Beam delay correction method and system

Abstract

The application relates to a light beam delay correction method and system, wherein the method comprises the following steps: a first acousto-optic modulation module receives a laser light beam to be modulated, controls a first modulation signal to modulate the laser light beam to be modulated along a first direction, and outputs a diffraction light beam; a second acousto-optic modulation module receives the diffraction light beam, controls a second modulation signal to modulate the diffraction light beam along a second direction, and outputs a target diffraction light beam after modulation, wherein the second direction is opposite to the first direction.

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 time delay differences at different radial positions. However, this method affects the diffraction efficiency of the acousto-optic modulator. Furthermore, the increased light intensity 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 time delay difference generated by the acousto-optic modulator when modulating the beam. Summary of the Invention

[0005] Therefore, it is necessary to provide a method and system that can compensate for the time 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, embodiments of this application provide a beam delay correction method, the method comprising:

[0007] The first acousto-optic modulation module receives the laser beam to be modulated and controls the first modulation signal to modulate the laser beam along the first direction, and outputs a diffracted beam.

[0008] The second acousto-optic modulation module receives the diffracted beam and controls the second modulation signal to modulate the diffracted beam along the second direction, outputting the modulated target diffracted beam, wherein the second direction is opposite to the first direction.

[0009] This application provides a beam delay correction method that utilizes a first acousto-optic modulation module to receive a laser beam to be modulated. The first acousto-optic modulation module controls a first modulation signal to modulate the laser beam along a first direction and outputs a diffracted beam. The diffracted beam can then be input to a second acousto-optic modulation module, which controls a second modulation signal to modulate the diffracted beam along a second direction, outputting a modulated target diffracted beam. Since the two modulation signals act in opposite directions to the laser beam, the beam that initially contacts the modulation signal will then contact it later when it is incident on the second acousto-optic modulator. This compensates for the radial delay difference in the beam, thereby preventing noise from being introduced during modulation by the acousto-optic modulator and improving modulation efficiency.

[0010] Optionally, in one embodiment of this application, before the first acousto-optic modulation module receives the laser beam to be modulated, the method further includes:

[0011] The first driver generates a first radio frequency signal and sends the first radio frequency signal to the first acousto-optic modulation module, so that the first acousto-optic modulation module generates the first modulation signal based on the first radio frequency signal;

[0012] The second driver generates a second radio frequency signal and sends the second radio frequency signal to the second acousto-optic modulation module, so that the second acousto-optic modulation module generates the second modulation signal based on the second radio frequency signal.

[0013] Optionally, in one embodiment of this application, before the first driver generates the first drive signal, the method further includes:

[0014] The signal generator generates a first drive signal and a second drive signal, sends the first drive signal to the first driver, and sends the second drive signal to the second driver, so that the first driver and the second driver generate a first radio frequency signal and a second radio frequency signal, and the first drive signal and the second drive signal are output synchronously.

[0015] Optionally, in one embodiment of this application, the signal generator generating the first drive signal and the second drive signal further includes:

[0016] The signal generator determines the input voltages of the first radio frequency signal and the second radio frequency signal based on the target diffraction efficiency, and generates the first driving signal and the second driving signal based on the input voltages.

[0017] Optionally, in one embodiment of this application, the angle between the first direction and the second direction is 180 degrees.

[0018] Secondly, embodiments of this application also provide a beam delay correction system, the system comprising a first acousto-optic modulation module and a second acousto-optic modulation module connected in sequence, wherein:

[0019] The first acousto-optic modulation module is used to receive the laser beam to be modulated, and control the first modulation signal to modulate the laser beam to be modulated along the first direction, and output the modulated first laser beam.

[0020] The second acousto-optic modulation module is used to receive the first laser beam and control the second modulation signal to modulate the first laser beam along the second direction, and output the modulated target laser beam, wherein the second direction is opposite to the first direction.

[0021] Optionally, in one embodiment of this application, the acousto-optic crystal material of the first acousto-optic modulation module and the second acousto-optic modulation module is the same.

[0022] Optionally, in one embodiment of this application, the distance between the input terminal of the first modulation signal in the first acousto-optic modulation module and the laser beam to be modulated is a first distance, and the distance between the input terminal of the second modulation signal in the second acousto-optic modulation module and the first laser beam is a second distance, wherein the first distance and the second distance are equal.

[0023] Optionally, in one embodiment of this application, the first and second acousto-optic modulation modules are Bragg-type acousto-optic modulators.

[0024] Optionally, in one embodiment of this application, the angle between the first direction and the second direction is 180 degrees. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the module structure of an acousto-optic modulator provided in one embodiment of this application;

[0026] Figure 2 This is a schematic diagram illustrating an application scenario provided in one embodiment of this application;

[0027] Figure 3 A schematic diagram illustrating the principle of a beam delay correction method provided in one embodiment of this application;

[0028] Figure 4 A flowchart illustrating a beam delay correction method provided in this application embodiment;

[0029] Figure 5 A schematic diagram of a first direction provided for one embodiment of this application;

[0030] Figure 6This is a system architecture diagram of a beam delay correction system provided in one embodiment of this application. Detailed Implementation

[0031] 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.

[0032] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[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 this application embodiment, " / " can indicate that the objects before and after are in an "or" relationship. For example, A / B can represent A or B. "And / or" can be used to describe three relationships between the 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 more preferred or advantageous than other embodiments or designs. The use of "exemplary" or "for example" is intended to present related concepts in a concrete manner for ease of understanding.

[0035] 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".

[0036] 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.

[0037] In existing technologies, the intensity of a laser beam can be modulated using an acousto-optic modulator. Figure 1 The structure of the acousto-optic modulator is shown, as follows: Figure 1 As shown, the acousto-optic modulator 100 may include an electro-acoustic transducer 101, an acousto-optic medium 103, a sound-absorbing (or reflecting) device 105, and a driver 107. When the acousto-optic modulator 100 is in operation, the driving signal emitted by the driver 107 first acts on the electro-acoustic transducer 101. The electro-acoustic transducer 101 converts the electrical power of the driving signal into acoustic power, and then generates ultrasonic waves in the acousto-optic medium 103. The generated ultrasonic waves interact with the incident light signal, thereby producing diffraction. The intensity of the diffracted light is controlled by the ultrasonic driving power, that is, the diffraction efficiency is controlled by the output electrical power of the driving source. Therefore, the generated diffracted light can be used to transmit relevant information of the signal.

[0038] However, modulating a laser beam using the acousto-optic modulator 100 introduces noise. Specifically, because ultrasound travels slowly, and the laser beam incident within the acousto-optic medium 103 has a certain width, the ultrasound requires a certain transit time to pass through the laser beam cross-section, resulting in a radial delay difference in beam modulation. When DC modulation is applied to the acousto-optic modulator 100, this delay difference has no immediate impact on the radial intensity distribution of the beam. However, when AC modulation is applied to the acousto-optic modulator 100, the radial delay difference causes a phase difference in that dimension, introducing radially distributed phase noise. In practical applications, this affects the modulation effect and reduces system performance.

[0039] Based on the aforementioned technical requirements, this application provides a beam delay correction method. A first acousto-optic modulation module receives a laser beam to be modulated. This module controls a first modulation signal to modulate the laser beam along a first direction and outputs a diffracted beam. The diffracted beam is then input to a second acousto-optic modulation module, which controls a second modulation signal to modulate the beam along a second direction, outputting a modulated target diffracted beam. The second direction is opposite to the first direction. Because the two modulation signals act in opposite directions to the laser beam, the beam that initially contacts the modulation signal will then contact it later when it is incident on the second acousto-optic modulator. This compensates for the radial delay difference in the beam, thereby preventing noise from being introduced during modulation and improving modulation efficiency.

[0040] To better understand the embodiments of this application, the system architecture to which the embodiments of this application can be applied is described below.

[0041] like Figure 2As shown, the system architecture includes a first acousto-optic modulation module 1, a second acousto-optic modulation module 2, a signal generator 3, a first driver 4, and a second driver 5. The first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be of the same type or different types. The different types can include different acousto-optic media in the two modulation modules. For example, the acousto-optic media can include lead molybdate crystal (PM), sulfur oxide crystal, quartz crystal, antimony oxide, etc. The acousto-optic media of the first acousto-optic modulation module 1 can be antimony oxide, and the acousto-optic media of the second acousto-optic modulation module 2 can be quartz crystal. The signal generator 1 can be a device capable of providing electrical signals of various frequencies, waveforms, and output levels. For example, it can be a device capable of generating sine waves, square waves, triangular waves, sawtooth waves, and positive and negative pulse wave signals of different frequencies and amplitudes. Specifically, the signal generator can include, but is not limited to, pulse signal generators, function generators, radio frequency generators, microwave signal generators, etc. Preferably, in one embodiment of this application, the signal generator may include a Direct Digital Synthesizer (DDS). A DDS can generate various waveforms such as sine waves, triangle waves, square waves, and sawtooth waves. It not only has advantages such as low cost, low power consumption, and high resolution, but also the advantage of fast switching. Therefore, it can achieve rapid switching between multiple waveform types or different waveform frequencies, thereby improving the modulation efficiency of the acousto-optic modulation module. The signal generator 1 can be connected to the first driver 4 and the second driver 5 respectively, and is used to send the generated electrical level signal to the first driver 4 and the second driver 5. After receiving the electrical level signal, the first driver 4 and the second driver 5 can generate a radio frequency signal with a specific frequency. It is understood that the signal sent by the signal generator 1 to the first driver 4 and the second driver 5 can be a synchronization signal. This ensures that the radio frequency signals received by the two acousto-optic modulation modules are synchronized, avoiding time delay differences introduced by asynchronous radio frequency signals. In one embodiment of this application, the first driver 4 is connected to the first acousto-optic modulation module 1 to output a first radio frequency signal to the first acousto-optic modulation module 1; the second driver 5 is connected to the second acousto-optic modulation module 2 to output a second radio frequency signal to the second acousto-optic modulation module 2. To compensate for the time delay difference introduced by the acousto-optic modulation modules when modulating the laser beam, the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be placed in opposite directions. This reverse placement may include placing the drivers of the two acousto-optic modulation modules on opposite sides of the input laser beam. Thus, the direction of the first ultrasonic wave generated by the first acousto-optic modulation module 1 is opposite to the direction of the first ultrasonic wave generated by the acousto-optic modulation module 2.The laser beam received by the first acousto-optic modulation module 1 can be 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 first acousto-optic modulation module 1 is disposed in the transmission path of the laser beam and can modulate the laser beam to output a diffracted beam. The second acousto-optic modulation module 2 is disposed in the transmission path of the diffracted beam and is used to receive the diffracted beam and modulate the diffracted beam to output a target diffracted beam.

[0042] In order to better understand the embodiments of this application, the core principles on which the embodiments of this application are based are explained below.

[0043] As described above, the laser beam generated by the laser can pass through the acousto-optic medium of the two acousto-optic modulation modules through their respective apertures. That is, the laser beam can interact with two ultrasonic waves within the acousto-optic medium of the two modulation modules. Specifically, a laser beam with a diameter of D can pass through the first acousto-optic medium through the aperture of the first modulation module. The first radio frequency signal generated by the first driver is input to the first acousto-optic modulation module 1, and a first ultrasonic wave is generated by the electro-acoustic transducer of the first acousto-optic modulation module 1. The intersection area of ​​the first ultrasonic wave and the laser beam is the operating area of ​​the first acousto-optic modulation module 1. Since the first ultrasonic wave has a propagation speed v1 in the first acousto-optic medium, the time required for the first ultrasonic wave to completely pass through the cross-section of the laser beam can be t = D / v1. In other words, for the cross-section of the laser beam, the beam closer to the first ultrasonic wave signal will interact with it first, while the beam farther away will interact with it later. This results in a modulation time delay, which can be up to D / v1. Furthermore, because the first ultrasonic wave propagates at a uniform speed in the first acousto-optic medium, the time delay on the cross-section of the beam can increase uniformly from the point near the first ultrasonic signal along a direction away from the first ultrasonic signal. For example, as... Figure 3 As shown, the first ultrasonic wave generated by the first acousto-optic modulation module 1 propagates at a speed of v1 in the first acousto-optic medium, and its propagation direction is direction 1. The second ultrasonic wave generated by the second acousto-optic modulation module 2 propagates at a speed of v2 in the second acousto-optic medium, and its propagation direction is direction 2. Directions 1 and 2 are opposite. If the positive x-axis is defined as the propagation direction of the first ultrasonic wave in the first acousto-optic modulation module 1, then the second ultrasonic wave in the second acousto-optic modulation module 2 propagates along the negative x-axis. Figure 3As shown, the position coordinate of beam 1, which is closer to the first ultrasonic wave, can be x1. Therefore, the time delay between the interaction between beam 1 and the first ultrasonic wave can be t11 = x1 / v1. The coordinate of beam 2, which is farther from the first ultrasonic wave, can be x2. Therefore, the time delay between the interaction between beam 2 and the first ultrasonic wave can be t21 = x2 / v1.

[0044] To compensate for the delay caused by the first acousto-optic modulation module 1 modulating the laser beam, such as Figure 3 As shown, the diffracted light output after modulation by the first acousto-optic modulation module 1 is incident on the acousto-optic modulation module 2. This causes beams that were originally close to the first ultrasonic signal, such as beam 1, to move away from the second ultrasonic signal, while beams that were originally far from the first ultrasonic signal, such as beam 2, to move closer to the second ultrasonic signal. Therefore, when the second ultrasonic wave interacts with the diffracted light, the time delay between beam 1 and the ultrasonic wave can be t12 = (D - x1) / v1, and the time delay between beam 2 and the ultrasonic wave can be t22 = (D - x2) / v2. After two acousto-optic modulators, the time delay generated by beam 1 can be t1 = t11 + t12 = x1 / v1 + (D - x1) / v2 = D / v2 + (1 / v1 - 1 / v2)x1. The time delay generated by beam 2 can be t2 = t21 + t22 = x2 / v1 + (D - x2) / v2 = D / v2 + (1 / v1 - 1 / v2)x2. When the transmission speed v1 of the first ultrasonic wave and the transmission speed v2 of the second ultrasonic wave are the same, for example, both have a propagation speed of v, the time delay generated by beam 1 is t1 = D / v, and the time delay generated by beam 2 is t1 = D / v. Therefore, it can be seen that the time delay generated by the beam at different positions on the beam cross-section is the same when modulated, and is a fixed value. That is, the radial time delay of the beam does not vary with the beam position, and the delay difference can be completely compensated.

[0045] Of course, in other embodiments of this application, when the propagation speed v1 of the first ultrasonic wave is different from the propagation speed v2 of the second ultrasonic wave, the time delay generated when the beam 1 is modulated is t1 = D / v2 + (1 / v1 - 1 / v2)x1. In this formula, D / v2 and (1 / v1 - 1 / v2) are both constant values, so the time delay t1 can be equivalently expressed as t1 = a + bx1. It can be seen that the time delay is a function of the beam position x, and the radial delay of the beam varies with the beam position. If the propagation directions of the first ultrasonic wave and the second ultrasonic wave are the same, the time delay generated when the beam 1 passes through the two acousto-optic modulators sequentially is t1. ，= x1 / v1 + x1 / v2. The compensation effect achieved by this method is explained when the position coordinate x1 of beam 1 is D. When x1 = D, t1 ， =D / v1 + D / v2, where t1 = D / v2 + (1 / v1 - 1 / v2)D. Compare t1 with t2. ， It can be seen that since (1 / v1-1 / v2)D < D / v1, therefore t1 < t1 ， In other words, the delay difference caused by the modulation of the beam at different radial positions can be partially compensated. The degree of compensation is related to the difference in the ultrasonic propagation speeds of the two acousto-optic modulation modules; that is, the closer the propagation speeds of the first and second ultrasonic waves are, the more significant the improvement in radial delay difference. Therefore, the degree of compensation for the radial delay difference of the beam can be controlled by changing the acoustic wave propagation speeds of the crystals in the two acousto-optic modulation modules. Furthermore, since the speed of light is approximately 10... 8 On the order of m / s, much faster than 10 times the speed of sound. 3 Since the beam travels on the order of m / s, the time required for the beam to propagate between the two acousto-optic modulation modules is negligible. It can be assumed that the two ultrasonic waves arrive at the beam edges of the two acousto-optic modulation modules simultaneously.

[0046] 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).

[0047] The following is in conjunction with the appendix Figure 4 Please explain the method of beam delay correction in detail, such as Figure 4 As shown, the method may include:

[0048] S401: The first acousto-optic modulation module receives the laser beam to be modulated and controls the first modulation signal to modulate the laser beam to be modulated along the first direction, and outputs a diffracted beam.

[0049] S403: The second acousto-optic modulation module receives the diffracted beam and controls the second modulation signal to modulate the diffracted beam along the second direction, and outputs the modulated target diffracted beam, wherein the second direction is opposite to the first direction.

[0050] In this embodiment, the beam to be modulated can be generated by the aforementioned laser. The laser beam to be modulated can be directly incident into the first acousto-optic modulation module 1, or indirectly incident into the first acousto-optic modulation module 1 through various intermediate elements. These intermediate elements can include various optical devices, such as lenses, polarizers, encoders, collimators, etc. In one embodiment of this application, to ensure that the beam size of the laser beam to be modulated does not change during propagation and to improve the diffraction efficiency of the acousto-optic modulator, the laser beam to be modulated can be incident into the collimator. After collimation by the collimator, the laser beam to be modulated is input into the first acousto-optic modulation module 1. It is understood that the first acousto-optic modulation module 1 can be located on the transmission path of the laser beam to be modulated. In one embodiment of this application, the first modulation signal can be a first ultrasonic signal, which can be generated using the first electro-acoustic transducer of the first acousto-optic modulation module 1. The first ultrasonic signal is generated by the first electro-acoustic transducer based on the first driving signal generated by the first driver 4. Specifically, the first acousto-optic modulation module 1 can generate the first modulation signal, such as a first ultrasonic wave, using a first electro-acoustic transducer. The first direction can be the transmission direction of the first ultrasonic wave, or it can be the direction relative to the incident direction of the first ultrasonic wave and the laser beam to be modulated. For example, in one example, such as... Figure 5 As shown, the first direction can be direction 1, direction 2, etc. In one embodiment of this application, the first acousto-optic modulation module 1 can control the first direction by controlling its relative position to the laser. Of course, in other embodiments of this application, the first acousto-optic modulation module 1 can also control the first direction of the first modulation signal by selectively activating electro-acoustic transducers located at different positions of the first acousto-optic modulator to generate first ultrasonic waves in different directions. After determining the first direction, the first acousto-optic modulation module 1 can control the first modulation signal to modulate the laser beam to be modulated along the first direction to output a diffracted beam. It is understood that during the modulation process, since the laser beam to be modulated has a certain width, the interaction time of the first modulation signal and the beam at different radial positions of the laser beam to be modulated has a certain order, that is, there is a certain time delay. Therefore, the output diffracted beam has a radial delay difference.

[0051] Similarly, the second acousto-optic modulation module 2 can also generate the second modulation signal, such as the second ultrasonic wave, using a second electro-acoustic transducer. In one embodiment of this application, the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be of the same type or different types. For example, the acousto-optic media of the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be the same or different. When the acousto-optic media are different, the propagation speed of the ultrasonic signal is different in different acousto-optic media, therefore the propagation speed of the first modulation signal and the second modulation signal are different. In one embodiment of this application, the second direction can be the transmission direction of the first ultrasonic wave. In one embodiment of this application, in order to partially or completely compensate for the time delay generated during the modulation process of the first acousto-optic modulation module 1, the second acousto-optic modulation module 2 can control the second direction of the second modulation signal, so that the second modulation signal can modulate the diffracted beam according to the second direction. In one embodiment of this application, the second acousto-optic modulation module 2 can control the second direction by controlling its relative position to the first acousto-optic modulation module 1. In one embodiment of this application, the second direction can be controlled to be opposite to the first direction. This opposite direction may include an angle greater than 90° between the first direction vector and the second direction vector of the second direction. For example, in one example, the angle between the first direction vector and the second direction vector can be 180°. According to the delay compensation principle described above, the degree of compensation for the time delay caused by the first modulation signal of the first acousto-optic modulation module 1 modulating the laser beam to be modulated is related to the propagation speeds of the first modulation signal and the second modulation signal. For example, when the propagation speeds are the same, the time delay can be fully compensated; while when the propagation speeds are different, the time delay can be partially compensated. The smaller the difference between the first and second propagation speeds, the higher the degree of compensation. Of course, in other embodiments of this application, when the angle between the first direction vector and the second direction vector is less than 180°, the degree of compensation for the time delay caused by the first modulation signal of the first acousto-optic modulation module 1 modulating the laser beam to be modulated is not only related to the propagation speed, but also to the component of the first direction decomposed to the radial direction of the beam and the component of the second direction decomposed to the radial direction of the beam. Based on this, the second acousto-optic modulation module 2 can determine the second direction according to the compensation requirements, such as the magnitude of the compensation degree. In one embodiment of this application, after determining the second direction according to the compensation requirements, the second acousto-optic modulation module 2 can control the second modulation signal to modulate the diffracted beam according to the second direction and output the modulated target diffracted beam. The target diffracted beam can be the diffracted beam modulated from the diffracted beam.

[0052] The beam delay correction method provided in this application embodiment can utilize a first acousto-optic modulation module 1 to receive a laser beam to be modulated. The first acousto-optic modulation module 1 can control a first modulation signal to modulate the laser beam to be modulated along a first direction and output a diffracted beam. Then, the diffracted beam can be input to a second acousto-optic modulation module 2, which controls a second modulation signal to modulate the diffracted beam along a second direction and output a modulated target diffracted beam. The second direction is opposite to the first direction. Since the two modulation signals act in opposite directions to the laser beam, the beam that initially contacts the modulation signal will then contact the modulation signal later when it is incident on the second acousto-optic modulation module for the second time. This compensates for the radial delay difference of the beam, thereby avoiding noise introduced by the acousto-optic modulation module during modulation and improving modulation efficiency.

[0053] Based on the working principle of an acousto-optic modulator, the modulation signal can act as an electroacoustic transducer in the form of an electrical signal, which then converts it into ultrasonic waves in the form of changing electrical signals. In one embodiment of this application, before the first acousto-optic modulation module receives the laser beam to be modulated, the method may further include:

[0054] S501: The first driver generates a first radio frequency signal and sends the first radio frequency signal to the first acousto-optic modulation module, so that the first acousto-optic modulator generates the first modulation signal based on the first radio frequency signal;

[0055] S503: The second driver generates a second radio frequency signal and sends the second radio frequency signal to the second acousto-optic modulation module, so that the second acousto-optic modulator generates the second modulation signal based on the second radio frequency signal.

[0056] In this embodiment, the first driver 4 can be a power converter that generates a first radio frequency (RF) signal based on a first-level electrical signal of a set frequency and amplitude after receiving such a signal. The first RF signal can be a modulated radio wave with a set frequency. In one embodiment, the first driver 4, categorized by its driving method, can include a constant current driver, a voltage regulator driver, a pulse driver, an AC driver, etc. This application does not limit the type of the first driver 4. In one embodiment, after receiving the first RF signal, the first acousto-optic modulation module 1 can apply the first RF signal to its first electro-acoustic transducer, enabling the transducer to generate a first ultrasonic wave, i.e., a first modulation signal, based on the first RF signal. The first ultrasonic wave can be transmitted to the acousto-optic medium of the first acousto-optic modulation module 1 to interact with the laser beam to be modulated. Similarly, the second driver 5 can also receive a second-level electrical signal of a set frequency and amplitude. The frequency and amplitude of the second-level electrical signal can be the same as or different from the first-level electrical signal. Subsequently, the second acousto-optic modulation module 2 can generate the second modulation signal according to the determination method of the first modulation signal described above, which will not be elaborated here.

[0057] In one embodiment of this application, the electrical signal received by the first driver 4 may be a signal sent by the signal generator 3. Specifically, before the first driver generates the first drive signal, the method further includes:

[0058] S601: The signal generator generates a first drive signal and a second drive signal, sends the first drive signal to the first driver, and sends the second drive signal to the second driver, so that the first driver and the second driver generate a first radio frequency signal and a second radio frequency signal, and the first drive signal and the second drive signal are output synchronously.

[0059] In this embodiment, the signal generator 3 can be a device capable of providing electrical signals of various frequencies, waveforms, and output levels. For example, it can be a device capable of generating sine waves, square waves, triangle waves, sawtooth waves, and positive and negative pulse wave signals of different frequencies and amplitudes. Specifically, the signal generator 3 can include, but is not limited to, a sine wave signal generator, a rectangular pulse signal generator, a function signal generator, and a random signal generator. The signal generator 3 can generate drive signals of different frequencies and amplitudes according to specific application requirements, and the drive signals can be electrical signals. In one embodiment of this application, the signal generator 3 can be connected to the first driver 4 and the second driver 5 respectively, to send the generated first drive signal to the first driver 4 and to generate the generated second drive signal to the second driver 5. In one embodiment of this application, the signal generator 3 can simultaneously output the first drive signal and the second drive signal to ensure that the first driver 4 and the second driver 5 simultaneously receive the drive signal and simultaneously generate the radio frequency signal, thereby avoiding unnecessary time delay differences caused by asynchronous radio frequency signals.

[0060] Of course, in other embodiments of this application, there may also be two signal generators, such as a first signal generator connected to the first driver and a second signal generator connected to the second driver, so that the driving signals of the two acousto-optic modulators can be controlled independently to independently regulate the beam.

[0061] In one embodiment of this application, the signal generator 3 can generate drive signals with different signal parameters according to specific application requirements. The signal parameters may include amplitude, frequency, waveform type, etc. Specifically, generating the first drive signal and the second drive signal may further include:

[0062] S701: The signal generator determines the input voltages of the first radio frequency signal and the second radio frequency signal based on the target diffraction efficiency, and generates the first driving signal and the second driving signal based on the input voltages.

[0063] In this embodiment, the diffraction efficiency of the acousto-optic modulation module is related to the ultrasonic power, that is, to the power of the radio frequency signal output by the driver of the acousto-optic modulation module. The power of the radio frequency signal is related to the input voltage of the driver. For example, the higher the input voltage, the higher the power of the radio frequency signal. Therefore, in one embodiment of this application, the signal generator 3 can determine the corresponding input voltage based on the target diffraction efficiency, and then send the input voltage to the first driver 4 and the second driver 5 respectively to generate the first driving signal and the second driving signal. The target diffraction power can be set by the user according to actual modulation requirements.

[0064] Based on the same inventive concept, embodiments of this application also provide a beam delay correction system, such as... Figure 6 As shown, the system 600 includes a first acousto-optic modulation module 1 and a second acousto-optic modulation module 2 connected in sequence, wherein:

[0065] The first acousto-optic modulation module 1 is used to receive the laser beam to be modulated, and control the first modulation signal to modulate the laser beam to be modulated along the first direction, and output the modulated first laser beam.

[0066] The second acousto-optic modulation module 2 is used to receive the first laser beam and control the second modulation signal to modulate the first laser beam along the second direction, and output the modulated target laser beam, wherein the second direction is opposite to the first direction.

[0067] It should be noted that the specific workflow of the beam delay correction system 600 can be referred to the steps of the beam delay correction method described in the above embodiments, and will not be repeated here.

[0068] In one embodiment of this application, in order to maximize the compensation for the time delay generated during the modulation process of the first acousto-optic modulation module 1, based on the above-mentioned compensation principle, the propagation speeds of the first modulation signal and the second modulation signal can be made the same. Specifically, the acousto-optic crystal materials of the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be made the same. The acousto-optic crystal material may include lead molybdate crystal (PM), sulfur oxide crystal, quartz crystal, antimony oxide crystal, etc. For example, in one example, the acousto-optic crystal materials of the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can both be antimony oxide crystals, which can ensure that the first modulation signal and the second modulation signal have the same propagation speed in the same acousto-optic crystal material.

[0069] In one embodiment of this application, in order to ensure that the ultrasonic fields generated by the radio frequency signals of the two acousto-optic modulation modules reach the laser beam in the same time, the distances between the laser beams input to the two acousto-optic modulation modules and the input terminals of the radio frequency signals can be made equal. Specifically, the distance between the input terminal of the first modulation signal in the first acousto-optic modulation module 1 and the laser beam to be modulated is a first distance, and the distance between the input terminal of the second modulation signal in the second acousto-optic modulation module 2 and the first laser beam is a second distance, wherein the first distance and the second distance are equal.

[0070] In one embodiment of this application, the first acousto-optic modulation module 1 and the second acousto-optic modulation module 2 can be Bragg-type acousto-optic modulators. Correspondingly, the laser beam to be modulated can be incident on the first acousto-optic modulation module 1 at a Bragg angle, and the diffracted beam can be incident on the second acousto-optic modulation module 2 at a Bragg angle.

[0071] The following specific example illustrates the beneficial effects of the beam delay correction method and system described in various embodiments of this application. For example... Figure 2 As shown, the two acousto-optic modulators can be Bragg-type free-space acousto-optic modulators. The acousto-optic medium of the first acousto-optic modulator 1 is antimony oxide, and the velocity of the first ultrasonic wave is 4.2 mm / μs. The acousto-optic medium of the second acousto-optic modulator 2 is quartz crystal, and the velocity of the second ultrasonic wave is 5.74 mm / μs. The input laser beam wavelength is 1064 nm. The laser beam is collimated light with a diameter of 1 mm, and the input light intensity is stable. The two drive signals generated by the signal generator 3 are V1 = V... 01 sin(2πft), V2=V 02 sin(2πft), the diffraction efficiency η1 of the first acousto-optic modulator 1 is related to the driving signal V1 by η1 = k1V1, and the diffraction efficiency η2 of the second acousto-optic modulator 2 is related to the driving signal V2 by η2 = k2V2, where k1 and k2 are constants. Therefore, the diffracted light intensity I1 output by the first acousto-optic modulator 1 is related to both the driving signal V1 and the input light intensity I0 by I1 = η1I0 = k1V1I0 = k1V 01 sin(2πft)I0, the target diffracted light intensity I2 output by the second acousto-optic modulator 2, the driving signal V2, and the input light intensity I0 ‘ The relationship between ' is I2=η2I0 ‘ =k2V2I0 ‘ =k2V 02 sin(2πft)I0 ‘ After the input light passes through the first acousto-optic modulator 1, the intensity of the diffracted light is I1 = k1V. 01 sin(2πft)I0; The intensity of the target diffracted light generated after the beam continues to pass through the second acousto-optic modulator 2 can be:

[0072] I2=k1V 01 k2V 02 sin 2 (2πft)I0=[k1V 01 k2V 02 I0cos(4πft)] / 2

[0073] Therefore, the final output light intensity varies with time and frequency, achieving sinusoidal modulation of the light intensity. The time required for the sound wave from the first acousto-optic modulator 1 to pass through the beam cross-section is 0.24 μs, and the time required for the sound wave from the second acousto-optic modulator 2 to pass through the beam cross-section is 0.17 μs. According to the above compensation principle, the radial cross-sectional delay difference of the final output light is 0.07 μs, which is at least 0.1 μs less than when using a single acousto-optic modulator.

[0074] 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.

[0075] 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 first acousto-optic modulation module receives a laser beam to be modulated, and controls a first modulation signal to modulate the laser beam to be modulated in a first direction, and outputs a diffracted beam; The second acousto-optic modulation module receives the diffracted beam, and controls a second modulation signal to modulate the diffracted beam in a second direction, and outputs a target diffracted beam after modulation, the second direction being opposite to the first direction; the opposite includes that the included angle between the first direction and the second direction is greater than 90°; the second direction is determined according to the compensation degree of the radial delay difference of the speed of light.

2. The method of claim 1, wherein, Before the first acousto-optic modulation module receives the laser beam to be modulated, the method further comprises: The first driver generates a first radio frequency signal, and sends the first radio frequency signal to the first acousto-optic modulation module, so that the first acousto-optic modulation module generates the first modulation signal based on the first radio frequency signal; The second driver generates a second radio frequency signal, and sends the second radio frequency signal to the second acousto-optic modulation module, so that the second acousto-optic modulation module generates the second modulation signal based on the second radio frequency signal.

3. The method of claim 2, wherein, Before the first driver generates the first radio frequency signal, the method further comprises: The signal generator generates a first driving signal and a second driving signal, sends the first driving signal to the first driver, and sends the second driving signal to the second driver, so that the first driver and the second driver generate a first radio frequency signal and a second radio frequency signal, and the first driving signal and the second driving signal are synchronously output.

4. The method of claim 3, wherein, The signal generator generates a first driving signal and a second driving signal further comprises: The signal generator determines the input voltage of the first radio frequency signal and the second radio frequency signal based on the target diffraction efficiency, and generates the first driving signal and the second driving signal based on the input voltage.

5. The method of claim 1, wherein, The included angle between the first direction and the second direction is 180 degrees.

6. A beam delay correction system characterized by, The system comprises a first acousto-optic modulation module and a second acousto-optic modulation module connected in sequence, wherein: The first acousto-optic modulation module is used to receive a laser beam to be modulated, and control a first modulation signal to modulate the laser beam to be modulated in a first direction, and output a modulated first laser beam; The second acousto-optic modulation module is used to receive the first laser beam, and control a second modulation signal to modulate the first laser beam in a second direction, and output a target laser beam after modulation, the second direction being opposite to the first direction; the opposite includes that the included angle between the first direction and the second direction is greater than 90°; the second direction is determined according to the compensation degree of the radial delay difference of the speed of light.

7. The system of claim 6, wherein, The acousto-optic crystal materials of the first acousto-optic modulation module and the second acousto-optic modulation module are the same.

8. The system of claim 6, wherein, The distance between the input end of the first modulation signal in the first acousto-optic modulation module and the laser beam to be modulated is a first distance, and the distance between the input end of the second modulation signal in the second acousto-optic modulation module and the first laser beam is a second distance, and the first distance is equal to the second distance.

9. The system of claim 6, wherein, The first acousto-optic modulation module and the second acousto-optic modulation module are Bragg acousto-optic modulators.

10. The system of claim 6, wherein, The included angle between the first direction and the second direction is 180 degrees.

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