Beam delay correction method and system

Abstract

The application relates to a light beam delay correction method and system, the method comprising: an acousto-optic modulation module receiving a laser light beam incident in a first direction and outputting diffracted light; a light beam deflection module receiving the diffracted light and deflecting the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction to compensate for the delay generated by the acousto-optic modulation module modulating the laser light beam; and 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 that can compensate for 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 acousto-optic modulation module receives a laser beam incident in a first direction and outputs diffracted light;

[0008] The beam deflection module receives the diffracted light and deflects the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction to compensate for the delay caused by the acousto-optic modulation module modulating the laser beam; the second direction is opposite to the first direction.

[0009] The various embodiments of this application provide a beam delay correction method in which the diffracted light of a laser beam modulated by an acousto-optic modulation module is used as compensation light and incident in the opposite direction onto the acousto-optic modulation module. The incident direction of the compensation light is opposite to the incident direction of the original laser beam. Therefore, the beam that initially contacts the ultrasonic wave in the original laser beam will contact the ultrasonic wave later when it is incident on the 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.

[0010] Optionally, in one embodiment of this application, before the beam deflection module receives the diffracted light and deflects the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction, the method further includes:

[0011] The controller acquires the position of the incident point of the laser beam and determines a reference position corresponding to the incident position of the incident point; the incident position is located at one end of the acousto-optic modulation module, and the reference position is located at the other end of the acousto-optic modulation module;

[0012] The controller adjusts the transmission parameters of the beam deflection module according to the reference position, so that the diffracted light received by the beam deflection module is incident on the reference position of the acousto-optic modulation module in the second direction.

[0013] Optionally, in one embodiment of this application, before the acousto-optic modulation module receives the laser beam incident in a first direction and outputs diffracted light, the method further includes:

[0014] The controller acquires a first preset position and a second preset position, which are positioned opposite each other at both ends of the acousto-optic modulation module;

[0015] The controller adjusts the laser parameters of the laser according to the first preset position, so that the laser beam emitted by the laser is incident on the first preset position of the acousto-optic modulation module in the first direction;

[0016] The controller adjusts the transmission parameters of the beam deflection module according to the second preset position, so that the diffracted light received by the beam deflection module is incident on the second preset position of the acousto-optic modulation module in the second direction.

[0017] Optionally, in one embodiment of this application, before the acousto-optic modulation module receives the laser beam incident in a first direction and outputs diffracted light, the following steps are included:

[0018] The controller acquires the beam incident angle that matches the acousto-optic modulation module;

[0019] The controller adjusts the laser parameters of the laser according to the incident angle of the beam, so that the laser beam output by the laser is incident on the acousto-optic modulation module in the first direction at the incident angle of the beam.

[0020] Optionally, in one embodiment of this application, the method further includes:

[0021] The controller acquires the frequency of the change of the driving signal in the acousto-optic modulation module, and determines the frequency of the intensity change of the modulated beam finally output by the acousto-optic modulation module based on the frequency of the driving signal.

[0022] Secondly, embodiments of this application also provide a beam delay correction system, the system comprising an acousto-optic modulation module and a beam deflection module, wherein:

[0023] The acousto-optic modulation module is used to receive a laser beam incident in a first direction and output diffracted light;

[0024] The beam deflection module is disposed on the transmission path of the diffracted light and is used to receive the diffracted light and deflect the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction to compensate for the delay caused by the acousto-optic modulation module modulating the laser beam; the second direction is opposite to the first direction.

[0025] Optionally, in one embodiment of this application, the beam deflection module includes multiple mirrors, and the diffracted light, after being reflected by the multiple mirrors, is incident on the acousto-optic modulation module in the second direction.

[0026] Optionally, in one embodiment of this application, the system further includes a collimator disposed between the laser and the acousto-optic modulation module, the collimator being used to collimate the laser beam output by the laser.

[0027] Optionally, in one embodiment of this application, the acousto-optic modulation module is a Bragg-type acousto-optic modulation module, and correspondingly, the laser is used to incident the laser beam onto the Bragg-type acousto-optic modulation module at a Bragg angle in a first direction.

[0028] Optionally, in one embodiment of this application, the transmission direction of the driving signal of the acousto-optic modulation module is perpendicular to the transmission direction of the laser beam. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the module structure of an acousto-optic modulator provided in one embodiment of this application;

[0030] Figure 2This is a schematic diagram illustrating an application scenario provided in one embodiment of this application;

[0031] Figure 3 A schematic diagram illustrating the principle of a beam delay correction method provided in one embodiment of this application;

[0032] Figure 4 A flowchart illustrating a beam delay correction method provided in this application embodiment;

[0033] Figure 5 This is a schematic diagram of an acousto-optic modulation module modulating a light beam according to an embodiment of this application;

[0034] Figure 6 A schematic diagram of a first direction provided for one embodiment of this application;

[0035] Figure 7 This is a schematic diagram illustrating the alternating incident of a laser beam and diffracted light onto an acousto-optic modulation module, as provided in one embodiment of this application.

[0036] Figure 8 This is a schematic diagram of the relationship between input voltage and diffraction efficiency provided in one embodiment of this application;

[0037] Figure 9 A system architecture diagram of a beam delay correction system provided in one embodiment of this application;

[0038] Figure 10 This is a schematic diagram of an application scenario provided in another embodiment of this application. Detailed Implementation

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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".

[0044] 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.

[0045] 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 driving source 107. When the acousto-optic modulator 100 is in operation, the driving signal emitted by the driving source 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 a diffraction phenomenon. 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.

[0046] 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.

[0047] Based on the aforementioned technical requirements, this application provides a beam delay correction method. The method uses the diffracted light from a laser beam modulated by an acousto-optic modulation module as compensation light, which is then incident on the acousto-optic modulation module in the opposite direction. The compensation light and the original laser beam are incident on the acousto-optic modulation module in opposite directions. Therefore, the beam that initially contacts the ultrasonic wave will contact it later in the second reverse incident phase, thus compensating for the radial delay difference in the beam. This avoids noise introduction during modulation by the acousto-optic modulator and improves modulation efficiency.

[0048] To better understand the embodiments of this application, the system architecture to which the embodiments of this application can be applied is described below.

[0049] like Figure 2As shown, the system architecture includes a polarization beam splitter 1, an acousto-optic modulator 2, a polarization converter 3, a polarizer 4, a first reflector 5, and a second reflector 6. The beam passing through the polarization beam splitter 1 can be a laser beam 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 polarization beam splitter 1 is disposed in 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 1 include YVO4, α-BBO, Iceland spar, etc. The acousto-optic modulator 2 is disposed in the transmission path of the polarized light and is used to modulate the polarized light. It is understood that the polarized light can be either P-beams or S-beams; in one embodiment of this application, the polarized light can be P-beams. The acousto-optic modulator 2 can modulate the polarized light based on the acousto-optic effect to output multi-order diffracted light. It is understood that the acousto-optic modulator 2 does not change the polarization state of the beam; therefore, the polarization state of the multi-order diffracted light is the same, all being P-light. In one embodiment of this application, taking the diffracted light as including 0th-order and 1st-order diffracted light as an example, the 0th-order diffracted light has the same transmission direction as the incident beam. The second reflecting mirror 6 can be disposed on the transmission path of the 0th-order diffracted light to reflect it to the first reflecting mirror 5. The 0th-order diffracted light reflected by the first reflecting mirror 5 is incident on the polarizer 4. The polarizer 4 is configured to only allow S-light to pass through; therefore, the 0th-order reflected light cannot pass through the polarizer 4. The 1st-order diffracted light can be incident on the polarization converter 3. The polarization converter 3 can change the polarization state of the beam; for example, the polarization converter 3 can be a half-wave plate, a Faraday rotator, etc. In one embodiment of this application, the polarization converter 3 is configured to convert P-light into S-light. Therefore, the first-order diffracted light is converted into S-light after passing through the polarization converter 3, smoothly passes through the polarizer 4, and then sequentially passes through the first reflector 5 and the second reflector 6 before being re-intruded into the acousto-optic modulator 2. It can be understood that the incident direction of the first-order diffracted light re-intruded into the acousto-optic modulator 2 is 180° to the incident direction of the polarized light, that is, the incident directions of the two beams are opposite to each other.

[0050] 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.

[0051] As described above, the light beam incident on the acousto-optic modulator 2 consists of two beams: one is polarized laser light, and the other is first-order diffracted light. The two beams propagate in opposite directions and are incident on the acousto-optic modulator 2 from opposite ends. Figure 3 As shown, a polarized light beam with a diameter of D passes through the aperture of the acousto-optic modulator 2 into the acousto-optic medium. A radio frequency (RF) signal generated by the driver is input to the acousto-optic modulator 2, and ultrasonic waves are generated through an electro-acoustic transducer. The ultrasonic waves propagate radially along the light beam. The intersection of the ultrasonic waves and the polarized light is the operating region of the acousto-optic modulator 2. Since the ultrasonic waves have a propagation speed in the acousto-optic medium, the time required for the ultrasonic waves to completely pass through the cross-section of the polarized light beam can be t = D / v. Here, v is the propagation speed of the ultrasonic waves, for example, 4.2 mm / μs. Therefore, for the cross-section of the polarized light beam, the beam closer to the RF signal will interact with the ultrasonic waves first, while the beam farther from the RF signal will interact with the ultrasonic waves later. This results in a time delay in modulation, which can be up to D / v. Figure 3 As shown, the x-axis is the direction of ultrasonic wave transmission, with the positive x-axis pointing towards the direction of the incident sound wave near the acousto-optic modulator 2. The position coordinate of beam 1, which is closer to the radio frequency signal, can be x1, and the time delay between beam 1 and the ultrasonic wave can be t11 = x1 / v. The coordinate of beam 2, which is farther from the radio frequency signal, can be x2, and the time delay between beam 2 and the ultrasonic wave can be t21 = x2 / v.

[0052] To compensate for the delay caused by the modulation of the acousto-optic modulator 2, such as Figure 3 As shown, the first-order diffracted light can be incident on the other end of the acousto-optic modulator 2. This causes beam points that were initially close to the radio frequency (RF) signal, such as beam 1, to move away from the RF signal, while beam points that were initially far from the RF signal, such as beam 2, will move closer to the RF signal. Thus, when the ultrasonic wave interacts with the first-order diffracted light, the time delay between beam 1 and the ultrasonic wave can be t12 = (D - x1) / v, and the time delay between beam 2 and the ultrasonic wave can be t22 = (D - x2) / v. Therefore, after passing through the acousto-optic modulator twice, the time delay generated by beam 1 can be t1 = t11 + t12 = x1 / v + (D - x1) / v = D / v, which is a constant value. The time delay generated by beam 2 can be t2 = t21 + t22 = x2 / v + (D - x2) / v = D / v, which is also a constant value. Therefore, the time delay on the cross-section of the first-order diffracted light beam can be a fixed value D / v, compensating for the difference in modulation time between the radial directions of the beam. It should be noted that the diffracted light ultimately output by the acousto-optic modulator 2 is the diffracted light of the first-order diffracted light.

[0053] 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).

[0054] 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:

[0055] S401: The acousto-optic modulation module receives a laser beam incident in the first direction and outputs diffracted light.

[0056] In this embodiment of the application, the acousto-optic modulation module can be an acousto-optic modulator, which can include a Bragg-type acousto-optic modulator or a Raman-Nice-type acousto-optic modulator. As follows... Figure 5 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 multi-order diffraction. 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 6 As shown, if the acousto-optic modulation module is located on the right side 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, that is, the output diffracted beam will have a radial delay difference.

[0057] S403: The beam deflection module receives the diffracted light and deflects the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction to compensate for the delay caused by the acousto-optic modulation module modulating the laser beam; the second direction is opposite to the first direction.

[0058] In this embodiment, the beam deflection module may include one or more optical devices that change the beam transmission direction, such as mirrors, laser deflectors, lenses, etc. The mirrors may include total reflection mirrors, semi-transparent mirrors, etc., and the lenses may include concave lenses, convex lenses, etc. The beam deflection module can change the transmission direction of the diffracted light and also change the deflection angle of the diffracted light. In one embodiment, the beam deflection module can change the transmission direction of the diffracted light so that the diffracted light can be incident on the other end of the acousto-optic modulation module in a second direction. In one embodiment, the first direction being opposite to the second direction may include an angle greater than 90° between the direction vectors of the first and second directions. For example, in one example, the angle may be 180°. According to the delay compensation principle described above, the time delay generated when the laser beam first incident on the acousto-optic modulation module can be fully compensated. Of course, in other embodiments of this application, when the angle is less than 180°, the time delay generated when the laser beam first incident on the acousto-optic modulation module can be partially compensated; the larger the angle, the better the compensation effect. Specifically, the compensation effect can be determined based on the first component decomposed from the first direction to the radial direction of the beam and the second component decomposed from the second direction to the radial direction of the beam. In one embodiment of this application, the laser beam and the diffracted light can be incident on both ends of the acousto-optic modulation module relative to each other, or they can be incident on both ends of the acousto-optic modulation module alternately. When the laser beam and the diffracted light are incident on both ends of the acousto-optic modulation module relative to each other, according to the delay compensation principle described above, the time delay can be the ratio of the beam diameter to the ultrasonic velocity. When the laser beam and the diffracted light are incident on both ends of the acousto-optic modulation module alternately, after determining the positional difference between the incident point of the laser beam and the incident point of the diffracted light, the time delay can be determined as the ratio of the sum of the beam diameter and the positional difference, i.e., t = D / v, to the ultrasonic velocity. For example, in one example, such as Figure 7As shown, the position difference can be M, and the time delay t = (D + M) / v. However, regardless of whether the laser beam and the diffracted beam are incident on the two ends of the acousto-optic modulation module opposite to each other or interleaved, as long as the laser beam and the diffracted beam are incident on the acousto-optic modulation module in opposite directions, the time delay remains a fixed value. This ensures compensation for the delay difference caused by the modulation of the acousto-optic modulation module, avoiding the introduction of noise during modulation and thus improving modulation efficiency.

[0059] The various embodiments of this application provide a beam delay correction method in which the diffracted light of a laser beam modulated by an acousto-optic modulation module is used as compensation light and incident in the opposite direction onto the acousto-optic modulation module. The incident direction of the compensation light is opposite to the incident direction of the original laser beam. Therefore, the beam that initially contacts the ultrasonic wave in the original laser beam will contact the ultrasonic wave later when it is incident on the 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.

[0060] In one embodiment of this application, the position of the diffracted light incident on the acousto-optic modulation module can be set by the modulation of the controller. Specifically, before the beam deflection module receives the diffracted light and deflects the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction, the method may further include:

[0061] S501: The controller acquires the position of the incident point of the laser beam and determines a reference position corresponding to the incident position of the incident point; the incident position is located at one end of the acousto-optic modulation module, and the reference position is located at the other end of the acousto-optic modulation module;

[0062] S503: The controller changes the transmission parameters of the beam deflection module according to the reference position, so that the diffracted light received by the beam deflection module is incident on the reference position of the acousto-optic modulation module in the second direction.

[0063] In this embodiment, the controller can be a processing device capable of data transmission and processing. The processing device can be a physical device or a cluster of physical devices, such as a terminal, a server, or a server cluster. In one embodiment, the controller can perform image processing on the image of the laser beam incident on the acousto-optic modulation obtained by the acquisition module to obtain the position of the laser beam incident point. The acquisition module can be, for example, a charge-coupled device (CCD) photosensitive element, a complementary metal-oxide-semiconductor (CMOS) photosensitive element, etc. After determining the position of the laser beam incident point, since it is necessary to control the diffracted light to be incident on the acousto-optic modulation module in a transmission direction opposite to that of the incident beam, the incident position of the diffracted light should be located at the other end of the acousto-optic modulation module. Based on this, after determining the incident position of the incident point, a reference position and position information of the diffracted light incident can be determined at the other end of the acousto-optic modulation module. The position information can be position coordinates, such as two-dimensional position coordinates. In one embodiment of this application, after determining the reference position, the controller can configure the transmission parameters of the beam deflection module according to the position information of the reference position. The transmission parameters can be the position parameters, deflection angles, etc., of each optical component in the beam deflection module. The deflection angle can be the angle between the center of the optical component and the optical axis of the laser beam or the diffracted beam. In one embodiment of this application, each optical component can be mounted on a rotational displacement device, which can be connected to a stepper motor. It is understood that each optical component can be mounted on a different rotational displacement device, or multiple optical components can be combined and mounted on the same rotational displacement device. Furthermore, the transmission parameters can also include the displacement parameters, rotation angle, rotation direction, etc., of the stepper motor. In one embodiment of this application, the controller can change the rotation angle and displacement parameters of the stepper motor according to the reference position, so that the diffracted light received by the beam deflection module can be incident on the reference position of the acousto-optic modulation module in the second direction.

[0064] Through the above embodiments, the controller can quickly and accurately determine the incident position of the diffracted light based on the incident point position of the laser beam, thereby enabling the diffracted light to be incident on the acousto-optic modulation module at an accurate incident position, thus improving the accuracy of compensating for the delay caused by the acousto-optic modulation module modulating the laser beam.

[0065] Of course, in other embodiments of this application, the controller can not only control the beam deflection module to set the incident position of the diffracted beam, but also control the laser to set the incident position of the laser beam. Specifically, before the acousto-optic modulation module receives the laser beam incident in the first direction and outputs the diffracted light, the method further includes:

[0066] S601: The controller acquires a first preset position and a second preset position, wherein the first preset position and the second preset position are positioned opposite each other at both ends of the acousto-optic modulation module;

[0067] S603: The controller changes the laser parameters of the laser according to the first preset position, so that the laser beam emitted by the laser is incident on the first preset position of the acousto-optic modulation module in the first direction;

[0068] S605: The controller adjusts the transmission parameters of the beam deflection module according to the second preset position, so that the diffracted light received by the beam deflection module is incident on the second preset position of the acousto-optic modulation module in the second direction.

[0069] In this embodiment, before the laser emits a laser beam, the controller can obtain a first preset position and a second preset position in advance. The first preset position is the predetermined incident position of the laser beam onto the acousto-optic modulation module, and the second preset position is the predetermined incident position of the diffracted light re-incidentally onto the acousto-optic modulation module. In one embodiment, the first and second preset positions can be set by the user at opposite ends of the acousto-optic modulation module according to actual application requirements; for example, the first preset position can be (2, 3), and the second preset position can be (5, 3). After determining the first preset position, the controller can adjust the laser parameters of the laser based on the first preset position and the corresponding position coordinates, so that the laser beam emitted by the laser is incident on the first preset position of the acousto-optic modulation module in the first direction. The laser parameters may include transmission direction, deflection angle, beam diameter, etc. In another embodiment, the controller can also adjust the transmission parameters of the beam deflection module based on the second preset position. The specific adjustment process can refer to the adjustment method described in the above embodiments, and will not be repeated here.

[0070] Through the above embodiments, the laser parameters and the transmission parameters can be adjusted by the controller so that the laser beam and the diffracted light can be incident on both ends of the acousto-optic modulation module at accurate relative positions, thereby improving the accuracy and stability of beam delay correction.

[0071] In practical applications, the diffracted light output by the acousto-optic modulation module can include multi-order diffracted light. To improve the intensity of the diffracted light, in one embodiment of this application, the controller can further modulate the laser parameters of the laser so that the diffracted light output after the laser beam is incident at a certain incident angle contains only 0th-order and 1st-order diffracted light, or only 0th-order and -1st-order diffracted light, thereby improving the intensity of the diffracted light. Specifically, before the acousto-optic modulation module receives the laser beam incident in the first direction and outputs the diffracted light, it includes:

[0072] S701: The controller acquires the beam incident angle that matches the acousto-optic modulation module;

[0073] S703: The controller adjusts the laser parameters of the laser according to the incident angle of the beam, so that the laser beam output by the laser enters the acousto-optic modulation module in the first direction at the incident angle of the beam.

[0074] In this embodiment, based on the modulation characteristics of the acousto-optic modulation module, when the incident angle of the laser light wave meets certain conditions, diffracted light of each order can interfere with each other within the acousto-optic medium. After the higher-order diffracted light cancels each other out, only the 0th and +1st (or -1st) order diffracted light remains, thereby improving the diffraction efficiency of the acousto-optic modulation module. This phenomenon can be called Bragg diffraction. Based on this, the controller can obtain the type of the acousto-optic modulation module and determine the beam incident angle matching that type. For example, if the acousto-optic modulation module is a Bragg acousto-optic modulation module, the beam incident angle can be the Bragg angle. In one embodiment of this application, after determining the beam incident angle, the controller can adjust the laser parameters of the laser according to the beam incident angle, so that the laser beam output by the laser is incident on the acousto-optic modulation module in a first direction at the beam incident angle. For example, the deflection angle of the laser can be adjusted so that the angle between the laser's output direction and the radial direction of the acousto-optic modulation module is the Bragg angle.

[0075] In the above embodiments, by adjusting the laser parameters of the laser, the laser beam can be incident on the acousto-optic modulation module at a required angle, so as to maximize the diffraction efficiency of the acousto-optic modulation module and maximize the diffracted light intensity.

[0076] In practical applications, the diffraction efficiency of the acousto-optic modulation module is related to the power of the ultrasonic wave, that is, 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. For example, in one example, the relationship between the diffraction efficiency of the acousto-optic modulation module and the input voltage of the driver is as follows: Figure 8 As shown, the input voltage and the diffraction efficiency are positively correlated; that is, as the input voltage increases, the diffraction efficiency also increases. Based on this, in one embodiment of this application, the change in the modulation signal finally output by the acousto-optic modulation module can be determined based on the change in the driving signal. Specifically, in one embodiment of this application, the method may further include:

[0077] S801: The controller acquires the frequency of change of the driving signal in the acousto-optic modulation module, and determines the frequency of intensity change of the modulated beam finally output by the acousto-optic modulation module based on the frequency of the driving signal.

[0078] In this embodiment, the driving signal can be a driving signal applied to the driver of the acousto-optic modulation module, such as a voltage signal, a current signal, etc. In one embodiment, the frequency of the driving signal can be a sine change, a cosine change, etc. For example, in one example, when the driving signal is a sinusoidal voltage signal with frequency f, the diffraction efficiency of the acousto-optic modulation module is also a sine function with frequency f. Moreover, since the light intensity of the first-order diffracted light of the acousto-optic modulation module is the product of the light intensity of the input beam and the diffraction efficiency, the first-order diffracted light of the acousto-optic modulation module is also a sinusoidal signal with frequency f. In one embodiment, after acquiring the frequency of the driving signal, the controller can determine the intensity change frequency of the modulated beam finally output by the acousto-optic modulation module based on the frequency of ... Since the speed of light is much faster than the speed of sound, the time difference between the two passes of the beam through the acousto-optic modulation module is negligible. It can be assumed that the driving signals when the beam passes through the acousto-optic modulation module are completely synchronized. Therefore, when a sinusoidal voltage with a frequency of f / 2 is applied to the driver, the change in the output light intensity of the system can be a sinusoidal signal with a frequency of f.

[0079] On the other hand, such as Figure 9 As shown in the figure, this application embodiment also provides a beam delay correction system, the system 900 including an acousto-optic modulation module 901 and a beam deflection module 903, wherein:

[0080] The acousto-optic modulation module 901 is used to modulate the laser beam and output diffracted light;

[0081] The beam deflection module 903 is disposed on the transmission path of the diffracted light, and is used to receive the diffracted light and deflect the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction to compensate for the delay caused by the acousto-optic modulation module modulating the laser beam; the second direction is opposite to the first direction.

[0082] In this embodiment, the acousto-optic modulation module 901 can modulate the laser beam based on the acousto-optic effect to output diffracted light. The laser beam can be generated by a laser, which can include various types. For example, according to the working substance, 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. In one embodiment of this application, in order to ensure that the laser beam size 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 901, 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.

[0083] In this embodiment, the acousto-optic modulation module 901 can be of various types. Taking a Bragg-type acousto-optic modulation module as an example, to improve the diffraction efficiency of the Bragg-type acousto-optic modulation module, the relative position of the Bragg-type acousto-optic modulation module 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 modulation module is the Bragg angle. Thus, the laser beam can be incident on the Bragg-type acousto-optic modulation module in a first direction at the Bragg angle. Based on this, the diffracted light output by the Bragg-type acousto-optic modulation module can contain only 0th-order diffracted light and 1st-order diffracted light (-1st-order diffracted light).

[0084] In this embodiment, the beam deflection module 903 can receive the diffracted light and deflect its transmission direction. The beam deflection module 903 may include multiple mirrors, and the diffracted light, after being reflected by these mirrors, is incident on the acousto-optic modulation module 901 in the second direction. The specific structure and operation of the beam deflection module 903 are illustrated below with two concrete examples.

[0085] In Example 1, such as Figure 2 As shown, the beam deflection module 903 may include a polarization converter 3, a polarizer 4, a first reflector 5, and a second reflector 6. The first-order diffracted light output from the acousto-optic modulator 2, after its polarization direction is changed by the polarization converter 3, is incident on the polarizer 4. During this process, the angle of the transmission axis of the polarizer 4 can be adjusted to maximize the output light. Subsequently, the first-order diffracted light can pass sequentially through the first reflector 5 and the second reflector 6, re-injecting into the acousto-optic modulator 2 in a direction opposite to that of the laser beam.

[0086] In Example 2, such as Figure 10 The beam deflection module 903 may include a polarization beam splitter 13, a half-wave plate 14, a first reflector 15, a second reflector 16, and a third reflector 17. In one embodiment of this application, the 0th-order diffracted light generated by the acousto-optic modulator 11 can be incident on the optical trash can 12 and then collected. The 1st-order diffracted light can be incident sequentially on the polarization beam splitter 13 and the half-wave plate 14. Then, the optical axis angle of the half-wave plate 14 can be adjusted so that the polarization state of the outgoing light from the half-wave plate 14 is rotated by 90 degrees from that at the time of incident. Finally, the 1st-order diffracted light passes through the three reflectors in sequence. By reasonably adjusting the angle of the reflectors, the beam can pass through the polarization beam splitter 13 again and be incident in the opposite direction on the acousto-optic modulator 11, where it will diffract.

[0087] It should be noted that the beam deflection module 903 is not limited to the above examples. Any module that can deflect the beam and re-incidentally onto the other end of the acousto-optic modulation module 901 is within the protection scope of this application.

[0088] 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.

[0089] 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 for beam delay correction, characterized in that, The method includes: The acousto-optic modulation module receives a laser beam incident in a first direction and outputs diffracted light; The beam deflection module receives the first-order diffracted light from the diffracted light and deflects the transmission direction of the first-order diffracted light so that the first-order diffracted light is incident on the acousto-optic modulation module in a second direction, so as to compensate for the radial delay difference caused by the acousto-optic modulation module modulating the laser beam through the modulation of the first-order diffracted light by the acousto-optic modulation module; the second direction is opposite to the first direction; the first-order diffracted light is either a +1st-order diffracted light or a -1st-order diffracted light.

2. The method according to claim 1, characterized in that, Before the beam deflection module receives the diffracted light and deflects the transmission direction of the diffracted light so that the diffracted light is incident on the acousto-optic modulation module in a second direction, the method further includes: The controller acquires the position of the incident point of the laser beam and determines a reference position corresponding to the incident position of the incident point; the incident position is located at one end of the acousto-optic modulation module, and the reference position is located at the other end of the acousto-optic modulation module; The controller adjusts the transmission parameters of the beam deflection module according to the reference position, so that the diffracted light received by the beam deflection module is incident on the reference position of the acousto-optic modulation module in the second direction.

3. The method according to claim 1, characterized in that, Before the acousto-optic modulation module receives the laser beam incident in a first direction and outputs diffracted light, the method further includes: The controller acquires a first preset position and a second preset position, which are positioned opposite each other at both ends of the acousto-optic modulation module; The controller adjusts the laser parameters of the laser according to the first preset position, so that the laser beam emitted by the laser is incident on the first preset position of the acousto-optic modulation module in the first direction; The controller adjusts the transmission parameters of the beam deflection module according to the second preset position, so that the diffracted light received by the beam deflection module is incident on the second preset position of the acousto-optic modulation module in the second direction.

4. The method according to claim 1, characterized in that, Before the acousto-optic modulation module receives the laser beam incident in a first direction and outputs diffracted light, it includes: The controller acquires the beam incident angle that matches the acousto-optic modulation module; The controller adjusts the laser parameters of the laser according to the incident angle of the beam, so that the laser beam output by the laser is incident on the acousto-optic modulation module in the first direction at the incident angle of the beam.

5. The method according to claim 1, characterized in that, The method further includes: The controller acquires the frequency of the change of the driving signal in the acousto-optic modulation module, and determines the frequency of the intensity change of the modulated beam finally output by the acousto-optic modulation module based on the frequency of the driving signal.

6. A beam delay correction system, characterized in that, The system includes an acousto-optic modulation module and a beam deflection module, wherein: The acousto-optic modulation module is used to receive a laser beam incident in a first direction and output diffracted light; The beam deflection module is positioned on the transmission path of the first-order diffracted light in the diffracted light. It is used to receive the first-order diffracted light and deflect its transmission direction so that the first-order diffracted light is incident on the acousto-optic modulation module in a second direction. The modulation of the first-order diffracted light by the acousto-optic modulation module compensates for the radial delay difference generated by the modulation of the laser beam by the acousto-optic modulation module. The second direction is opposite to the first direction. The first-order diffracted light is either a +1st-order diffracted light or a -1st-order diffracted light.

7. The system according to claim 6, characterized in that, The beam deflection module includes multiple mirrors. After being reflected by the multiple mirrors, the diffracted light is incident on the acousto-optic modulation module in the second direction.

8. The system according to claim 6, characterized in that, The system also includes a collimator disposed between the laser and the acousto-optic modulation module, the collimator being used to collimate the laser beam output by the laser.

9. The system according to claim 6, characterized in that, The acousto-optic modulation module is a Bragg-type acousto-optic modulation module, and the laser beam is incident on the Bragg-type acousto-optic modulation module at a Bragg angle in a first direction.

10. The system according to claim 6, characterized in that, The transmission direction of the driving signal of the acousto-optic modulation module is perpendicular to the transmission direction of the laser beam.

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