Beam delay correction method and system

Abstract

The application relates to a light beam delay correction method and system. The method comprises the following steps: an acousto-optic modulation module receives a laser light beam to be modulated, modulates the laser light beam to be modulated, and outputs a diffraction light beam; a spatial light modulation module receives the diffraction light beam, modulates the diffraction light beam based on a delay phase, and outputs a target diffraction light beam, wherein the delay phase is determined based on the laser light beam to be modulated and parameters of the acousto-optic modulation module. The method can reduce the delay difference generated by the acousto-optic modulation module when the light beam is modulated.

Description

Technical Field

[0001] This application relates to the field of optical modulation technology, and in particular to a method and system for beam delay correction. Background Technology

[0002] An acousto-optic modulator is a device that uses electronic drive signals to control the power of a laser beam. Because the beam incident on the acousto-optic modulator has a certain width, the modulated acoustic waves require a certain transit time to pass through the beam cross-section. Therefore, there is a delay difference at different positions in the radial direction of the beam, resulting in a radial delay variation. When DC modulation is applied to the acousto-optic modulator, this delay difference has no immediate effect on the radial intensity distribution of the beam. However, when AC modulation is applied, the radial delay difference causes an optical phase difference in that dimension, introducing radially distributed optical phase noise. In practical applications, this affects the modulation effect and degrades system performance.

[0003] In related technologies, laser beams can generally be focused to reduce their width and thus decrease the delay differences at different radial positions. However, this method affects the diffraction efficiency of the acousto-optic modulator. Furthermore, the increased light intensity density after focusing may exceed the damage threshold of the acousto-optic crystal, leading to damage to the acousto-optic modulator.

[0004] Therefore, there is an urgent need in related technologies for a method to reduce the delay difference generated by the acousto-optic modulator when modulating the beam. Summary of the Invention

[0005] Therefore, it is necessary to provide a beam delay correction method and system that can reduce the delay difference generated by the acousto-optic modulator when modulating the beam, in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a beam delay correction method. The method includes:

[0007] The acousto-optic modulation module receives the laser beam to be modulated, modulates the laser beam, and outputs a diffracted beam.

[0008] The spatial light modulation module receives the diffracted beam, modulates the diffracted beam based on the delay phase, and outputs the target diffracted beam. The delay phase is determined based on the laser beam to be modulated and the parameters of the acousto-optic modulation module.

[0009] In one embodiment, the process of modulating the diffracted beam based on the delayed phase includes: the controller acquiring parameters of the laser beam to be modulated and parameters of the acousto-optic modulation module, determining the delayed phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, generating a control command based on the delayed phase, and sending it to the spatial light modulation module.

[0010] In one embodiment, the controller generates control commands based on the delayed phase and sends them to the spatial light modulation module, including: the controller generates a holographic image based on the delayed phase and sends the holographic image to the spatial light modulation module.

[0011] In one embodiment, before the spatial light modulation module receives the diffracted beam, it further includes: a beam expander receiving the diffracted beam, expanding the diffracted beam to a preset diameter, and outputting the expanded beam to the spatial light modulation module.

[0012] In one embodiment, the polarization control optical path receives the diffracted beam and adjusts the polarization state of the diffracted beam to obtain linearly polarized light, which is then output to the spatial light modulation module.

[0013] Secondly, this application also provides a beam delay correction system. The system includes an acousto-optic modulation module and a spatial light modulation module connected in sequence, wherein:

[0014] The acousto-optic modulation module is used to receive the laser beam to be modulated, modulate the laser beam to be modulated, and output a diffracted beam.

[0015] The spatial light modulation module is used to receive the diffracted beam, modulate the diffracted beam based on the delay phase, and output the target diffracted beam. The delay phase is determined based on the laser beam to be modulated and the parameters of the acousto-optic modulation module.

[0016] In one embodiment, the system further includes a controller connected to the spatial light modulation module; the controller is used to acquire parameters of the laser beam to be modulated and parameters of the acousto-optic modulation module, determine the delay phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, and generate control commands based on the delay phase and send them to the spatial light modulation module.

[0017] In one embodiment, the system further includes a beam expander connected to the acousto-optic modulation module and the spatial light modulation module, respectively; the beam expander is used to receive the diffracted beam, expand the diffracted beam to a preset diameter, and output the expanded beam to the spatial light modulation module.

[0018] In one embodiment, the system further includes a polarization control optical path, which is connected to the acousto-optic modulation module and the spatial light modulation module respectively; the polarization control optical path is used to receive the diffracted beam and adjust the polarization state of the diffracted beam to obtain linearly polarized light, and output it to the spatial light modulation module.

[0019] In one embodiment, the acousto-optic modulation module is a Bragg-type acousto-optic modulation module.

[0020] The aforementioned beam delay correction method and system receive a laser beam to be modulated via an acousto-optic modulation module, modulates the laser beam to be modulated, and outputs a diffracted beam; a spatial light modulation module receives the diffracted beam, modulates the diffracted beam based on the delay phase, and outputs a target diffracted beam. The delay phase is determined based on the parameters of the laser beam to be modulated and the acousto-optic modulation module. This solves the problem of delay differences in acousto-optic modulators when modulating beams in related technologies, and achieves the technical effect of reducing the delay differences generated by acousto-optic modulators when modulating beams. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the acousto-optic modulation module of the beam delay correction system according to an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the beam delay correction system according to an embodiment of this application;

[0023] Figure 3 This is a schematic diagram of the structure of a beam delay correction system according to another embodiment of this application;

[0024] Figure 4 This is a schematic diagram of the correction principle of the beam delay correction system according to an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of the structure of a beam delay correction system according to another embodiment of this application;

[0026] Figure 6 This is a schematic flowchart of the beam delay correction method according to an embodiment of this application;

[0027] Figure 7 This is a schematic diagram of the acousto-optic modulation module modulating the beam in the beam delay correction system according to an embodiment of this application.

[0028] Figure 8 This is a schematic diagram of the first direction of the beam delay correction system according to an embodiment of this application. Detailed Implementation

[0029] 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.

[0030] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0031] In this application embodiment, " / " can indicate that the related objects are in an "or" relationship. For example, A / B can represent A or B. "And / or" can be used to describe three relationships between related objects. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. A and B can be singular or plural. To facilitate the description of the technical solutions in this application embodiment, the terms "first" and "second" can be used to distinguish technical features with the same or similar functions. These terms do not limit the quantity or execution order, and they are not necessarily different. In this application embodiment, the words "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary" or "for example" should not be construed as being better or more advantageous than other embodiments or design solutions. The use of "exemplary" or "for example" is intended to present related concepts in a specific manner for ease of understanding.

[0032] In the embodiments of this application, for a technical feature, the technical features in the technical feature are distinguished by "first", "second", "third", "A", "B", "C" and "D", and there is no order of priority or size among the technical features described by "first", "second", "third", "A", "B", "C" and "D".

[0033] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0034] In existing technologies, laser beams can be modulated using an acousto-optic modulator. Figure 1 The structure of the acousto-optic modulator is shown, as follows: Figure 1As shown, the acousto-optic modulator 100 includes an electro-acoustic transducer 101, an acousto-optic medium 103, a sound-absorbing (or reflecting) device 105, and a driving source 107. When the acousto-optic modulator is in operation, the driving signal emitted by the driving source first acts on the electro-acoustic transducer. The transducer converts the electrical power of the driving signal into acoustic power, which is then used to generate ultrasonic waves in the acousto-optic crystal. The generated ultrasonic waves interact with the incident light signal, resulting in diffraction. The intensity of the diffracted beam is controlled by the ultrasonic driving power, meaning the diffraction efficiency is controlled by the output electrical power of the driving source. Therefore, the generated diffracted beam can be used to transmit relevant signal information.

[0035] However, modulating a laser beam using an acousto-optic modulator introduces noise. Specifically, because ultrasound travels slowly, and the laser beam incident within the acousto-optic medium has a certain width, the ultrasound requires a certain transit time to pass through the laser beam's cross-section, resulting in a radial delay difference in beam modulation. When DC modulation is applied to the acousto-optic modulator, this delay difference has no immediate impact on the radial intensity distribution of the beam. However, when AC modulation is applied, the radial delay difference causes an optical phase difference in that dimension, introducing radially distributed optical phase noise. In practical applications, this affects the modulation effect and degrades system performance.

[0036] Based on the above technical requirements, this application provides a beam delay correction method, which can determine the delay phase based on the parameters of the laser beam to be modulated and the acousto-optic modulation module, and then perform phase compensation on the diffracted beam generated after the acousto-optic modulation module modulates the laser beam to be modulated by the spatial light modulation module, thereby achieving the technical effect of reducing the delay difference generated by the acousto-optic modulation module when modulating the beam.

[0037] To better understand the embodiments of this application, the system architecture to which the embodiments of this application can be applied is described below.

[0038] like Figure 2 As shown, the system architecture includes an acousto-optic modulation module 1 and a spatial light modulation module 4. The acousto-optic modulation module 1 receives the laser beam to be modulated and modulates the laser beam to be modulated to output a diffracted beam. The spatial light modulation module 4 receives the diffracted beam and modulates the diffracted beam based on a delay phase to output a target diffracted beam. The delay phase is determined based on the parameters of the laser beam to be modulated and the acousto-optic modulation module 1.

[0039] Specifically, the acousto-optic modulation module can modulate the laser beam based on the acousto-optic effect and output a diffracted beam. In this embodiment, the acousto-optic modulation module is an acousto-optic modulator. The laser beam is generated by a laser. The laser can include, but is not limited to, gas lasers, solid-state lasers, semiconductor lasers, fiber lasers, and dye lasers. Taking a gas laser as an example, the gas laser can include, but is not limited to, He-Ne lasers, CO2 lasers, Ar ion lasers, etc. The acousto-optic modulation module can modulate the laser beam to be modulated based on the acousto-optic effect to output a multi-order diffracted beam. In one embodiment of this application, in order to ensure that the beam size of the laser beam does not change during propagation, the laser beam can be collimated. Specifically, the system also includes a collimator disposed between the laser and the acousto-optic modulation module, which is used to collimate the laser beam output by the laser. The collimator can convert the divergent beam output by the laser into a parallel beam. The collimator can be disposed on the optical axis of the laser beam transmission. In one embodiment of this application, the focal length and aperture of the collimator can be set according to the actual application scenario.

[0040] A spatial light modulation module, also known as a spatial light modulator, refers to a device that, under active control, modulates a parameter of a light field using liquid crystal molecules. This can be achieved by modulating the amplitude of the light field, modulating the phase through refractive index, modulating the polarization state through rotation of the polarization plane, or converting incoherent to coherent light, thereby incorporating certain information into the light wave to achieve optical wave modulation. The delay phase refers to the radial phase difference in the beam caused by the slower propagation speed of ultrasonic waves as they pass through the laser beam interface in the acousto-optic modulation module. In the beam delay correction system of this implementation, the spatial light modulation module can determine the compensation amount for the diffracted beam based on the delay phase, and by compensating for the phase of the diffracted beam, a target diffracted beam with reduced beam delay differences is obtained.

[0041] The beam delay correction system of this embodiment addresses the problem of distributed noise caused by radial time delay differences in the output light of the acousto-optic modulation module. This system eliminates the need to reduce the beam diameter by focusing, avoiding the reduction in diffraction efficiency caused by the mismatch between the light and sound field divergence angles, thus ensuring the performance of the device. At the same time, it avoids the risk of damaging the acousto-optic crystal due to excessively high light intensity density caused by focusing the beam.

[0042] In one embodiment, the beam delay correction system further includes a controller connected to the spatial light modulation module; the controller is used to acquire the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, determine the delay phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, and generate a control command based on the delay phase and send it to the spatial light modulation module.

[0043] Specifically, the controller can be a computer or a microcontroller. The parameters of the laser beam to be modulated include the beam diameter, and the parameters of the acousto-optic modulation module include the acoustic wave propagation speed and the optical intensity modulation frequency. The beam diameter, acoustic wave propagation speed, and optical intensity modulation frequency can be input into the controller by the operator, or pre-configured into the control software's adjustment system. Alternatively, the relevant parameters can be automatically acquired by connecting the control system to the laser and the acousto-optic modulation module. Based on the above parameters, the delay phase is determined, and a control command is generated and sent to the spatial light modulation module. Preferably, the controller can also determine a holographic image based on the delay phase and send the holographic image to the spatial light modulator, which performs delay phase compensation based on the holographic image.

[0044] In one embodiment, the beam delay correction system of this embodiment further includes a beam expander, which is connected to the acousto-optic modulated spatial light modulation module. The beam expander is used to receive the diffracted beam, expand the diffracted beam to a preset diameter, and output the expanded beam to the spatial light modulation module.

[0045] Specifically, a beam expander is a lens assembly capable of altering the diameter and divergence angle of a laser beam. Without a beam expander, the beam can be considered as expanded by a single factor; with a beam expander, the beam can be considered as expanded by multiple factors. In this embodiment, a single beam expander is placed in the optical path for beam expansion, or multiple beam expanders can be grouped together to expand the diffracted beam. The beam expander expands the diffracted beam emitted from the optical modulator to a preset diameter, which is greater than or equal to the diameter of the diffracted beam and does not exceed the effective size of the spatial light modulation module. Beam expansion improves the resolution of the diffracted beam. Because the spatial light modulation module has a certain size, for the same phase difference in space, a larger spot size allows for higher adjustment precision by the spatial light modulation module, which is beneficial for improving the final delay phase compensation effect.

[0046] In one embodiment, the beam delay correction system of this embodiment further includes a polarization control optical path, which is connected to the acousto-optic modulation module and the spatial light modulation module respectively; the polarization control optical path is used to receive the diffracted beam and adjust the polarization state of the diffracted beam to obtain linearly polarized light, and output it to the spatial light modulation module.

[0047] Specifically, the polarization control optical path can adjust the polarization state of the light beam to meet the polarization requirements of the incident light of the spatial light modulation module. The polarization states of light generally include natural light, partially polarized light, linearly polarized light, elliptically polarized light, and circularly polarized light. Linearly polarized light refers to light whose light vector always vibrates in a certain direction. Preferably, the polarization control optical path adjusts the light beam to obtain linearly polarized light and outputs it to the spatial light modulation module. This is because the optical modulator is a polarization-sensitive device, and since this embodiment requires phase modulation of all components of the light beam, the polarization state needs to be consistent with the modulation direction of the spatial light modulation module.

[0048] In one embodiment, the acousto-optic modulation module in the beam delay correction system of this embodiment is a Bragg-type acousto-optic modulator.

[0049] In this embodiment, the acousto-optic modulation module can be of various types. Taking a Bragg-type acousto-optic modulator as an example, to improve the diffraction efficiency of the Bragg-type acousto-optic modulator, the relative position of the Bragg-type acousto-optic modulator and the laser can be adjusted so that the angle between the optical axis of the laser beam and the longitudinal direction of the Bragg-type acousto-optic modulator is the Bragg angle. Thus, the laser beam can be incident on the Bragg-type acousto-optic modulator in a first direction at the Bragg angle. Based on this, the diffracted light output by the Bragg-type acousto-optic modulator can contain only 0th-order diffracted light and 1st-order diffracted light (-1st-order diffracted light).

[0050] In one preferred embodiment, a beam delay correction system is provided. Figure 3 This is a schematic diagram of the beam delay correction system according to an embodiment of this application, as shown below. Figure 3 As shown, the system includes: an acousto-optic modulation module 1, a beam expander 2, a polarization control optical path 3, a spatial light modulator 4, and a controller 5. The acousto-optic modulation module is a Bragg-type acousto-optic modulation module; the beam expander amplifies the beam emitted from the acousto-optic modulation module, ensuring the expanded beam size does not exceed the effective size of the spatial light modulation module; the polarization control optical path adjusts the polarization state of the beam to meet the polarization requirements of the incident light in the spatial light modulation module; the spatial light modulation module is phase-type, allowing for phase control of the incident light; and the controller generates the hologram required by the spatial light modulation module.

[0051] In this implementation of the beam delay correction system, the laser beam is first emitted; the angle of the acousto-optic modulation module is adjusted so that the laser beam, as the input light, passes through the acousto-optic modulation module; the output light of the acousto-optic modulation module is expanded by a beam expander and then passes through a polarization control optical path, where the beam polarization state is adjusted to linearly polarized light in the polarization direction required by the spatial light modulation module; the controller generates a holographic image and loads it onto the spatial light modulation module, causing the spatial light modulation module to modulate the radial phase of the incident beam, which is opposite to the phase distribution caused by the time delay introduced by the acousto-optic modulation module in the radial direction of the beam, thereby achieving correction of the beam delay phase.

[0052] To better understand the embodiments of this application, the core principles on which the embodiments of this application are based are explained below.

[0053] like Figure 4 As shown, a beam of diameter D1 passes through the acousto-optic crystal via the aperture of the acousto-optic modulation module. The radio frequency signal generated by the driver is input to the acousto-optic modulation module, and after passing through an electro-acoustic transducer, a sound wave is generated, propagating radially along the beam. The intersection of the light and sound fields is the effective region of the acousto-optic modulation module. The modulation frequency of the acousto-optic modulation module for the input light intensity is f. The beam expanded from the acousto-optic modulation module is then incident on the spatial light modulation module with a diameter D2.

[0054] Since sound waves propagate at a speed of v in an acousto-optic crystal, the time required for the sound wave to completely pass through the beam is t = D1 / , meaning that for the beam cross-section, there is a time delay t between the area near and away from the radio frequency signal. Furthermore, because the sound wave propagates at a uniform speed in the acousto-optic crystal, the time delay on the beam cross-section increases uniformly from the area near the radio frequency signal towards the area away from the radio frequency signal.

[0055] Since the speed of light is 10 8 On the order of m / s, much faster than 10 times the speed of sound. 3 The beam's speed is on the order of m / s, therefore the propagation time required between the two entry points of the beam into the acousto-optic modulation module is negligible. Thus, after the acousto-optic interaction, the phase delay corresponding to the time delay t = D1 / v on the beam's cross-section by the acousto-optic modulation module is... A hologram is generated by a computer and loaded onto a spatial light modulation module to modulate the phase of the incident light beam, that is, to modulate the delay distribution of the beam. The modulation function is: make It can be known that the total phase modulation value of the spatial light modulation module for the beam cross-section with diameter D2 is... Therefore, after passing through the acousto-optic modulation module and the spatial light modulation module, the radial phase difference of the beam is compensated, that is, the delay difference is compensated.

[0056] The beam delay correction system in this embodiment compensates for the delay difference generated when the acousto-optic modulation module modulates the beam, thus avoiding the introduction of noise during modulation and improving modulation efficiency.

[0057] In another specific embodiment, a beam delay correction system is provided, such as Figure 5 As shown, the system includes an acousto-optic modulation module 1, a first beam expander group 52 and a second beam expander group 53, a first reflector 54 and a second reflector 55, a first half-wave plate 56, a polarization beam splitter 57, an optical trash can 58, a second half-wave plate 59, a right-angle reflector 10, a spatial light modulation module 4, and a computer 12.

[0058] In this embodiment, the acousto-optic modulation module used is a Bragg-type free-space acousto-optic modulation module, with antimony oxide as the acousto-optic medium and a sound velocity of 4.2 mm / μs. The acousto-optic modulation module operates at a wavelength of 1064 nm. The input laser beam has a diameter of 2 mm and a constant intensity. A beam expander doubles the beam to a diameter of 4 mm before inputting it into the spatial light modulation module. The acousto-optic modulation module applies sinusoidal modulation to the laser beam intensity.

[0059] The first reflecting mirror 54, the second reflecting mirror 55, the first half-wave plate 56, the polarization beam splitter 57, the optical trash can 58, the second half-wave plate 59, and the right-angle reflecting mirror 10 together form the polarization control optical path. The polarization beam splitter is positioned on the transmission path of the laser beam and can split the laser beam into two beams of orthogonally polarized light, such as P-beams and S-beams. Common materials for the polarization beam splitter include YVO4, a-BBO, Iceland spar, etc. The acousto-optic modulation module is positioned on the transmission path of the laser beam to be modulated and is used to modulate the laser beam. The acousto-optic modulation module can modulate the polarized light based on the acousto-optic effect to output a multi-level diffracted beam. It is understood that the acousto-optic modulation module does not change the polarization state of the beam; therefore, the polarization states of the multi-level diffracted beams are the same. The spatial light modulation module modulates the polarized light; it is understood that the polarized light can be either P-beam or S-beam. In one embodiment of this application, the polarized light can be P-beam.

[0060] In this embodiment, the acousto-optic modulation module operates in a region with good linearity, facilitating light intensity modulation. Based on the sound velocity in the acousto-optic medium and the beam size, the time Δt required for the sound wave to penetrate the beam cross-section can be calculated to be approximately 0.48 μs. For a sinusoidal light intensity signal with frequency f, the 0.48 μs delay difference results in a radial phase difference in the beam. Therefore, as the modulation frequency increases, the radial phase difference of the beam caused by this time delay gradually increases, and the noise of light intensity distribution change introduced in the direction of sound wave field propagation gradually increases.

[0061] Taking a light intensity modulation frequency of 200kHz as an example, the acousto-optic modulation module will cause a phase difference of 0.6rad in the radial direction of the beam. By using a spatial light modulation module to modulate the phase distribution of the beam at a rate of -0.15rad / mm, the phase modulation generated on the 4mm diameter beam will be -0.6rad, which cancels out the phase difference generated by the acousto-optic modulation module, thus compensating for the radial delay difference of the beam generated by the acousto-optic modulation module.

[0062] The beam delay correction method described in this application will be described in detail below with reference to the accompanying drawings. Although this application provides method operation steps as shown in the following embodiments or drawings, more or fewer operation steps may be included in the method based on conventional or non-inventive effort. For steps that do not have a logically necessary causal relationship, the execution order of these steps is not limited to the execution order provided in the embodiments of this application. In actual beam delay correction processes or when the device executes the method, it can be executed in the order shown in the embodiments or drawings, or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0063] The beam delay correction method is explained in detail below with reference to the accompanying drawings, such as... Figure 6 As shown, the method may include:

[0064] In step S601, the acousto-optic modulation module receives the laser beam to be modulated, modulates the laser beam to be modulated, and outputs a diffracted beam.

[0065] In this embodiment, the acousto-optic modulation module can be an acousto-optic modulation module, which may include a free-space acousto-optic modulation module, an optical fiber coupled acousto-optic modulation module, etc. As follows: Figure 7 As shown, the acousto-optic modulation module can modulate the incident laser beam. The ultrasonic waves generated by the acousto-optic modulation module, after entering the acousto-optic medium, cause a change in the refractive index within the medium. When the incident laser beam passes through the acousto-optic medium, an acousto-optic interaction occurs, changing its propagation direction and generating a multi-order diffracted beam. In one embodiment of this application, the laser beam can be generated by the aforementioned laser, and the laser can be configured with laser parameters, including beam diameter, output power, beam quality factor, propagation direction, etc. In one embodiment of this application, the laser beam can be incident into the acousto-optic modulation module along a first direction. The first direction can be the propagation direction of the laser beam. In one embodiment of this application, the first direction can be adjusted by adjusting the relative positions of the laser and the acousto-optic modulation module. For example, in one example, as... Figure 8As shown, if the acousto-optic modulation module is located to the right of the laser, the first direction can be either direction 1 or direction 2. In another embodiment of this application, the first direction can also be adjusted by modifying the laser parameters of the laser. The acousto-optic modulation module can modulate the laser beam. During the modulation process, since the laser beam has a certain width, such as D, the ultrasonic waves from the acousto-optic modulation module will have a certain time delay when interacting with the laser beam. Therefore, the output diffracted beam will have a radial delay difference.

[0066] In step S602, the spatial light modulation module receives the diffracted beam, modulates the diffracted beam based on the delay phase, and outputs the target diffracted beam. The delay phase is determined based on the laser beam to be modulated and the parameters of the acousto-optic modulation module.

[0067] In this embodiment, the delay phase refers to the manifestation of the radial delay difference of the diffracted beam in terms of phase. Based on the delay phase, the spatial light modulation module performs phase compensation on the diffracted beam, achieving the technical effect of reducing the delay difference generated by the acousto-optic modulation module when modulating the beam.

[0068] In one embodiment, the process of modulating the diffracted beam based on the delayed phase includes: the controller acquiring parameters of the laser beam to be modulated and parameters of the acousto-optic modulation module, determining the delayed phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, generating a control command based on the delayed phase, and sending it to the spatial light modulation module.

[0069] Specifically, the parameters of the laser beam to be modulated mainly include its beam diameter, frequency, and intensity. The parameters of the acousto-optic modulation module mainly include the ultrasonic power of the acousto-optic modulation module and / or the radio frequency signal power output by the acousto-optic modulation module driver. In practical applications, the diffraction efficiency of the acousto-optic modulation module is related to the power of the ultrasonic wave, i.e., to the power of the radio frequency signal output by the acousto-optic modulation module driver. Based on this, the power of the output radio frequency signal can be changed by altering the driving signal of the acousto-optic modulation module driver, such as the input voltage, thereby changing the diffraction efficiency of the acousto-optic modulation module. The delay phase can be determined based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module.

[0070] In one embodiment, the controller generates control commands based on the delayed phase and sends them to the spatial light modulation module. The controller also generates a holographic image based on the delayed phase and sends the holographic image to the spatial light modulation module.

[0071] Specifically, the controller calculates the holographic image based on the beam diameter, acoustic velocity, and optical intensity modulation frequency. Because the phase changes linearly, the phase distribution can be determined based on the total phase change. The beam diameter, acoustic velocity, and optical intensity modulation frequency can be input into the controller by the operator, pre-configured into the control software's adjustment system, or automatically acquired by connecting the control system to the laser and the acousto-optic modulation module. The holographic image is a grayscale image formed using code, acting as a phase plate that determines how much the phase is modulated at each location in space. The information in the holographic image is opposite to the phase distribution of the diffracted beam itself, thus providing compensation.

[0072] In one embodiment, before the spatial light modulation module receives the diffracted beam, it further includes: a beam expander receiving the diffracted beam, expanding the diffracted beam to a preset diameter, and outputting the expanded beam to the spatial light modulation module.

[0073] Specifically, a beam expander is a lens assembly capable of altering the diameter and divergence angle of a laser beam. Without a beam expander, the beam can be considered as expanded by a single factor; with a beam expander, the beam can be considered as expanded by multiple factors. In this embodiment, a single beam expander is placed in the optical path for beam expansion, or multiple beam expanders can be grouped together to expand the diffracted beam. The beam expander expands the diffracted beam emitted from the optical modulator to a preset diameter, which is greater than or equal to the diameter of the diffracted beam and does not exceed the effective size of the spatial light modulation module. Beam expansion improves the resolution of the diffracted beam. Because the spatial light modulation module has a certain size, for the same phase difference in space, a larger spot size allows for higher adjustment precision by the spatial light modulation module, which is beneficial for improving the final delay phase compensation effect.

[0074] In one embodiment, the polarization control optical path receives the diffracted beam and adjusts the polarization state of the diffracted beam to obtain linearly polarized light, which is then output to the spatial light modulation module.

[0075] Specifically, the polarization control optical path can adjust the polarization state of the light beam to meet the polarization requirements of the incident light of the spatial light modulation module. The polarization states of light generally include natural light, partially polarized light, linearly polarized light, elliptically polarized light, and circularly polarized light. Linearly polarized light refers to light whose light vector always vibrates in a certain direction. Preferably, the polarization control optical path adjusts the light beam to obtain linearly polarized light and outputs it to the spatial light modulation module. This is because the optical modulator is a polarization-sensitive device, and since this embodiment requires phase modulation of all components of the light beam, the polarization state needs to be consistent with the modulation direction of the spatial light modulation module.

[0076] It should be noted that the specific workflow of the beam delay correction method can be referred to the beam delay correction system described in the above embodiments, and will not be repeated here.

[0077] In one specific embodiment, the beam delay correction method of this application includes: adjusting the angle of the acousto-optic modulation module so that the input light passes through the acousto-optic modulation module. The output light of the acousto-optic modulation module is expanded by a beam expander and then passes through a polarization control optical path, and the beam polarization state is adjusted to linearly polarized light with the polarization direction required by the spatial light modulation module. A hologram is generated by a computer and loaded onto the spatial light modulation module. The linearly polarized light initially incident on the polarization control optical path and the effective area of ​​the hologram loaded on the spatial light modulation module are phase-modulated and emitted as output light, wherein when the spatial light modulation module modulates the linearly polarized light, the phase modulation distribution is opposite to the phase distribution caused by the time delay introduced by the acousto-optic modulation module in the radial direction of the beam.

[0078] The implementation principle of the beam delay control method in this embodiment is as follows: Figure 4 As shown, a beam of diameter D1 passes through the acousto-optic crystal via the aperture of the acousto-optic modulation module. The radio frequency signal generated by the driver is input to the acousto-optic modulation module, and after passing through an electro-acoustic transducer, a sound wave is generated, propagating radially along the beam. The intersection of the light and sound fields is the effective region of the acousto-optic modulation module. The modulation frequency of the acousto-optic modulation module for the input light intensity is f. The beam of light emitted from the acousto-optic modulation module is expanded and then incident on the spatial light modulation module with a diameter D2.

[0079] Since sound waves propagate at a speed of v in an acousto-optic crystal, the time required for the sound wave to completely pass through the beam is t = D1 / v. This means that for the beam cross-section, there is a time delay t between the area near and away from the radio frequency (RF) signal. Furthermore, because the sound wave propagates at a uniform speed in the acousto-optic crystal, the time delay on the beam cross-section increases uniformly from the area near the RF signal towards the area away from the RF signal.

[0080] Since the speed of light is 10 8 On the order of m / s, much faster than 10 times the speed of sound. 3 The beam's speed is on the order of m / s, therefore the propagation time required between the two entry points of the beam into the acousto-optic modulation module is negligible. Thus, after the acousto-optic interaction, the phase delay corresponding to the time delay t = D1 / v on the beam's cross-section by the acousto-optic modulation module is... A hologram is generated by a computer and loaded onto a spatial light modulation module to modulate the phase of the incident light beam, that is, to modulate the delay distribution of the beam. The modulation function is: make It can be known that the total phase modulation value of the spatial light modulation module for the beam cross-section with diameter D2 is... Therefore, after passing through the acousto-optic modulation module and the spatial light modulation module, the radial phase difference of the beam is compensated, that is, the delay difference is compensated.

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. 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 application should be determined by the appended claims.

Claims

1. A method of beam delay correction, characterized by, The method comprises: The acousto-optic modulation module receives a laser beam to be modulated and modulates the laser beam to be modulated to output a diffracted beam; The spatial light modulation module receives the diffracted beam, modulates the diffracted beam based on a delay phase, and outputs a target diffracted beam, wherein the delay phase is determined based on parameters of the laser beam to be modulated and the acousto-optic modulation module; the parameters of the laser beam to be modulated include a beam diameter of the laser beam to be modulated, and the parameters of the acousto-optic modulation module include a sound wave propagation speed and a light intensity modulation frequency.

2. The method of claim 1, wherein, Before modulating the diffracted beam based on the delay phase, the method comprises: The controller obtains the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, determines the delay phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, generates a control instruction based on the delay phase, and sends the control instruction to the spatial light modulation module.

3. The method of claim 2, wherein, The controller generates a holographic image based on the delay phase and sends the holographic image to the spatial light modulation module. Before the spatial light modulation module receives the diffracted beam, the method further comprises:

4. The method of claim 1, wherein, The beam expander receives the diffracted beam, expands the diffracted beam to a preset diameter, and outputs the expanded diffracted beam to the spatial light modulation module.

5. The method of claim 1, before the spatial light modulation module receives the diffracted beam, the method further comprises: The polarization control optical path receives the diffracted beam and adjusts the polarization state of the diffracted beam to obtain linearly polarized light, and outputs the linearly polarized light to the spatial light modulation module. The system comprises an acousto-optic modulation module and a spatial light modulation module connected in sequence, wherein:

6. A beam delay correction system characterized by, The acousto-optic modulation module is configured to receive a laser beam to be modulated, modulate the laser beam to be modulated, and output a diffracted beam; The spatial light modulation module is configured to receive the diffracted beam, modulate the diffracted beam based on a delay phase, and output a target diffracted beam, wherein the delay phase is determined based on parameters of the laser beam to be modulated and the acousto-optic modulation module; the parameters of the laser beam to be modulated include a beam diameter of the laser beam to be modulated, and the parameters of the acousto-optic modulation module include a sound wave propagation speed and a light intensity modulation frequency. The system further comprises a controller connected with the spatial light modulation module; 7. The system of claim 6, wherein, The controller is configured to obtain the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, determine the delay phase based on the parameters of the laser beam to be modulated and the parameters of the acousto-optic modulation module, generate a control instruction based on the delay phase, and send the control instruction to the spatial light modulation module. The system further comprises a beam expander connected with the acousto-optic modulation module and the spatial light modulation module, respectively; 8. The system of claim 6, wherein, The beam expander is configured to receive the diffracted beam, expand the diffracted beam to a preset diameter, and output the expanded diffracted beam to the spatial light modulation module. The system further comprises a polarization control optical path connected with the acousto-optic modulation module and the spatial light modulation module, respectively; 9. The system of claim 6, wherein, ​ The polarization control light path is used for receiving the diffracted light beam and adjusting a polarization state of the diffracted light beam to obtain linearly polarized light and output to the spatial light modulation module.

10. The system of claim 6, wherein, The acousto-optic modulation module is a Bragg type acousto-optic modulation module.

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