High-speed laser micro-nano machining device and control method

Abstract

The application discloses a high-speed laser micro-nano processing device and a control method, and mainly relates to the technical field of laser micro-nano processing, and aims to solve the problems of complicated process and low efficiency of the existing laser micro-nano processing. The device comprises a laser, the laser is connected with an acousto-optic modulator, the acousto-optic modulator is connected with a first beam splitter, the first beam splitter is connected with a rotating mirror system, the rotating mirror system is connected with a first focusing lens, the first focusing lens is connected with a second focusing lens, the second focusing lens is connected with a galvanometer, the galvanometer is connected with a third focusing lens, the third focusing lens is connected with a fourth focusing lens, the fourth focusing lens is connected with a second beam splitter, the second beam splitter is connected with an objective lens and a microscopic imaging module, the objective lens is connected with a three-dimensional moving stage, and the microscopic imaging module and the three-dimensional moving stage are connected with a control card. The device and the control method realize the rapid processing of laser micro-nano, and improve the processing efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser micro-nano processing, and particularly relates to a high-speed laser micro-nano processing device and a control method. BACKGROUND

[0002] Micro-nano manufacturing technology can manufacture components with micron and nanometer scales, and is a basic means for manufacturing micro-sensors, micro-structures and functional micro-nano systems. Traditional mechanical micro-processing technologies, including micro-grinding, micro-turning, micro-milling, micro-drilling, micro-stamping and micro-forming, can process three-dimensional complex curved surface parts, and the processing materials are not limited, but the processing precision is limited, and cannot meet the manufacturing of high-precision micro-nano structure devices and systems. Photolithography technology based on semiconductor manufacturing processes, such as extreme ultraviolet projection exposure technology, can achieve a processing precision below 10 nanometers, but generally has problems such as single processing material and expensive processing equipment, and cannot process complex three-dimensional structures. Electron beam and ion beam etching can achieve nanometer-level high-precision processing, but such equipment can only process two-dimensional plane structures or simple three-dimensional structures, and it is difficult to realize any complex three-dimensional structure, and the processing time is long. Nano-imprinting is also a high-precision processing method, but this technology requires a template, and the template has requirements, and not all three-dimensional structures can be processed. Face projection stereolithography technology can realize three-dimensional structure processing, but the processing precision is limited, especially the processing precision in the z-axis direction, which needs precise mechanical parts to control. Laser direct writing technology can simultaneously consider high precision and complex three-dimensional structure processing capability. By scanning photoresist with a three-dimensional path, three-dimensional design freedom can be met, no mask is needed, and one-step forming is achieved. At the same time, based on the principle of two-photon or multi-photon polymerization, high-precision processing below 100 nanometers can be achieved. However, the processing efficiency of laser direct writing is low, which is the main factor limiting its application in the field of micro-nano processing industry. Therefore, a high-speed laser micro-nano processing device is needed.

[0003] Meanwhile, to realize high-speed laser micro-nano processing, the high-speed motion control problem also needs to be solved. There are various ways to improve the speed, but basically they involve the mechanical motion of the motion shaft. In the vector motion process of the mechanical shaft, such as a galvanometer, if open-loop motion is performed, the motion process cannot be accurately synchronized with the laser, causing the designed laser switch point to mismatch the actual processing position, resulting in the problem of early light-on and late light-off, and ultimately causing a large deviation between the processed structure and the design. If closed-loop motion is performed, the position feedback accuracy of the mechanical shaft and the bandwidth requirement of the returned data are extremely high, and extremely fast response speed is also required to adjust the mechanical shaft motion synchronization and laser synchronization in real time. Due to the existence of the "feedback-motion" cycle, the motion speed of the mechanical shaft is greatly reduced. At the same time, due to the vector motion of the mechanical shaft, the deviation between the actual position and the designed position also needs to be adjusted in real time within a limited error, which can only further reduce the motion speed of the mechanical shaft. If not, the feedback frequency needs to be increased, and the feedback data bandwidth needs to be higher.

[0004] In summary, a high-speed laser micro-nano processing device and control method are designed to solve the problem of low processing efficiency of laser direct writing. At the same time, a scanning laser processing scheme without acceleration and deceleration of the motion shaft is designed, so that the mechanical shaft can move at a constant speed. A simple model can be used to predict the motion position of the mechanical shaft. A unique feedback optical path and photoelectric module are used to synchronize each row of scanning lines, greatly reducing the demand for feedback bandwidth. High speed in open-loop motion and accuracy in closed-loop motion can be achieved at the same time, avoiding the errors in open-loop motion and the speed reduction caused by the "feedback-motion" cycle in closed-loop motion. SUMMARY

[0005] In view of the above problems of the prior art, the present application provides a high-speed laser micro-nano processing device and control method to solve the above technical problems.

[0006] In a first aspect, the present application provides a high-speed laser micro-nano processing device, which comprises: a laser, the laser being connected to an acousto-optic modulator, the acousto-optic modulator being connected to a first beam splitter, the first beam splitter being connected to a rotating mirror system, the rotating mirror system being connected to a first focusing lens, the first focusing lens being connected to a second focusing lens, the second focusing lens being connected to a galvanometer, the galvanometer being connected to a third focusing lens, the third focusing lens being connected to a fourth focusing lens, the fourth focusing lens being connected to a second beam splitter, the second beam splitter being connected to an objective lens and a microscopic imaging module, the objective lens being connected to a three-dimensional moving stage, the microscopic imaging module and the three-dimensional moving stage being connected to a control card, and the control card being connected to the acousto-optic modulator, the rotating mirror system, the galvanometer, an interface detection module, and a computer; and the interface detection module is also connected to the first beam splitter and the rotating mirror system.

[0007] Further, the device further comprises a longitudinal-axis mechanical arm supporting the longitudinal movement of the galvanometer mirror; the rotating mirror system comprises a rotating mirror and a transverse-axis mechanical arm supporting the uniform rotation of the rotating mirror, and the interface detection module is on the same transverse axis as the transverse-axis mechanical arm.

[0008] Further, the interface detection module at least comprises a light source detector, a photoelectric detection device and a controller; and the microscopic imaging module at least comprises an LED illumination light source, an imaging detector and a controller.

[0009] Further, the first focusing lens and the second focusing lens are f=100mm focusing lenses; the third focusing lens and the fourth focusing lens are f=200mm focusing lenses; the objective lens is a lens group with a numerical aperture of NA=1.3 and a magnification of 100 times, and is an oil immersion objective lens placed in a sample cell, and the sample cell contains photoresist.

[0010] In a second aspect, the application provides a control method of a high-speed laser micro-nano processing device, which comprises: detecting the scanning angle of a rotating mirror rotating at a uniform speed by an interface detection device; wherein the rotating mirror rotates at a uniform speed along a preset transverse-axis mechanical arm; when the rotating mirror rotates to a preset scanning angle, the interface detection device generates a position signal; so that a control card outputs a laser switch signal of an acousto-optic modulator; the laser switch signal is used to control the laser to complete a laser switching processing action, and a light beam is emitted to the rotating mirror; so that the rotating mirror reflects the light beam to a galvanometer mirror, and then to a sample surface, to realize laser line segment scanning processing.

[0011] Further, the method further comprises: in order to realize continuous laser line segment scanning processing, the control card provides a motion signal for the galvanometer mirror, so that the galvanometer mirror moves a preset distance along the longitudinal-axis mechanical arm, and waits for a next position signal.

[0012] Further, the control card outputs the laser switch signal of the acousto-optic modulator, specifically comprising: when the rotating mirror rotates to a preset scanning angle, the interface detection device generates a position signal; when the control card receives the position signal sent by the interface detection device, the control card outputs the laser switch signal of the acousto-optic modulator according to the pre-cached switch data and the preset output logic.

[0013] Further, the method further comprises: caching the switch data into the control card by a computer.

[0014] Those skilled in the art can understand that the present application has at least the following beneficial effects:

[0015] The control card can detect and respond to the in-place signal at a very fast speed. Therefore, it can be ensured that the corresponding laser switch point positions on each scanning line are synchronized and aligned. Thus, the misalignment problem caused by cumulative error or jitter can be avoided. Since the movement mode of the rotating mirror is single-direction uniform rotation, the movement logic is very simple, and frequent acceleration and deceleration is not required. Once accelerated to the specified rotating speed, only uniform motion is required, so that a very high scanning speed can be achieved. The interface detection module can synchronize the rotating speed of the rotating mirror to align the scanning lines, without changing the direction. Therefore, the frequent acceleration and deceleration of the mechanical structure can be effectively avoided, so that the rotating mirror can be accelerated to the specified rotating speed and then rotated at a very high speed. Thus, the processing efficiency can be greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Some embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which:

[0017] Figure 1 is a schematic diagram of an internal structure of a high-speed laser micro-nano processing device provided by an embodiment of the present application.

[0018] Figure 2 is a flowchart of a control method of a high-speed laser micro-nano processing device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0019] Those skilled in the art should understand that the embodiments described below are only preferred embodiments of the present disclosure, and do not represent that the present disclosure can only be implemented by the preferred embodiments. The preferred embodiments are only used to explain the technical principles of the present disclosure, and are not used to limit the protection scope of the present disclosure. Based on the preferred embodiments provided by the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative labor should still fall within the protection scope of the present disclosure.

[0020] It should also be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed, or other elements inherent in such a process, method, article, or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0021] The technical solutions provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0022] Figure 1 A high-speed laser micro-nano processing device is provided by an embodiment of the present application. As shown in Figure 1As shown, the device provided by the embodiment of the present application mainly comprises:

[0023] The laser 1 is any feasible laser device capable of emitting laser light; the acousto-optic modulator 2 is connected to the laser 1 and used for controlling laser power and switching light; the first beam splitter 3 is connected to the acousto-optic modulator 2 and used for combining probe light into an optical path; the rotating mirror system 4 (rotating mirror) is connected to the first beam splitter 3 and used for deflecting laser light; the first focusing lens 5 is connected to the rotating mirror system 4, and the second focusing lens 6 (the first focusing lens 5 and the second focusing lens 6 can adopt focusing lenses with a focal length f = 100 mm) is connected to the first focusing lens 5; the two lenses form a 4f system and are used for delaying projection of scanning laser light onto the galvanometer 7 (for example, an optical scanning galvanometer); the third focusing lens 8 is further connected to the fourth focusing lens 9 to form another 4f system (the third focusing lens 8 and the fourth focusing lens 9 can adopt focusing lenses with a focal length f = 200 mm), which is used for projecting laser light emitted by the galvanometer 7 to an entrance pupil of the objective lens 11; the second beam splitter 10 (which can be a dichroic mirror) is used for splitting micro-imaging light and processing light; the objective lens 11 (for example, an oil immersion objective lens) can enter into a sample cell (the objective lens 11 can adopt a lens group with a numerical aperture NA = 1.3 and a magnification of 100 times), and the sample cell contains photoresist; the three-dimensional moving stage (for example, an optical machine three-dimensional translation stage) can realize precise movement in three-dimensional directions; the interface detection module 14 (for example, a Thorlabs 20GHz photodetector) contains a light source detector, a photodetector, and a controller (a single-chip microcomputer chip, etc.), and is used for interface positioning in a processing process; the micro-imaging module 15 (for example, an intelligent digital micro-imaging instrument) contains an LED illumination light source, an imaging detector (any feasible existing imaging detector), and a controller (a single-chip microcomputer chip, etc.); the control card 16 is used for signal synchronization and control of the entire device; and the computer 17 is used for controlling the entire device and a processing process. It should be noted that the light source detector, the photodetector, the controller, the LED illumination light source, the imaging detector, and the controller are all existing devices.

[0024] As an example one, femtosecond laser emitted from the laser 1, after the acousto-optic modulator 2, the first beam splitter 3, enters the rotating mirror system 4, the incident femtosecond laser beam is deflected and scanned in one-dimensional direction; the deflected laser passes through the first focusing lens 5 and the second focusing lens 6 to form a 4f system, and the scanning laser is delayed projected to the galvanometer 7. Through the control of the scanning galvanometer 7, the laser can be deflected in another direction. The laser emitted from the galvanometer 7 passes through the third focusing lens 8 and the fourth focusing lens 9 to form a 4f system, and the collimated parallel light enters the objective lens 11 after the second beam splitter 10. After focusing by the objective lens 11, the light enters the sample cell. By controlling the card 16 connected to the rotating mirror, the galvanometer 7 and the three-dimensional moving platform 13, the three-dimensional structure machining is realized. The interface detection module 14 in the device is added before the rotating mirror, which can be used for automatic focusing positioning and judging the machining position during the machining process. The microscopic imaging module 15 can real-time image the machined object. The control card 16 is also connected to the acousto-optic modulator 2, the rotating mirror system 4, the galvanometer 7, the interface detection module 14 and the computer 17 respectively; the rotating angle of the rotating mirror in the rotating mirror system 4 is obtained through the interface detection module 14; when the rotating angle is loaded with a preset angle, the laser 1 is controlled to be turned on through the acousto-optic modulator 2; the starting and stopping of the rotating mirror system 4 is controlled; the operation of the galvanometer 7 is controlled; the cache data transmitted by the computer 17 is obtained. The rotating mirror system 4, the first focusing lens 5, the second focusing lens 6 and the galvanometer 7 form a 4f optical system, and the galvanometer 7, the third focusing lens 8, the fourth focusing lens 9 and the entrance pupil plane of the objective lens 11 form a 4f system machining.

[0025] In addition, the rotating mirror system 4 includes a rotating mirror and a horizontal shaft mechanical arm supporting the rotating mirror to rotate at a constant speed. The rotating mirror serves as the main shaft of the beam deflection, and can perform high-speed scanning along the surface X axis (the movement direction of the horizontal shaft mechanical arm) of the sample to be machined. The galvanometer 7 moves along the vertical shaft mechanical movement, and can perform Y axis movement (the movement direction of the vertical shaft mechanical arm) by moving the relative position of the light spot and the sample along the scanning completion signal. The horizontal shaft mechanical arm and the vertical shaft mechanical arm cooperate to realize high-speed scanning machining of two-dimensional patterns. When the rotating mirror rotates to a specific angle, the interface detection module 14 can give a specific trigger signal. The signal is used as the scanning start signal of each line to achieve the purpose of machining synchronization. The control card 16 and the computer 17 cooperate with the rotating mirror to sequentially give the signal of the laser switch after receiving the starting position trigger signal. The signal can control the laser switch. Due to the synchronization function of the starting position trigger signal, the scanning lines are connected, and the laser scanning machining is realized with high efficiency.

[0026] According to the above description, those skilled in the art can understand that the acousto-optic modulator 2 can be designed to accurately control the deflection of the light beam. In addition to realizing high-speed laser three-dimensional processing, it is also applicable in the field of planar lithography processing. The interface detection module 14 is designed on the same horizontal axis as the horizontal mechanical arm, which can accurately match the motion of the rotating mirror. By designing a unique detection light path and photoelectric auxiliary device, a nanosecond-level synchronous scanning line can be realized, and a small deviation between the motion model and the actual situation can be corrected, so that high-precision scanning processing can be realized. The control card 16 can respond to the starting position trigger signal very stably, control the switching of the laser 1, and at the same time give the control signal of the auxiliary shaft to synchronize the motion of the main shaft and the auxiliary shaft. The control logic in the control card 16 can match the galvanometer 7, the platform and other motion units as auxiliary shafts to cooperate with the rotating mirror processing.

[0027] In addition, the embodiment of the application also provides a control method of the high-speed laser micro-nano processing device. Figure 2 As shown in the method provided by the embodiment of the application, the method mainly comprises the following steps:

[0028] Step 210: detecting the scanning angle of the rotating mirror rotating at a constant speed by the interface detection device.

[0029] It should be noted that the interface detection device can be any feasible device or arrangement that can perform photoelectric detection and detect the scanning angle of the rotating mirror, for example, a 20GHz ultrafast photoelectric detector produced by Thorlabs. The rotating mirror rotates at a constant speed along the preset horizontal mechanical arm.

[0030] Step 220: when the rotating mirror rotates to the preset scanning angle, the interface detection device generates a signal indicating that the rotating mirror has reached the preset scanning angle; and the control card outputs the laser switching signal of the acousto-optic modulator.

[0031] It should be noted that the control card is any feasible device or arrangement that can perform hardware control and output control signals. The acousto-optic modulator is any feasible device or arrangement that can control the switching of the laser.

[0032] The control card outputs the laser switching signal of the acousto-optic modulator, which can be specifically:

[0033] When the rotating mirror rotates to the preset scanning angle, the interface detection device generates a signal indicating that the rotating mirror has reached the preset scanning angle; when the control card receives the signal indicating that the rotating mirror has reached the preset scanning angle sent by the interface detection device, the control card outputs the laser switching signal of the acousto-optic modulator according to the pre-stored switching data and the preset output logic. It should be noted that the preset output logic can be any feasible logic, which can be determined by those skilled in the art according to the actual situation.

[0034] In addition, the computer can store the switching data in the control card.

[0035] Step 230, the laser switch processing action is completed by the acousto-optic modulator controlling the laser, and the light beam is emitted to the rotating mirror; so that the rotating mirror reflects the light beam to the galvanometer, and then to the sample surface, so as to perform laser scanning processing.

[0036] In addition, the application also includes: the galvanometer is provided with a motion signal by the control card, so that the galvanometer moves along the longitudinal axis mechanical arm by a preset distance, and the next arrival signal is waited.

[0037] Based on the above description, those skilled in the art can understand that, since the arrival signal is only generated when the rotating mirror rotates to a specific angle, the control card can detect and respond to the arrival signal at an extremely fast speed. Therefore, it can be ensured that the corresponding laser switch point positions on each scanning line are synchronized and aligned. Thus, the misalignment problem caused by cumulative error or jitter can be avoided. Since the movement mode of the rotating mirror is single-direction uniform rotation, the direction does not need to be changed, so the frequent acceleration and deceleration of the mechanical structure can be effectively avoided, and the rotating mirror can accelerate to a specified rotating speed and then rotate at a high speed, thereby greatly improving the processing efficiency.

[0038] So far, the technical solutions of the present disclosure have been described in combination with the foregoing embodiments, but those skilled in the art can easily understand that the protection scope of the present disclosure is not limited to these specific embodiments. Those skilled in the art can split and combine the technical solutions in the above embodiments, or make equivalent changes or replacements to the related technical features, without deviating from the technical principles of the present disclosure. Any changes, equivalent replacements, improvements, etc. made within the technical concept and / or technical principles of the present disclosure will fall within the protection scope of the present disclosure.

Claims

1. A control method of a high-speed laser micro-nano processing apparatus, characterized by, The application discloses a high-speed laser micro-nano processing device, which comprises a laser, an acousto-optic modulator, a first beam splitter, a rotating mirror system, a first focusing lens, a second focusing lens, a galvanometer, a third focusing lens, a fourth focusing lens, a second beam splitter, an objective lens and a microscopic imaging module. The application also discloses a control method of the high-speed laser micro-nano processing device. The interface detection module comprises a light source detector, a photoelectric detector and a controller. The microscopic imaging module comprises an LED illumination light source, an imaging detector and a controller. The first focusing lens and the second focusing lens are f=100mm focusing lenses. The third focusing lens and the fourth focusing lens are f=200mm focusing lenses. The objective lens is a lens group with a numerical aperture of 1.3 and a magnification of 100 times. The objective lens is an oil immersion objective lens and is placed in a sample cell. The sample cell contains photoresist. The method further comprises the following steps.

4. The control method of the high-speed laser micro-nano processing apparatus according to claim 1, wherein In order to realize continuous laser line segment scanning processing, the control card provides a motion signal for the galvanometer so that the galvanometer moves along the longitudinal mechanical arm by a preset distance and waits for a next in-place signal. The control card outputs a laser switch signal of the acousto-optic modulator. 5.The method of claim 1, wherein When the interface detection device generates an in-place signal when the rotating mirror rotates to a preset scanning angle, the control card outputs a laser switch signal of the acousto-optic modulator according to pre-stored switch data and a preset output logic. The method further comprises the following steps. 6.The method of claim 5, wherein The computer stores the switch data in the control card. ​

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