An optical element surface defect detection device
The optical component surface defect detection device based on the Michelson interferometry principle utilizes a wavelength modulator and an interferometric detection module to achieve efficient and accurate detection of large-area optical components, solving the problems of low efficiency and insufficient accuracy in batch detection in existing technologies.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- O NET COMM (SHENZHEN) LTD
- Filing Date
- 2025-06-24
- Publication Date
- 2026-06-23
AI Technical Summary
Existing methods for detecting surface defects in optical components are inefficient and inaccurate in batch testing, especially in dealing with situations where there are discontinuous abrupt changes in surface shape on the optical component.
An optical element surface defect detection device based on the Michelson interferometry principle is used. The light is modulated into polarized light with a fixed direction and adjustable equivalent wavelength by a wavelength modulator. Combined with a collimation and beam expansion module and an interferometric detection module, the detection of large-area optical elements is realized, and the defect area is monitored by using interference fringes.
It improves the efficiency and accuracy of batch testing, is applicable to optical components with complex surface changes, reduces testing time, and improves testing stability and accuracy.
Smart Images
Figure CN224399291U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical inspection technology, and in particular to a device for detecting surface defects of optical components. Background Technology
[0002] Methods for detecting surface defects in optical components are mainly divided into two types: contact and non-contact. Contact detection methods primarily utilize coordinate measuring machines (CMMs) to perform point-by-point scanning measurements. While the measurement accuracy is at the micrometer level, the speed is slow. The biggest problem is that contact probes can cause scratches on the surface, affecting its optical performance. Non-contact detection methods, such as microlens array methods, interferometry, and structured light three-dimensional measurement, do not cause surface scratches and are more widely used in practical applications.
[0003] Because the number of optical components required in low-level applications is large and the required detection range is large, especially when there are discontinuous abrupt changes in the surface shape of the optical components, the current interferometer has a narrow measurement range and cannot effectively deal with the detection of such surface shapes, resulting in low efficiency of batch detection and inaccurate detection results. Utility Model Content
[0004] This utility model provides an optical element surface defect detection device that is applicable to batch detection, improves the problem of insufficient inherent modulation phase, and enhances the accuracy of detection results during batch detection.
[0005] This utility model discloses an optical element surface defect detection device, comprising: a light source, and a wavelength modulator, a collimation and beam expansion module, and an interference detection module arranged sequentially along the outgoing light path of the light source; wherein, the wavelength modulator is used to modulate the incident light into polarized light with a fixed direction and an equivalent wavelength adjustable; the collimation and beam expansion module is used to expand the light spot to a size larger than the area of the optical element under test; the interference detection module includes a beam splitter corresponding to the collimation and beam expansion module, and a camera and a plane mirror corresponding to the beam splitter; the optical element under test is located on one side of the beam splitter, so that the light spot incident on the beam splitter is incident on the plane mirror and the optical element under test respectively, and then reflected and incident on the beam splitter to form interference; the camera is used to monitor the interference fringes.
[0006] Optionally, the wavelength modulator includes a first filter module and a second filter module corresponding to the light source, respectively. The first filter module is used to transmit light of a first wavelength, and the second filter module is used to transmit light of a second wavelength.
[0007] Optionally, the first filtering module includes a first filter, a first attenuator, and a first polarizer arranged in sequence; the second filtering module includes a second filter, a second attenuator, and a second polarizer arranged in sequence; wherein the polarization direction of the output light from the first polarizer and the second polarizer is the same.
[0008] Optionally, the expression corresponding to the equivalent wavelength λ is: ;
[0009] Where λ1 is the first wavelength and λ2 is the second wavelength.
[0010] Optionally, the beam splitter is square, and the diagonally opposite corners of the beam splitter have reflective and transmissive surfaces. The collimating and beam expanding module, the plane mirror, the optical element under test, and the camera are respectively located on the four peripheral surfaces of the beam splitter. The collimating and beam expanding module and the optical element under test are located on opposite sides of the beam splitter, and the plane mirror and the camera are located on opposite sides of the beam splitter.
[0011] Optionally, the collimating and beam expanding module includes a concave lens and a convex lens arranged sequentially along the optical path; the focal points of the concave lens and the convex lens coincide, and the focal length of the convex lens is greater than the focal length of the concave lens.
[0012] Optionally, the collimating and beam expanding module includes a first convex lens and a second convex lens arranged sequentially along the optical path direction; the focal points of the first convex lens and the second convex lens coincide, and the focal length of the second convex lens is greater than the focal length of the first convex lens.
[0013] Optionally, the light source is an amplified spontaneous emission light source, and the output optical power spectral density meets the range of ±5%.
[0014] Optionally, the slow-axis transmission polarization extinction ratio of the first polarizer and the second polarizer is greater than or equal to 32dB.
[0015] Optionally, the area of the light spot emitted from the collimating and expanding module is larger than the area of the optical element under test, and the beam waist of the light spot is located on the surface of the optical element under test.
[0016] The beneficial effects of the optical element surface defect detection device provided in this embodiment are as follows: By using an interferometric detection module based on the Michelson interferometry principle, combined with a wavelength modulator, the light emitted from the light source is modulated into polarized light with a fixed direction and adjustable equivalent wavelength. The wavelength of the deflected light can be adjusted within a certain range, so that the brightness changes of the interference pattern in the defect area can be controlled by the interferometric detection module, and the physical depth of the defect can be calculated in reverse. In practical applications, it is only necessary to modulate equivalent wavelength polarized light of different wavelengths through the wavelength modulator, and then expand the light spot through the collimation and beam expansion module. A large area of optical element can be detected at once without multiple movements or adjustments to the detection position, which greatly reduces the detection time and improves the efficiency of batch detection. At the same time, with the synergistic effect of the interferometric detection module, the problem of insufficient modulation phase can be overcome. Moreover, within the coherent detection range, no mechanical displacement is required to provide optical path difference, which is conducive to further improving the stability of detection. Since the equivalent wavelength is adjustable, only the equivalent wavelength needs to be adjusted to generate interference fringes with different fits, which helps to eliminate the problem of ambiguous phase. Even for optical elements with complex surface abrupt changes, comprehensive detection can be performed. The above method can be applied to batch testing, improving the problem of insufficient inherent modulation phase and enhancing the accuracy of testing results during batch testing. Attached Figure Description
[0017] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:
[0018] Figure 1 This is a schematic diagram of the optical element surface defect detection device provided in this embodiment of the utility model;
[0019] Figure 2 The wavelength interval of polarized light modulated by the wavelength modulator provided in this embodiment of the present invention is the equivalent wavelength of the polarized light.
[0020] Figure 3 This is one of the schematic diagrams of the collimation and beam expansion module provided in this embodiment of the utility model;
[0021] Figure 4 This is the second schematic diagram of the collimation and beam expansion module provided in this embodiment of the utility model.
[0022] The labels for the attached figures are as follows:
[0023] 100. Surface defect detection device for optical components; 105. Optical component under test; 110. Light source; 120. Wavelength modulator; 122. First filter module; 1222. First filter; 1224. First attenuator; 1226. First polarizer; 124. Second filter module; 1242. Second filter; 1244. Second attenuator; 1246. Second polarizer; 130. Collimation and beam expansion module; 132. Concave lens; 134. Convex lens; 136. First convex lens; 138. Second convex lens; 140. Interference detection module; 142. Beam splitter prism; 1422. Reflection and transmission surface; 144. Camera; 146. Plane mirror. Detailed Implementation
[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0025] like Figure 1 and Figure 2 As shown, this utility model embodiment provides an optical element surface defect detection device 100, including: a light source 110, and a wavelength modulator 120, a collimation and beam expansion module 130, and an interference detection module 140 arranged sequentially along the outgoing light path of the light source 110; wherein, the wavelength modulator 120 is used to modulate the incident light into polarized light with a fixed direction and an equivalent wavelength adjustable, the collimation and beam expansion module 130 is used to expand the light spot to a size larger than the area of the optical element 105 under test, the interference detection module 140 includes a beam splitter 142 corresponding to the collimation and beam expansion module 130, and a camera 144 and a plane mirror 146 corresponding to the beam splitter 142, the optical element 105 under test is located on one side of the beam splitter 142, so that the light spot incident on the beam splitter 142 is incident on the plane mirror and the optical element 105 under test respectively, and then reflected and incident on the beam splitter 142 to form interference, and the camera 144 is used to monitor the interference fringes.
[0026] Specifically, the light source 110 provides the necessary light to the optical element surface defect detection device 100, so that the wavelength modulator 120 can modulate the incident light into polarized light with adjustable equivalent wavelength in a specific direction, thereby optimizing the interference effect and improving the accuracy and sensitivity of the detection. The collimation and beam expansion module 130 expands the light spot to an area larger than that of the optical element under test 105. This ensures that the entire surface of the optical element under test 105 is uniformly covered by light, avoiding the situation where some areas cannot be detected due to insufficient light spot area. The interference detection module 140 includes a beam splitter 142, and a camera 144 and a plane mirror 146 corresponding to the beam splitter 142. The optical element under test 105 is located on one side of the beam splitter 142. When light is incident on the beam splitter 142, the light spot is split into two parts, which are incident on the plane mirror 146 and the optical element under test 105, respectively. These two portions of light are reflected and then incident again on the beam splitter 142. Due to the optical path difference, interference fringes are formed. The camera 144 is used to monitor these interference fringes. By analyzing the interference fringes, information about the surface of the optical element 105 under test can be obtained, thereby determining whether defects exist and their location and shape.
[0027] The optical element surface defect detection device 100 provided in this application embodiment is based on the Michelson interferometry principle. Combined with a wavelength modulator 120, it modulates the light emitted from the light source 110 into polarized light with a fixed direction and adjustable equivalent wavelength. The wavelength of the deflected light can be adjusted within a certain range, allowing the interference detection module 140 to control the brightness changes of the interference pattern in the defect area and inversely calculate the physical depth of the defect. In practical applications, only different wavelengths of equivalent wavelength polarized light need to be modulated by the wavelength modulator 120, and then the beam spot is enlarged by the collimation and beam expansion module 130. This allows for the detection of a large area of optical elements at once, eliminating the need for multiple movements or adjustments to the detection position, significantly reducing detection time and improving the efficiency of batch detection. Simultaneously, with the synergistic effect of the interference detection module 140, the problem of insufficient modulation phase can be overcome. Moreover, within the coherent detection range, no mechanical displacement is required to provide an optical path difference, which is beneficial for further improving the stability of the detection. Because the equivalent wavelength is tunable, interference fringes with different fits can be generated simply by adjusting the equivalent wavelength, which helps to eliminate the problem of phase ambiguity. Even for optical elements with complex surface abrupt changes, comprehensive inspection can be performed. This method is applicable to batch inspection, improving the problem of insufficient inherent modulation phase and enhancing the accuracy of inspection results in batch testing.
[0028] It should be noted that the wavelength modulator 120 should meet the requirements of a narrowband optical signal with a bandwidth greater than or equal to 3dB and less than 50GHz, thereby increasing the coherence length of the dual wavelengths and reducing the phase ambiguity effect.
[0029] like Figure 1 As shown, the wavelength modulator 120 includes a first filter module 122 and a second filter module 124, which are respectively corresponding to the light source 110. The first filter module 122 is used to transmit light of a first wavelength, and the second filter module 124 is used to transmit light of a second wavelength.
[0030] Specifically, in practical applications, different types of optical components may have different requirements for detection wavelengths. For example, some optical components are more sensitive to defects at specific wavelengths. By setting up the first filter module 122 and the second filter module 124, appropriate wavelength combinations can be flexibly selected according to the specific detection object and requirements, improving the versatility and adaptability of the detection device. By controlling the first and second wavelengths of light separately, the optical path difference and the characteristics of the interference fringes during the interference process can be adjusted more precisely. Different wavelengths of light produce different interference effects during interference. Reasonable selection and combination of wavelengths can make the interference fringes clearer and the contrast higher, thereby improving the detection capability of small defects on the surface of optical components.
[0031] like Figure 1 As shown, the first filter module 122 includes a first filter 1222, a first attenuator 1224 and a first polarizer 1226 arranged in sequence; the second filter module 124 includes a second filter 1242, a second attenuator 1244 and a second polarizer 1246 arranged in sequence; wherein the polarization direction of the output light from the first polarizer 1226 and the second polarizer 1246 is the same.
[0032] Specifically, the first filter 1222 and the second filter 1242 respectively filter out light of the first wavelength and the second wavelength, ensuring that the light entering the subsequent optical elements has a specific wavelength. In practical applications, one of the first wavelength or the second wavelength can be kept constant, while the other is adjusted to generate an equivalent wavelength. For example, the first filter 1222 can modulate the first wavelength to 1520nm, and the second filter 1242 can adjust the second wavelength, i.e., control the wavelength difference from the fixed wavelength, to obtain the equivalent wavelength. By controlling the equivalent wavelength, the brightness changes of the interference pattern in the defect area can be controlled, and the physical depth of the defect can be calculated in reverse. In addition, the first attenuator 1224 and the second attenuator 1244 can perform equal energy processing on light of different wavelengths, which facilitates the correspondence of adjustment information and helps to improve detection accuracy. The first polarizer 1226 and the second polarizer 1246 modulate the light into polarized light in a specific direction, which helps to ensure that the two beams of light have the same polarization characteristics during the subsequent interference process, thereby enabling effective interference and forming clear and stable interference fringes.
[0033] In an optional embodiment of this application, the expression corresponding to the equivalent wavelength λ is: Where λ1 is the first wavelength and λ2 is the second wavelength.
[0034] Specifically, the first wavelength The corresponding phase difference is Second wavelength The corresponding phase difference is The phase difference of the synthesized modulation wavelength is :
[0035]
[0036]
[0037]
[0038] From the above relationship, we can see that the expression corresponding to the equivalent wavelength λ is: That is, simply by changing the first wavelength Second wavelength The monitoring interval allows for modulation of the equivalent wavelength. .
[0039] like Figure 1 As shown, the beam splitter 142 is square, and the diagonally opposite corners of the beam splitter 142 have reflective and transmissive surfaces 1422. The collimating and beam expanding module 130, the plane mirror 146, the optical element under test 105, and the camera 144 are located on the four peripheral surfaces of the beam splitter 142, respectively. The collimating and beam expanding module 130 and the optical element under test 105 are located on opposite sides of the beam splitter 142, and the plane mirror 146 and the camera 144 are located on opposite sides of the beam splitter 142.
[0040] Using the above method, after the light rays exit from the collimating and expanding module 130, they are split into two beams by the reflecting and transmitting surface 1422 of the beam splitter 142, which then strike the plane mirror 146 and the optical element under test 105, respectively. The two beams are reflected back to the beam splitter 142, where they interfere, and the resulting interference fringes are captured by the camera 144 located on opposite sides. This symmetrical layout ensures the stability and symmetry of the optical path, reducing interference errors caused by optical path asymmetry.
[0041] like Figure 3 As shown, in an optional embodiment of this application, the collimating and beam expanding module 130 includes a concave lens 132 and a convex lens 134 arranged sequentially along the optical path direction; the focal points of the concave lens 132 and the convex lens 134 coincide, and the focal length of the convex lens 134 is greater than the focal length of the concave lens 132.
[0042] Specifically, concave lens 132 diverges light rays, while convex lens 134 converges them. When light rays pass through concave lens 132 and convex lens 134 sequentially, and their focal points coincide, concave lens 132 first diverges the light rays, and then convex lens 134 converges the diverged light rays, thereby expanding and collimating the light spot. By rationally designing the focal length parameters of concave lens 132 and convex lens 134, parameters such as the size of the expanded light spot, divergence angle, and beam waist position can be precisely controlled to meet the testing requirements of optical elements 105 of different sizes.
[0043] like Figure 4 As shown, in another optional embodiment of this application, the collimating and beam expanding module 130 includes a first convex lens 136 and a second convex lens 138 arranged sequentially along the optical path direction; the focal points of the first convex lens 136 and the second convex lens 138 coincide, and the focal length of the second convex lens 138 is greater than the focal length of the first convex lens 136.
[0044] Specifically, the first convex lens 136 first converges the light beam, and then the second convex lens 138 further expands the converged light beam. By rationally designing the focal lengths of the first convex lens 136 and the second convex lens 138, the characteristics of the expanded light spot, such as the spot size, divergence angle, and beam waist position, can be controlled. Using this combination, the light spot becomes more uniform, the edges are sharper, and aberrations and distortions are reduced, which helps ensure detection accuracy.
[0045] In an optional embodiment of this application, the light source 110 is an amplified spontaneous emission light source, and the output optical power spectral density satisfies the range of ±5%.
[0046] Specifically, the amplified spontaneous emission source has a wide spectral range and high output power, providing sufficient light energy for interferometric detection. Simultaneously, requiring the output optical power spectral density to be within ±5% is to ensure the stability and consistency of the light source 110's output. In actual detection, the stability of the light source 110's output directly affects the quality of the interference fringes and the accuracy of the detection results. A stable optical power spectral density ensures that the output characteristics of the light source 110 are essentially the same in each detection, reducing detection errors caused by fluctuations in the light source 110.
[0047] It should be noted that, in this application, C-band and L-band light are preferably used, with an output power greater than -20dBm / nm and a power stability requirement of 0.001dB, in order to better adapt to the optical components under test 105 used in the communication field. Understandably, in practical applications, other bands of light, such as the visible light band, can also be used for detection as needed.
[0048] In an optional embodiment of this application, the slow-axis transmission polarization extinction ratio (PER) of the first polarizer 1226 and the second polarizer 1246 is greater than or equal to 32dB.
[0049] Specifically, a higher polarization extinction ratio means that the polarizer can more effectively modulate light into unidirectional polarized light, reducing stray light perpendicular to the polarization direction. In this detection device, the slow-axis polarization extinction ratio of the first polarizer 1226 and the second polarizer 1246 reaches 32dB or higher, which can ensure that the output light has high polarization purity, thereby improving the contrast and clarity of the interference fringes.
[0050] In an optional embodiment of this application, the area of the light spot emitted from the collimating beam expanding module 130 is larger than the area of the optical element under test 105, and the beam waist of the light spot is located on the surface of the optical element under test 105.
[0051] Specifically, the area of the light spot is larger than the area of the optical element under test 105, ensuring that the entire surface of the optical element under test 105 is covered by light, avoiding detection blind spots. Positioning the beam waist of the light spot on the surface of the optical element under test 105 ensures optimal focusing and energy distribution of the light on the surface, improving the interaction efficiency between the light and the surface of the optical element under test 105, enhancing the interference effect, and thus improving the accuracy of the detection.
[0052] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.
Claims
1. A device for detecting surface defects in optical components, characterized in that, include: The light source includes a wavelength modulator, a collimation and beam-expanding module, and an interference detection module arranged sequentially along the outgoing light path of the light source. The wavelength modulator modulates the incident light into polarized light with a fixed direction and adjustable equivalent wavelength. The collimation and beam-expanding module expands the light spot to an area larger than that of the optical element under test. The interference detection module includes a beam splitter corresponding to the collimation and beam-expanding module, a camera corresponding to the beam splitter, and a plane mirror. The optical element under test is located on one side of the beam splitter, so that the light spot incident on the beam splitter is incident on the plane mirror and the optical element under test, respectively, and then reflected back onto the beam splitter to form interference. The camera is used to monitor the interference fringes.
2. The optical element surface defect detection device according to claim 1, characterized in that, The wavelength modulator includes a first filter module and a second filter module corresponding to the light source, respectively. The first filter module is used to transmit light of a first wavelength, and the second filter module is used to transmit light of a second wavelength.
3. The optical element surface defect detection device according to claim 2, characterized in that, The first filtering module includes a first filter, a first attenuator, and a first polarizer arranged in sequence; the second filtering module includes a second filter, a second attenuator, and a second polarizer arranged in sequence; wherein the polarization direction of the output light from the first polarizer and the second polarizer is the same.
4. The optical element surface defect detection device according to claim 3, characterized in that, The expression corresponding to the equivalent wavelength λ is: ; Where λ1 is the first wavelength and λ2 is the second wavelength.
5. The optical element surface defect detection device according to claim 1, characterized in that, The beam splitter is square, and its diagonally opposite corners have reflective and transmissive surfaces. The collimating and beam expanding module, the plane mirror, the optical element under test, and the camera are located on the four peripheral surfaces of the beam splitter. The collimating and beam expanding module and the optical element under test are located on opposite sides of the beam splitter, and the plane mirror and the camera are located on opposite sides of the beam splitter.
6. The optical element surface defect detection device according to any one of claims 1-5, characterized in that, The collimating and beam expanding module includes a concave lens and a convex lens arranged sequentially along the optical path; the focal points of the concave lens and the convex lens coincide, and the focal length of the convex lens is greater than the focal length of the concave lens.
7. The optical element surface defect detection device according to any one of claims 1-5, characterized in that, The collimating and beam expanding module includes a first convex lens and a second convex lens arranged sequentially along the optical path; the focal points of the first convex lens and the second convex lens coincide, and the focal length of the second convex lens is greater than the focal length of the first convex lens.
8. The optical element surface defect detection device according to any one of claims 1-5, characterized in that, The light source is an amplified spontaneous emission light source, and the output optical power spectral density meets the range of ±5%.
9. The optical element surface defect detection device according to claim 3 or 4, characterized in that, The slow-axis transmission polarization extinction ratio of the first polarizer and the second polarizer is greater than or equal to 32dB.
10. The optical element surface defect detection device according to any one of claims 1-5, characterized in that, The area of the light spot emitted from the collimating and expanding module is larger than the area of the optical element under test, and the beam waist of the light spot is located on the surface of the optical element under test.