Dynamic shearing interference detection system and method
Through the dynamic shear interference detection system, the coordination of electronically controlled liquid crystal and wave plates can realize the detection of plane defects and scratches of optical devices, solving the problems of high detection cost and low efficiency in the existing technology, and achieving fast and convenient Batch inspection.
Patent Information
- Application Number
- CN202411368971.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2025-01-10
AI Technical Summary
The detection methods of plane defects and scratches of existing optical devices are costly and are not suitable for batch detection and are inefficient, especially coherent detection and electron microscopy device detection.
Design a dynamic shear interference detection system, including light source, polarization spectroscopic prism, electronically controlled liquid crystal, wave plate, reflector and CCD detector, to separate and shear O and E light through electronically controlled liquid crystal, and pass through wave plate In combination with the reflector, the birefringence effect of the electronically controlled liquid crystal can be used to achieve twice the shear amount, which improves the sensitivity of shear amount control, and is suitable for batch inspection.
It effectively solves the problem of insufficient space offset of two beams of light in one-way transmission, improves detection efficiency and sensitivity, and achieves fast and convenient batch detection capabilities.
Smart Images
Figure CN119290752A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of micro-nano detection technology, and in particular to a dynamic shearing interference detection system and method. Background Art
[0002] Rapid inspection of planar defects and scratches on optical devices is a powerful process to ensure the optical performance and mass production of products. Existing detection methods are generally coherent detection or electron microscope detection. Among them, coherent detection is costly, has poor sensitivity and stability, requires an unpacking algorithm, and the application environment of coherent detection is relatively harsh. The cost of electron microscope detection is also high, and it is not suitable for batch detection and has very low efficiency.
[0003] Therefore, it is very important for those skilled in the art to design a dynamic shearing interference detection system and method that is convenient, fast and suitable for batch detection. Summary of the invention
[0004] The technical problem to be solved by the embodiments of the present invention is to provide a dynamic shear interference detection system and method that is convenient and fast and suitable for batch detection, so as to solve the problems of high cost, unsuitability for batch detection and low efficiency in the prior art.
[0005] The invention discloses a dynamic shearing interference detection system for detecting planar defects and scratches of optical devices. The system comprises: a light source, a polarization beam splitter prism, an electrically controlled liquid crystal, a wave plate, a reflector and a CCD detector; the light source emits signal light, the signal light is transmitted to the polarization beam splitter prism through a sample to be tested, and is transmitted through the polarization beam splitter prism to form P polarized light; after the P polarized light passes through the electrically controlled liquid crystal, a part of it is transmitted to form O light, and the other part is refracted to form E light parallel to the O light; the O light and the E light are modulated by the wave plate and incident on the reflector, and are reflected back to the wave plate by the reflector, so that the original O light is converted into E light, and the original E light is converted into O light; the converted O light is transmitted to the polarization beam splitter prism through the electrically controlled liquid crystal, and the converted E light is refracted to the polarization beam splitter prism through the electrically controlled liquid crystal, so as to be reflected to the CCD detector through the polarization beam splitter prism, and an interference pattern is formed.
[0006] Among them, a preferred solution is that the polarization separation plane of the polarization beam splitter prism is at an angle of 45° to the main axis rotation plane of the electrically controlled liquid crystal.
[0007] Among them, a preferred solution is that the fast and slow axes of the wave plate are perpendicular or parallel to the main axis rotation plane of the electrically controlled liquid crystal.
[0008] Among them, a preferred solution is that the polarization beam splitter prism, the electrically controlled liquid crystal, the wave plate, the reflector and the CCD detector are all designed to be integrated.
[0009] Among them, a preferred solution is that the wave plate is a 1 / 4 wave plate or a 3 / 4 wave plate.
[0010] Among them, a preferred solution is that the incident angle of the reflector is greater than 10°.
[0011] Among them, a preferred solution is that the front surface and the rear surface of the electrically controlled liquid crystal are both coated with a high-transmittance film, and the incident angle is less than 10°.
[0012] In order to solve the problems existing in the prior art, the present invention further provides a dynamic shearing interference detection method, which is implemented by the dynamic shearing interference detection system as described above, and the solution thereof is that it comprises the following steps:
[0013] The signal light is emitted by a light source, and the signal light is transmitted through the polarization beam splitter prism to form P polarized light, and is incident on the electrically controlled liquid crystal to achieve O and E light shearing;
[0014] By adjusting the electrically controlled liquid crystal, the shearing amount of O and E light can be adjusted;
[0015] The shearing interference image is acquired through the CCD detector, and the defect information is calculated based on the light intensity information of the shearing interference image.
[0016] Among them, a preferred solution is that the wavefront information of the signal light and the light intensity information of the CCD imaging satisfy the following relationship:
[0017] I(x,y)=A 2 +B 2 +2AB·cos(φ(xD x ,yD y )-φ(x,y))
[0018] Among them, φ(x,y) is the wavefront information of the signal light, that is, the phase information of the sample to be measured; I(x,y) is the light intensity information of CCD imaging, A is the amplitude of O light, B is the amplitude of E light, and D x To adjust the shear amount in the x-axis direction, D y is the shear amount modulated in the y-axis direction.
[0019] Among them, a preferred solution is that the adjustment of the shear amount by the electrically controlled liquid crystal satisfies the following relationship:
[0020]
[0021] Where D is the shear amount, n o is the refractive index of O light in the electrically controlled liquid crystal, n e is the refractive index of E light in the electrically controlled liquid crystal, d is the thickness of the liquid crystal layer in the electrically controlled liquid crystal, and θ is the angle between the electrically controlled liquid crystal director and the surface of the electrically controlled liquid crystal.
[0022] Compared with the prior art, the beneficial effect of the dynamic shearing interference detection system provided by the embodiment of the present invention is that: by designing a dynamic shearing interference detection system for detecting planar defects and scratches of optical devices, the system includes a light source, a polarization beam splitter prism, an electrically controlled liquid crystal, a wave plate, a reflector and a CCD detector arranged in sequence, and a placement space for the sample to be tested is reserved between the light source and the polarization beam splitter prism. The O and E light are separated and sheared by utilizing the electrically controlled liquid crystal, and the O light and the E light are reflected back to the electrically controlled liquid crystal through the cooperation of the wave plate and the reflector, so as to utilize the birefringence effect of the electrically controlled liquid crystal to achieve twice the shearing amount. This system can not only effectively solve the problem of insufficient spatial offset of two beams of light in unidirectional transmission, but also improve the sensitivity of shearing amount control. The degree of defects of the object to be tested can be monitored by dynamically controlling the shearing amount, which has the advantages of faster and batch detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which:
[0024] Figure 1 is a structural schematic diagram of a dynamic shearing interference detection system provided by an embodiment of the present invention;
[0025] Figure 2 is a flow chart of a dynamic shearing interference detection method provided by an embodiment of the present invention;
[0026] Figure 3 is a schematic diagram of polarization change of the dynamic shearing interferometry detection method provided by an embodiment of the present invention;
[0027] Figure 4 It is a shearing interference imaging principle diagram of the dynamic shearing interference detection method provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0028] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.
[0029] like Figure 1 As shown, the present invention provides a specific embodiment of a dynamic shearing interference detection system.
[0030] A dynamic shearing interferometry detection system for detecting planar defects and scratches on optical devices, reference Figure 1 The dynamic shearing interference detection system includes: a light source 100, a polarization beam splitter prism 200, an electrically controlled liquid crystal 300, a wave plate 400, a reflector 500 and a CCD detector 600. A space for placing a sample 10 to be tested is reserved between the light source 100 and the polarization beam splitter prism 200.
[0031] Specifically, refer to Figure 1 The light source 100 is used to emit signal light; the polarization beam splitter prism 200 is used to perform polarization separation on the signal light, so as to convert the signal light transmitted through the sample 10 to be tested into P polarized light and output it; the electrically controlled liquid crystal 300 can make the O and E lights spatially offset inside it, so as to achieve shearing of the signal space, and the shearing amount can be adjusted by adjusting the electrically controlled liquid crystal 300; the wave plate 400 can reverse polarization conversion on the input signal light, so as to achieve double shearing amount; the reflector 500 is used to reflect the signal light, so that the signal light reverses to the wave plate 400 for polarization conversion, so as to achieve double shearing amount; the CCD detector 600 is used to receive the signal light and form an image, so as to facilitate the detection of defects and scratches of the sample 10 to be tested according to the imaging information.
[0032] Among them, reference Figure 1 The light source 100 emits signal light to the sample to be tested 10. The signal light is transmitted to the polarization beam splitter prism 200 through the sample to be tested 10, and is transmitted through the polarization beam splitter prism 200 to form P polarized light. After the P polarized light passes through the electrically controlled liquid crystal 300, the O light and the E light are separated. The O light will be transmitted to the wave plate 400 through the electrically controlled crystal, and the E light will be refracted to the wave plate 400 through the electrically controlled crystal. The E light emitted after refraction is parallel to the O light transmitted after transmission. After entering the wave plate 400, the O light and the E light are modulated by the wave plate 400 and incident on the reflector 500, and are reflected back to the wave plate 400 by the reflector 500.
[0033] Further, refer to Figure 1 The O light and E light in the reflected echo plate 400 will be converted into O light and E light, that is, the original O light is converted into E light, and the original E light is converted into O light. The converted O light is incident on the electrically controlled crystal and transmitted to the polarization beam splitter prism 200 through the electrically controlled liquid crystal 300. The converted E light is incident on the electrically controlled liquid crystal 300 and refracted to the polarization beam splitter prism 200 through the electrically controlled crystal, and then reflected to the CCD detector 600 through the polarization beam splitter prism 200 to form an interference pattern in the CCD detector 600. The defect information of the sample 10 to be tested can be calculated through the interference pattern.
[0034] Rapid inspection of planar defects and scratches on optical devices is a powerful process to ensure the optical performance and mass production of products. Existing detection methods are generally coherent detection or electron microscope detection. Among them, coherent detection is costly, has poor sensitivity and stability, requires an unpacking algorithm, and the application environment of coherent detection is relatively harsh. The cost of electron microscope detection is also high, and it is not suitable for batch detection and has very low efficiency.
[0035] In this embodiment, a dynamic shearing interference detection system is designed to detect planar defects and scratches of optical devices, including a light source 100, a polarization beam splitter prism 200, an electrically controlled liquid crystal 300, a wave plate 400, a reflector 500 and a CCD detector 600 arranged in sequence. A placement space for the sample 10 to be tested is reserved between the light source 100 and the polarization beam splitter prism 200. The electrically controlled liquid crystal 300 is used to separate and shear the O and E light, and the wave plate 400 and the reflector 500 cooperate to make the O and E light reflected back to the electrically controlled liquid crystal 300. The birefringence effect of the electrically controlled liquid crystal 300 is used to achieve twice the shearing amount. This can not only effectively solve the problem of insufficient spatial offset of two beams of light in unidirectional transmission, but also improve the sensitivity of shearing amount control. The degree of defects of the object to be tested is monitored by dynamically controlling the shearing amount, which has the advantages of faster and batch detection.
[0036] In one embodiment, the polarization separation plane of the polarization beam splitter prism 200 is at an angle of 45° to the main axis rotation plane of the electrically controlled liquid crystal 300 .
[0037] Specifically, by designing the polarization separation plane of the polarization beam splitter prism 200 and the main axis rotation plane of the electrically controlled liquid crystal 300 to be at an angle of 45°, the amplitudes of the O light and the E light separated by the electrically controlled liquid crystal 300 can be made the same.
[0038] In one embodiment, the fast and slow axes of the wave plate 400 are perpendicular or parallel to the main axis rotation plane of the electrically controlled liquid crystal 300 .
[0039] Specifically, the wave plate 400 is an optical element for adjusting the phase of light, which has two special directions, a fast axis and a slow axis. The propagation speeds of light in the fast axis and the slow axis are different, so that the phase of the light changes. Among them, the fast axis is the direction in which the light propagates faster in the wave plate 400. When the linearly polarized light propagates along the fast axis, its phase will not change. The slow axis is the direction in which the light propagates slower in the wave plate 400. When the linearly polarized light propagates along the slow axis, its phase will change.
[0040] By aligning the fast and slow axes of the wave plate 400 perpendicularly or parallel to the main axis rotation plane of the electrically-controlled liquid crystal 300, when the O light and the E light are reflected by the reflector 500 and pass through the wave plate 400 again, the original O light will become the E light relative to the electrically-controlled crystal, and the original E light will become the O light relative to the electrically-controlled crystal, and the converted E light and O light will be incident on the electrically-controlled crystal in parallel.
[0041] In one embodiment, the polarization beam splitter prism 200, the electrically controlled liquid crystal 300, the wave plate 400, the reflector 500 and the CCD detector 600 are all designed to be integrally formed.
[0042] Specifically, one-piece molding design is a design method that designs multiple parts or components into an integral structure. This design can reduce the number of optical devices, thereby reducing the time and cost required for assembling multiple optical devices, reducing the connection and coupling process between optical devices, and simplifying the assembly process. More importantly, the integrated molding structure can improve the integrity and common optical path characteristics of the system.
[0043] In one embodiment, the wave plate 400 is a 1 / 4 wave plate 400 or a 3 / 4 wave plate 400 .
[0044] Specifically, by selecting the 1 / 4 wave plate 400 or the 3 / 4 wave plate 400 , it is possible to cooperate with the reflector 500 to reverse the propagation path of light while realizing the function of the 1 / 2 wave plate 400 .
[0045] In one embodiment, the incident angle of the reflector 500 is greater than 10°; the front surface and the rear surface of the electrically controlled liquid crystal 300 are both coated with a high-transmittance film, and the incident angle is less than 10°.
[0046] like Figures 1 to 4 As shown, the present invention also provides a specific embodiment of a dynamic shearing interference detection method.
[0047] A dynamic shearing interference detection method is implemented by the above-mentioned dynamic shearing interference detection system, referring to Figure 2 , including the following steps:
[0048] S1. The signal light is emitted through the light source, and the signal light is transmitted through the polarization beam splitter prism to form P polarized light, and is incident on the electrically controlled liquid crystal to achieve O and E light shearing;
[0049] S2, by adjusting the electrically controlled liquid crystal to adjust the shearing amount of O and E light;
[0050] S3. Obtain a shearing interference image through a CCD detector, and calculate defect information based on the light intensity information of the shearing interference image.
[0051] Specifically, refer to Figure 1 and Figure 2 First, the light source 100 is turned on to emit signal light. The signal light will be transmitted through the sample 10 to the polarization beam splitter prism 200, and will be transmitted through the polarization beam splitter prism 200 to form P polarized light. After the P polarized light passes through the electrically controlled liquid crystal 300, the O light and the E light will be separated. The O light will be transmitted to the wave plate 400 through the electrically controlled crystal. The E light will be refracted to the wave plate 400 through the electrically controlled crystal, and the E light emitted after refraction is parallel to the O light transmitted after transmission. After entering the wave plate 400, the O light and the E light are modulated by the wave plate 400 and incident on the reflector 500, and are both reflected back to the wave plate 400 by the reflector 500.
[0052] Further, refer to Figure 1 and Figure 2 , the O light and E light reflected in the echo plate 400 will be converted into O light and E light, that is, the original O light is converted into E light, and the original E light is converted into O light. The converted O light is incident on the electrically-controlled crystal and transmitted to the polarization beam splitter prism 200 through the electrically-controlled liquid crystal 300. The converted E light is incident on the electrically-controlled liquid crystal 300 and refracted to the polarization beam splitter prism 200 through the electrically-controlled crystal, and then reflected to the CCD detector 600 through the polarization beam splitter prism 200 to form an interference pattern in the CCD detector 600.
[0053] Further, refer to Figure 1 and Figure 2 By adjusting the crystal element direction of the electrically controlled liquid crystal 300, the size of the spatial separation of O and E light is controlled, that is, the shear amount is adjusted; through the different interference patterns formed under different shear amounts, the defect information of the sample 10 to be tested is analyzed and calculated.
[0054] In this embodiment, reference Figure 1 and Figure 2 The signal light transmitted by the sample to be tested 10 can use the red light 632.8nm in the visible light as the detection light. The detection light transmits the P light signal light after passing through the polarization splitter prism 200, wherein the light transmission area of the liquid crystal box of the electrically controlled liquid crystal 300 is larger than 1.5X of the spot area, and the thickness of the liquid crystal box is larger than 200um. The preset angle of the liquid crystal is 5°, and the liquid crystal director reaches an angle of 80° during the power-on process; based on the birefringence of the electrically controlled liquid crystal 300, the separation of O and E light is realized, that is, shearing is realized, and the E light and the O light are interchanged through the back and forth transmission of the 1 / 4 wave plate 400 to achieve double shearing.
[0055] refer to Figure 3 , Z is the beam transmission direction, and the XOY plane is the plane perpendicular to the beam propagation direction, corresponding to the beam polarization direction of the polarization beam splitter prism 200 (reference Figure 3 201 in the figure), located in the XOY plane and at an angle of 45° to the X axis, i.e. the P light direction; the liquid crystal director rotation plane YOZ, the unpowered direction is close to 0° with the Y axis (reference Figure 3 202); corresponds to the level of the fast (slow) axis of the glass slide and the P light; that is, the angle between the XOY plane and the X axis is 45° (reference Figure 3 203).
[0056] refer to Figure 4 , the wavefront of the object phase information (refer to Figure 4 301 in the figure contains corresponding scratches and circular spot damage, which form a shear interference pattern after being detected by the dynamic shear interference detection system (reference Figure 4 302), that is, the overlapping part presents shear interference patterns; by modulating the liquid crystal to obtain different shear interference patterns, the defect information is calculated.
[0057] In one embodiment, the wavefront information of the signal light and the light intensity information of the CCD imaging satisfy the following relationship:
[0058] I(x,y)=A 2 +B 2 +2AB·cos(φ(xD x ,yD y )-φ(x,y))
[0059] Among them, φ(x, y) is the wavefront information of the signal light, that is, the phase information of the sample 10 to be tested; I(x, y) is the light intensity information of CCD imaging, A is the amplitude of O light, B is the amplitude of E light, and D x To adjust the shear amount in the x-axis direction, D y is the shear amount modulated in the y-axis direction.
[0060] In one embodiment, the adjustment of the shear amount by the electrically controlled liquid crystal 300 satisfies the following relationship:
[0061]
[0062] Where D is the shear amount, n o is the refractive index of O light in the electrically controlled liquid crystal 300, n e is the refractive index of E light in the electrically controlled liquid crystal 300 , d is the thickness of the liquid crystal layer in the electrically controlled liquid crystal 300 , and θ is the angle between the director of the electrically controlled liquid crystal 300 and the surface of the electrically controlled liquid crystal 300 .
[0063] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the protection scope of the claims attached to the present invention.
Claims
1. A dynamic shearing interferometer detection system for detecting planar defects and scratches of optical devices, characterized in that: include: Light source, polarization beam splitter prism, electrically controlled liquid crystal, wave plate, reflector and CCD detector; The light source emits signal light, and the signal light is transmitted to the polarization beam splitter prism through the sample to be tested, and is transmitted through the polarization beam splitter prism to form P polarized light. After the P polarized light passes through the electrically controlled liquid crystal, a part of it is transmitted to form O light, and the other part is refracted to form E light parallel to the O light. The O light and the E light are modulated by the wave plate and then incident on the reflector, and are both reflected back to the wave plate by the reflector, so that the original O light is converted into E light, and the original E light is converted into O light. The converted O light is transmitted to the polarization beam splitter prism through the electrically controlled liquid crystal, and the converted E light is refracted to the polarization beam splitter prism through the electrically controlled liquid crystal, so as to be reflected to the CCD detector through the polarization beam splitter prism to form an interference pattern.
2. The dynamic shearing interference detection system according to claim 1, characterized in that: The polarization separation plane of the polarization beam splitter prism forms an angle of 45° with the main axis rotation plane of the electrically controlled liquid crystal.
3. The dynamic shearing interference detection system according to claim 1, characterized in that: The fast and slow axes of the wave plate are perpendicular or parallel to the rotation plane of the main axis of the electrically controlled liquid crystal.
4. The dynamic shearing interference detection system according to claim 1, characterized in that: The polarization beam splitter prism, the electrically controlled liquid crystal, the wave plate, the reflector and the CCD detector are all designed to be integrally formed.
5. The dynamic shearing interference detection system according to claim 1, characterized in that: The wave plate is a 1 / 4 wave plate or a 3 / 4 wave plate.
6. The dynamic shearing interference detection system according to claim 1, characterized in that: The incident angle of the reflector is greater than 10°.
7. The dynamic shearing interference detection system according to claim 1, characterized in that: The front surface and the rear surface of the electrically controlled liquid crystal are both coated with a high-transmittance film, and the incident angle is less than 10°.
8. A dynamic shearing interference detection method, implemented by a dynamic shearing interference detection system as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: The signal light is emitted by a light source, and the signal light is transmitted through the polarization beam splitter prism to form P polarized light, and is incident on the electrically controlled liquid crystal to achieve O and E light shearing; By adjusting the electrically controlled liquid crystal, the shearing amount of O and E light can be adjusted; The shearing interference image is acquired through the CCD detector, and the defect information is calculated based on the light intensity information of the shearing interference image.
9. The dynamic shearing interference detection method according to claim 8, characterized in that: The wavefront information of the signal light and the light intensity information of the CCD imaging satisfy the following relationship: I(x,y)=A 2 +B 2 +2AB·cos(φ(x-D x ,y-D y )-φ(x,y)) Among them, φ(x,y) is the wavefront information of the signal light, that is, the phase information of the sample to be measured; I(x,y) is the light intensity information of CCD imaging, A is the amplitude of O light, B is the amplitude of E light, and D x To adjust the shear amount in the x-axis direction, D y is the shear amount modulated in the y-axis direction.
10. The dynamic shearing interference detection method according to claim 1, characterized in that: The adjustment of the shear amount by the electrically controlled liquid crystal satisfies the following relationship: Where D is the shear amount, n o is the refractive index of O light in the electrically controlled liquid crystal, n e is the refractive index of E light in the electrically controlled liquid crystal, d is the thickness of the liquid crystal layer in the electrically controlled liquid crystal, and θ is the angle between the electrically controlled liquid crystal director and the surface of the electrically controlled liquid crystal.