Laser tracking and pointing control method and device based on acousto-optic deflector

Abstract

The invention discloses a laser tracking and pointing control method and device based on an acousto-optic deflector, and the device comprises a pulse laser source, an optical antenna module, an acousto-optic deflection module and a synchronous control module, and comprises the steps: generating narrow-linewidth pulse laser, and splitting the narrow-linewidth pulse laser into intrinsic light and detection light; the synchronous controller applies driving signals with horizontal and vertical deflection frequencies to the acousto-optic deflection module, and after direction driving is stable, the optical antenna module triggers and emits the probe light; after the reflected light reflected by the target object is received, coherent detection is carried out on the reflected light and the intrinsic light, a beat frequency electric signal is generated, the beat frequency electric signal is processed, and existence of the target object is determined; recording deflection frequency (fx1, fy1) when the target object is hit, taking the deflection frequency as reference frequency, and converting the deflection frequency into local scanning taking the reference frequency as the center of a scanning view field; and the reference frequency is tracked and corrected by repeated tracking and aiming.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection and tracking technology, specifically to a laser tracking and aiming control method and device based on an acousto-optic deflector. Background Technology

[0002] Laser tracking and aiming technology achieves continuous, high-precision target locking by controlling a laser beam to point at a moving target in real time, and has wide applications in fields such as space laser communication, optoelectronic countermeasures, and precision measurement. Currently, the core component of mainstream laser beam pointing control revolves around a fast reflecting mirror (FSM). Its working principle involves controlling the angle of the mirror using displacement elements such as motors or piezoelectric materials, thereby changing the direction of the reflected beam. However, this mechanical structure is limited by mechanical inertia and structural resonance, with a response speed typically on the order of milliseconds, making it difficult to track high-speed targets. Secondly, there is a contradiction between the system's angle deflection range and pointing accuracy; accuracy decreases significantly with large angle deflections. Furthermore, wear and tear on mechanical moving parts affects the long-term reliability of the system, and complex servo control algorithms increase the system's complexity. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a laser tracking and aiming control method based on an acousto-optic deflector with faster response speed, higher control accuracy, and no mechanical wear.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A laser tracking and aiming control method based on an acousto-optic deflector is implemented using a system comprising a pulsed laser source, an optical antenna module, an acousto-optic deflection module, and a synchronization control module. The implementation method includes the following steps:

[0006] (1) Generate a narrow linewidth pulsed laser and split it into intrinsic light and probe light;

[0007] (2) Output the probe light to the acousto-optic deflection module, and perform tracking and aiming under the control of the synchronization control module:

[0008] (a) The synchronous controller applies a horizontal deflection frequency to the acousto-optic deflection module. and vertical deflection frequency The drive signal is generated, and after the direction drive stabilizes, the optical antenna module triggers the emission of probe light;

[0009] (b) After receiving the reflected light from the target object, coherently detect it with the intrinsic light to generate a beat frequency electrical signal, process the beat frequency electrical signal, and determine the existence of the target object;

[0010] (c) Record the deflection frequency (f) when hitting the target.x1 f y1 Using this as the reference frequency, it is converted into a local scan with the reference frequency as the center of the scanning field of view;

[0011] (d) Repeat steps (a) through (c) to track and correct the reference frequency.

[0012] This invention eliminates the reliance on complex inertial servo control in traditional mechanical tracking, and achieves beam pointing through electronic frequency control, fundamentally obtaining microsecond-level ultra-fast response capability; at the same time, its "search-lock-track" strategy enables the system to automatically capture the target and switch to high-precision local scanning, solving the inherent contradiction that large range and high precision are difficult to be compatible, and realizing stable, continuous and high-precision locking of moving targets.

[0013] As an optimization, in step (2), there is a time delay Δt between the establishment time of the driving signal and the trigger emission time of the probe light, where Δt is greater than or equal to the response time of the acousto-optic deflection module to the driving signal. This ensures that each laser pulse passes through only after the acousto-optic deflection module has stabilized, avoiding random beam pointing deviations and energy scattering losses caused by the deflection state not being ready.

[0014] As an optimization, the acousto-optic deflection module includes two cascaded acousto-optic deflectors with orthogonal deflection directions, and the horizontal deflection frequency... and the vertical deflection frequency It can drive two acousto-optic deflectors separately. Independent control in two dimensions ensures that the horizontal and vertical deflections do not interfere with each other, simplifying the control algorithm.

[0015] As an optimization, the horizontal deflection frequency and the vertical deflection frequency The deflection angles generated by the corresponding acousto-optic deflectors are linearly related. The spatial coordinates (x, y) are directly converted into specific frequency values ​​(f). x f y This control method eliminates the need for complex nonlinear calibration and angle feedback calculations in the control system, resulting in a simpler control model.

[0016] As an optimization, in step (b), the reflected light and the intrinsic light are coherently detected by a balanced detector.

[0017] As an optimization, in step (c), the local scan range is less than one-quarter of the global search scan range. After locking onto the target, the system concentrates its limited laser energy and control bandwidth on the narrow field of view where the target is most likely to appear, avoiding resource waste in large invalid areas. This allows the system to observe and control the target with a higher data refresh rate and finer frequency steps.

[0018] This invention also discloses an apparatus for implementing the aforementioned laser tracking control method, comprising a narrow-linewidth pulsed laser source, an optical circulator, an acousto-optic deflection module, an optical antenna module, a balanced detector, and a synchronization control module. The narrow-linewidth pulsed laser source receives TTL signals and generates a beam split into intrinsic light and probe light. Port I of the optical circulator receives the probe light, port II outputs the probe light and receives reflected light, and port III outputs reflected light. The acousto-optic deflection module is disposed on the output optical path of port II of the optical circulator and receives horizontal deflection drive signals and vertical deflection drive signals to perform two-dimensional deflection of the probe light. The optical antenna module emits the probe light and receives the reflected light. The balanced detector receives the reflected light and intrinsic light and performs coherent detection on the reflected light and intrinsic light to generate a beat frequency signal. The synchronization control module receives the beat frequency signal and outputs the horizontal deflection drive signals and vertical deflection drive signals controlled by the acousto-optic deflection module, as well as the TTL signal controlled by the narrow-linewidth pulsed laser source.

[0019] Compared with existing technologies, this invention completely eliminates the limitations of mechanical inertia, improves the beam deflection response time to the microsecond level, and solves the contradiction between speed and accuracy in fast-reflecting mirror technology; the beam deflection angle is linearly related to the driving radio frequency, and the spatial coordinates can be directly mapped to frequency pairs, simplifying the control algorithm; the closed-loop control strategy of "global search → target locking → local tracking" can quickly capture and continuously lock onto distant targets. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0021] Figure 2 This is a timing diagram of the three control signals output by the synchronous control module of the present invention;

[0022] Figure 3 The flowchart illustrates the control method for tracking and aiming according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] like Figure 1 and Figure 2 As shown, the laser tracking and aiming control method based on an acousto-optic deflector in this specific embodiment is implemented based on a system including a pulsed laser source, an optical antenna module, an acousto-optic deflection module, and a synchronization control module. The implementation method includes the following steps:

[0025] (1) Generate a narrow linewidth pulsed laser and split it into intrinsic light and probe light;

[0026] (2) Output the probe light to the acousto-optic deflection module, and perform tracking and aiming under the control of the synchronization control module:

[0027] (a) The synchronous controller applies a horizontal deflection frequency to the acousto-optic deflection module. and vertical deflection frequency The drive signal is generated, and after the direction drive stabilizes, the optical antenna module triggers the emission of probe light;

[0028] (b) After receiving the reflected light from the target object, coherently detect it with the intrinsic light to generate a beat frequency electrical signal, process the beat frequency electrical signal, and determine the existence of the target object;

[0029] (c) Record the deflection frequency (f) when hitting the target. x1 f y1 Using this as the reference frequency, it is converted into a local scan with the reference frequency as the center of the scanning field of view;

[0030] (d) Repeat steps (a) through (c) to track and correct the reference frequency.

[0031] In step (2), there is a time delay Δt between the establishment time of the driving signal and the trigger emission time of the probe light, and Δt is greater than or equal to the response time of the acousto-optic deflection module to the driving signal.

[0032] The acousto-optic deflection module includes two cascaded acousto-optic deflectors with orthogonal deflection directions, and the horizontal deflection frequency... and the vertical deflection frequency It can drive two acousto-optic deflectors separately.

[0033] The horizontal deflection frequency and the vertical deflection frequency The deflection angles generated by the corresponding acousto-optic deflectors are linearly related.

[0034] In step (b), the reflected light and the intrinsic light are coherently detected by a balanced detector.

[0035] In step (c), the range of the local scan is less than one-quarter of the range of the global search scan.

[0036] An apparatus for implementing the laser tracking control method described in any one of the above-mentioned methods includes a narrow-linewidth pulsed laser source, an optical circulator, an acousto-optic deflection module, an optical antenna module, a balanced detector, and a synchronization control module. The narrow-linewidth pulsed laser source receives a TTL signal and generates a beam split into intrinsic light and a probe light. Port I of the optical circulator receives the probe light, port II outputs the probe light and receives reflected light, and port III outputs reflected light. The acousto-optic deflection module is disposed on the output optical path of port II of the optical circulator and receives horizontal deflection drive signals and vertical deflection drive signals to perform two-dimensional deflection of the probe light. The optical antenna module emits the probe light and receives the reflected light. The balanced detector receives the reflected light and the intrinsic light, and performs coherent detection on the reflected light and the intrinsic light to generate a beat frequency signal. The synchronization control module receives the beat frequency signal and outputs the horizontal deflection drive signals and vertical deflection drive signals controlled by the acousto-optic deflection module, as well as the TTL signal controlled by the narrow-linewidth pulsed laser source.

[0037] After receiving the TTL pulse signal from the synchronization control module, the narrow linewidth pulsed laser source emits a narrow linewidth laser pulse. This laser pulse is split into two paths through an optical fiber coupler: one path is used as intrinsic light and is directly sent to the reference input of the balanced detector, while the other path is used as probe light and is input to port I of the optical circulator.

[0038] The probe light output from port II of the optical circulator passes sequentially through the first and second acousto-optic deflectors in the acousto-optic deflection module. The acousto-optic action planes of these two deflectors are orthogonally placed, enabling independent deflection of the beam in two-dimensional space. The horizontal deflection drive signal (RF)... x The first acousto-optic deflector drives the beam to deflect horizontally and the vertical deflection drive signal (RF) to control the beam's deflection. yThe second acousto-optic deflector 3 drives the beam to deflect vertically. The deflection angle θ and the deflection drive signal RF satisfy Bragg's equation: θ = λ / V·f, where λ is the light wavelength and V is the sound wavelength. Therefore, each frequency combination (f... x f y The beam is one-to-one with the spatial coordinates (x, y) of the emitted light. After being deflected, the beam is collimated and expanded by the optical antenna module and emitted into free space, illuminating the target object.

[0039] The reflected light from the target is received by the optical antenna module and returns along the original optical path. After passing through the acousto-optic deflection module, the reflected light enters from port II of the optical circulator and exits from port III to the signal input of the balanced detector. The balanced detector performs coherent detection on the weak target reflected light and the intrinsic light, outputting a beat frequency electrical signal containing information such as the target distance and velocity, and sends this signal to the synchronization control module.

[0040] The synchronization control module internally includes a digital signal processor, a frequency synthesizer, and timing logic circuits. It receives and processes the beat frequency signal from the balanced detector and simultaneously generates a radio frequency drive signal (RF). x RF y ) and TTL pulse signal.

[0041] like Figure 3 As shown, the control method for tracking and aiming implemented in this application is as follows:

[0042] Step 1: First, the synchronization control module sends an appropriate frequency to perform a full-range scan;

[0043] Step 2: During the scanning process, when the laser hits the target, it reflects the laser signal. At this time, the balanced detector generates a coherent signal and sends it to the synchronization control module. The radio frequency combination at this time is (f x1 f y1 The corresponding spatial coordinates (x1, y1) are the target location;

[0044] Step 3: After the synchronization control module detects the target signal, it outputs the radio frequency f at this time. x1 f y1 To establish the new center of the scanning field of view, while simultaneously narrowing the scanning frequency range, at f x1 ±Δf and f y1 ±Δf is scanned;

[0045] Step 4: Repeat step 3 to achieve target tracking and aiming.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described with reference to preferred embodiments, those skilled in the art should understand that various changes in form and detail can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A laser tracking and aiming control method based on an acousto-optic deflector, characterized in that: The system implementation, based on a pulsed laser source, optical antenna module, acousto-optic deflection module, and synchronization control module, includes the following steps: (1) Generate a narrow linewidth pulsed laser and split it into intrinsic light and probe light; (2) Output the probe light to the acousto-optic deflection module, and perform tracking and aiming under the control of the synchronization control module: (a) The synchronous controller applies a horizontal deflection frequency to the acousto-optic deflection module. and vertical deflection frequency The drive signal is generated, and after the direction drive stabilizes, the optical antenna module triggers the emission of probe light; (b) After receiving the reflected light from the target object, coherently detect it with the intrinsic light to generate a beat frequency electrical signal, process the beat frequency electrical signal, and determine the existence of the target object; (c) Record the deflection frequency (f) when hitting the target. x1 f y1 Using this as the reference frequency, it is converted into a local scan with the reference frequency as the center of the scanning field of view; (d) Repeat steps (a) through (c) to track and correct the reference frequency.

2. The laser tracking and aiming control method based on an acousto-optic deflector according to claim 1, characterized in that: In step (2), there is a time delay Δt between the establishment time of the driving signal and the trigger emission time of the probe light, and Δt is greater than or equal to the response time of the acousto-optic deflection module to the driving signal.

3. The laser tracking and aiming control method based on an acousto-optic deflector according to claim 1, characterized in that: The acousto-optic deflection module includes two cascaded acousto-optic deflectors with orthogonal deflection directions, and the horizontal deflection frequency... and the vertical deflection frequency It can drive two acousto-optic deflectors separately.

4. The laser tracking and aiming control method based on an acousto-optic deflector according to claim 3, characterized in that: The horizontal deflection frequency and the vertical deflection frequency The deflection angles generated by the corresponding acousto-optic deflectors are linearly related.

5. The laser tracking and aiming control method based on an acousto-optic deflector according to claim 1, characterized in that: In step (b), the reflected light and the intrinsic light are coherently detected by a balanced detector.

6. The laser tracking and aiming control method based on an acousto-optic deflector according to claim 1, characterized in that: In step (c), the range of the local scan is less than one-quarter of the range of the global search scan.

7. An apparatus for implementing the laser tracking and aiming control method according to any one of claims 1 to 6, characterized in that: The system includes a narrow-linewidth pulsed laser source, an optical circulator, an acousto-optic deflection module, an optical antenna module, a balanced detector, and a synchronization control module. The narrow-linewidth pulsed laser source receives TTL signals and splits the beam into intrinsic and probe light. Port I of the optical circulator receives the probe light, port II outputs the probe light and receives reflected light, and port III outputs reflected light. The acousto-optic deflection module is located on the output optical path of port II of the optical circulator and receives horizontal and vertical deflection drive signals to perform two-dimensional deflection of the probe light. The optical antenna module emits the probe light and receives the reflected light. The balanced detector receives the reflected light and intrinsic light and performs coherent detection on the reflected light and intrinsic light to generate a beat frequency signal. The synchronization control module receives the beat frequency signal and outputs the horizontal and vertical deflection drive signals controlled by the acousto-optic deflection module, as well as the TTL signal controlled by the narrow-linewidth pulsed laser source.

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