Global detection device for LCoS liquid crystal cell thickness based on low-coherence light Mirau interferometry

Abstract

The present invention belongs to the technical field of liquid crystal box thickness detection, and in particular discloses a global detection device for the thickness of an LCoS liquid crystal box based on low-coherence light Mirau interference, comprising a nanopositioning stage, an imaging system, a computer, an illumination system, a Mirau interference objective lens, and a silicon-based liquid crystal box, wherein the imaging system comprises a beam splitter prism, an imaging lens, and a planar array camera, and the illumination system comprises a low-coherence light source, a condenser lens, and a projection lens, and the illumination system is connected to the computer via a low-coherence light source. The present invention measures the three-dimensional morphology data of the lower surface of the cover glass and the three-dimensional morphology data of the upper surface of the silicon substrate, and fits the three-dimensional morphology data of the two surfaces into a plane, and calculates the thickness H of the silicon-based liquid crystal box by calculating the coordinate difference of the two fitting planes in the vertical direction, so as to be able to perform global and comprehensive detection of the silicon-based liquid crystal box, and the global detection speed is fast and the accuracy is high.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid crystal box thickness detection, and in particular relates to an LCoS liquid crystal box thickness global detection device based on low coherent light Mirau interference. Background Art

[0002] Liquid Crystal on Silicon (LCoS) is a reflective liquid crystal micro-panel display technology with the characteristics of high light utilization efficiency, small size, high aperture ratio and mature manufacturing technology. However, in the existing LCoS packaging, LCoS is made of a single piece, and the consistency of the thickness of its liquid crystal box is not easy to ensure, and the thickness is prone to deviation, which is prone to product failure.

[0003] The traditional method for detecting the thickness of the liquid crystal box requires individual detection of each point of the liquid crystal box thickness, and cannot perform global detection of the LCoS liquid crystal box thickness, resulting in low detection efficiency.

[0004] Therefore, it is necessary to invent a global detection device for LCoS liquid crystal box thickness based on low-coherence light Mirau interference to solve the above problems. Summary of the invention

[0005] In view of the above problems, the present invention provides a global detection device for LCoS liquid crystal box thickness based on low-coherence light Mirau interference to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a global detection device for the thickness of an LCoS liquid crystal box based on low-coherence light Mirau interference, comprising a nanopositioning stage, an imaging system, a computer, an illumination system, a Mirau interference objective lens and a silicon-based liquid crystal box, wherein the imaging system comprises a beam splitter prism, an imaging lens and a planar array camera, the illumination system comprises a low-coherence light source, a condenser lens and a projection lens, the illumination system is connected to the computer via a low-coherence light source, the light emitted by the low-coherence light source is aggregated by the condenser lens, and then projected onto the beam splitter prism of the imaging system via the projection lens, the beam splitter prism irradiates the light into the Mirau interference objective lens, the silicon-based liquid crystal box comprises a cover glass, a plurality of spacers and a silicon substrate, liquid crystals are added between the plurality of spacers, and the The silicon-based liquid crystal box is placed on the top surface of the nanopositioning stage. The nanopositioning stage is connected to the computer through a wire. Piezoelectric ceramics are arranged inside the nanopositioning stage. The computer controls the operation of the nanopositioning stage. The nanopositioning stage realizes nano-level positioning of the silicon-based liquid crystal box in the vertical direction through the piezoelectric ceramics. Light irradiates the silicon-based liquid crystal box through a Mirau interference objective lens. Light reflected from the top surface of the silicon substrate or the bottom surface of the cover glass returns to the inside of the Mirau interference objective lens. Interference light is formed in the Mirau interference objective lens and then transmitted to a beam splitter prism. The beam splitter prism images the interference light into the inside of the area array camera through an imaging lens. The area array camera transmits the light intensity data of the interference light to the computer. The computer globally detects the liquid crystal thickness of the silicon-based liquid crystal box according to the light intensity data of the interference light.

[0007] Furthermore, the Mirau interference objective lens includes a first objective lens, a second objective lens, a third objective lens, a first glass plate and a second glass plate. The first glass plate and the second glass plate are both tilted and have the same tilt angle. The lower surface of the first glass plate and the lower surface of the second glass plate are both coated with a spectroscopic film. After the light passes through the first objective lens, the second objective lens, the third objective lens and the first glass plate in sequence, a part of the light irradiates the silicon-based liquid crystal box through the second glass plate, and after being reflected by the top surface of the silicon substrate or the bottom surface of the cover glass, a test light is formed on the bottom surface of the second glass plate. Another part of the light is reflected from the bottom surface of the second glass plate to the bottom surface of the first glass plate, and after being reflected again from the bottom surface of the first glass plate, a reference light is formed on the bottom surface of the second glass plate. The test light and the reference light are combined on the bottom surface of the second glass plate to form interference light, and the interference light is projected into the spectroscopic prism of the imaging system through the Mirau interference objective lens.

[0008] Furthermore, a plurality of spacers are arranged on the top surface of the silicon substrate, a void layer is formed between the plurality of spacers, and the cover glass is correspondingly placed on the top of the plurality of spacers.

[0009] Furthermore, the second glass plate and the cover glass have the same thickness and are made of the same material.

[0010] Furthermore, the nanopositioning platform includes a slide plate and a base plate, and the slide plate is configured as a piezoelectric ceramic, which is connected to a computer via a controller, the slide plate is located on the top of the base plate, and the silicon-based base plate is correspondingly placed on the top surface of the slide plate, both sides of the inner concave surface at the top of the base plate are fixed with slide rails by screws, both sides of the bottom of the slide plate are fixed with sliders that slide with the slide rails, the base plate is connected to a computer via a controller, and when the controller works, the slide plate slides on the inner side of the slide rail of the base plate using the slider, and the sliding slide plate drives the silicon-based liquid crystal box to move horizontally synchronously.

[0011] Furthermore, the silicon base plate is installed on the top surface of the skateboard by means of a fixing component, and the fixing component includes two relative clamping frames, and the clamping frames include a first frame plate and a second frame plate relative to each other, and the outer sides of the first frame plate and the second frame plate are both fixed with protrusions, and a screw rod vertically passes through the center of the protrusion, and the bottom end of the screw rod is spirally inserted into the top surface of the skateboard, and the protrusion is fixedly installed on the top surface of the skateboard by the screw rod.

[0012] Furthermore, the fixing component also includes two cross bars, the outer side surfaces of the cross bars are in contact with the sides of the silicon base plate, the cross bars pass through the two clamps correspondingly, and nuts are spirally sleeved at both ends of the cross bars. The two clamps cooperate to clamp the silicon base plate through the cooperation of the nuts and the cross bars.

[0013] Furthermore, the first frame plate is fixed with a first plug rod that is plugged into the second frame plate, and the second frame plate is fixed with a second plug rod that is plugged into the first frame plate. The surfaces of the first plug rod and the second plug rod are both spirally sleeved with limiting rings, the top limiting ring is close to the first frame plate, and the bottom limiting ring is close to the second frame plate. A bracket is sleeved on the surface of the limiting ring. The outer sides of the first frame plate and the second frame plate are fixed with side plates, and the two side plates correspond to the two brackets one by one. A limiting rod is fixed on the inner side of the side plate, and the outer end of the bracket is sleeved on the surface of the limiting rod. A spring is sleeved on the surface of the limiting rod, one end of the spring is connected to the bracket, and the other end of the spring is connected to the inner end of the limiting rod.

[0014] Furthermore, the spring is in a compressed state, and the elastic force of the spring brings the first frame plate and the second frame plate closer to each other through the limiting rod.

[0015] Technical effects and advantages of the present invention:

[0016] 1. The present invention measures the three-dimensional morphology data of the lower surface of the cover glass and the three-dimensional morphology data of the upper surface of the silicon substrate, and fits the three-dimensional morphology data of the two surfaces into a plane. The thickness H of the silicon-based liquid crystal box is calculated by calculating the coordinate difference of the two fitting planes in the vertical direction. The silicon-based liquid crystal box can be globally and comprehensively detected, and the global detection speed is fast and the accuracy is high.

[0017] 2. The present invention limits the silicon-based liquid crystal box on the top of the slide plate by cooperating with the frame and the screw rod, thereby preventing the silicon-based liquid crystal box from being misplaced and moving on the top surface of the slide plate, and improving the stability of the silicon-based liquid crystal box on the top of the nanopositioning stage.

[0018] 3. The present invention uses the elastic force of the spring to bring the first frame plate and the second frame plate closer to each other. The first frame plate and the second frame plate both pull the crossbar close to the silicon base plate until the outer side surface of the crossbar fits with the side edge of the silicon base plate, making it easy for the frame to adapt to silicon-based liquid crystal boxes of different shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 1 is an overall schematic diagram of a global detection device for LCoS liquid crystal box thickness based on low-coherence light Mirau interference according to an embodiment of the present invention;

[0020] Figure 2 is a low-coherence light interference intensity curve and a fitted envelope curve diagram of an embodiment of the present invention;

[0021] Figure 3 is a schematic diagram of the liquid crystal box thickness measurement principle of an embodiment of the present invention;

[0022] Figure 4 is a three-dimensional data diagram of the upper and lower surface morphologies of a liquid crystal cell according to an embodiment of the present invention;

[0023] Figure 5 3D data curves and fitted straight line graphs of the upper and lower surface morphologies of a liquid crystal cell according to an embodiment of the present invention;

[0024] Figure 6 is a schematic diagram of a silicon-based liquid crystal cell according to an embodiment of the present invention being placed on top of a slide plate;

[0025] Figure 7 is an overall schematic diagram of a clamping frame according to an embodiment of the present invention;

[0026] Figure 8 It is a schematic diagram of a bracket according to an embodiment of the present invention being sleeved on a surface of a limiting ring;

[0027] In the figure: 1, low coherence light source; 2, focusing lens; 3, projection lens; 4, dichroic prism; 401, imaging system; 5, first objective lens; 6, second objective lens; 7, third objective lens; 8, first glass plate; 9, second glass plate; 10, cover glass; 11, spacer; 12, silicon substrate; 13, nanopositioning stage; 14, imaging lens; 15, area array camera; 16, computer; 17, illumination system; 18, Mirau interference objective lens; 19, silicon-based liquid crystal box; 20, slide plate; 21, bottom plate; 22, slide rail; 23, slider; 24, first frame plate; 25, second frame plate; 26, bump; 27, screw rod; 28, cross bar; 29, first plug rod; 30, second plug rod; 31, limiting ring; 32, bracket; 33, side plate; 34, limiting rod; 35, spring. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0029] The present invention provides a global detection device for LCoS liquid crystal box thickness based on low coherence light Mirau interference, such as Figure 1 As shown, the nanopositioning stage 13, the imaging system 401, the computer 16, and the lighting system 17 are provided. The lighting system 17 is configured as a Kohler lighting system, a Mirau interference objective lens 18, and a silicon-based liquid crystal box 19. The imaging system 401 includes a beam splitter prism 4, an imaging lens 14, and a planar array camera 15. The lighting system 17 includes a low-coherence light source 1, a condensing lens 2, and a projection lens 3. The lighting system 17 is connected to the computer 16 via the low-coherence light source 1. The light emitted by the low-coherence light source 1 is aggregated by the condensing lens 2 and then projected onto the beam splitter prism 4 of the imaging system 401 through the projection lens 3. The beam splitter prism 4 irradiates the light onto the Mi Inside the Mirau interference objective lens 18, the Mirau interference objective lens 18 includes a first objective lens 5, a second objective lens 6, a third objective lens 7, a first glass plate 8 and a second glass plate 9, wherein the first glass plate 8 is set as a reference glass plate, and the second glass plate 9 is set as a splitting / compensation glass plate. The first glass plate 8 and the second glass plate 9 are both tilted, and the tilt angles of the two are the same, and the lower surface of the first glass plate 8 and the lower surface of the second glass plate 9 are both coated with a splitting film, and the first glass plate 8, the second glass plate 9 cooperate with the silicon-based liquid crystal box 19 to form interference light on the bottom surface of the second glass plate 9.

[0030] The silicon-based liquid crystal box 19 includes a cover glass 10, a plurality of spacers 11 and a silicon base plate 12. Liquid crystal is added between the plurality of spacers 11. The silicon-based liquid crystal box 19 is placed on the top surface of the nanopositioning stage 13. The nanopositioning stage 13 is connected to a computer 16 via a wire. Piezoelectric ceramics are arranged inside the nanopositioning stage 13. The computer 16 controls the operation of the nanopositioning stage 13. The nanopositioning stage 13 realizes nano-level positioning of the silicon-based liquid crystal box 19 in the vertical direction through piezoelectric ceramics, that is, drives the silicon-based liquid crystal box 19 to move up and down in the vertical (Z-axis) direction, so as to facilitate the vertical scanning and detection of the silicon-based liquid crystal box 19.

[0031] The computer 16 controls the operation of the nanopositioning stage 13. The nanopositioning stage 13 uses piezoelectric ceramics to move the silicon-based liquid crystal box 19 up and down in the vertical direction. The beam splitter 4 transmits the other separated part of the light to the Mirau interference objective lens 18. After the light passes through the first objective lens 5, the second objective lens 6, the third objective lens 7 and the first glass plate 8 in sequence, a part of the light irradiates the silicon-based liquid crystal box 19 through the second glass plate 9, and after being reflected from the top surface of the silicon base plate 12 or the bottom surface of the cover glass 10, a test light is formed on the bottom surface of the second glass plate 9. The other part of the light is reflected from the bottom surface of the second glass plate 9 to the bottom surface of the first glass plate 8, and after being reflected again from the bottom surface of the first glass plate 8, a reference light is formed on the bottom surface of the second glass plate 9. The test light and the reference light are combined on the bottom surface of the second glass plate 9 to form interference light, and the interference light is projected into the beam splitter prism 4 of the imaging system 401 through the Mirau interference objective lens 18.

[0032] The beam splitter prism 4 images the interference light into the area array camera 15 through the imaging lens 14. The area array camera 15 transmits the light intensity data of the interference light to the computer 16. The computer 16 globally detects the liquid crystal thickness of the silicon-based liquid crystal box 19 based on the light intensity data of the interference light.

[0033] Exemplarily, the upper surface of the cover glass 10 is coated with an anti-reflection film, and the lower surface is coated with an ITO conductive film. The integrated circuit is integrated on the top surface of the silicon substrate 12 using CMOS technology, and an aluminum reflective layer is coated on the surface of the silicon substrate 12. There are spacers 11 around the edges of the top surface of the silicon substrate 12 to separate the cover glass 10 and the silicon substrate 12. The empty layer formed between the multiple spacers 11 is used to inject liquid crystal. The second glass plate 9 and the cover glass 10 have the same thickness and are made of the same material, so that interference light can be formed on the bottom surface of the second glass plate 9. The optical paths introduced by the second glass plate 9 and the cover glass 10 are equal, so that the optical paths of the reference light and the test light can easily meet the equal optical path condition, so that low coherence light can form interference on the bottom surface of the second glass plate 9.

[0034] exist Figure 2 and Figure 3 In the envelope fitting algorithm, we get Figure 2 The fitting envelope curve corresponding to the interference light in the vertical direction (Z axis) of the liquid crystal is obtained. Among them, the nanopositioning stage 13 drives the silicon-based liquid crystal box 19 to move up and down at the nanometer level in the vertical direction through piezoelectric ceramics, which can form a change in the intensity of the interference light on the bottom surface of the cover glass 10 or the top surface of the silicon substrate 12, and obtain Figure 3 The interference light intensity curve in the image is changed to obtain the maximum value point of the interference light on the lower surface of the cover glass 10 and the maximum value point on the upper surface of the silicon substrate 12. The height difference between the two maximum value points is the liquid crystal thickness of the silicon-based liquid crystal box 19. Figure 2 In the figure, the Z axis is the direction perpendicular to the silicon-based liquid crystal box 19, and the I axis is the interference light intensity in the vertical direction of the silicon-based liquid crystal box 19.

[0035] exist Figure 4 and Figure 5 In the example, the light intensity data of the interference light is used to obtain the three-dimensional morphology data of the bottom surface of the cover glass 10 and the top surface of the silicon substrate 12 in the silicon-based liquid crystal cell 19, and the linear fitting algorithm is used to obtain Figure 5 The fitting straight line corresponding to the three-dimensional data of the morphology. Figure 5 As shown, by measuring the 3D topography data of the lower surface of the cover glass 10 and the upper surface of the silicon substrate 12, and fitting the 3D topography data of the two surfaces into a plane, the thickness H of the silicon-based liquid crystal box 19 is calculated by calculating the coordinate difference of the two fitting planes in the vertical (Z-axis) direction. Since the device has the characteristics of a large field of view, and the field of view can cover the size of the silicon-based liquid crystal box 19, it can realize the global measurement of the thickness of the silicon-based liquid crystal box 19, with fast measurement speed and high efficiency. Figure 4 and Figure 5 In the figure, the X-axis is the front-to-back direction of the Si-based liquid crystal box 19, and the Y-axis is the left-to-right direction of the Si-based liquid crystal box 19.

[0036] exist Figure 6 In the embodiment, the nanopositioning stage 13 includes a slide plate 20 and a bottom plate 21, and the slide plate 20 is configured as a piezoelectric ceramic. The slide plate 20 is connected to the computer 16 through a controller. The slide plate 20 is located on the top of the bottom plate 21, and the silicon-based substrate 12 is correspondingly placed on the top surface of the slide plate 20. Slide rails 22 are fixed to both sides of the inner concave surface of the top of the bottom plate 21 by screws. Slide blocks 23 that slide with the slide rails 22 are fixed to both sides of the bottom of the slide plate 20. The bottom plate 21 is connected to the computer 16 by a controller. When the controller is working, the slide plate 20 slides on the inner side of the slide rail 22 of the bottom plate 21 by the slide block 23. The sliding slide plate 20 drives the silicon-based liquid crystal box 19 to move horizontally synchronously. After the nanopositioning stage 13 is installed on the top surface of the slide plate 20, the controller controls the slide plate 20 to move. The moving slide plate 20 slides on the inner side of the slide rail 22 by the slide block 23. The translation of the slide plate 20 is achieved by the sliding cooperation between the slide block 23 and the slide rail 22.

[0037] exist Figure 6 and Figure 7 In the figure, the silicon base plate 12 is mounted on the top surface of the skateboard 20 by means of a fixing component, and the fixing component includes two relative clamping frames, and the clamping frames include a first frame plate 24 and a second frame plate 25 relative to each other. The outer sides of the first frame plate 24 and the second frame plate 25 are fixed with a protrusion 26, and a screw rod 27 vertically penetrates the center of the protrusion 26. The bottom end of the screw rod 27 is spirally inserted into the top surface of the skateboard 20, and the protrusion 26 is fixedly mounted on the top surface of the skateboard 20 through the screw rod 27. After the silicon base plate 12 of the silicon-based liquid crystal box 19 is placed on the top surface of the slide plate 20, the two clamps are respectively located on both sides of the silicon base plate 12, and the clamps use the inner sides of the first frame plate 24 and the second frame plate 25 to fit on the side of the silicon base plate 12. The two clamps cooperate to limit the silicon-based liquid crystal box 19, and the first frame plate 24 and the second frame plate 25 are limited and installed on the top surface of the slide plate 20 by the screw 27, that is, the clamps are fixed to the top surface of the slide plate 20 under the spiral cooperation of the screw 27 and the slide plate 20, and the two clamps are respectively limited on both sides of the silicon-based liquid crystal box 19.

[0038] The fixing member also includes two crossbars 28, the outer circumferential side of the crossbar 28 is in contact with the side of the silicon substrate 12, the crossbar 28 passes through the two clamps, and nuts are screwed on both ends of the crossbar 28. The two clamps cooperate to clamp the silicon substrate 12. Before fixing the clamps, the two crossbars 28 are respectively placed on the front and rear sides of the silicon-based liquid crystal box 19, and the crossbar 28 passes through the ends of the two clamps. The nuts are used to make the crossbar 28 and the clamps cooperate to connect. The two clamps cooperate with the two crossbars 28 to form a frame, and the silicon-based liquid crystal box 19 is limited to the top of the slide 20 by the frame to prevent the silicon-based liquid crystal box 19 from being misplaced and moving on the top surface of the slide 20.

[0039] exist Figure 7 and Figure 8In the embodiment, the first frame plate 24 is fixed with a first plug rod 29 plugged into the second frame plate 25, and the second frame plate 25 is fixed with a second plug rod 30 plugged into the first frame plate 24. The surfaces of the first plug rod 29 and the second plug rod 30 are both spirally sleeved with a limiting ring 31. The top limiting ring 31 is close to the first frame plate 24, and the bottom limiting ring 31 is close to the second frame plate 25. The surface of the limiting ring 31 is sleeved with a bracket 32. The outer sides of the first frame plate 24 and the second frame plate 25 are both fixed with side plates 33. The two side plates 33 correspond to the two brackets 32 one by one. The inner side of the side plate 33 is fixed with a limiting rod 34. The outer end of the bracket 32 ​​is sleeved on the surface of the limiting rod 34. The surface of the limiting rod 34 is sleeved with a spring 35. One end of the spring 35 is connected to the bracket 32, and the other end of the spring 35 is connected to the inner end of the limiting rod 34. The spring 35 is in a compressed state, and the elastic force of the spring 35 makes the first frame plate 24 and the second frame plate 25 approach each other through the limiting rod 34. After the cross bar 28 passes through the end of the clamp, the limiting ring 31 is screwed, and the two limiting rings 31 move on the surfaces of the first plug rod 29 and the second plug rod 30 respectively. The top limiting ring 31 gradually approaches the second frame plate 25, and the bottom limiting ring 31 gradually approaches the first frame plate 24. The elastic force of the spring 35 acts on the limiting rod 34, that is, the top limiting rod 34 pulls the first frame plate 24 to move, and the bottom limiting rod 34 pulls the second frame plate 25 to move. The first frame plate 24 and the second frame plate 25 approach each other under the action of the spring 35. At this time, the first frame plate 24 and the second frame plate 25 both pull the cross bar 28 close to the silicon base plate 12 until the outer side surface of the cross bar 28 is in contact with the side edge of the silicon base plate 12. At this time, the clamp is fixedly installed on the top surface of the slide plate 20 using the screw 27 to complete the limitation of the silicon-based liquid crystal box 19 and improve the stability of the silicon-based liquid crystal box 19 on the top of the nanopositioning stage 13.

[0040] Working principle of the present invention:

[0041] Reference Figures 1 to 8 As shown, after the silicon base plate 12 of the silicon-based liquid crystal box 19 is placed on the top surface of the slide plate 20, the two clamps are respectively located on both sides of the silicon base plate 12, and the clamps use the inner sides of the first frame plate 24 and the second frame plate 25 to fit the side of the silicon base plate 12, and the two cross bars 28 are respectively located on the front and back sides of the silicon-based liquid crystal box 19, and the cross bars 28 pass through the ends of the two clamps, and the limiting rings 31 are screwed. The two limiting rings 31 move on the surfaces of the first plug rod 29 and the second plug rod 30 respectively, and the top limiting ring 31 gradually approaches As the limiting ring 31 approaches the second frame plate 25, the bottom limiting ring 31 gradually approaches the first frame plate 24. The elastic force of the spring 35 acts on the limiting rod 34, that is, the top limiting rod 34 pulls the first frame plate 24 to move, and the bottom limiting rod 34 pulls the second frame plate 25 to move. The first frame plate 24 and the second frame plate 25 approach each other under the action of the spring 35. At this time, the first frame plate 24 and the second frame plate 25 both pull the cross bar 28 to approach the silicon base plate 12 until the outer side surface of the circumference of the cross bar 28 fits with the side of the silicon base plate 12.

[0042] The cross bar 28 is connected to the clamp frame by using a nut, and the two clamp frames cooperate with the two cross bars 28 to form a frame. The frame cooperates with the screw 27 to confine the silicon-based liquid crystal box 19 to the top of the slide 20, thereby preventing the silicon-based liquid crystal box 19 from being misplaced on the top surface of the slide 20 and improving the stability of the silicon-based liquid crystal box 19 on the top of the nano positioning platform 13.

[0043] After the silicon-based liquid crystal box 19 is installed on the top surface of the slide plate 20, the controller controls the movement of the slide plate 20. The moving slide plate 20 slides on the inner side of the slide rail 22 using the slider 23. The sliding cooperation between the slider 23 and the slide rail 22 realizes the translation of the slide plate 20. The nanopositioning stage 13 realizes nano-level positioning of the silicon-based liquid crystal box 19 in the vertical direction through piezoelectric ceramics.

[0044] The light source emitted by the low coherence light source 1 is converged by the condenser lens 2 and then projected onto the beam splitter prism 4 by the projection lens 3. The beam splitter prism 4 irradiates the light into the Mirau interference objective lens 18. After the light passes through the first objective lens 5, the second objective lens 6, the third objective lens 7 and the first glass plate 8 in sequence, a part of the light irradiates the silicon-based liquid crystal box 19 through the second glass plate 9, and after being reflected by the top surface of the silicon base plate 12 or the bottom surface of the cover glass 10, a test light is formed on the bottom surface of the second glass plate 9. Another part of the light is reflected by the bottom surface of the second glass plate 9 to the bottom surface of the first glass plate 8, and after being reflected again by the bottom surface of the first glass plate 8, a reference light is formed on the bottom surface of the second glass plate 9. The test light and the reference light are combined on the bottom surface of the second glass plate 9 to form interference light, and the interference light is projected into the beam splitter prism 4 of the imaging system 401 through the Mirau interference objective lens 18. The beam splitter prism 4 images the interference light into the area array camera 15 through the imaging lens 14. The area array camera 15 transmits the light intensity data of the interference light to the computer 16. The computer 16 globally detects the liquid crystal thickness of the silicon-based liquid crystal box 19 based on the light intensity data of the interference light.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A global detection device for LCoS liquid crystal cell thickness based on low-coherence light Mirau interference, characterized in that: The invention comprises a nanopositioning stage (13), an imaging system (401), a computer (16), an illumination system (17), a Mirau interference objective lens (18) and a silicon-based liquid crystal box (19). The imaging system (401) comprises a beam splitter prism (4), an imaging lens (14) and a surface array camera (15). The illumination system (17) comprises a low-coherence light source (1), a focusing lens (2) and a projection lens (3). The illumination system (17) is connected to the computer (16) via the low-coherence light source (1). 16), after the light source emitted by the low coherence light source (1) is converged by the focusing lens (2), it is projected onto the beam splitter prism (4) of the imaging system (401) through the projection lens (3), and the beam splitter prism (4) irradiates the light into the interior of the Mirau interference objective lens (18), the silicon-based liquid crystal box (19) comprises a cover glass (10), a plurality of spacers (11) and a silicon substrate (12), liquid crystals are added between the plurality of spacers (11), and the silicon-based liquid crystal box (19) is placed correspondingly The nanopositioning stage (13) is connected to a computer (16) via a wire. The nanopositioning stage (13) is provided with piezoelectric ceramics inside. The computer (16) controls the operation of the nanopositioning stage (13). The nanopositioning stage (13) realizes nano-level positioning of the silicon-based liquid crystal box (19) in a vertical direction via the piezoelectric ceramics. Light is irradiated on the silicon-based liquid crystal box (19) via a Mirau interference objective lens (18). Light reflected from the top surface of the silicon substrate (12) or the bottom surface of the cover glass (10) returns to the inside of the Mirau interference objective lens (18). Interference light is formed in the Mirau interference objective lens (18) and then transmitted to the beam splitter prism (4). The beam splitter prism (4) images the interference light into the inside of the array camera (15) via an imaging lens (14). The array camera (15) transmits light intensity data of the interference light to the computer (16). The computer (16) globally detects the liquid crystal thickness of the silicon-based liquid crystal box (19) based on the light intensity data of the interference light. The nanopositioning platform (13) comprises a slide plate (20) and a base plate (21), and the slide plate (20) is configured as a piezoelectric ceramic. The slide plate (20) is connected to a computer (16) via a controller. The slide plate (20) is located on the top of the base plate (21), and the silicon-based base plate (12) is correspondingly placed on the top surface of the slide plate (20). Slide rails (22) are fixed to both sides of the inner concave surface of the top of the base plate (21) by screws. Slide blocks (23) that slidably cooperate with the slide rails (22) are fixed to both sides of the bottom of the slide plate (20). The base plate (21) is connected to the computer (16) via a controller. When the controller is in operation, the slide plate (20) slides on the inner side of the slide rail (22) of the base plate (21) by means of the slide block (23). The sliding slide plate (20) drives the silicon-based liquid crystal box (19) to move horizontally synchronously. The silicon substrate (12) is mounted on the top surface of the slide plate (20) by means of a fixing component, wherein the fixing component comprises two opposite clamping frames, wherein the clamping frames comprise a first frame plate (24) and a second frame plate (25) opposite to each other, wherein the outer side surfaces of the first frame plate (24) and the second frame plate (25) are both fixed with a protrusion (26), wherein a screw rod (27) vertically penetrates the center of the protrusion (26), wherein the bottom end of the screw rod (27) is spirally inserted into the top surface of the slide plate (20), and the protrusion (26) is fixedly mounted on the top surface of the slide plate (20) via the screw rod (27); The Mirau interference objective lens (18) comprises a first objective lens (5), a second objective lens (6), a third objective lens (7), a first glass plate (8) and a second glass plate (9); the first glass plate (8) and the second glass plate (9) are both arranged to be inclined, and the inclination angles of the two are the same; the lower surface of the first glass plate (8) and the lower surface of the second glass plate (9) are both coated with a light splitting film; after light passes through the first objective lens (5), the second objective lens (6), the third objective lens (7) and the first glass plate (8) in sequence, a portion of the light passes through the second glass plate (9) to The silicon-based liquid crystal box (19) is irradiated, and after being reflected by the top surface of the silicon-based substrate (12) or the bottom surface of the cover glass (10), a test light is formed on the bottom surface of the second glass plate (9); another part of the light is reflected by the bottom surface of the second glass plate (9) to the bottom surface of the first glass plate (8); after being reflected again by the bottom surface of the first glass plate (8), a reference light is formed on the bottom surface of the second glass plate (9); the test light and the reference light are combined on the bottom surface of the second glass plate (9) to form interference light; the interference light is projected onto the beam splitter (4) of the imaging system (401) through the Mirau interference objective lens (18).

2. The LCoS liquid crystal box thickness global detection device based on low coherence light Mirau interference according to claim 1, characterized in that: A plurality of spacers (11) are arranged on the top surface of the silicon substrate (12), a void layer is formed between the plurality of spacers (11), and the cover glass (10) is correspondingly placed on the top of the plurality of spacers (11).

3. The LCoS liquid crystal box thickness global detection device based on low coherence light Mirau interference according to claim 1, characterized in that: The second glass plate (9) and the cover glass (10) have the same thickness and are made of the same material.

4. The LCoS liquid crystal box thickness global detection device based on low coherence light Mirau interference according to claim 1, characterized in that: The fixing component also includes two cross bars (28), the outer circumferential side surfaces of the cross bars (28) are in contact with the side edges of the silicon base plate (12), the cross bars (28) correspondingly pass through the two clamping frames, and nuts are spirally sleeved at both ends of the cross bars (28), so that the two clamping frames cooperate to clamp the silicon base plate (12) through the cooperation of the nuts and the cross bars (28).

5. The LCoS liquid crystal box thickness global detection device based on low coherence light Mirau interference according to claim 1, characterized in that: The first frame plate (24) is fixed with a first plugging rod (29) plugged into the second frame plate (25), and the second frame plate (25) is fixed with a second plugging rod (30) plugged into the first frame plate (24). The surfaces of the first plugging rod (29) and the second plugging rod (30) are both spirally sleeved with limiting rings (31), the top limiting ring (31) is close to the first frame plate (24), and the bottom limiting ring (31) is close to the second frame plate (25). The surfaces of the limiting rings (31) are sleeved with brackets (32). The first frame plate (24) and the second frame plate (25) are both fixed with side plates (33) on their outer sides, the two side plates (33) correspond to the two brackets (32) one by one, the inner sides of the side plates (33) are fixed with limiting rods (34), the outer ends of the brackets (32) are sleeved on the surfaces of the limiting rods (34), the surfaces of the limiting rods (34) are sleeved with springs (35), one end of the springs (35) is connected to the brackets (32), and the other end of the springs (35) is connected to the inner ends of the limiting rods (34).

6. The LCoS liquid crystal box thickness global detection device based on low coherence light Mirau interference according to claim 5, characterized in that: The spring (35) is in a compressed state, and the elastic force of the spring (35) causes the first frame plate (24) and the second frame plate (25) to move closer to each other via the limiting rod (34).

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