An optical lens surface defect detection device based on the principle of dark-field microscopy

Abstract

The present invention discloses an optical lens surface defect detection device based on the principle of dark-field microscopy for detecting surface defects of optical lenses, which includes a cabinet for shielding, a reflection light source module and a transmission light source module with automatically adjustable height arranged in the cabinet, an industrial camera for collecting defect images of optical lenses, a light source control module for controlling the above two light source modules, a lens fixture for supporting the lens to be detected, a transfer module for transferring the lens fixture to the lens detection station, and a total control module for overall control and pattern analysis; it realizes the transmission detection and reflection detection of the lens, the detection is more comprehensive, the analysis results of the defect images collected by the industrial camera have good consistency and high reliability, the light source module can automatically adjust the height and can achieve halo removal, improving the detection accuracy; the overall automation degree of the product is high, the reliability is good, the manual participation is reduced, and the detection cost is effectively reduced and the detection efficiency is improved in industrial applications.

Description

Technical Field

[0001] The present invention relates to an optical lens surface defect detection device, and in particular to an optical lens surface defect detection device based on the principle of dark-field microscopy imaging. Background Art

[0002] Optical lenses are indispensable key components in optical systems. In the processing of optical lenses, they need to go through "cold processing" technological processes such as cutting, rough grinding, polishing, and core cutting to be initially formed. During this process, affected by factors such as external vibration, power grid fluctuations, human interference, cutting edge passivation, uneven sizes of grinding and polishing particles, and unclean cleaning, surface defects such as scratches, scuffs, pits, and broken edges are likely to form on the lens surface. These surface defects will affect the optical performance of the lens and thus the performance of the entire optical system. Therefore, optical lens manufacturers need to conduct surface defect detection on lenses after multiple processing steps.

[0003] Currently, the detection of lens surface defects mainly adopts the traditional manual detection method. This method requires the inspector to select an appropriate transmission or reflection lighting method according to the detection standards of surface defects in a dark-field environment, and observe the surface defect situation of the measured area through a 5 - 10 times optical magnifying glass with the naked eye, and judge the type and grade of the defects based on experience or a standard comparison pattern. This method has a certain degree of subjectivity, and affected by factors such as the inspector's experience, attention, and eye fatigue, it is difficult to ensure the stability and reliability of the detection results.

[0004] The applicant applied for a patent named: Method and Device for Removing Halation Influence in the Detection of Surface Defects of Large-Curvature Optical Lenses on June 28, 2021, with the application number 202110716475.0. Although this patent realizes partial automation, the degree of automation is limited. Summary of the Invention

[0005] In view of the above problems, the present invention provides an optical lens surface defect detection device based on the principle of dark-field microscopy imaging, which can improve the detection efficiency and reduce manual participation.

[0006] To solve the above technical problems, the present invention provides an optical lens surface defect detection device based on the principle of dark-field microscopy imaging, including a cabinet for shielding, a transmissive light source module with an automatically adjustable height and a reflective light source module with an automatically adjustable height arranged in the cabinet, an industrial camera for collecting images of optical lens defects, a light source control module for controlling the above two light source modules, a lens fixture for supporting the lens to be detected, a transfer module for transferring the lens fixture to the lens detection station, and a total control module for overall control and pattern analysis.

[0007] During implementation, in the detection state, the industrial camera is located directly above the lens to be detected on the lens fixture, the light source of the transmission light source module is located directly below the lens to be detected, and the light source of the reflection light source module is located directly above the lens to be detected.

[0008] During implementation, at the lens detection station, the lens fixture is in a suspended state (i.e., having a certain distance from the dark background), a dark background is provided below the cabinet, and the dark background is outside the depth of field of the industrial camera. This ensures that there are no other objects in the pattern captured by the industrial camera except the lens to be detected and the lens fixture, making the scattered light emitted from the defective part more obvious. The dark background being outside the depth of field of the industrial camera can prevent dust, reflections, etc. on the dark background from imaging on the industrial camera and avoid interfering with the defect recognition.

[0009] During implementation, the total control module is a computer, and the light source control module is a single-chip microcomputer, an embedded system, a PLC, or integrated in the computer.

[0010] During implementation, the reflection light source module includes a linear motion module for the reflection light source module with a fixed position. The linear motion module for the reflection light source module includes a slider that can move vertically, and a reflection light source is fixed on the slider through a reflection light source module bracket.

[0011] During implementation, the reflection light source is a diffused reflection ring light source, and the center line of the diffused reflection ring light source coincides with the optical axis of the industrial camera.

[0012] During implementation, the transmission light source module includes a linear motion module for the transmission light source module with a fixed position. The linear motion module for the transmission light source module includes a slider that can move vertically, and a transmission light source is fixed on the slider through a transmission light source module bracket.

[0013] During implementation, the transmission light source uses a diffused reflection light source.

[0014] During implementation, the lens fixture is a flat plate structure, and one or more supporting holes matching the size of the lens to be detected are provided on its main plane.

[0015] During implementation, the transfer module includes a limiting part (a part or device that plays a limiting role) adapted to the lens fixture, and the transfer module is provided with a moving mechanism at least in the horizontal front-back and left-right directions, and can send the lens fixture into or out of the cabinet during the transfer process.

[0016] During implementation, the transfer module is a robotic arm, and the robotic arm is provided with a mechanical claw for clamping the lens fixture.

[0017] During implementation, the transfer module further includes a vision guiding mechanism.

[0018] During implementation, the robotic arm is at least a three-axis robotic arm.

[0019] During implementation, the transmission module includes a base, a column fixed on the base, a first connecting block extending from the side of the column, a first deflection arm with one end rotatably connected to the lower part of the first connecting block, a second deflection arm rotatably connected to the other end under the first deflection arm, a mechanical claw rotatably connected to the lower end of the second deflection arm, and two claw arms that can be retracted or opened and are arranged at the driving end of the mechanical claw.

[0020] The beneficial effects of the present invention are as follows: an optical lens surface defect detection device based on the principle of dark field microscopy imaging, comprising a cabinet for shielding, a reflective light source module and a transmissive light source module that can automatically adjust the height and are arranged in the cabinet, an industrial camera for collecting optical lens defect images, a light source control module for controlling the above two light source modules, a lens fixture for supporting the lens to be detected, a transmission module for transferring the lens fixture to the lens detection station, and a master control module for overall control and pattern analysis; the transmission module can realize automatic lens transmission, the irradiation of the transmissive light source module and the reflective light source module is switched or combined, and the transmission detection and reflection detection or combined detection of the lens are realized, the detection is more comprehensive, the industrial camera collects defect image analysis results with good consistency and high reliability, the light source module can automatically adjust the height, can realize halo removal, and improve detection accuracy. The product has a high overall degree of automation and good reliability, reduces manual participation, reduces detection costs and improves detection efficiency in industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the implementation manner will be briefly introduced below. Obviously, the drawings described below are only some implementation manners of the present application. For ordinary technicians in this field, these drawings can also be used to obtain other drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of a reflective light source module according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of a transmission light source module according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of a lens fixture and a transmission module according to an embodiment of the present invention;

[0026] Figure 5 A detection flow chart of an embodiment of the present invention;

[0027] Figure 6 To Figure 5 detect the current lens analysis and display (single lens detection) flowchart. Specific embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0029] The present invention discloses an optical lens surface defect detection device based on the principle of dark field microscopy. Referring to Figures 1-6 as shown, its solution includes a cabinet 5 that plays a shielding role, a reflection light source module 2 and a transmission light source module 1 with automatically adjustable height arranged in the cabinet 5, an industrial camera 3 for collecting optical lens defect images, a light source control module 8 for controlling the above two light source modules, a lens fixture 7 for supporting the lens to be detected, a transmission module 4 for transferring the lens fixture 7 to the lens detection station, and a total control module for overall control and pattern analysis. Through the transmission module 4, automatic transmission of the lens can be realized, and the illumination switching or combination of the transmission light source module 1 and the reflection light source module 2 can be realized to achieve transmission detection, reflection detection or transmission / reflection combination detection of the lens, with more comprehensive detection, good consistency and high reliability of the defect image analysis results collected by the industrial camera, and the light source module can automatically adjust the height to achieve halo removal and improve the detection accuracy. The overall product has a high degree of automation and good reliability, reduces manual participation, and reduces the detection cost and improves the detection efficiency in industrial applications.

[0030] In one embodiment, the industrial camera 3 is located directly above the lens to be detected on the lens fixture 7, the light source of the transmission light source module 1 is located directly below the lens to be detected, and the light source of the reflection light source module 2 is located directly above the lens to be detected. Such a position setting ensures the coaxiality of the light source and the lens, maximally avoids the influence of halos, improves the detection accuracy, and it is easy to perform dehaloing processing in case of halos; and it provides the imaging quality of the camera.

[0031] In one embodiment, during the inspection, the lens fixture 7 at the lens inspection station is suspended (i.e., at a certain distance from the dark background), and a dark background 6 is provided at the inner bottom of the cabinet 5, and the dark background 6 is located outside the depth of field of the industrial camera 3. This ensures that the pattern captured by the industrial camera 3 contains no other objects except the lens to be tested and the lens fixture 7, making the scattered light emitted from the defective part of the lens more obvious. The dark background 6 is located outside the depth of field of the industrial camera 3, which can prevent dust and reflections on the dark background 6 from being imaged on the industrial camera 3, thereby avoiding interference with defect identification.

[0032] In one embodiment, the master control module may be a computer 9, which can realize control, analysis, data processing, imaging, etc. through various software and hardware, and the light source control module 8 is a single chip microcomputer, an embedded system, a PLC, or is integrated in the computer 9 to further reduce the cost. Of course, it is not ruled out that there are improvements, such as replacing the computer 9 with a display output module such as a display screen, etc., identifying lens defects by manually observing photos, or integrating the functions of the master control module into the light source control module 8, and re-dividing the functions of the master control module and the light source control module 8.

[0033] In one embodiment, referring to Figure 2 , the reflective light source module 2 includes a fixed reflective light source module linear motion module 2-1, the reflective light source module linear motion module 2-1 includes a vertically movable slider, and a reflective light source 2-2 is fixed to the slider through a reflective light source module bracket 2-3. Preferably, the reflective light source 2-2 is a diffuse reflection ring light source, and the center line of the diffuse reflection ring light source coincides with the visual axis of the industrial camera 3. The structure is simple and height-adjustable, so as to maintain a suitable distance from the lens, and for lenses with large curvature, it is convenient to take pictures at two heights for dehalation processing (refer to the following text, or patent 202110716475.0). The diffuse reflection ring light source allows the lens to obtain more sufficient angles and more light, thereby increasing the reflectivity of the defective part. And the ring avoids the formation of halos on the lens as much as possible.

[0034] In one embodiment, referring to Figure 3 The transmission light source module 1 includes a fixed transmission light source module linear motion module 1-1, the transmission light source module linear motion module 1-1 includes a vertically movable slider, and a transmission light source 1-2 is fixed on the slider through a transmission light source module bracket 1-3. Preferably, the transmission light source 1-2 adopts a diffuse reflection light source. The structure is simple and the height is adjustable, and a suitable distance can be maintained with the lens. The diffuse reflection annular light source allows the lens to obtain more sufficient light at more angles, thereby improving the presentation of defective parts.

[0035] In one embodiment, the lens fixture 7 has a flat plate structure, and one or more supporting holes matching the size of the lens to be detected are provided on its main plane. Through this structure, the positioning of one or more lenses can be achieved, and it is convenient for the lenses to be transferred during the processing and detection process, and the safety of the lenses can be protected. Especially when there are multiple lenses, the transfer efficiency can be improved.

[0036] In one embodiment, the transfer module 4 includes a limiting part (a part or device that limits the lens fixture 7) adapted to the lens fixture 7, and the transfer module 4 is provided with a moving mechanism at least in the horizontal front-back and left-right directions. During the transfer process, the lens fixture 7 can be sent into or out of the cabinet 5. For example, a conveyor belt mechanism can be used. In addition to the transfer direction, a moving mechanism can be provided in the lateral position to facilitate the switching detection of juxtaposed lenses. Another example is to use a double lead screw slider mechanism that can move in the X and Y directions. In an extremely degraded situation, the transfer module 4 can have a moving mechanism with only one degree of freedom for serially sending a single lens into / out of the cabinet 5 for detection. However, in this case, lenses cannot be sent in parallel, and the loading capacity of the lens fixture 7 is reduced. And the lens fixture 7 can even be integrated with the transfer module 4 to reduce costs, but it will have a negative impact on the cleaning and retention of the lenses and the convenience of transfer.

[0037] In one embodiment, the transfer module 4 is a robotic arm, and the robotic arm is provided with a mechanical claw for clamping the lens fixture 7. The robotic arm technology is mature and responds quickly, and it has good applicability and adjustability according to different detection requirements and equipment design adjustment requirements.

[0038] In one embodiment, the transfer module 4 further includes a vision guiding mechanism. Through the cooperation of the vision guiding mechanism, automatic picking up of the lens / lens fixture 7 outside the cabinet 5, inputting to the detection device, and placing the output device at an appropriate position after the detection is completed can be realized, improving the degree of automation.

[0039] In one embodiment, the robotic arm is at least a three-axis robotic arm. Thus, at least the automatic picking up of the lens / lens fixture 7, transferring into / transferring out of the cabinet 5, and position adjustment in one direction can be achieved.

[0040] Refer to Figure 1 As shown in a specific embodiment of the present invention, an optical lens surface defect detection device based on the principle of dark field microscopy mainly includes a cabinet 5, and an industrial camera 3, a reflection light source module 2, a transmission light source module 1, a lens fixture 7, a transfer module 4, a light source control module 8, and a computer 9 are equipped inside the cabinet.

[0041] Among them, the cabinet 5: mainly used to block external stray light, realize a dark field observation environment, avoid the interference of other indoor light sources, and also used to fix the equipment.

[0042] Among them, industrial camera 3: An industrial camera with a microscopic lens can be used to collect images of optical lens defects. The industrial camera 3 is fixed inside the cabinet 5 using a camera bracket. The bottom of the camera bracket is fixedly connected to the cabinet 5; the inner wall of the cabinet within the camera's field of view is black, that is, the observation background of the measured lens is black (set the dark background 6) to avoid stray light interference.

[0043] Among them, the lens fixture 7 and the transfer module 4: In the present invention, the lenses to be detected are fixed using the lens fixture 7. The material of the lens fixture is plastic or metal, and there are holes on the fixture that match the size of the lens, which can fix one or more lenses (the lens fixture 7 can be made according to the situation or existing fixtures in other lens processing procedures can also be used). The lens fixture 7 is transferred to the detection position by the transfer module 4. The transfer module 4 consists of a multi-degree-of-freedom robotic arm with a mechanical claw 4-6 and its driving mechanism. The transfer module 4 can grasp the lens fixture 7, control the fixture's attitude, and move the fixture to within the depth of field of the industrial camera 3 along a predetermined path, so that the lenses 10 in the lens fixture 7 are sequentially imaged on the camera's target surface. After the detection is completed, the lens fixture 7 is placed at a specified position. Of course, in implementation, the transfer module 4 can also adopt other transfer structures such as a conveyor belt with a hollowed-out embedded station.

[0044] Among them, as Figure 2 shown, the reflected light source module 2: During the detection process, with the main plane of the measured lens as the reference plane, it is on the same side as the industrial camera 3 and provides a movable light source module for reflected light. In the present invention, the optimal solution for the reflected light source 2-2 is a diffuse reflection ring light source, and the center line of the ring light source coincides with the camera's optical axis. This light source is fixed on the slider of the reflected light source module linear motion module 2-1 through the reflected light source module bracket 2-3, and the base of the reflected light source module linear motion module 2-1 is fixedly connected to the cabinet 5 (or indirectly connected to the cabinet 5 after being connected through the main body of the transmitted light source module 1). During the observation process, by controlling the position of the slider, the relative position between the light source and the measured lens 10 is controlled, and thus the irradiation angle of the light source is controlled.

[0045] Among them, as Figure 3 shown, the transmitted light source module 1: During the detection process, with the main plane of the measured lens as the reference plane, it is on the opposite side of the industrial camera 3 and provides a movable light source module for transmitted light. In the present invention, the optimal solution for the transmitted light source 1-2 is a diffuse reflection light source. This light source is fixed on the slider of the transmitted light source module linear motion module 1-1 through the transmitted light source module bracket 1-3, and the base of the transmitted light source module linear motion module 1-1 is fixedly connected to the cabinet 5. During the observation process, by controlling the position of the slider, the relative position between the light source and the measured lens 10 is controlled, and thus the irradiation angle of the light source is controlled.

[0046] Light source control module 8: It is a device used to control the coordinated operation of the reflected light source module 2 and the transmitted light source module 1. The core control device of the light source control module 8 can be implemented by, but not limited to, the following types of devices: single-chip microcomputer, embedded system, PLC, personal computer, industrial control computer. The main functions of the light source control module 8 include: switching the light source module according to the lens type, controlling the light source to move to a specified height, and sending the status of the light source to the host computer (computer), etc.

[0047] Computer 9: It is mainly responsible for sending instructions to the industrial camera 3, the conveying module 4, and the light source control module 8 to ensure the coordinated operation of each component in this device. At the same time, it analyzes the surface image of the lens collected by the industrial camera 3 to identify defects in the image.

[0048] Such as Figure 1 , 2 , 3, 4, 5, 6 shown in the specific embodiments. An optical lens surface defect detection device based on the principle of dark field microscopy, including a cabinet 5, an industrial camera 3, a lens fixture 7, a conveying module 4, a reflected light source module 2, a transmitted light source module 1, a light source control module 8, and a computer 9.

[0049] First, build an aluminum profile cabinet 5 with an external dimension of 1m×1m×1m. The surface of the cabinet 5 uses a light-tight material to block stray light and avoid interference from other indoor light sources. At the same time, combined with the black dark background 6 set at the bottom inside the cabinet 5, a dark field observation environment is realized.

[0050] In this embodiment, the lens of the industrial camera 3 is a microscopic lens. The camera is fixed inside the cabinet by a bracket. The bracket base is made of die-cast aluminum plate, and the surface is subjected to black sandblasting treatment to avoid the interference of reflected light on the lens defect detection environment. The bracket base is connected upward to a stainless steel threaded pipe with an outer diameter of 25mm, an inner diameter of 20mm, a wall thickness of 4mm, and a height of 600mm. A solid chrome-plated rod is used on the stainless steel threaded pipe to connect the camera clamping device, which is convenient for adjusting the forward extension distance of the camera. The camera clamping device is located in the upper half of the stainless steel threaded pipe and is equipped with a knob for conveniently fine-tuning the height of the camera. The clamping distance of the camera clamping device is 20 - 85mm, and the camera is protected by PU material. Both the transmitted light source module 1 and the reflected light source group 2 are composed of a linear motion module, a bracket, and an annular light source. The bases of the transmitted light source module linear motion module 1-1 and the reflected light source module linear motion module 2-1 are fixedly connected to the bottom of the cabinet 5, that is, the base is fixed relative to the cabinet 5, and the annular light source is fixedly connected to the sliders of the transmitted light source module linear motion module 1-1 and the reflected light source module linear motion module 2-1 through the transmitted light source module bracket 1-3 and the reflected light source module bracket 2-3. The annular light sources are all annular light sources powered by 24v. To ensure uniform transmission of light through the measured lens, the central axis of the annular light source coincides with the optical axis of the industrial camera 3.

[0051] In this embodiment, the lens 10 to be tested is fixed by a lens fixture 7, the outer contour of which is a square with a side length of 8.14 cm and is made of metal or plastic. The lens fixture 7 has holes that match the size of the lens 10, and each fixture has 25 holes in 5 rows and 5 columns, which can fix 25 lenses (the number of holes in each fixture can be customized according to the size of the lens).

[0052] In this embodiment, the transmission module 4 uses a five-degree-of-freedom mechanical arm and a matching mechanical claw 4-6 to clamp the lens fixture 7 and transmit the lens fixture 7 to the detection position. The transmission module 4 can be modified from a SCARA-configured desktop robot, with an additional fifth-axis rotating device, a claw arm 4-7, and a mechanical claw 4-6 with an opening / clamping function. The shape of the claw arm 4-7 of the mechanical claw 4-6 is set according to the shape of the lens fixture 7. (The structure of the transmission module 4: a base 4-1, a column 4-2 fixed on the base 4-1, a first connecting block 4-3 extending from the side of the column 4-2, a first deflection arm 4-4 rotatably connected at one end to the lower part of the first connecting block 4-3, a second deflection arm 4-5 rotatably connected to the other end under the first deflection arm 4-4, a mechanical claw 4-6 rotatably connected to the lower end of the second deflection arm 4-5, and two claw arms 4-7 that can be retracted or opened are set at the driving end of the mechanical claw 4-6).

[0053] Furthermore, as needed, the mechanical claw 4-6 itself can also drive the claw arm 4-7 to rotate to adjust the angle between the lens fixture 7 and the light source.

[0054] Furthermore, although the light sources of the reflective light source module 2 and the transmissive light source module 1 have a height adjustment function, the transmission module 4 / robotic arm may include a vertical height adjustment mechanism as needed to facilitate height adjustment of the lens fixture 7.

[0055] During the inspection process, the clamping device should ensure that the lens to be tested is suspended in the air, and there are no objects other than the lens and the clamp within the depth of field of the industrial camera 3. There are no other objects including the background within the depth of field. Otherwise, dust and reflections on the background will affect the observation effect.

[0056] In this embodiment, the light source control module 8 is used to control the transmitted light source module 1 and the reflected light source module 2, and upload the light source status. The computer 9 is responsible for coordinating the work of the light source control module 8, the transmission module 4, the lens fixture 7, and the industrial camera 3, and analyzing the collected image of the lens 10.

[0057] When this patent is implemented, Figure 5 As shown, the detection process is:

[0058] 1. The operator selects the lens type and fixture type in the human - machine interaction interface of the computer 9 application software.

[0059] 2. The computer 9 sends an instruction to the light source control module 8, turns on the transmission light source module 1 or the reflection light source module 2 according to the lens type selection, moves the light source to the corresponding height, and loads the relevant parameters of the lens fixture 7.

[0060] 3. Place the lens fixture 7 on the test bench, the robotic arm of the transfer module 4 moves to the corresponding position, and the claw arm 4 - 7 of the robotic claw 4 - 6 automatically grabs the lens fixture 7.

[0061] 4. After grabbing the lens fixture 7, move the lens fixture 7 to the position to be measured in front of the industrial camera 3 through a preset path, so that the first lens forms an image at the center of the camera target surface.

[0062] 5. The computer 9 analyzes the lens images collected by the industrial camera 3, identifies the surface defects therein according to the detection standard, stores the defect information and displays it in the human - machine interaction interface.

[0063] 6. After the first lens is detected, according to the information of the lens fixture 7, move the robotic arm, and sequentially move the other lenses in the fixture to the position to be measured, repeat step 5 for defect detection. After all lenses are detected, the transfer device 4 moves the detected lens fixture 7 out of the detection position and places it at the designated position. (Judge whether it is the last lens on the fixture. If not, move the next lens to the position to be measured. If so, move the fixture out.)

[0064] During implementation, in step 5 above, when the lens to be measured is a lens with a large curvature, under the illumination of the reflection light source 2 - 2, there will be a halo on the defective surface. It is necessary to place the reflection light source 2 - 2 at different heights, take two pictures, and then use image - processing methods to eliminate the halo. This step can be divided into the following 10 sub - steps, as shown in Figure 6 the single - lens analysis sub - process shown:

[0065] (1) Turn on the transmission light source 1 - 2 and move it to the preset observation position.

[0066] (2) The industrial camera 3 takes an image of the lens surface under the illumination of the transmission light source 1 - 2 to obtain picture P1.

[0067] (3) The computer 9 analyzes picture P1 and identifies the surface defects therein.

[0068] (4) Turn off the transmission light source 1 - 2 and move it to the starting position.

[0069] (5) Turn on the reflection light source 2 - 2 and move it to the illumination position A.

[0070] (6) Take an image of the lens surface to obtain picture P2;

[0071] (7) Move the reflected light source 2-2 to the illumination position B;

[0072] (8) Take an image of the lens surface to obtain picture P3;

[0073] (9) Combine and analyze pictures P2 and P3, eliminate the influence of halos, and identify surface defects;

[0074] (10) Synthesize the analysis results of steps (3) and (9), record and display.

[0075] During implementation, further expand the method of combining and analyzing pictures P2 and P3 in step (9). You can refer to the method and device for removing the influence of halos in the detection of surface defects of large-curvature optical lenses with the application number 202110716475.0. The method process is as follows:

[0076] Step 1: Based on the dark-field scattering microscopy method, select two different heights for the illumination light source to ensure that when the light source illuminates at these two heights, the halos on the lens surface can be staggered;

[0077] Step 2: Take pictures of the lens to be measured - picture P2 and picture P3 respectively when the light source is at these two heights;

[0078] Step 3: Eliminate the halo part by covering to obtain an image of the lens surface without the influence of halos - picture P4.

[0079] Preferably, the dark-field scattering microscopy method is specifically: in a dark-field environment, place the optical lens to be measured under the imaging system, and the light beam emitted by the illumination system irradiates the surface of the optical lens to be measured; if there are no defects on the lens surface, the illumination light beam will exit from the other side and will not enter the upper imaging system; when there are defects on the surface of the optical element, due to the local microscopic structure of the defects, the incident light beam will generate a large range of scattering, and part of the scattered light will enter the imaging system, thereby obtaining a bright image of the defect against a dark background.

[0080] Preferably, between step 2 and step 3, it is also necessary to preprocess the image to achieve image noise reduction and position alignment.

[0081] Preferably, the specific steps of step three are as follows: find the halo positions in pictures P2 and P3 respectively, and then construct a mask according to the halo shape; at the same time, use two different merging methods to obtain the merged pictures Smax and Smin. Each pixel in picture Smax takes the maximum gray value of the corresponding pixels in P2 and picture P3, that is: Smax(i,j) = max(A(i,j), B(i,j)), and each pixel in picture Smin is the minimum gray value of the corresponding pixels in P2 and picture P3: Smin(i,j) = min(A(i,j), B(i,j)); use the mask and the merged pictures Smax and Smin for operation to cover the halo and obtain the picture P4 without halo; use image processing methods such as edge detection and threshold segmentation or artificial intelligence methods to extract the defect image in picture P4.

[0082] Preferably, the step of using the mask and the merged pictures Smax and Smin for operation to cover the halo and obtain the picture P4 without halo; the specific method is: at the halo position C(i,j) = Smin(i,j), and at other positions C(i,j) = Smax(i,j).

[0083] Corresponding to an optical lens surface defect detection device based on the principle of dark field microscopy, its light source control module 8 includes a height control module, which is used to adjust the light source in the reflection light source group 2 to two different heights respectively for taking pictures (industrial camera 3) during the reflection light test of the large curvature optical lens. The total control module also includes a halo removal module, which is used to perform merging and halo removal processing on the pictures taken at the above two different heights.

[0084] The present invention uses a lens fixture to fix the lens to be measured, and uses a mechanical claw to hold the fixture, ensuring that the lens to be measured is suspended during the detection process, there are no other objects within the depth of field of the camera, and the background is black, making the scattered light emitted from the defect more obvious. Compared with the prior art method of placing the lens on carriers such as opaque solids and glass slides, it can eliminate the interference of factors such as unevenness on the surface of the carrier and dust on the surface of the carrier.

[0085] The present invention uses a movable transmitted light source and a reflected light source for lighting, and can switch the lighting method and lighting angle. For different application scenarios, it has higher flexibility and can obtain better observation effects. Defects such as scratches are suitable for combined observation of reflected light and transmitted light; halos will be generated when the large curvature lens is irradiated by reflected light, which will affect the observation effect. The reflected light source needs to irradiate twice at different heights, and then the influence of the halo is eliminated through image processing methods; defects such as color spots have better observation effects under reflected light irradiation.

[0086] The present invention adopts a multi-degree-of-freedom robotic arm and a mechanical claw to clamp a lens fixture, which can adjust the posture of the lens to facilitate obtaining a better observation angle. During the detection, for scratches, there is a better observation effect under the illumination condition of combining transmitted light and reflected light, while for color spots, there is a better observation effect under the observation of reflected light. This patent has both a controllable and adjustable transmitted light source and a reflected light source, and can achieve automated optimal detection under the control of the light source control module 8 and the total control module.

[0087] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described methods, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein. Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0088] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An optical lens surface defect detection device based on the principle of dark-field microscopy, characterized in that, It includes a cabinet (5) for shielding, a reflection light source module (2) and a transmission light source module (1) with automatically adjustable height arranged in the cabinet (5), an industrial camera (3) for collecting optical lens defect images, a light source control module (8) for controlling the above two light source modules, a lens fixture (7) for supporting the lens to be detected, a transmission module (4) for transferring the lens fixture (7) to the lens detection station, and a general control module for overall control and pattern analysis; In the detection state, the industrial camera (3) is located directly above the lens to be detected on the lens fixture (7), the light source of the transmission light source module (1) is located directly below the lens to be detected, and the light source of the reflection light source module (2) is located directly above the lens to be detected; At the lens detection station, the lens fixture (7) is in a suspended state, and a dark background (6) is arranged below the cabinet (5), and the dark background (6) is outside the depth of field of the industrial camera (3); Among them, the general control module is used to send instructions to the light source control module (8) to turn on the transmission light source module (1) and the reflection light source module (2) and move them to the corresponding heights, load the relevant parameters of the lens fixture (7), send instructions to the transmission module (4) to control the transmission module (4) to move the lens fixture (7) to the corresponding position between the transmission light source module (1) and the reflection light source module (2) according to the preset path, and according to the first picture taken by the industrial camera (3) when only the transmission light source module (1) is turned on, the second picture and the third picture taken by the industrial camera (3) at different heights when only the reflection light source module (2) is turned on, eliminate the halo of the second picture and the third picture to obtain a fourth picture without halo influence, and finally obtain the surface defects of the optical lens according to the first picture and the fourth picture.

2. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 1, characterized in that The general control module is a computer (9), and the light source control module (8) is a single-chip microcomputer, an embedded system, a PLC, or integrated in the computer (9).

3. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 1, characterized in that, The reflection light source module (2) includes a reflection light source module linear motion module (2-1) with a fixed position. The reflection light source module linear motion module (2-1) includes a slider that can move vertically, and a reflection light source (2-2) is fixed on the slider through a reflection light source module bracket (2-3).

4. The optical lens surface defect detection device based on the principle of dark-field microscopy according to claim 3, wherein The reflection light source (2-2) is a diffuse reflection ring light source, and the center line of the diffuse reflection ring light source coincides with the optical axis of the industrial camera (3).

5. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 1, characterized in that, The transmission light source module (1) includes a transmission light source module linear motion module (1-1) with a fixed position. The transmission light source module linear motion module (1-1) includes a slider that can move vertically, and a transmission light source (1-2) is fixed on the slider through a transmission light source module bracket (1-3).

6. The optical lens surface defect detection device based on the principle of dark-field microscopy according to claim 5, characterized in that, The transmission light source (1-2) adopts a diffuse reflection light source.

7. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 1, characterized in that, The lens fixture (7) is a flat structure, and one or more supporting holes matching the size of the lens to be detected are arranged on its main plane.

8. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 1, characterized in that, The conveying module (4) comprises a limiting portion adapted to the lens fixture (7), and the conveying module (4) has a moving mechanism at least in the horizontal front-back and left-right directions, so that the lens fixture (7) can be sent into or out of the cabinet (5) during the conveying process.

9. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 8, wherein, The transfer module (4) is a mechanical arm having a mechanical claw for clamping the lens fixture (7).

10. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 8, characterized in that, The transmission module (4) also includes a visual guidance mechanism.

11. The optical lens surface defect detection device based on the principle of dark field microscopy according to claim 9, characterized in that, The robotic arm is at least a three-axis robotic arm.

12. The optical lens surface defect detection device based on the principle of dark-field microscopy according to claim 11, characterized in that, The transmission module (4) comprises a base (4-1), a column (4-2) fixed on the base (4-1), a first connection block (4-3) extending from the side of the column (4-2), a first deflection arm (4-4) with one end rotatably connected to the lower part of the first connection block (4-3), a second deflection arm (4-5) rotatably connected to the other end under the first deflection arm (4-4), a mechanical claw (4-6) rotatably connected to the lower end of the second deflection arm (4-5), and two claw arms (4-7) arranged at the driving end of the mechanical claw (4-6) that can be retracted or opened.

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