An optical element surface defect measuring device

Abstract

The application discloses a device for measuring surface defects of optical elements. The device comprises an imaging unit, a scanning motion unit, a profile measurement unit, an automatic focusing unit, a sample clamping unit, a leveling and centering unit and a master control unit. The imaging unit is composed of a coarse measurement light path and a fine measurement light path; the profile measurement unit generates a focusing topographic map through fitting; the automatic focusing unit adjusts the up-and-down micro motion of a microscope objective lens to realize automatic focusing imaging; the sample clamping unit is used for fixing a sample to be measured; and the leveling and centering unit is an automatic device integrating leveling and centering. The device combines low-magnification dark-field scattering with high-magnification bright-and-dark-field imaging mode, can quickly find surface defects of optical elements and accurately measure the defect size, and guarantees the efficiency and precision of defect identification and classification.

Description

TECHNICAL FIELD

[0001] The present application relates to precision detection technology, in particular to a kind of optical element surface defect measuring device.The present application can be used for the quality detection of precision optical element, and is suitable for measuring optical element surface defect. BACKGROUND

[0002] With the rapid development of modern industry, precision optical elements are widely used in various industrial fields, and optical elements, as the carrier of optical function, play a crucial role in the development and use of various optical instruments. Therefore, in view of the scattering characteristics of the surface of optical elements, how to better detect the defects on the surface of the elements is also put forward. The detection process of optical elements is very complicated and full of uncertainty, and the optical elements can be divided into ordinary optical glass, neodymium glass, fused quartz optical glass, calcium fluoride (CaF2) and a series of materials according to the composition material; According to the aperture of optical element, it can be large to several meters or small to one or two millimeters, and the difference can reach thousands of times; According to the different shapes of optical elements, it can be divided into flat plate, non-spherical target mirror, spherical lens, cylindrical lens, corner cube prism, polarizing mirror, glass ball, etc. In order to meet the needs of various optical elements in the above three aspects, the measuring instruments, environment, equipment and technology must be various. In the face of such a variety of optical elements with different functions and shapes, it is necessary to explore the corresponding detection technology.

[0003] The harm of optical element surface defects to itself and the whole optical system is shown in the following aspects: the quality of light beam is reduced. The surface defects of the element will produce light scattering effect, so that the energy of the light beam is consumed after passing through the defects, thereby reducing the quality of the light beam; the thermal effect phenomenon of defects. Because the area where the surface defects are located is more likely to absorb more energy than other areas, the thermal effect phenomenon may cause local deformation and damage of the film layer of the element defect, thereby endangering the whole optical system; damage other optical elements in the system. In the laser system, under the irradiation of high-energy laser beam, the scattered light produced by the surface defects of the element will be absorbed by other optical elements in the system, thereby causing uneven light absorption of the element. When the damage threshold of the optical element material is reached, the quality of the propagating light will be affected, the optical element will be damaged, and the optical system will be seriously damaged; the defect will affect the field of view. When there are too many defects on the optical element, the micro-aesthetics will be affected, in addition, the defect will also leave small dust, microorganisms, polishing powder and other impurities, which will cause the element to be corroded, moldy and foggy, and will obviously affect the basic performance of the element. Therefore, it is very important to carry out research on the surface defects of optical elements.

[0004] In view of the above-mentioned needs, the present application discloses an optical element surface defect measuring device, which realizes automatic leveling and centering of the optical element through a leveling and centering device, adopts a low-magnification dark-field scattering combined with a high-magnification bright-dark field imaging mode, uses the low-magnification dark-field scattering method to quickly find surface defects, and uses the high-magnification bright-dark field imaging to accurately measure the defect size, thereby realizing automatic detection of the surface defects of the optical element. SUMMARY

[0005] The present application aims at the deficiencies of the prior art and provides an optical element surface defect measuring device.

[0006] The technical scheme adopted by the present application to solve the technical problems is as follows:

[0007] The present application comprises an imaging unit (100), a scanning motion unit (200), a profile measurement unit (300), an automatic focusing unit (400), a sample clamping unit (500), a leveling and centering unit (600), and a main control unit (800).

[0008] The imaging unit (100) is composed of a coarse measurement light path and a fine measurement light path, and the coarse measurement light path and the fine measurement light path share an integrated optical module (102-2), and the automatic switching of the low-magnification and high-magnification objectives is realized through a piezoelectric resonant micro-rotary table (102-1).

[0009] The scanning motion unit (200) comprises a five-axis cylindrical coordinate scanning measurement structure and a macro-micro two-stage driving structure; the five-axis cylindrical coordinate scanning measurement structure integrates three linear shafts and two rotary shafts and adopts an RTTTR structure form; the optical device is placed on the C-axis (205-5) rotating around the vertical axis in the leveling and centering unit (600), and the entire imaging unit (100) is placed on the P-axis (205-4) rotating around the horizontal axis, and the rotary shafts C-axis and P-axis are connected through the linear motion shaft and the base; the C-axis (205-5) is integrally placed on the X-axis (205-1), the P-axis (205-4) is integrally placed on the Z-axis (205-3), the Z-axis (205-3) is placed on the Y-axis (205-2), the Y-axis (205-2) is placed on the marble beam, and the X-axis (205-1) is installed on the marble table surface; the macro-micro two-stage driving structure is composed of the Z-axis (205-3) in the five-axis cylindrical coordinate scanning measurement structure and the focusing displacement table to form the F-axis (205-6) of the device, and the clear image is realized through the macro-micro two-stage driving structure.

[0010] The profile measurement unit (300) measures the surface distance of the measured element by using a spectral confocal displacement sensor (306-1), drives the voice coil motor (306-2) to move through spatial transformation, swings the P-axis (205-4) to make the spectral confocal displacement sensor (306-1) perpendicular to the horizontal plane, drives the Z-axis (205-3) to make the highest point and the lowest point of the measured element within the measurement range of the spectral confocal displacement sensor (306-1); fixes the Z-axis (205-3), drives the X-axis (205-1) and the Y-axis (205-2) to perform grid scanning (306-3) on the measured element in the X-Y plane, obtains the spectral confocal measurement value and the X-Y plane coordinate, and fits to generate a focusing topographic map (306-4);

[0011] The automatic focusing unit (400) is composed of a PSD position converter (407-1), a motion controller (407-2), a semiconductor laser (407-4), and a voice coil motor (407-3) to drive the microscopic objective lens (103-12) to perform fine focusing; the output of the PSD position converter (407-1) is used as the feedback input signal of the motion controller (407-2), the motion controller (407-2) controls the voice coil motor (407-3) according to the feedback input signal, thereby adjusting the up-and-down fine movement of the microscopic objective lens (103-12), realizing automatic focusing imaging, and the semiconductor laser (407-4) is used for emitting laser;

[0012] The sample clamping unit (500) is used for fixing the measured sample, and includes a three-jaw elastic chuck and a radial locking device (508-1).

[0013] The leveling and centering unit (600) is an automatic device integrating leveling and centering.

[0014] The coarse measurement light path is based on a low magnification microscopic objective lens to perform dark field scanning imaging, and is used for quickly finding element surface defects; the dark field light source adopts a ring-shaped downlighting (103-13) design, the dark field LED light source (103-1) enters the optical fiber bundle (103-3) through the light guide column (103-2), and then the light beam is ring-shaped irradiated on the element through the ring-shaped lens, so as to form the ring-shaped downlighting (103-13); the diffused reflection and diffraction light rays first enter the first imaging lens group (103-6) through the 5 times microscopic objective lens (103-12), and then enter the second thin film beam splitter (103-7) behind the first imaging lens group (103-6), after being split by the second thin film beam splitter (103-7), enter the area array camera (103-8) and the linear array camera (103-9), and complete image acquisition.

[0015] The imaging unit (100) is also integrated with a bright field illumination module (103-5) including a bright field light source (103-11) and a second condenser lens group (103-10); when bright field observation is needed, a first film beamsplitter (103-4) is moved in between the objective lens (103-12) and the first condenser lens group (103-6); and the bright field and dark field switching is realized by the light of the bright field illumination module (103-5).

[0016] The fine measurement optical path has two working modes of bright field and dark field, in the dark field working mode, the film beamsplitter (103-4) for bright field and dark field switching in the optical path is moved out, and the camera switching film beamsplitter (103-7) is also moved out, and is switched to a 20 times microscopic objective lens (104-1), in this working mode, the light reflected by the surface defects of the sample will enter the area array camera (103-8) to the greatest extent, ensuring the sensitivity of defect detection; in the bright field working mode, the fine measurement optical path completes collimation and uniformization after the light emitted by the bright field LED light source passes through the bright field light source adaptive lens group, and is coaxial with the 20 times microscopic objective lens (104-1); through the reflection of the film beamsplitter (103-4), the light beam enters the 20 times microscopic objective lens (104-1) and irradiates on the sample surface, the reflected light passes through the 20 times microscopic objective lens (104-1), the film beamsplitter (103-4) and the condenser lens group (103-6) in turn, is split by the second film beamsplitter (103-7), and is finally captured and imaged by the area array camera (103-8) and the linear array camera (103-9).

[0017] The sample clamping unit (500) is specifically implemented as follows: the three-jaw elastic chuck includes three sets of torsion springs (508-2) fixed on a chuck outer ring mounting ring, and the three-jaw pre-tightening force is uniform; the radial locking device (508-1) is distributed on the outer edge of the three-jaw elastic chuck, and the position of the radial locking device (508-1) is adjustable; when measuring small-sized elements, the radial locking device (508-1) is installed in the reserved installation area (508-3) in the middle of the three-jaw elastic chuck, and the top rod head of the radial locking device (508-1) is designed with replaceable matching blocks (508-4).

[0018] The matching surface of the matching block (508-4) is designed as a cylindrical surface structure; the material of the contact head of the three-jaw elastic chuck is preferably POM material; and the material of the matching block is preferably nylon material.

[0019] The leveling and centering unit (600) is an automatic device integrating leveling and centering, adopts a Kelvin hinge structure, uses three supporting balls (609-1) to accurately constrain the position of components, the three supporting balls (609-1) are in contact with three V-shaped grooves (609-2), the center lines of the three V-shaped grooves intersect at a point; the upper surfaces of two V-shaped grooves are inclined downward from inside to outside; and the structure is symmetrically designed with respect to the other V-shaped groove; two leveling knobs (609-3) respectively adjust the positions of the supporting balls in the two inclined V-shaped grooves through corresponding step servo motors (609-5).

[0020] The device also is provided with a clean control unit (700), including a hundred-level laminar flow cover (7011-4), a low-noise fan (7011-1), a high-clean air filter (7011-2), a damping layer (7011-3) and a shock-absorbing layer (7011-6); the main equipment of the whole device is arranged inside the clean control unit (700), i.e., the imaging unit (100), the scanning motion unit (200), the profile measurement unit (300), the automatic focusing unit (400), the sample clamping unit (500) and the leveling and centering unit (600) are all arranged inside the clean control unit (700).

[0021] The clean control unit is provided with the hundred-level laminar flow cover (7011-4) above, clean air is generated after ambient air passes through the high-efficiency air filter (7011-2) with stable air pressure, the clean air forms a uniform flow layer after pressure equalization by the damping layer (7011-3) and is sent into the detection area in vertical unidirectional flow, and the air in the detection area is discharged through the lower exhaust hole (7011-5).

[0022] The main control unit (800) includes a motion control system, an illumination light source control system, an image acquisition control system and an automatic leveling control system.

[0023] The core motion control system adopts an 8-axis motion controller EC and two 4-axis motor drivers, the 8-axis motion controller is connected with a high-performance computer through Ethernet, and the 8-axis motion controller and the 4-axis motor drivers are connected through an EtherCAT bus, so as to realize driving and control of an X-axis linear displacement table, a Y-axis linear displacement table, a Z-axis linear displacement table, an F-axis focusing displacement table, a C-axis workpiece rotating table, a P-axis probe swinging table and a magnification switching table.

[0024] In the illumination light source control system, the computer is connected with an LED driver through a USB port and controls the brightness and on-off of the bright-field LED light source and the dark-field LED light source through a CDC virtual serial protocol.

[0025] The image acquisition control system, in a dark field mode, exposes and acquires images of a linear array camera controlled by a computer through a CameraLink acquisition card; in a bright field mode, a high frame rate area array camera is connected to the computer through a USB3.0 interface, and the camera exposure and image acquisition are controlled by external triggering;

[0026] The automatic leveling control system is mainly used for controlling the leveling and centering unit, the computer is connected to two stepper servo motors through an OpenCAN motion control card, and the automatic leveling device is controlled to work through a CAN protocol; the spectral confocal sensor in the profile measurement unit is connected to a spectrometer and a high-performance computer, and the PSD signal processor in the automatic focusing unit is also connected to the high-performance computer through an 8-axis motion controller.

[0027] The beneficial effects of the present application relative to the prior art are:

[0028] The present application uses low-magnification dark field scattering combined with high-magnification bright-dark field imaging to quickly find surface defects of optical elements and accurately measure the defect size.

[0029] The present application realizes automatic leveling and centering of optical elements through the leveling and centering device, uses low-magnification dark field scattering combined with high-magnification bright-dark field imaging, uses the low-magnification dark field scattering method to quickly find surface defects, uses the high-magnification bright-dark field imaging to accurately measure the defect size, realizes automatic detection of surface defects of optical elements, and guarantees the efficiency and accuracy of defect recognition and classification.

[0030] The present application sets the imaging unit to consist of a coarse measurement light path and a fine measurement light path, the coarse measurement light path and the fine measurement light path share a set of integrated optical modules, automatic switching of low-magnification and high-magnification objectives is realized through a piezoelectric resonant micro-rotary table, the low-magnification objective and the high-magnification objective are designed to be parfocal, and the focal point positions are basically consistent after switching magnification. The coarse measurement light path performs dark field scanning imaging based on a low-magnification microscope objective, is used for quickly finding surface defects of elements, and the fine measurement light path has bright-dark field two working modes. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a device composition schematic diagram of surface defect detection of an optical element according to an embodiment of the present application;

[0032] Figure 2 is a working mode switching and integrated optical module schematic diagram of the imaging unit coarse measurement and fine measurement according to an embodiment of the present application;

[0033] Figure 3 is a coarse measurement light path (fine measurement dark field light path) schematic diagram according to an embodiment of the present application;

[0034] Figure 4is a fine measurement bright field light path schematic view of an embodiment of the present application;

[0035] Figure 5 is a mechanical structure principle block diagram of a scanning motion unit of an embodiment of the present application;

[0036] Figure 6 is a focusing terrain map generation principle schematic view based on spectral confocal sensor ranging of an embodiment of the present application;

[0037] Figure 7 is an automatic focusing control principle schematic view of an embodiment of the present application;

[0038] Figure 8 is a compatible size sample clamping design schematic view of an embodiment of the present application;

[0039] Figure 9 is a automatic leveling and centering device schematic view based on a kelvin hinge of an embodiment of the present application;

[0040] Figure 10 is a hundred-level clean device schematic view of an embodiment of the present application;

[0041] Figure 11 is a system control overall scheme electrical constitution schematic view of an embodiment of the present application; DETAILED DESCRIPTION

[0042] The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0043] Embodiments of the present application relate to a device and method for measuring surface defects of optical elements, which can be used for quality detection of precision optical elements. An embodiment of the device for measuring defects according to the present application is described below with reference to the accompanying drawings.

[0044] As shown in Figure 1 , an embodiment of the device for measuring defects according to the present application includes an imaging unit 100, a scanning motion unit 200, a profile measurement unit 300, an automatic focusing unit 400, a sample clamping unit 500, a leveling and centering unit 600, a clean control unit 700, and a master control unit 800.

[0045] In this embodiment, the imaging unit 100 is composed of a coarse measurement light path and a fine measurement light path, as shown in Figure 2 , the coarse measurement light path and the fine measurement light path share a set of integrated optical module 102-2 (the specific internal structure is shown in Figure 3 ), and automatic switching of the low-power and high-power objectives is realized by a piezoelectric resonant micro-rotary table 102-1. The low-power objective and the high-power objective are designed to be parfocal, and the focal point positions are basically consistent after switching the magnification.

[0046] In the present embodiment, as shown in Figure 3 The coarse measurement light path is based on a low magnification microscope objective for dark field scanning imaging to quickly find component surface defects. The dark field light source adopts a ring-shaped downlighting design. The dark field LED light source 103-1 enters the optical fiber bundle 103-3 through the light guide column 103-2, and then the light beam is ring-shapedly irradiated on the component by the ring-shaped lens, thereby forming the ring-shaped downlighting 103-13. The diffused reflection and diffraction light rays first enter the first imaging lens group 103-6 through the 5x microscope objective 103-12, and then the second thin film beam splitter 103-7 (camera switching / movable) behind the first imaging lens group 103-6, and after being split by the second thin film beam splitter 103-7, the face array camera 103-8 and the linear array camera 103-9 are entered to complete image acquisition.

[0047] The imaging unit 100 of the present application is also integrated with a bright field illumination module 103-5, which includes a bright field light source 103-11 and a second imaging lens group 103-10. When bright field observation is needed, the first thin film beam splitter 103-4 is moved in between the objective 103-12 and the first imaging lens group 103-6; and the bright-dark field switching is realized by the light of the bright field illumination module 103-5.

[0048] As shown in Figure 3 and 4 The fine measurement light path has two working modes of bright field and dark field, as shown in Figure 3 In the dark field working mode, the thin film beam splitter 103-4 for bright-dark field switching in the light path is moved out, and the camera switching thin film beam splitter 103-7 is also moved out, and is switched to the 20x microscope objective 104-1. In this way, the light reflected by the sample surface defects will enter the face array camera 103-8 to the greatest extent, thereby ensuring the sensitivity of defect detection. As shown in Figure 4 In the bright field working mode, the fine measurement light path collimates and homogenizes the light emitted by the bright field LED light source after passing through the bright field light source adapter lens group, and is co-axial with the 20x microscope objective 104-1. After the reflection of the thin film beam splitter 103-4 (bright-dark field switching / movable), the light beam enters the 20x microscope objective 104-1 to irradiate on the sample surface. The reflected light rays pass through the 20x microscope objective 104-1, the thin film beam splitter 103-4 (bright-dark field switching / movable) and the imaging lens group 103-6 in turn, are split by the second thin film beam splitter 103-7 (camera switching / movable), and are finally captured and imaged by the face array camera 103-8 and the linear array camera 103-9.

[0049] In the present embodiment, as shown in Figure 5As shown, the scanning motion unit 200 includes a five-axis cylindrical coordinate scanning measurement structure and a macro-micro two-stage driving structure. The five-axis cylindrical coordinate scanning measurement structure integrates three linear axes and two rotary axes, adopts an RTTTR (R represents a rotary axis, and T represents a linear axis) structure form, and the optical device is placed on the C-axis 205-5 rotating around a vertical axis in the leveling and centering unit 600. The entire imaging unit 100 is placed on the P-axis 205-4 rotating around a horizontal axis. The rotary axes C-axis and P-axis are connected through linear motion axes and a base. The C-axis 205-5 is integrally placed on the X-axis 205-1, the P-axis 205-4 is integrally placed on the Z-axis 205-3, the Z-axis 205-3 is placed on the Y-axis 205-2, the Y-axis 205-2 is placed on a marble beam, and the X-axis 205-1 is installed on a marble table. In the system, the X and Y linear moving axes are driven by linear motors, the Z-axis is driven by a servo motor with a high-precision ball screw with a brake function, and the three axes are supported by high-precision guide rails; the C and P rotary axes are driven to rotate by torque motors.

[0050] The macro-micro two-stage driving structure is composed of the Z-axis 205-3 in the five-axis cylindrical coordinate scanning measurement structure and a focusing displacement table to form the F-axis 205-6 of the device. Clear images are realized through the macro-micro two-stage driving structure.

[0051] In the embodiment, as shown in Figure 6 The profile measurement unit 300 measures the surface distance of the measured element by using a spectral confocal displacement sensor 306-1. The spectral confocal displacement sensor 306-1 is made to be perpendicular to the horizontal plane by swinging the P-axis 205-4 to drive the voice coil motor 306-2 to move. The highest point and the lowest point of the measured element are made to be within the measurement range of the spectral confocal displacement sensor 306-1 by driving the Z-axis 205-3. The X-axis 205-1 and the Y-axis 205-2 are driven to perform grid scanning 306-3 on the measured element in the X-Y plane. The spectral confocal measurement value and the X-Y plane coordinates are obtained, and the focusing topographic map 306-4 is generated by fitting.

[0052] In the embodiment, as shown in Figure 7 The automatic focusing unit 400 drives the microscopic objective lens 103-12 to focus by a PSD position converter 407-1, a motion controller 407-2, a semiconductor laser 407-4, and a voice coil motor 407-3. The output of the PSD position converter 407-1 is used as the feedback input signal of the motion controller 407-2. The motion controller 407-2 controls the voice coil motor 407-3 according to the feedback input signal, thereby adjusting the up-and-down movement of the microscopic objective lens 103-12, realizing automatic focusing imaging, and the semiconductor laser 407-4 is used for emitting laser.

[0053] In the embodiment, as shown inFigure 8 As shown in the figure, the sample clamping unit 500 includes a three-jaw elastic chuck and a radial locking device 508-1. The three-jaw elastic chuck includes three sets of torsion springs 508-2 fixed on a chuck outer ring mounting ring, and the three-jaw pre-tightening force is uniform. The radial locking device 508-1 is distributed on the outer edge of the three-jaw elastic chuck, and the position of the radial locking device 508-1 is adjustable. When measuring small-sized elements, the radial locking device 508-1 is installed in the middle reserved installation area 508-3 of the three-jaw elastic chuck, and the top rod head of the radial locking device 508-1 is designed with a replaceable matching block 508-4, and the matching surface of the matching block 508-4 is designed as a cylindrical surface structure. The material of the contact head of the three-jaw elastic chuck is preferably POM (race steel).

[0054] In this embodiment, as shown in the figure, Figure 9 The leveling and centering unit 600 is an automatic device integrating leveling and centering, and has two modes of automatic adjustment mode and manual adjustment mode. The leveling device in the leveling and centering unit 600 adopts a Kelvin hinge structure, and three supporting balls 609-1 are used to accurately constrain the position of the component. The three supporting balls 609-1 are in contact with three V-shaped grooves 609-2, and the center lines of the three V-shaped grooves 609-2 intersect at a point. The upper surfaces of two V-shaped grooves are inclined downward from inside to outside, and the structure of the leveling device is symmetrically designed with respect to the other V-shaped groove. Two leveling knobs 609-3 respectively adjust the positions of the supporting balls in the two inclined V-shaped grooves through corresponding step servo motors 609-5.

[0055] Specifically, the automatic leveling control system in the main control unit detects the specific parameters of the spectral confocal sensor 306-1, and then the main control unit drives the step servo motor 609-5 to adjust through the parameters.

[0056] The centering process is similar to the leveling process, and is adjusted through two centering knobs 609-4. The two centering knobs 609-4 can adjust the position through corresponding step servo motors.

[0057] In this embodiment, as shown in the figure, Figure 10 As shown in the figure, the clean control unit 700 includes a hundred-level laminar flow cover 7011-4, a low-noise fan 7011-1, a high-clean air filter 7011-2, a damping layer 7011-3, and a shock absorption layer 7011-6. The main equipment of the entire device is arranged inside the clean control unit 700, that is, the imaging unit 100, the scanning motion unit 200, the profile measurement unit 300, the automatic focusing unit 400, the sample clamping unit 500, and the leveling and centering unit 600 are all arranged inside the clean control unit 700.

[0058] The clean control unit is installed with a hundred-level laminar flow cover 7011-4. The ambient air is converted into clean air by the high-efficiency air filter 7011-2 under stable wind pressure. The clean air is evenly distributed by the damping layer 7011-3 and then sent into the detection area in vertical unidirectional flow. The air in the detection area is discharged through the lower air outlet 7011-5.

[0059] In this embodiment, as shown in Figure 11 The main control unit 800 includes a motion control system 8012-27, an illumination light source control system 8012-24, an image acquisition control system 8012-25, and an automatic leveling control system 8012-26.

[0060] The motion control system 8012-27 of the core adopts an 8-axis motion controller EC 8012-10 and two 4-axis motor drivers 8012-13 (supporting linear motors, voice coil motors, and rotary servo motors). The 8-axis motion controller 8012-10 is connected to the high-performance computer 8012-9 through Ethernet, and the 8-axis motion controller 8012-10 and the 4-axis motor driver 8012-13 are connected using an EtherCAT bus, thereby achieving driving and control of the X-axis linear displacement table 8012-16, the Y-axis linear displacement table 8012-17, the Z-axis linear displacement table 8012-18, the F-axis focusing displacement table 8012-19, the C-axis workpiece rotating table 8012-20, the P-axis probe swinging table 8012-21, and the magnification switching table 8012-22.

[0061] In the illumination light source control system 8012-24, the computer is connected to the LED driver 8012-8 through the USB port and controls the brightness and on-off of the bright-field LED light source 8012-1 and the dark-field LED light source 8012-2 through the CDC virtual serial protocol.

[0062] In the image acquisition control system 8012-25, the computer controls the exposure and image acquisition of the high-frequency line-scan camera 8012-4 (i.e., a line array camera) through the CameraLink acquisition card 8012-7 in dark-field mode. In bright-field mode, the computer is connected to the high-frame-rate area array camera through the USB3.0 interface and controls the exposure and image acquisition of the camera by external triggering.

[0063] The automatic leveling control system 8012-26 is mainly used to control the leveling and centering unit. The computer is connected with two stepping servo motors 8012-6 through the OpenCAN motion control card 8012-23, and controls the automatic leveling device 8012-5 to work through the CAN protocol. The spectral confocal sensor 8012-15 in the profile measurement unit is connected with the spectrometer 8012-12 and the high-performance computer. The PSD signal processor 8012-11 in the automatic focusing unit and the AF Probe 8012-14 are also connected with the high-performance computer through the 8-axis motion controller.

[0064] The above-described embodiments are only a preferred scheme of the present application, and are not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A device for measuring surface defects of optical elements, characterized in that... It includes an imaging unit (100), a scanning motion unit (200), a contour measurement unit (300), an autofocus unit (400), a sample clamping unit (500), a leveling and centering unit (600), and a main control unit (800). The imaging unit (100) consists of a coarse measurement optical path and a fine measurement optical path, and the coarse measurement optical path and the fine measurement optical path share a set of integrated optical modules (102-2), and the automatic switching between low magnification and high magnification objectives is achieved through a piezoelectric resonant micro turntable (102-1); The scanning motion unit (200) includes a five-axis cylindrical coordinate scanning measurement structure and a macro-micro two-stage drive structure; the five-axis cylindrical coordinate scanning measurement structure integrates three linear axes and two rotational axes, adopting an RTTTR structure; the optical components are placed on the C-axis (205-5) rotating around the vertical axis in the leveling and centering unit (600), and the entire imaging unit (100) is placed on the P-axis (205-4) rotating around the horizontal axis. The rotational axes C-axis and P-axis are connected to the base through a linear motion axis; the C-axis (205-5) is placed on the vertical axis rotating around the vertical axis rotating around the horizontal ... 05-5) The entire structure is placed on the X-axis (205-1), the P-axis (205-4) is placed on the Z-axis (205-3), the Z-axis (205-3) is placed on the Y-axis (205-2), the Y-axis (205-2) is placed on the marble beam, and the X-axis (205-1) is installed on the marble tabletop; the macro-micro two-stage drive structure consists of the Z-axis (205-3) in the five-axis cylindrical coordinate scanning measurement structure and the F-axis (205-6) of the focusing displacement stage, and a clear image is achieved through the macro-micro two-stage drive structure; The contour measurement unit (300) uses a spectral confocal displacement sensor (306-1) to measure the surface distance of the measured element. It drives the voice coil motor (306-2) to move through spatial transformation, and rotates the P-axis (205-4) to make the spectral confocal displacement sensor (306-1) perpendicular to the horizontal plane. It drives the Z-axis (205-3) to make the highest and lowest points of the measured element within the measurement range of the spectral confocal displacement sensor (306-1). It fixes the Z-axis (205-3) and drives the X-axis (205-1) and Y-axis (205-2) to perform grid scanning (306-3) on the measured element in the XY plane to obtain the spectral confocal measurement value and its XY plane coordinates, and fits to generate a focused topographic map (306-4). The autofocus unit (400) consists of a PSD position converter (407-1), a motion controller (407-2), a semiconductor laser (407-4), and a voice coil motor (407-3), which drive the microscope objective (103-12) to perform micro-motion focusing. The output of the PSD position converter (407-1) serves as the feedback input signal for the motion controller (407-2). The motion controller (407-2) controls the voice coil motor (407-3) according to the feedback input signal, thereby adjusting the micro-motion of the microscope objective (103-12) to achieve autofocus imaging. The semiconductor laser (407-4) is used to emit laser light. The sample clamping unit (500) is used to fix the sample to be tested, including a three-jaw elastic chuck and a radial locking device (508-1). The leveling and centering unit (600) is an automated device that integrates leveling and centering.

2. The apparatus for measuring surface defects of optical elements according to claim 1, characterized in that, The coarse measurement optical path is based on dark-field scanning imaging using a low-magnification microscope objective to quickly detect surface defects of components. The dark-field light source adopts a ring-shaped incident illumination (103-13) design. The dark-field LED light source (103-1) enters the fiber optic bundle (103-3) through the light guide column (103-2), and then the light beam is irradiated onto the component in a ring through the ring lens, thus forming the ring-shaped incident illumination (103-13). The diffuse reflection and diffraction light first enters the first imaging lens group (103-6) through the 5x microscope objective (103-12), and then the second thin-film beam splitter (103-7) behind the first imaging lens group (103-6). After being split by the second thin-film beam splitter (103-7), the light enters the area array camera (103-8) and the line array camera (103-9) to complete image acquisition.

3. The apparatus for measuring surface defects of optical elements according to claim 2, characterized in that... The imaging unit (100) also integrates a bright field illumination module (103-5), which includes a bright field light source (103-11) and a second imaging lens group (103-10). When bright field observation is required, a first thin film beam splitter (103-4) is moved between the objective lens (103-12) and the first imaging lens group (103-6). The switching between bright and dark fields is achieved by the light from the bright field illumination module (103-5).

4. The apparatus for measuring surface defects of optical elements according to claim 3, characterized in that, The precision measurement optical path has two working modes: bright field and dark field. In dark field mode, the thin-film beam splitter (103-4) used for switching between bright and dark fields is removed, as is the camera switching thin-film beam splitter (103-7), which is then switched to a 20x microscope objective (104-1). In this mode, the light reflected from surface defects on the sample will enter the area array camera (103-8) to the maximum extent, ensuring the sensitivity of defect detection. In bright field mode, the light emitted from the bright field LED light source in the precision measurement optical path is adapted to the bright field light source. After collimation and homogenization are completed by the lens group, the beam is co-imaged with the 20x microscope objective (104-1). After reflection by the thin-film beam splitter (103-4), the beam enters the 20x microscope objective (104-1) and illuminates the sample surface. The reflected light passes sequentially through the 20x microscope objective (104-1), the thin-film beam splitter (103-4), and the imaging lens group (103-6), and is then split by the second thin-film beam splitter (103-7). Finally, it is captured and imaged by the area array camera (103-8) and the line array camera (103-9).

5. The apparatus for measuring surface defects of optical elements according to claim 4, characterized in that, The sample clamping unit (500) is specifically structured as follows: the three-jaw elastic chuck includes three sets of torsion springs (508-2), which are fixed on the outer ring mounting ring of the chuck, and the preload of the three jaws is uniform; the radial locking device (508-1) is distributed on the outer edge of the three-jaw elastic chuck, and the position of the radial locking device (508-1) is adjustable; when measuring small-sized components, it is installed in the reserved installation area (508-3) in the middle of the three-jaw elastic chuck, and the top rod head of the radial locking device (508-1) is designed with a replaceable fitting block (508-4).

6. The apparatus for measuring surface defects of an optical element according to claim 5, characterized in that, The bonding surface of the bonding block (508-4) is designed as a cylindrical structure; the contact head of the three-jaw elastic chuck is made of POM material; and the bonding block is made of nylon material.

7. The apparatus for measuring surface defects of optical elements according to claim 1, characterized in that, The leveling and centering unit (600) is an automated device that integrates leveling and centering. The leveling and centering unit (600) adopts a Kelvin hinge structure and uses three support balls (609-1) to precisely constrain the position of the component. The three support balls (609-1) are in contact with three V-grooves (609-2), and the center lines of the three V-grooves (609-2) intersect at one point. The upper surfaces of two of the V-grooves are inclined downward from the inside out, and the structure is symmetrically designed about the other V-groove. The two leveling knobs (609-3) respectively fine-tune the position of the support balls in the two inclined V-grooves through the corresponding stepper servo motors (609-5).

8. The apparatus for measuring surface defects of optical elements according to claim 1, characterized in that, The device is also equipped with a clean control unit (700), including a Class 100 laminar flow hood (7011-4), a low-noise fan (7011-1), a high-cleanliness air filter (7011-2), a damping layer (7011-3), and a shock-absorbing layer (7011-6). The main equipment of the entire device is located inside the clean control unit (700), namely, the imaging unit (100), the scanning motion unit (200), the contour measurement unit (300), the autofocus unit (400), the sample clamping unit (500), and the leveling and centering unit (600) are all located inside the clean control unit (700).

9. The apparatus for measuring surface defects of an optical element according to claim 8, characterized in that, A Class 100 laminar flow hood (7011-4) is installed above the clean control unit. The ambient air is passed through the high-efficiency air filter (7011-2) at a stable wind pressure to generate clean air. The clean air is then evenly pressurized by the damping layer (7011-3) to form a uniform flow layer and is sent into the detection area in a vertical unidirectional flow. The air in the inspection area is then discharged through the exhaust port (7011-5) on the lower side.

10. The apparatus for measuring surface defects of an optical element according to claim 1, characterized in that, The main control unit (800) includes a motion control system, a lighting source control system, an image acquisition control system, and an automatic leveling control system; The core motion control system uses an 8-axis motion controller (EC) and two 4-axis motor drivers. The 8-axis motion controller is connected to a high-performance computer via Ethernet, and the 8-axis motion controller and the 4-axis motor drivers are connected via EtherCAT bus, thereby realizing the driving and control of the X-axis linear stage, Y-axis linear stage, Z-axis linear stage, F-axis focusing stage, C-axis workpiece rotary stage, P-axis probe swivel stage, and magnification switching stage. In the lighting source control system, the computer is connected to the LED driver via a USB port and controls the brightness and on / off state of the bright field LED light source and the dark field LED light source via the CDC virtual serial protocol. In the image acquisition and control system, in dark field mode, the computer controls the exposure and image acquisition of the linear scan camera through the CameraLink acquisition card; in bright field mode, the computer connects to a high frame rate area scan camera through a USB 3.0 interface, and the camera's exposure and image acquisition are controlled by external triggers. The automatic leveling control system is mainly used to control the leveling and centering unit. The computer is connected to two stepper servo motors through the OpenCAN motion control card and controls the automatic leveling device through the CAN protocol. The spectral confocal sensor in the contour measurement unit is connected to the spectrometer and the high-performance computer. The PSD signal processor and AF Probe in the automatic focusing unit are also connected to the high-performance computer through the 8-axis motion controller.

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