A light field conversion device and method based on an acousto-optic deflector

Abstract

This invention discloses an optical field transformation device and method based on an acousto-optic deflector. The device includes: a pulsed laser arranged along the optical path, two acousto-optic deflection modules, a signal synchronization control unit, a vector optical field transformation module, a reflective spatial light modulator, and a focusing lens; the pulsed laser outputs linearly polarized light; the signal synchronization control unit simultaneously controls the first and second acousto-optic deflection modules to load radio frequency signals of the same frequency; the first acousto-optic deflection module deflects the linearly polarized light to obtain a first deflected beam, the deflection angle being determined by the radio frequency signal frequency; the vector optical field transformation module converts the linearly polarized light into radial, angular, or higher-order vector light, and reflects or refracts it to obtain a second deflected beam; the second acousto-optic deflection module re-integrates the second deflected beam into the main optical path, and after passing through the reflective spatial light modulator and focusing lens, obtains a processing beam, which acts on the processing component. This achieves efficient and precise transformation of the optical field type.

Description

Technical Field

[0001] This invention belongs to the field of laser micro-nano fabrication technology, and more specifically, relates to an optical field conversion device and method based on an acousto-optic deflector. Background Technology

[0002] Since the invention of the laser in the 1860s, laser technology has been widely applied in industry, science, and the military over the past half-century. With the surge in demand for small electronic products and microelectronic components, traditional manufacturing methods are far from meeting the precision manufacturing needs of delicate parts (such as semiconductor chips). Compared to traditional mechanical micromachining, laser processing is non-contact, eliminating tool wear, significant mechanical force, and deformation. Therefore, laser micro / nano fabrication has become one of the fastest-growing areas of laser application in industry.

[0003] Traditional laser beams typically have a Gaussian cross-sectional profile. In such cases, processing these special shapes using ultrafast laser direct writing technology requires point scanning, which is time-consuming and inconvenient to adjust. Multi-focus parallel processing can significantly shorten processing time, and Bessel beams allow for convenient adjustment of the radial and axial intensity distribution. When the microstructure's profile becomes very small, the required laser beam focusing spot diameter becomes extremely critical. The spot diameter of Gaussian linearly polarized light is generally far from meeting these requirements, while radially polarized light, after tight focusing, has a pure longitudinal electric field component, enabling super-diffraction-limited focusing and thus obtaining a smaller spot. Furthermore, due to the varying structural morphology and processing requirements of the parts being processed, different processing areas of the same part often require different optical fields to complete the manufacturing process, posing new challenges to laser micro / nano manufacturing, such as higher processing efficiency and cross-scale processing.

[0004] Therefore, traditional laser micro-nano processing suffers from technical problems such as a single optical field form, complex optical field conversion, poor processing quality, and low processing efficiency. Summary of the Invention

[0005] In view of the shortcomings of related technologies, the purpose of this invention is to provide an optical field transformation device and method based on an acousto-optic deflector, which aims to solve the problems of single optical field form, complex optical field transformation, poor processing quality and low processing efficiency in traditional laser micro-nano processing.

[0006] To achieve the above objectives, in a first aspect, the present invention provides an optical field conversion device based on an acousto-optic deflector, comprising: a pulsed laser, two acousto-optic deflection modules, a signal synchronization control unit, a vector optical field conversion module, a reflective spatial light modulator, and a focusing lens arranged sequentially along the optical path;

[0007] The pulsed laser is used to output linearly polarized light, which is transmitted along the main optical path and injected into the first acousto-optic deflection module;

[0008] The signal synchronization control unit simultaneously controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency.

[0009] The first acousto-optic deflection module is used to deflect the outgoing light direction of the linearly polarized light to obtain a first deflected beam, which enters the deflection optical path. The magnitude of its deflection angle is determined by the frequency of the radio frequency signal.

[0010] The vector light field transformation module is used to transform the first deflected beam from linearly polarized light into radial, angular, or higher-order vector light, and to reflect or refract it to obtain a second deflected beam that enters the second acousto-optic deflection module.

[0011] The second acousto-optic deflection module is used to re-integrate the second deflected beam into the main optical path, and then, after being reflected by the reflective spatial light modulator and converged by the focusing lens, obtain the processing beam, which acts on the processing component.

[0012] Optionally, the vector light field transformation module includes an S-slide and a plane mirror;

[0013] The S-slide is used for light field transformation, converting the light field of the first deflected beam from linearly polarized light into a radial, angular, or higher-order vector light field. The plane mirror is used to reflect the transformed first deflected beam to obtain a second deflected beam, which is then injected into the second acousto-optic deflection module.

[0014] Optionally, the number of S-slides and plane mirrors are equal, and each is greater than or equal to 1;

[0015] Each S-slide corresponds to a plane mirror and belongs to the same deflection optical path;

[0016] The signal synchronization control unit controls the first acousto-optic deflection module to load different radio frequency signal frequencies through a drive signal, so that the first deflection beam enters the corresponding deflection optical path; wherein, the signal synchronization control unit controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency, and the deflection angle of the second deflection beam is the same as the deflection angle of the first deflection beam.

[0017] Optionally, the angle Δθ between the Nth deflection optical path and the first deflection optical path satisfies Where N is greater than or equal to 2; where λ0 represents the wavelength of the incident laser, and n and V s f represents the refractive index and internal sound velocity of the acousto-optic medium in the first acousto-optic deflection module, respectively. s This indicates the frequency of the radio frequency signal.

[0018] Optionally, the vector light field transformation module is a wedge-shaped light field transformation mirror; the wedge-shaped light field transformation mirror includes different etching areas, the etching areas are etched with different grating patterns, the arrangement direction of the etching areas is consistent with the scanning direction of the first acousto-optic deflection module and the second acousto-optic deflection module, the wedge-shaped light field transformation mirror is used to transform the first deflected beam from linearly polarized light into radial, angular or higher-order vector light when it passes through the etching area, refract it to obtain a second deflected beam, and then enter the second acousto-optic deflection module.

[0019] Optionally, both the first and second acousto-optic deflection modules include two acousto-optic deflectors placed perpendicular to each other, and the acousto-optic deflectors in the first and second acousto-optic deflection modules are arranged symmetrically about the center.

[0020] The etching region array arrangement of the wedge-shaped optical field transformation mirror;

[0021] The synchronization control unit includes multiple output channels, with each pair of output channels forming a group, which respectively output drive signals to the first acousto-optic deflection module and the second acousto-optic deflection module, so that the radio frequency signals loaded on the two symmetrically arranged acousto-optic deflectors have the same frequency.

[0022] The first acousto-optic deflection module is used to deflect the direction of the emitted linearly polarized light and diffract it to obtain a first deflected beam. The first deflected beam passes through a certain etched area in the wedge-shaped optical field transformation mirror.

[0023] Optionally, the optical field conversion device further includes a beam expander and collimator, a motion controller, and a central control unit;

[0024] The beam expanding and collimating device is disposed between the pulsed laser and the first acousto-optic deflection module, and is used to collimate and expand the linearly polarized light to generate parallel light.

[0025] The processing component is fixedly mounted on the motion controller and moves with the motion controller.

[0026] The central control unit stores the processing data of the processing component in advance. The central control unit is connected to the motion controller and the signal synchronization control unit. It is used to control the motion direction of the motion controller according to the processing data, and to control the signal synchronization control unit to send drive signals to the first and second acousto-optic deflection modules so that they are loaded with the corresponding radio frequency signal frequency to perform the pre-set processing program.

[0027] Optionally, when the signal synchronization control unit does not apply a driving signal to the first acousto-optic deflection module and the second acousto-optic deflection module, the reflective spatial light modulator is connected to the central control unit.

[0028] The linearly polarized light reaches the reflective spatial light modulator along the main optical path. The reflective spatial light modulator is used to apply different voltages according to the control signal of the central control unit to modulate the amplitude or phase of the linearly polarized light in different ways, and reflect and output different types of scalar light fields.

[0029] Optionally, the light field transformation device further includes a motor, which is connected to the plane mirror in the vector light field transformation module;

[0030] When the synchronous control unit controls the first and second acousto-optic deflection modules to load different radio frequency signal frequencies through the drive signal, the motor drives the plane mirror to rotate according to the control signal of the central control unit. The plane mirror changes its deflection angle when reflecting the first deflected beam to obtain the second deflected beam. The second deflected beam is then re-integrated into the main optical path through the second acousto-optic deflection module.

[0031] In a second aspect, the present invention also provides a light field transformation method based on an acousto-optic deflector, applied to any of the light field transformation devices based on an acousto-optic deflector as described in the first aspect, comprising:

[0032] Based on pre-stored data on the movement of processing components and the types of light fields required for different parts during the processing, the central control unit sends corresponding control signals to the signal synchronization control unit, the reflective spatial light modulator, and the motion controller.

[0033] The signal synchronization control unit simultaneously controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency.

[0034] The linearly polarized light output from the pulsed laser is generated into parallel light by the beam expander and collimator along the main optical path and then enters the first acousto-optic deflection module, where it is deflected to obtain the first deflected beam.

[0035] The vector light field transformation module transforms the first deflected beam from linearly polarized light into radial, angular, or higher-order vector light, and then reflects or refracts it to obtain a second deflected beam.

[0036] The second deflected beam enters the second acousto-optic deflection module and is re-integrated into the main optical path to obtain the processing beam.

[0037] The processing beam, after being reflected by a reflective spatial light modulator and focused by a focusing lens, acts on the processing component that moves with the motion controller.

[0038] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0039] 1. This invention provides an optical field conversion device based on an acousto-optic deflector. It utilizes the ultra-high scanning speed of two acousto-optic deflection modules. The first acousto-optic deflection module deflects parallel linearly polarized light at a certain angle. The vector optical field conversion module converts linearly polarized light into radial, angular, or higher-order vector light, meeting the needs of rapid optical field conversion. The second acousto-optic deflection module re-integrates the converted optical field beam into the main optical path to obtain the processed beam, achieving output from the same output end. The combination of the acousto-optic deflector and the vector optical field conversion module enables efficient and precise control of optical field type conversion. The vector optical field conversion module uses an S-plate and a plane mirror combination, or a wedge-shaped optical field conversion mirror, resulting in a simple structure and reliable output.

[0040] 2. The present invention provides an optical field conversion device based on an acousto-optic deflector. A signal synchronization control unit controls different radio frequency signal frequencies of the first acousto-optic deflection module, causing linearly polarized light to deflect at different angles. The first deflected beam enters the corresponding deflection optical path. The first and second acousto-optic deflection modules are loaded with radio frequency signals of the same frequency, resulting in the same deflection angle. Corresponding processing beams are generated for different needs. The optical field conversion device also includes a motion controller. The central control unit controls the movement direction of the motion controller, enabling rapid matching of different processing areas to the required optical field. This allows for flexible processing of micro / nano structures and improves processing efficiency and accuracy.

[0041] 3. This invention provides a light field conversion device based on an acousto-optic deflector. When the signal synchronization control unit is off, different voltages are applied to the reflective spatial light modulator through the control signal of the central control unit, modulating the amplitude or phase of the linearly polarized light in different ways, transforming Gaussian linearly polarized light into flat-top, array, Bessel, and other light fields. When the signal synchronization control unit is working, it can also be transformed into radial, angular, or higher-order vector light fields. That is, multiple light field transformations can be realized at the system output to adapt to various processing conditions.

[0042] 4. The optical field transformation device based on acousto-optic deflectors provided by the present invention uses two acousto-optic deflectors placed perpendicularly to each other in both the first and second acousto-optic deflection modules. The first and second acousto-optic deflection modules are controlled by four channels of the signal synchronization control unit, with each pair of channels forming a group. The output frequency of each group of channels can be the same or different as needed to ensure that the frequency signal applied by the parallel acousto-optic deflectors is the same. By cooperating with multiple acousto-optic deflectors and different types of gratings etched in different etched areas on the wedge-shaped optical field transformation mirror, rapid transformation of the optical field in a two-dimensional plane can be achieved, meeting more vector optical field transformation requirements. Attached Figure Description

[0043] Figure 1This is a schematic diagram of the structure of an optical field conversion device based on an acousto-optic deflector provided by the present invention;

[0044] Figure 2 This is a schematic diagram of the acousto-optic deflection module in this invention;

[0045] Figure 3 This is a schematic diagram of another optical field conversion device based on an acousto-optic deflector provided by the present invention;

[0046] Figure 4 This is a schematic diagram of linearly polarized light passing through S-plates with different rotation directions in an embodiment of the present invention, wherein (a) is radially polarized light and (b) is angularly polarized light;

[0047] Figure 5 This is a schematic diagram of another optical field conversion device based on an acousto-optic deflector provided by the present invention;

[0048] Figure 6 These are three views of the wedge-shaped light field transformation mirror provided in an embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of the structure of the reflective liquid crystal spatial light modulator in an embodiment of the present invention;

[0050] Figure 8 This is a schematic diagram of another optical field conversion device based on an acousto-optic deflector provided by the present invention;

[0051] Figure 9 These are three views of the wedge-shaped light field transformation mirror provided in an embodiment of the present invention.

[0052] In the diagram: 1. Pulsed laser; 2. Beam expander and collimator; 3. Acousto-optic deflection module; 4. Signal synchronization control unit; 5. Vector light field conversion device; 6. Reflective spatial light modulator; 7. Focusing lens; 8. Processing component; 9. Motion controller; 10. Central control unit; 31. First acousto-optic deflection module; 32. Second acousto-optic deflection module; 51. First S-slide; 52. First plane mirror; 53. Second S-slide; 54. Second... 55. Plane mirror, wedge-shaped light field transformation mirror, 301. Drive signal source, 302. Electroacoustic transducer, 303. Acousto-optic medium, 304. Sound absorption device, 311. First acousto-optic deflector, 312. Second acousto-optic deflector, 321. Third acousto-optic deflector, 322. Fourth acousto-optic deflector, 601. Glass layer, 602. Transparent electrode, 603. Alignment film, 604. Liquid crystal layer, 605. Reflective layer, 606. Control electrode. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0054] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0055] Example 1

[0056] like Figure 1 As shown, an optical field conversion device based on an acousto-optic deflector includes: a pulsed laser 1, a beam expander and collimator 2, two acousto-optic deflection modules (31 and 32) arranged sequentially along the optical path, a signal synchronization control unit 4, a vector optical field conversion module 5, a reflective spatial light modulator 6, and a focusing lens 7.

[0057] The pulsed laser 1 is used to output linearly polarized light, which is transmitted along the main optical path and injected into the first acousto-optic deflection module 31.

[0058] The signal synchronization control unit 4 simultaneously controls the first acoustic-optic deflection module 31 and the second acoustic-optic deflection module 32 to load radio frequency signals of the same frequency.

[0059] The first acousto-optic deflection module 31 is used to deflect the direction of the outgoing parallel light to obtain a first deflected beam, which enters the deflection optical path. The magnitude of its deflection angle is determined by the frequency of the radio frequency signal.

[0060] The vector light field transformation module 5 is used to transform the first deflected beam from linearly polarized light into radial, angular or higher-order vector light, and to reflect or refract it to obtain a second deflected beam that enters the second acousto-optic deflection module 32.

[0061] The second acousto-optic deflection module 32 is used to re-integrate the second deflected beam into the main optical path, and then, after being reflected by the reflective spatial light modulator 6 and converged by the focusing lens 7, obtain the processing beam, which acts on the processing component 8.

[0062] Optionally, the optical field conversion device further includes a beam expander and collimator 2, a motion controller 9, and a central control unit 10;

[0063] The beam expanding and collimating device 2 is disposed between the pulsed laser 1 and the first acousto-optic deflection module 31, and is used to collimate and expand the linearly polarized light to generate parallel light.

[0064] The processing component 8 is fixedly mounted on the motion controller 9 and moves with the motion controller 9;

[0065] The central control unit 10 stores the processing data of the processing component 8 in advance. The central control unit 10 is connected to the motion controller 9 and the signal synchronization control unit 4. It is used to control the movement direction of the motion controller 9 according to the processing data, and to control the signal synchronization control unit 4 to send drive signals to the first acoustic-optical deflection module 31 and the second acoustic-optical deflection module 32 so that they are loaded with the corresponding radio frequency signal frequency to perform the pre-set processing program.

[0066] After the linearly polarized light is expanded and collimated by the beam expander and collimator 2, the diameter of the parallel light beam is about 6mm. The aperture of the focusing lens 7 is generally between 30mm and 50mm. The size of the processing part 8 is 20mm*20mm. The accuracy of the motion controller 9 is at the μm level.

[0067] Both the acousto-optic deflection modules (31 and 32) employ acousto-optic deflectors. The acousto-optic deflector includes a drive signal source 301, an electroacoustic transducer 302, an acousto-optic medium 303, and a sound absorption device 304. The electroacoustic transducer 302 is a layer of metal sheet attached to the surface of the acousto-optic medium 303, and the electrode layers at both ends of the piezoelectric layer therein are connected to the drive signal source 301. When the acousto-optic deflector is working, the drive signal source 301 can output radio frequency signals of different frequencies, realizing the conversion of electromechanical motion at the position of the electroacoustic transducer 302, thereby generating ultrasonic waves in the acousto-optic medium 303, causing the refractive index of the acousto-optic medium 303 to change.

[0068] refer to Figure 2 The driving signal source 301 transmits radio frequency signals to the acousto-optic deflection module 3 to control the acousto-optic interaction within the module 3. The electroacoustic transducer 302 is a metal sheet attached to the surface of the acousto-optic interaction medium. The electrode layers at both ends of the piezoelectric layer in the electroacoustic transducer 302 are connected to the driving signal source 301 to convert electrical signals into ultrasonic signals in the acousto-optic medium 303, forming an ultrasonic volume grating. When the light wave passes through the acousto-optic medium 303, the optical carrier is modulated due to the acousto-optic interaction, becoming an intensity-modulated wave carrying information. The sound absorption device 304 prevents the sound wave from reflecting back along its original path and affecting the wavefront. In one embodiment, the acousto-optic medium 303 is made of tellurium dioxide or quartz crystal, the electroacoustic transducer 302 is made of lithium niobate crystal, and the frequency range of the radio frequency signal output by the driving signal source 301 is 59MHz to 91MHz, so that the scanning angle is in the range of 6.4mrad to 9.5mrad.

[0069] The first acoustic-optic deflection module 31 and the second acoustic-optic deflection module 32 use the same type of acoustic-optic deflector, and deflect the light beam at the same angle according to the control signal of the signal synchronization control unit 4.

[0070] refer to Figure 3 In this embodiment, the vector light field transformation device 5 is composed of several S-glass plates and a plane mirror; the S-glass plates are used for light field transformation, transforming the light field of the first deflected beam from linearly polarized light into a radial, angular, or higher-order vector light field; the plane mirror reflects the transformed first deflected beam to obtain a second deflected beam, which is then injected into the second acousto-optic deflection module.

[0071] Optionally, the number of S-slides and plane mirrors are equal, and each is greater than or equal to 1;

[0072] Each S-slide corresponds to a plane mirror and belongs to the same deflection optical path;

[0073] The signal synchronization control unit 4 controls the first acousto-optic deflection module 31 to load different radio frequency signal frequencies through a drive signal, so that the first deflection beam enters the corresponding deflection optical path; wherein, the signal synchronization control unit 4 controls the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 to load radio frequency signals of the same frequency, and the deflection angle of the second deflection beam is the same as the deflection angle of the first deflection beam.

[0074] For example, such as Figure 3 As shown, multiple deflection optical paths are included. Taking the two deflection optical paths shown as examples, they are the first deflection optical path and the second deflection optical path, respectively. The first S-slide 51 and the first plane mirror 52 belong to the first deflection optical path, and the second S-slide 53 and the second plane mirror 54 belong to the second deflection optical path. Further, as... Figure 3 As shown, based on multiple deflection optical paths (not shown), the vector light field transformation module can transform the first deflection beam into higher-order vector light other than angular and radial polarized light.

[0075] Furthermore, depending on the relative position of the linearly polarized light and the S-plate, the S-plate converts the first deflected beam into radially or angularly polarized light. For example, refer to... Figure 4 In (a) and (b), as Figure 4 As shown in (a), when the polarization direction of the linearly polarized light is parallel to the alignment mark 501 of the first S-plate 51, the first S-plate 51 can transform the optical field of the first deflected beam from a Gaussian type to a vector optical field of radially polarized light; as Figure 4 As shown in (b), when the polarization direction of the linearly polarized light is perpendicular to the alignment mark 502 of the second S-plate 53, the second S-plate 53 can transform the light field of the first deflected beam from Gaussian type to the vector light field of angularly polarized light.

[0076] like Figure 3As shown, the central control unit 10 controls the signal synchronization control unit 4 to send drive signals to the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 to load the corresponding radio frequency signal frequency; after the parallel light is deflected by a preset angle by the first acousto-optic deflection module 31, a first deflected beam is obtained and enters the deflection optical path; the plane mirror reflects the first deflected beam into the second acousto-optic deflection module 32. Since the deflection angle of the second deflected beam is the same as that of the first deflected beam, the second deflected beam re-enters the main optical path to obtain the processing beam; after being reflected by the spatial light modulator and converged by the focusing lens, the processing beam acts on the processing component; the central control unit 10 controls the movement direction of the motion controller 9 to drive the processing component 8 to move.

[0077] The central control unit 10 outputs control signals to the signal synchronization control unit 4 and the motion controller 9 respectively according to the pre-stored processing data, so as to perform the pre-set processing program and perform the preset processing operation on the processing part 8.

[0078] refer to Figure 3 Optionally, the angle Δθ between the Nth deflection optical path and the first deflection optical path satisfies Where N is greater than or equal to 2; where λ0 represents the wavelength of the incident laser, and n and V s f represents the refractive index and internal sound velocity of the acousto-optic medium in the first acousto-optic deflection module, respectively. s This indicates the frequency of the radio frequency signal.

[0079] The signal synchronization control unit 4 controls the frequency of the radio frequency signal output by the drive signal source 301 to be f. s At that time, the beam travels along the first deflection optical path, reference... Figure 4 In (a), linearly polarized light becomes radially polarized light after passing through the S-glass slide 51; the signal synchronization control unit 4 controls the frequency of the radio frequency signal output by the drive signal source 301 to be f. s +Δf s At that time, the beam travels along the second deflection optical path, reference... Figure 4 In (b), linearly polarized light becomes angularly polarized light after passing through the S-plate 53. The central control unit 10 controls the signal synchronization control unit 4, thereby controlling the frequency of the radio frequency signal output by the drive signal source 301, thus determining whether the output beam is radially polarized or angularly polarized.

[0080] In this embodiment, when the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 are in working state, that is, when the deflection angle is not zero, the reflected light is turned off by the spatial light modulator 6, which is used only as a reflector and outputs the processed beam after the light field change.

[0081] In an alternative embodiment, if neither the signal synchronization control unit 4 nor the reflective spatial light modulator 6 is working, the beam is focused along the main optical path by the focusing lens 7 onto the processing component 8, and the system outputs a Gaussian beam.

[0082] Based on the above embodiments, optionally, the light field transformation device further includes: a motor (not shown), the motor being connected to the plane mirror in the vector light field transformation module 5;

[0083] When the synchronous control unit 4 controls the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 to load different radio frequency signal frequencies through the drive signal, the motor is used to drive the plane mirror to rotate according to the control signal of the central control unit 10. The plane mirror is used to change its deflection angle when reflecting the first deflection beam to obtain the second deflection beam. The second deflection beam is then re-integrated into the main optical path through the second acousto-optic deflection module 32.

[0084] When the synchronous control unit 4 independently applies different frequency signals to the first acoustic-optic deflection module 31 and the second acoustic-optic deflection module 32, the angle of the first deflection beam is different according to the different frequencies applied by the first acoustic-optic deflection module 31 and the second acoustic-optic deflection module 32. It is necessary to drive the plane mirror to rotate by the motor to compensate for the frequency difference, so that the second deflection beam can also achieve the same optical path for output and input after passing through the second acoustic-optic deflection module 32.

[0085] This invention, through the use of two identical acousto-optic deflection modules, both controlled by a signal synchronization control unit, combined with a vector light field transformation module, can generate radially and angularly polarized light in space and time, meeting the needs of special processing. The acousto-optic deflection module features ultra-high scanning speed, while the vector light field transformation module can convert linearly polarized light into radial, angular, or higher-order vector light. Their combination satisfies the need for rapid light field transformation. By rationally arranging the positions of the acousto-optic deflection module and the vector light field transformation module, a device for rapid light field conversion is formed. This solves the problems of single light field form, complex light field conversion, poor processing quality, and low processing efficiency in traditional laser micro-nano processing, achieving the beneficial effects of easy assembly and meeting the needs of special processing. Furthermore, the vector light field transformation module uses a combination of an S-slide and a plane mirror, or a wedge-shaped light field transformation mirror, resulting in a simple structure and reliable output.

[0086] Example 2

[0087] Based on Embodiment 1, this embodiment further improves the vector light field transformation device 5. The vector light field transformation device 5 adopts a wedge-shaped light field transformation mirror, making the overall system more compact.

[0088] refer to Figure 5 and Figure 6 The S-slide and plane mirror combination in the vector light field transformation device 5 are replaced with a wedge-shaped light field transformation mirror 55. Similarly, the vector light field transformation device 5 contains multiple wedge-shaped light field transformation mirrors 55. Figure 5 The following explanation uses a wedge-shaped optical field transforming mirror 55 as an example. The wedge-shaped optical field transforming mirror 55 is a wedge-shaped fused silica glass with different grating patterns etched on it. It includes different etched areas, each with a different grating pattern. The etched areas are kept at a certain distance and arranged parallel to each other along the length of the glass, which can transform linearly polarized light into radial, angular, or higher-order vector light when it passes through the etched areas.

[0089] refer to Figure 6 The etching area arrangement direction of the wedge-shaped optical field transformation mirror 55 is consistent with the scanning direction of the first acousto-optic deflection module and the second acousto-optic deflection module.

[0090] When the acousto-optic deflection module is working, the signal synchronization control unit 4 controls the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 to load different radio frequency signal frequencies through the drive signal, and the diffracted beam passes through different etched areas on the wedge-shaped optical field transformation mirror 55.

[0091] In an alternative embodiment, the wedge-shaped light field transformation mirror 55 may also be a combination of two wedge-shaped S-plates of different thicknesses. (See reference...) Figure 5 The wedge-shaped light field transformation mirror 55 has a certain angle, which can refract the first deflected beam output by the first acousto-optic deflection module 31 into the second acousto-optic deflection module at the same angle.

[0092] refer to Figure 5 In this embodiment, the combination of the first acousto-optic deflection module 31, the second acousto-optic deflection module 32 and the wedge-shaped light field conversion mirror 55 can quickly switch the optical path. The wedge-shaped light field conversion mirror 55 can not only perform the function of light field conversion, but also refract the diffracted beam and then merge it into the main optical path. The structure is simple.

[0093] In application, similar to the light field transformation method in Embodiment 1, when neither the signal synchronization control unit 4 nor the reflective liquid crystal spatial light modulator 6 is working, the light beam is focused by the focusing lens 7 along the main light path onto the processing component 8, and the system outputs a Gaussian light beam at this time. When the central control unit 10 sends a command to the signal synchronization control unit 4 to make the drive signal source 301 output a radio frequency signal, different radio frequency signal frequencies can change the diffraction angle of the first deflection beam output by the first acousto-optic deflection module 31, so that the first deflection beam enters different etching areas of the wedge-shaped light field transformation mirror 55, thereby obtaining radial, angular or higher-order vector light, and after being refracted by the wedge-shaped light field transformation mirror 55, it enters the second acousto-optic deflection module and then merges into the main light path. At this time, the system output can output radial, angular or higher-order vector light.

[0094] Example 3

[0095] Based on the above embodiments, further, when the signal synchronization control unit 4 does not apply a driving signal to the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32, the reflective spatial light modulator 6 is connected to the central control unit 10.

[0096] The linearly polarized light reaches the reflective spatial light modulator 6 along the main optical path. The reflective spatial light modulator 6 is used to apply different voltages according to the control signal of the central control unit 11 to modulate the amplitude or phase of the linearly polarized light in different ways, and reflect and output different types of scalar light fields.

[0097] refer to Figure 7 Optionally, the spatial light modulator 6 is a reflective liquid crystal spatial light modulator, which includes, from top to bottom, a glass layer 601, a transparent electrode 602, an alignment film 603, a liquid crystal layer 604, a reflective layer 605, and a control electrode 606. The control electrode 606 controls the voltage across the liquid crystal layer 604 according to the control signal from the central control unit 10, so that the liquid crystal molecules in the liquid crystal layer 604 exhibit different deflection angles. The alignment film 603 on the surface of the liquid crystal layer 604 is used to make the alignment of the liquid crystal molecules parallel to the surface of the alignment film 603, and reflects them through the reflective layer 605.

[0098] refer to Figure 1 and Figure 7 The central control unit 10 is connected to the control electrode 606 in the reflective spatial light modulator 6, changing the voltage of the reflective spatial light modulator 6 to control the working state of the liquid crystal spatial light modulator. The reflective spatial light modulator 6 can modulate the amplitude or phase of linearly polarized light and reflect it through the reflective layer 605. The control electrode 606 and the transparent electrode 602 control the arrangement of liquid crystal molecules by controlling the voltage across the liquid crystal molecules in the liquid crystal layer 604. Depending on the voltage applied in the reflective spatial light modulator 6, the reflective spatial light modulator 6 can modulate linearly polarized light into a scalar light field with a flat-top, array, or Bessel distribution.

[0099] refer to Figure 3 The central control unit 10 controls the synchronous control unit 4, the spatial light modulator 6, and the motion controller 9 simultaneously according to the pre-set processing form and motion mode, which can realize the rapid matching of the required light field at different positions.

[0100] In this embodiment of the invention, when the acousto-optic deflector is not working, the central control unit controls the reflective spatial light modulator to modulate the amplitude or phase of linearly polarized light in different ways, generating radially polarized light, angularly polarized light, and different scalar light fields such as flat-top type, array type, and Bessel type at the output end. Not only are the light field forms diverse, but the light field transformation can also be performed efficiently and reliably to meet the needs of precision parts processing.

[0101] Example 4

[0102] Examples 1 and 2 allow for optical field transformation within the same region as the scanning direction of the acousto-optic deflection module, meaning transformations can only occur in a one-dimensional direction. Building upon the above examples, this embodiment enables rapid optical field transformation within a two-dimensional plane, satisfying more vector optical field transformation requirements.

[0103] refer to Figure 8 The first and second acoustic-optic deflection modules 31 and 32 each include two mutually perpendicular acoustic-optic deflectors. The acoustic-optic deflectors in the first and second acoustic-optic deflection modules 31 and 32 are arranged symmetrically about the center. For example, the first acoustic-optic deflection module 31 includes a first acoustic-optic deflector 311 and a second acoustic-optic deflector 312 that are perpendicularly placed to each other, and the second acoustic-optic deflection module 32 includes a third acoustic-optic deflector 321 and a fourth acoustic-optic deflector 322 that are perpendicularly placed to each other. The first acoustic-optic deflector 311 and the fourth acoustic-optic deflector 322 are symmetrical about the center, and the second acoustic-optic deflector 312 and the third acoustic-optic deflector 321 are symmetrical about the center.

[0104] The vector light field transformation module adopts a wedge-shaped light field transformation mirror 55, and the etching area array of the wedge-shaped light field transformation mirror 55 is arranged.

[0105] The synchronization control unit 4 includes multiple output channels, with each pair of output channels forming a group, which respectively output drive signals to the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32, so that the radio frequency signals loaded on the two symmetrically arranged acousto-optic deflectors (311 and 322, 312 and 321) have the same frequency; for example, the first acousto-optic deflector 311 and the fourth acousto-optic deflector 322 are loaded with radio frequency signals of the same frequency, and the second acousto-optic deflector 312 and the third acousto-optic deflector 321 are loaded with radio frequency signals of the same frequency.

[0106] The first acousto-optic deflection module 31 is used to deflect the outgoing direction of the linearly polarized light and diffract it to obtain a first deflected beam. The first deflected beam passes through a certain etched area in the wedge-shaped optical field transformation mirror 55.

[0107] Two acousto-optic deflectors placed perpendicularly to each other can achieve two-dimensional scanning. If the wedge-shaped optical field transformation mirror 55 etches several different types of gratings, when linearly polarized light passes through, it can be transformed into radially polarized light, angularly polarized light, or other higher-order vector beams as needed.

[0108] refer to Figure 9 The wedge-shaped light field transformation mirror 55 is a wedge-shaped fused silica glass with different grating patterns etched on it. It includes different etched areas, and a certain distance is maintained between each two etched areas. It forms an array within the wedge-shaped light field transformation mirror 55, and the overall structure is consistent with the wedge-shaped light field transformation mirror 55.

[0109] Based on the processing morphology characteristics of the processing component 8, the corresponding vector light field type is selected, and then the corresponding grating is etched on the wedge-shaped light field transformation mirror 55. The etching range and position depend on the scanning range of the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32 and the frequency of the radio frequency signal output by the driving signal source 301, so as to ensure that a certain diffraction light path can pass through a certain etching area and transform the required light field.

[0110] In an alternative embodiment, the wedge-shaped light field transformation mirror 55 may also be a combination of several wedge-shaped S-plates of different thicknesses.

[0111] The synchronous control unit 4 simultaneously controls the acousto-optic deflectors in the first acousto-optic deflection module 31 and the second acousto-optic deflection module 32, and the output radio frequency signal of the drive signal source 301 can be continuously adjusted within a certain range, thereby realizing surface scanning. When the drive signal source 301 is controlled to output a certain radio frequency signal, the output diffracted beam can just pass through a certain etched area in the wedge-shaped optical field transformation mirror 55.

[0112] This embodiment is similar to the light field transformation method in Embodiments 1 and 2. When neither the signal synchronization control unit 4 nor the reflective spatial light modulator 6 is working, the system outputs a Gaussian beam. When the central control unit 10 sends a command to the signal synchronization control unit 4 to make the drive signal source 301 output different radio frequency signals, the diffracted light enters different etching areas of the wedge-shaped light field transformation mirror, thereby obtaining different types of vector beams. The reflective spatial light modulator 6 is in the off state when the signal synchronization control unit 4 is working and is only used as a reflector.

[0113] Furthermore, similar to the principle in Embodiment 3, when the signal synchronization control unit 4 is in the off state and the reflective spatial light modulator 6 is in the working state, the central control unit 10 issues a command to the reflective spatial light modulator 6 to change the voltage of the reflective spatial light modulator 6, thereby modulating the amplitude or phase of the linearly polarized light that reaches the reflective spatial light modulator 6 along the main optical path, thereby changing the state of the light field. Depending on the voltage of the reflective spatial light modulator 6, the system output can obtain a flat-top type / array type / Bessel type light field distribution.

[0114] This invention, through the placement of two mutually perpendicular acousto-optic deflectors in the first and second acousto-optic deflection modules, controls the scanning range and the frequency of the output radio frequency signal, ensuring that a certain diffraction path can pass through a certain etched area, enabling two-dimensional scanning and transformation of the required optical field. When the signal synchronization control unit is turned off, the amplitude or phase of the linearly polarized light is modulated by a reflective spatial light modulator, allowing the acquisition of radially polarized light, angularly polarized light, and different types of optical field distributions such as Gaussian, flat-top, array, and Bessel types at the output end. This not only provides diverse optical field forms but also enables efficient and reliable optical field transformation, meeting the needs of precision component processing.

[0115] Example 5

[0116] A light field transformation method based on an acousto-optic deflector, applied to any of the light field transformation devices based on an acousto-optic deflector as described in the above embodiments, includes:

[0117] The central control unit sends corresponding control signals to the signal synchronization control unit and motion controller based on pre-stored data on the movement of the processing components and the types of light fields required for different parts during the processing.

[0118] The signal synchronization control unit simultaneously controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency.

[0119] The linearly polarized light output from the pulsed laser is generated into parallel light by the beam expander and collimator along the main optical path and then enters the first acousto-optic deflection module, where it is deflected to obtain the first deflected beam.

[0120] The vector light field transformation module transforms the first deflected beam from linearly polarized light into radial, angular, and higher-order vector light, and then reflects or refracts it to obtain the second deflected beam.

[0121] The second deflected beam enters the second acousto-optic deflection module and is re-integrated into the main optical path to obtain the processing beam.

[0122] The processing beam, after being reflected by a reflective spatial light modulator and focused by a focusing lens, acts on the processing component that moves with the motion controller.

[0123] Optional, also includes:

[0124] When the signal synchronization control unit does not apply a driving signal to the first acousto-optic deflection module and the second acousto-optic deflection module, the reflective spatial light modulator is connected to the central control unit.

[0125] The linearly polarized light reaches the reflective spatial light modulator along the main optical path. The reflective spatial light modulator applies different voltages according to the control signal of the central control unit to modulate the amplitude or phase of the linearly polarized light in different ways, and reflects and outputs different types of scalar light fields.

[0126] The optical field transformation method based on an acousto-optic deflector provided by this invention is applied to an optical field transformation device based on an acousto-optic deflector. It can achieve efficient optical field transformation, improve processing efficiency, and process parts according to the processing style required by the user, thus meeting a variety of practical needs.

[0127] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A light field conversion device based on an acousto-optic deflector, characterized in that, include: The components arranged sequentially along the optical path are a pulsed laser, two acousto-optic deflection modules, a signal synchronization control unit, a vector optical field transformation module, a reflective spatial light modulator, and a focusing lens. The pulsed laser is used to output linearly polarized light, which is transmitted along the main optical path and injected into the first acousto-optic deflection module; The signal synchronization control unit simultaneously controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency. The first acousto-optic deflection module is used to deflect the outgoing light direction of the linearly polarized light to obtain a first deflected beam, which enters the deflection optical path. The magnitude of its deflection angle is determined by the frequency of the radio frequency signal. The vector light field transformation module is used to transform the first deflected beam from linearly polarized light into radial, angular, or higher-order vector light, and to reflect or refract it to obtain a second deflected beam that enters the second acousto-optic deflection module. The second acousto-optic deflection module is used to deflect the second deflection beam and re-integrate it into the main optical path. After passing through the reflection of the reflective spatial light modulator and the focusing lens, the processing beam is obtained and acts on the processing component.

2. The optical field conversion device as described in claim 1, characterized in that, The vector light field transformation module includes an S-slide and a plane mirror; The S-slide is used for light field transformation, converting the light field of the first deflected beam from linearly polarized light into a radial, angular, or higher-order vector light field. The plane mirror is used to reflect the transformed first deflected beam to obtain a second deflected beam, which is then injected into the second acousto-optic deflection module.

3. The optical field conversion device as described in claim 2, characterized in that, The number of S-slides and plane mirrors are equal, and each is greater than or equal to 1; Each S-slide corresponds to a plane mirror and belongs to the same deflection optical path; The signal synchronization control unit controls the first acousto-optic deflection module to load radio frequency signals of different frequencies through a drive signal, so that the first deflection beam enters the corresponding deflection optical path; wherein, the signal synchronization control unit controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency, and the deflection angle of the second deflection beam is the same as the deflection angle of the first deflection beam.

4. The optical field conversion device as described in claim 3, characterized in that, The angle between the Nth deflection optical path and the first deflection optical path satisfy Where N is greater than or equal to 2; where, Indicates the wavelength of the incident laser. and These represent the refractive index and internal sound velocity of the acousto-optic medium in the first acousto-optic deflection module, respectively. and These represent the frequencies of different radio frequency signals output by the signal synchronization control unit, respectively, which are used to generate the Nth deflection optical path and the first deflection optical path.

5. The optical field conversion device as described in claim 1, characterized in that, The vector light field transformation module is a wedge-shaped light field transformation mirror; the wedge-shaped light field transformation mirror includes different etching areas, the etching areas are etched with different grating patterns, and the arrangement direction of the etching areas is consistent with the scanning direction of the first acousto-optic deflection module and the second acousto-optic deflection module. The wedge-shaped light field transformation mirror is used to transform the first deflected beam from linearly polarized light into radial, angular or higher-order vector light when it passes through the etching area, refract it to obtain a second deflected beam, and then enter the second acousto-optic deflection module.

6. The optical field conversion device as described in claim 5, characterized in that, The first acousto-optic deflection module includes a first acousto-optic deflector and a second acousto-optic deflector placed perpendicularly to each other. The second acousto-optic deflection module includes a third acousto-optic deflector and a fourth acousto-optic deflector placed perpendicularly to each other. The first acousto-optic deflector and the fourth acousto-optic deflector are arranged symmetrically about the center and are loaded with radio frequency signals of the same frequency. The second acousto-optic deflector and the third acousto-optic deflector are arranged symmetrically about the center and are loaded with radio frequency signals of the same frequency. The etching region array arrangement of the wedge-shaped optical field transformation mirror; The signal synchronization control unit includes multiple output channels, with each pair of output channels forming a group, which respectively output drive signals to the first acousto-optic deflection module and the second acousto-optic deflection module, so that the radio frequency signals loaded on the two acousto-optic deflectors arranged in a central symmetrical manner have the same frequency. The first acousto-optic deflection module is used to deflect the direction of the emitted linearly polarized light and diffract it to obtain a first deflected beam. The first deflected beam passes through a certain etched area in the wedge-shaped optical field transformation mirror.

7. The optical field conversion device as described in claim 2, characterized in that, The optical field conversion device also includes a beam expander and collimator, a motion controller, and a central control unit; The beam expanding and collimating device is disposed between the pulsed laser and the first acousto-optic deflection module, and is used to collimate and expand the linearly polarized light to generate parallel light. The processing component is fixedly mounted on the motion controller and moves with the motion controller. The central control unit stores the processing data of the processing component in advance. The central control unit is connected to the motion controller and the signal synchronization control unit. It is used to control the motion direction of the motion controller according to the processing data, and to control the signal synchronization control unit to send drive signals to the first and second acousto-optic deflection modules so that they are loaded with radio frequency signals of the corresponding frequency to perform the pre-set processing program.

8. The optical field conversion device as described in claim 7, characterized in that, When the signal synchronization control unit does not apply a driving signal to the first acousto-optic deflection module and the second acousto-optic deflection module, the reflective spatial light modulator is connected to the central control unit. The linearly polarized light reaches the reflective spatial light modulator along the main optical path. The reflective spatial light modulator is used to apply different voltages according to the control signal of the central control unit to modulate the amplitude or phase of the linearly polarized light in different ways, and reflect and output different types of scalar light fields.

9. The optical field conversion device as described in claim 7, characterized in that, The light field transformation device further includes a motor, which is connected to the plane mirror in the vector light field transformation module; When the signal synchronization control unit controls the first and second acousto-optic deflection modules to load radio frequency signals of different frequencies through the drive signal, the motor drives the plane mirror to rotate according to the control signal of the central control unit. The plane mirror changes its deflection angle when reflecting the transformed first deflected beam to obtain a second deflected beam. The second deflected beam is deflected by the second acousto-optic deflection module and then re-enters the main optical path.

10. A method for optical field transformation based on an acousto-optic deflector, applied to the optical field transformation device based on an acousto-optic deflector as described in any one of claims 1-9, characterized in that, include: Based on pre-stored data on the movement of processing components and the types of light fields required for different parts during the processing, the central control unit sends corresponding control signals to the signal synchronization control unit, the reflective spatial light modulator, and the motion controller. The signal synchronization control unit simultaneously controls the first acousto-optic deflection module and the second acousto-optic deflection module to load radio frequency signals of the same frequency. The linearly polarized light output from the pulsed laser is generated into parallel light by the beam expander and collimator along the main optical path and then enters the first acousto-optic deflection module, where it is deflected to obtain the first deflected beam. The vector light field transformation module transforms the first deflected beam from linearly polarized light into radial, angular, or higher-order vector light, and then reflects or refracts it to obtain a second deflected beam. The second deflected beam enters the second acousto-optic deflection module, and after deflection, it re-enters the main optical path to obtain the processing beam. The processing beam, after being reflected by a reflective spatial light modulator and focused by a focusing lens, acts on the processing component that moves with the motion controller.

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