle sensitivity coefficient is constructed at the system level, enabling enhanced representation of incident light angle changes at the detector end without relying on increasing the imaging focal length or improving detector resolution. Thus, under the constraints of detector performance and optical size, efficient separation and high-precision synchronous angle measurement of multi-wavelength laser signals are achieved, forming a compact and robust tracking beam detection method suitable for dynamic laser communication links.

[0046] In detail, before using the system for tracking and detection, the method of this embodiment requires the design of basic parameters for the multi-layer volume grating module. The design method is as follows: for the 1530-1570nm working band of the laser communication standard, combined with the system's angle detection range and tracking accuracy indicators, the grating period, grating tilt angle, thickness, and refractive index modulation of each layer of volume grating are optimized one by one; the Bragg diffraction working point of each layer of volume grating is strictly calibrated to ensure that the grating meets the accurate Bragg diffraction conditions in the entire 1530-1570nm band, and the diffraction efficiency in the band is consistently greater than 90%, effectively reducing the energy loss of communication laser light; at the same time, through spectral isolation design, diffraction crosstalk and spectral overlap of multi-wavelength gratings in the 1530-1570nm band are avoided, and accurate multi-wavelength beam splitting without crossover is achieved in this band.

[0047] In detail, the step of obtaining the multi-wavelength signal information in the incident laser beam based on the grating parameters, angular deviation information, and pose information of the multi-layer volume grating module includes: Step S41: Based on the change in emission angle, the minimum angle sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angle amplification unit, the gain weight coefficient of each volume beam in the angle amplification unit, and the angle sensitivity coefficient of each volume grating in the detection data, design the grating parameters of each layer of volume grating in the multilayer volume grating module.

[0048] In this step, a single-layer volume grating angular sensitivity coefficient is introduced. This is used to characterize the response capability of the i-th layer volume grating to small changes in incident angle near its Bragg operating point; simultaneously, an equivalent angular sensitivity coefficient of the system is introduced. It is used to characterize the degree of overall angular change corresponding to the angular deviation of the incident light at the system input end at the final detection end.

[0049] Detector spatial displacement and minimum resolvable resolution (system level) Set the focal length after the final stage volume grating as... The imaging lens then causes the diffracted light to shift spatially on the detector plane. deviation from incident angle The following relationship exists between them: ; Therefore, the minimum resolvable angle of the system can be obtained: ; in, The system-level angle sensitivity coefficient is composed of multiple gratings working together and directly determines the angle resolution capability of the entire system. This represents the minimum resolvable displacement of the detector.

[0050] As can be seen from the above relationships, when detector performance and imaging focal length are limited, the system's angular resolution is directly constrained by... .

[0051] (2) Design constraints of system angle sensitivity coefficient In system design, the minimum angular resolution of the target is usually known in advance. Detector pixel size or effective displacement resolution and the system's allowed imaging focal length range. Therefore, the minimum angular sensitivity coefficient required by the system can be determined: ; As a constraint condition for the design of volume gratings.

[0052] (3) Design constraints on the angle sensitivity coefficient of the angular magnification unit grating In a multilayer grating structure, the system angular sensitivity coefficient Composed of the angular responses of each layer of volume gratings, its equivalent form can be expressed as: ; in: For the first The angular sensitivity coefficient of the grating layers, the above equivalent relationship holds true under the condition that the grating layers are weakly coupled and the diffracted light mainly propagates along the main lobe.

[0053] Assume that the incident light has a small angular deviation relative to the Bragg angle of the volume grating. Under small-angle approximation conditions, the volume grating amplifies the angle deviation, and the change in its exit angle... It can be represented as: ; This is used to characterize the response of the grating layer to minute changes in the incident angle, based on the overall system objective. Reverse allocation ensures that the total sensitivity coefficient after multi-layer stacking meets the preset angular resolution index. The system reverse-calculates the formula for the single-layer index: ; Where N is the number of layers in the angular magnification unit cell grating. The gain weighting coefficients for each layer are matched according to the differences in the tilt angle and thickness parameters of each layer grating to achieve layer-by-layer parameter allocation, ensuring that the total sensitivity coefficient after stacking matches the system design specifications.

[0054] To ensure that the total angular sensitivity coefficient after multi-layer stacking strictly converges to the system's preset index and to prevent the accumulation of gain deviation, satisfy: ; This constraint ensures that the weight allocation only changes the distribution of the gain ratio of each layer, without changing the overall preset gain benchmark of the system, so as to achieve the system's angle detection accuracy without gain drift.

[0055] Step S42: Calculate the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters, angle deviation information and pose information of each volume grating in the multi-layer grating assembly.

[0056] In this embodiment, the multi-layer volume grating module adopts a combination design of a narrowband gating unit for wavelength splitting and a broadband gain unit for angle amplification. The wavelength splitting unit achieves multi-wavelength demultiplexing isolation through wavelength-customized period, low modulation amount, and narrowband filtering, while the angle amplification unit achieves superposition amplification of the system's angle sensitivity coefficient through a unified broadband period, high modulation amount, and controllable angle gain. The two units are matched with different parameters and complement each other's functions, ultimately achieving high-precision laser tracking and detection of multiple wavelengths within the target's working wavelength range.

[0057] In detail, each volume grating in the wavelength splitting unit corresponds to a wavelength splitting layer, and each wavelength splitting layer corresponds to a communication sub-wavelength channel; before the step of the signal processor processes the received electrical signal and obtains the multi-wavelength signal information in the incident laser beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the step includes: setting the grating parameters of each volume grating in the wavelength splitting unit.

[0058] The step of setting the grating parameters for each volume grating in the wavelength splitting unit includes: The grating period of each volume grating is determined based on the Bragg first-order diffraction condition; the grating tilt angle of each volume grating is determined based on the parallel and coaxial optical paths of each split laser beam; the thickness of each volume grating is determined based on the effective diffraction bandwidth of each volume grating; and the angle sensitivity coefficient is set based on the constant optical field distribution corresponding to the incident angle, and the channel crosstalk suppression ratio is determined based on the target channel diffraction efficiency and the crosstalk diffraction efficiency of adjacent bands.

[0059] The core function of the wavelength splitting unit is to achieve multi-wavelength spatial isolation and precise single-wavelength gating within the target laser communication wavelength range, while weakening angle gain and enhancing wavelength selectivity and low crosstalk characteristics. Each wavelength splitting layer adopts a single-wavelength single-grating, narrowband precise matching, and high isolation and low crosstalk design concept. Each layer of splitting grating corresponds to a communication sub-wavelength channel, independently satisfying narrowband optimal Bragg diffraction.

[0060] (1) Grating period Λ narrowband wavelength matching: The beam splitter layer requires no broadband adaptation and is precisely periodically designed based on the target sub-wavelength of each channel, ensuring efficient diffraction of a single wavelength and suppression of adjacent wavelengths. The core formula adopts the standard Bragg first-order diffraction condition. ; in, This corresponds to the center wavelength of the optical splitting channel (the wavelength of each sub-channel of the communication sub-channel within the target operating wavelength range). The average refractive index of the grating medium. The rated Bragg incident angle for the beam splitter.

[0061] Narrowband isolation constraint: Through differentiated periodic design, each layer of the beam splitter grating satisfies the optimal diffraction condition only for its own channel wavelength, while exhibiting significant diffraction mismatch for other wavelengths in the working band, thus achieving spectral physical isolation and structurally suppressing band crosstalk.

[0062] (2) Grating tilt angle Coaxial beam matching design: The core objective of the beam splitter tilt design is to ensure that the optical paths of each wavelength beam are parallel and the system is coaxial after beam splitting, without introducing additional angular offsets or interfering with the accuracy of back-end angle amplification and encoding.

[0063] ; Design constraints: The tilt angles of all beam splitter gratings are calibrated and compensated to ensure that the output angles of diffracted beams of different wavelengths are consistent and the optical paths are coaxial and parallel; at the same time, the tilt angle gain effect is weakened, so that the angle sensitivity coefficient of the beam splitter approaches 1, so that it only performs the beam splitting function and does not perform angle amplification, thus avoiding interference with the overall gain of the system.

[0064] (3) Thickness of the grating : The thickness of the spectral layer determines the spectral selection accuracy and the ability to suppress adjacent channel crosstalk. Thicker gratings have narrower diffraction bandwidth and higher wavelength selection capability. The thickness constraint formula is as follows: ; In the formula: This represents the effective diffraction bandwidth of the grating. The greater the grating thickness, the narrower the spectral bandwidth, the better the spectroscopic selectivity, and the lower the crosstalk.

[0065] (4) Angle sensitivity coefficient constraint (no gain design): To avoid introducing additional angular gain and angular nonlinearity errors into the beam-splitting layer, and to ensure the purity of the gain superposition of the back-end angular amplification layer, the angular response characteristics of the beam-splitting layer are strictly constrained: ; in, This represents the angle sensitivity coefficient of a single layer in the beam splitter. The beam splitter only separates the wavelength dimension of the beam without changing the optical field distribution corresponding to the incident angle, ensuring that all system angle information is controllably modulated by the angle amplification layer.

[0066] (5) Core performance constraints of the beam splitter layer: Channel crosstalk rejection ratio: ; in, For the target channel diffraction efficiency. To improve the crosstalk diffraction efficiency of adjacent bands and ensure that multiple wavelengths can work in parallel without mutual interference.

[0067] Furthermore, the angular amplification unit includes a multi-layer cascaded volume grating; before the step of the signal processor processing the received electrical signal and obtaining multi-wavelength signal information in the incident laser beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the method further includes: The grating parameters of each volume grating in the angular amplification unit are set. The steps of setting the grating parameters include: determining the grating period based on the Bragg diffraction condition that the target laser communication operating wavelength range meets; determining the grating tilt angle of each volume grating based on the angle sensitivity coefficient of a single volume grating, the small offset of the incident angle of the split laser beam, and the offset of the exit angle; and determining the grating thickness of each volume grating based on the diffraction modulation efficiency and refractive index modulation amount under the angle offset.

[0068] Design of core parameters for each element of the angular magnification unit layer volume grating: (1) Grating period Broadband adaptation: To ensure that the target laser communication operating wavelength range meets the Bragg diffraction conditions and the angular response is consistent across the entire band, an optimal broadband period design at the band center is adopted. The center wavelength of the operating band is used as the reference period design point to ensure that the wavelengths at the upper and lower edges of the band meet the effective diffraction tolerance.

[0069] Reference design formula (center wavelength Bragg condition): ; in: The center wavelength of the operating band. The average refractive index of the grating medium. The reference Bragg tilt angle.

[0070] Broadband adaptation constraints (ensuring effective diffraction in the operating band): ; The adaptation period is calculated using this formula, enabling full coverage of the working band in a single cycle, ensuring consistent angular response across all wavelengths, and eliminating band-specific deviations.

[0071] (2) Grating tilt angle Angle gain control: Besides satisfying diffraction conditions, the grating tilt angle is used to quantitatively control the angular sensitivity coefficient of a single layer, enabling differentiated configuration of layered gain. The coupling relationship between the volume grating angular sensitivity coefficient and the Bragg tilt angle is as follows: ; in, The single-layer angle sensitivity coefficient, This is a small offset of the incident angle. This represents the angular offset of the emitted light.

[0072] Precise design constraint formula for tilt angle: ; Through tiny adjustments The single-layer gain can be continuously adjusted. This achieves differentiated matching of multi-layer gain weights while constraining tilt angle deviation to ensure optimal linearity of angle response.

[0073] (3) Grating thickness : The grating thickness determines the angular diffraction coupling depth and the ability to modulate minute angles. Based on the theory of bulk grating thick grating diffraction coupling, a quantitative relationship between thickness and angular modulation sensitivity is established: ; in, This refers to the diffraction modulation efficiency under minute angular shifts. This is the refractive index modulation amount. The thickness is the grating thickness.

[0074] Design constraints: Considering the characteristics of the target laser communication wavelength range, in order to ensure that weak angular offsets can be effectively modulated, within the limited thickness range, the greater the thickness, the higher the angular coupling strength, and the more significant the modulation effect of small angular light fields.

[0075] In the method and system of this invention, each volume grating in the multilayer volume grating module has its own Bragg working angle and angular sensitivity coefficient. The final angular sensitivity of the system is not determined by a single volume grating, but by the equivalent construction result of the angular response of the multilayer volume grating at the system level. This invention elevates the angular sensitivity coefficient to a system-level design parameter and achieves unified design and control of the system's angular resolution capability through a weighted combination of the angular sensitivity coefficients of each volume grating layer. Through this mechanism, system-level resolution can be achieved while avoiding the processing limitations of single-layer volume gratings. Significant improvement.

[0076] This invention introduces a stacked multi-layer volume grating module. Different volume grating layers are designed with specific functions according to system requirements, each responsible for functions such as large field-of-view acquisition, wavelength decoupling, and angle-sensitive amplification. Through the synergistic effect of the angle responses of the multi-layer volume gratings, an equivalent angle sensitivity coefficient is constructed at the system level, enabling enhanced representation of incident light angle changes at the detector end without relying on increasing the imaging focal length or improving detector resolution. Thus, under the constraints of detector performance and optical size, efficient separation and high-precision synchronous angle measurement of multi-wavelength laser signals are achieved, forming a compact and robust tracking beam detection design method suitable for dynamic laser communication links.

[0077] This invention, through a multi-layer volume grating and optical beam splitting design, enables simultaneous detection of multi-wavelength laser signals within the same system, improving the system's angular resolution and sensitivity, and meeting the high-precision detection requirements of dynamic tracking, multi-node inter-satellite communication, and complex background light conditions. Furthermore, the multi-layer volume grating stacking and collaborative design integrates and matches the functions and structural parameters of each grating, achieving system-level equivalent superposition of angular response gains. Without relying on ultra-high precision single-layer grating fabrication, this significantly improves the system's angular sensitivity coefficient and tracking accuracy, balancing detection performance with engineering feasibility.

[0078] Secondly, this invention also discloses a multi-wavelength laser tracking and aiming detection system, such as... Figure 1 It includes: a collimation module 10 arranged in sequence, a multi-level series multilayer volume grating module 20 and a focusing detection module 30. The multilayer volume grating module 20 includes a wavelength splitting unit 210 and an angular amplification unit 220. The wavelength splitting unit 210 includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength.

[0079] The collimation module 10 is used to collimate the multi-wavelength beams input to the detection system to obtain parallel laser beams.

[0080] The wavelength splitting unit 210 is disposed in the optical path of the parallel laser beam and is used to perform wavelength separation on the parallel beam to obtain multiple split laser beams corresponding to different wavelengths.

[0081] The angle amplification unit 220 is disposed in the optical path of the split laser beam and is used to amplify the angle of the split laser beam to obtain outgoing laser beams with different wavelengths and different emission angles.

[0082] The focusing detection module 30 is used to collect the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and determine the multi-wavelength signal information in the incident laser beam based on the angle deviation information and pose information.

[0083] Furthermore, the system also includes: a parameter setting module for the multilayer volume grating module; the parameter setting module for the multilayer volume grating module is used to design the grating parameters of each layer of volume grating in the multilayer volume grating module based on the emission angle variation in the detection data, the minimum angular sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angular amplification unit, the gain weight coefficient of each volume beam in the angular amplification unit, and the angular sensitivity coefficient of each volume grating.

[0084] The method and system of this invention elevate the angular sensitivity coefficient M of the volume grating from a physical response parameter of a single optical element to a key design parameter at the system level, and establish an inverse constraint relationship between the angular sensitivity coefficient and the structural parameters of the volume grating. This allows the angular resolution capability of the tracking and aiming system to be predetermined during the optical structure design stage, thereby distinguishing it from and breaking through the existing technical path that mainly relies on increasing the imaging focal length or improving the detector resolution to achieve high-precision tracking and aiming.

[0085] Furthermore, under engineering conditions where the spatial resolution of the detector and the focal length of the imaging are limited, this invention determines the minimum angular sensitivity coefficient required by the system by pre-given the minimum angular resolution of the target, and uses this angular sensitivity coefficient as a design constraint to jointly reverse design structural parameters such as the thickness of the volume grating, the refractive index modulation depth, the grating period, and the Bragg working angle, thereby achieving the target angle measurement capability under given detection and imaging conditions.

[0086] This invention discloses a multi-wavelength laser tracking and aiming detection method and system based on volume gratings. The method utilizes a multi-layer volume grating module to separate the wavelengths of a received incident laser beam, obtaining multiple outgoing laser beams corresponding to different wavelengths. It acquires the angular deviation information of the outgoing laser beams at different wavelengths and determines the multi-wavelength signal information within the incident laser beam based on this angular deviation information. The proposed method and system, through the design of a multi-layer volume grating module, utilizes volume gratings with different grating parameters within the module to achieve efficient separation and high-precision detection of multi-wavelength laser signals. The system of this invention has a compact structure and strong robustness, making it suitable for tracking and aiming optical detection systems in dynamic laser communication scenarios such as inter-satellite and satellite-to-ground communication.

[0087] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A multi-wavelength laser tracking and aiming detection method, characterized in that, This invention relates to a multi-wavelength laser tracking and detection system, the detection system comprising: a collimation module, a multi-level series-connected multilayer volume grating module, and a focusing detection module arranged sequentially; the multilayer volume grating module includes a wavelength splitting unit and an angular amplification unit; the wavelength splitting unit includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength; the detection method includes: The multi-wavelength beam input to the detection system is collimated by the collimation module to obtain a parallel laser beam. The parallel laser beam is input to the wavelength splitting unit, and wavelength separation is performed by each volume grating in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths; The split laser beam is input to the angle amplification unit, and the angle amplification unit amplifies the beam to obtain laser beams with different wavelengths and different emission angles. The focusing detection module collects the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and determines the multi-wavelength signal information in the multi-wavelength beam based on the angle deviation information and pose information.

2. The multi-wavelength laser tracking and detection method according to claim 1, characterized in that, The collimation module includes multiple collimation elements, each corresponding to a different wavelength beam. The step of collimating the multi-wavelength beams input to the detection system through the collimation module to obtain a parallel laser beam includes: The multi-wavelength optical signals contained in the multi-wavelength beam pass through various collimating elements. After collimation processing by each collimating element, a parallel beam of multi-wavelength optical signals is obtained.

3. The multi-wavelength laser tracking and detection method according to claim 1, characterized in that, The steps of inputting the parallel laser beam into the wavelength splitting unit, and separating the wavelengths through the volume gratings in the wavelength splitting unit to obtain multiple split laser beams corresponding to different wavelengths include: The parallel laser beam is input to each volume grating of the wavelength splitting unit. Each volume grating performs beam splitting modulation on the optical signals of different wavelengths in the received parallel beam, so that the split beams corresponding to the optical signals of different wavelengths are transmitted independently, resulting in multiple split laser beams.

4. The multi-wavelength laser tracking and detection method according to claim 1, characterized in that, The angular amplification unit includes multiple volume gratings with different tilt angles and multiple diffraction angles and different gain coefficients; the steps of inputting the split laser beam into the angular amplification unit, and having it amplified by the angular amplification unit to obtain emitted laser beams with different wavelengths and different emission angles include: The angle amplification unit amplifies and modulates the angle of each received split laser beam, converting the angular offset of the incident angle of each split laser beam into the spatial angle and / or energy distribution difference of the output beam, thereby obtaining output laser beams with different wavelengths and different output angles.

5. The multi-wavelength laser tracking and detection method according to any one of claims 2-4, characterized in that, The focusing detection module includes an imaging lens, a photodetector, and a signal processor; the step of the focusing detection module acquiring angular deviation information and pose information of different wavelength light signals in the emitted laser beam, and determining the multi-wavelength signal information in the multi-wavelength beam based on the angular deviation information and pose information includes: The imaging lens receives the emitted laser beam and focuses the emitted laser beam to obtain a focused beam; The photodetector detects the focused beam, converts the optical signal of the focused beam into an electrical signal, and transmits the electrical signal to the signal processor; The signal processor processes the received electrical signal to obtain angular deviation information and pose information relative to the emitted laser beam; Based on the grating parameters, angle deviation information, and pose information of the multi-layer volume grating module, the multi-wavelength signal information in the multi-wavelength beam is obtained.

6. The multi-wavelength laser tracking and detection method according to claim 5, characterized in that, The step of obtaining multi-wavelength signal information in the multi-wavelength beam based on the grating parameters, angle deviation information, and pose information of the multi-layer volume grating module includes: Based on the change in the emission angle in the detection data, the minimum angle sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angle amplification unit, the gain weight coefficient of each volume beam in the angle amplification unit, and the angle sensitivity coefficient of each volume grating, the grating parameters of each layer of volume grating in the multilayer volume grating module are designed. The multi-wavelength signal information in the multi-wavelength beam is calculated based on the grating parameters, angle deviation information, and pose information of each volume grating in the multi-layer volume grating module.

7. The multi-wavelength laser tracking and detection method according to claim 5, characterized in that, Each volume grating in the wavelength splitting unit corresponds to a wavelength splitting layer, and each wavelength splitting layer corresponds to a communication sub-wavelength channel; before the step of the signal processor processing the received electrical signal and obtaining the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the following steps are included: The grating parameters of each volume grating in the wavelength splitting unit are set; the steps of setting the grating parameters include: Determine the grating period of each volume grating based on Bragg first-order diffraction conditions; Based on the fact that the optical paths of each split laser beam are parallel and coaxial, the grating tilt angle of each volume grating is determined. The thickness of each volume grating is determined based on its effective diffraction bandwidth. Furthermore, based on the unchanged light field distribution corresponding to the incident angle, the angle sensitivity coefficient is set, and the channel crosstalk suppression ratio is determined based on the target channel diffraction efficiency and the crosstalk diffraction efficiency of adjacent bands.

8. The multi-wavelength laser tracking and detection method according to claim 6, characterized in that, The angular magnification unit includes a multi-layer cascaded grating; Before the step of processing the received electrical signal by the signal processor and obtaining the multi-wavelength signal information in the multi-wavelength beam based on the grating parameters of the multi-layer volume grating module and the detection data of the electrical signal, the method further includes: The grating parameters of each volume grating in the angular magnification unit are set; the steps of setting the grating parameters include: The grating period is determined based on the fact that the target laser communication operating wavelength range meets the Bragg diffraction condition. The tilt angle of each volume grating is determined based on the angular sensitivity coefficient of a single volume grating, the minute offset of the incident angle of the split laser beam, and the offset of the exit angle. The grating thickness of each volume grating is determined based on the diffraction modulation efficiency and refractive index modulation amount under angular offset.

9. A multi-wavelength laser tracking and aiming detection system, characterized in that, include: The system comprises a collimation module, a multi-level series-connected multi-layer volume grating module, and a focusing detection module arranged in sequence. The multi-layer volume grating module includes a wavelength splitting unit and an angular amplification unit. The wavelength splitting unit includes multiple volume gratings axially stacked along the same optical axis, and each volume grating corresponds to a different separation wavelength. The collimation module is used to collimate the multi-wavelength beams input to the detection system to obtain a parallel laser beam; The wavelength splitting unit is disposed in the optical path of the parallel laser beam and is used to perform wavelength separation on the parallel laser beam to obtain multiple split laser beams corresponding to different wavelengths. The angle amplification unit is disposed in the optical path of the split laser beam and is used to amplify the angle of the split laser beam to obtain outgoing laser beams with different wavelengths and different emission angles. The focusing detection module is used to collect the angle deviation information and pose information of different wavelength light signals in the emitted laser beam, and to determine the multi-wavelength signal information in the multi-wavelength beam based on the angle deviation information and pose information.

10. The multi-wavelength laser tracking and detection system according to claim 9, characterized in that, The system also includes: a parameter setting module for the multilayer volume grating module; The parameter setting module of the multilayer volume grating module is used to design the grating parameters of each layer of volume grating in the multilayer volume grating module based on the change in the emission angle in the detection data, the minimum angle sensitivity coefficient of the multilayer volume grating module, the number of volume gratings in the angle amplification unit, the gain weight coefficient of each volume beam in the angle amplification unit, and the angle sensitivity coefficient of each volume grating.

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