Polarization splitting prism, polarization splitting plate, projector and head-up display

Abstract

The utility model discloses a polarization splitting prism, a polarization splitting plate, a projector and a head-up display. According to the polarization splitting prism, through the H-Lak7 base material and the adaptive beam splitting film structure design, the film layer thickness is greatly reduced, and the polarization splitting prism has better optical performance, machinability and appearance. The utility model also provides a polarization beam splitter, a projector and a head-up display.

Description

Technical Field

[0001] The utility model relates to the technical field of optical materials, and particularly relates to a polarization beam splitting prism, a polarization beam splitting plate, a projector and a head-up display. Background Art

[0002] Light has a polarization state. If the polarization vector of the light is in the plane where the incident light and the reflected light are located, it is called p-polarization. If the polarization vector is perpendicular to this plane, it is called s-polarization. When light is incident on a film at a non-perpendicular angle, it can be decomposed into P light and S light. The polarization beam splitting film is a film used to achieve the transmission of P light and the cut-off of S light, and has been widely used in the fields of laser technology, optical fiber communication technology and optoelectronic instruments.

[0003] One application method is to laminate a polarization beam splitting film on the surface of an optical substrate (such as optical glass) to form a polarization beam splitting prism, and glue multiple polarization beam splitting prisms to form a polarization beam splitting plate for use. Most of the commercially available polarization beam splitting plates currently use B270 glass or BK7 glass with high light transmittance, and their supporting film systems are relatively thick. Defects are easily introduced during the coating process, and the substrate is easily deformed after coating, resulting in bubbles easily appearing in the subsequent gluing process and affecting the optical performance.

[0004] Therefore, it is necessary to develop a polarization beam splitting plate with better optical performance. Summary of the Utility Model

[0005] The utility model aims to solve at least one of the technical problems existing in the prior art. For this purpose, the utility model provides a polarization beam splitting prism, which can improve the polarization beam splitting performance of optical elements (such as polarization beam splitting plates) including the above polarization beam splitting prism.

[0006] The utility model also provides a polarization beam splitting plate.

[0007] The utility model also provides a projector.

[0008] The utility model also provides a head-up display.

[0009] The first aspect embodiment of the utility model relates to a polarization beam splitting prism, comprising: a first base layer made of H-Lak7 optical glass; a first beam splitting film formed on at least one surface of the base layer, and the film layer structure of the first beam splitting film is: starting from the first base layer side, including Ta 2 O 5 layers and SiO 2There are 23 layers in total, and the layer thicknesses are successively 26.65 - 28.65 nm, 283.08 - 287.08 nm, 109.67 - 111.67 nm, 218.28 - 222.28 nm, 91.28 - 93.28 nm, 177.06 - 181.06 nm, 84.37 - 86.37 nm, 204.95 - 208.95 nm, 66.32 - 68.32 nm, 127.51 - 131.51 nm, 52.63 - 54.63 nm, 226.66 - 230.66 nm, 68.04 - 70.04 nm, 107.92 - 111.92 nm,

[0010] 50.9 - 52.9 nm, 106.58 - 110.58 nm, 55.85 - 57.85 nm, 101.03 - 105.03 nm, 50.27 - 52.27 nm, 85.08 - 89.08 nm, 52.44 - 54.44 nm, 94.43 - 98.43 nm, 33.18 - 35.18 nm.

[0011] The polarization beam splitting prism according to the first - aspect embodiment of the present utility model has at least the following beneficial effects:

[0012] H - Lak7 is a lanthanum crown glass, and its main components include oxides such as silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), calcium oxide (CaO), lanthanum oxide (La 2 O 3 ). Compared with the commonly used B270 or BK7 glass, H - Lak7 has a higher refractive index, in the range of 1.71 - 1.72, which is beneficial to achieving excellent polarization beam splitting effects in a wider wavelength range. Through the H - Lak7 substrate and the adapted film system design, the film layer thickness is greatly reduced. The total film layer thickness is about 2500 nm, which is significantly lower than the film system (about 9000 nm) adapted to the conventional B270 or BK7 substrate. The film layer is thin, the substrate is not easily deformed, and it is easier to glue, reducing appearance defects such as air bubbles and splashes.

[0013] The applicable wavelength range of the polarization beam splitting prism is 425 nm - 650 nm, and the air incident angle is 0 ± 8°. In the working wavelength range, when the incident angle is 0°, the average transmittance of the beam - splitting film for S - polarized light ≤ 0.1%, and the average transmittance for P - polarized light ≥ 97%; when the incident angle is 0° ± 8°, the average transmittance of the beam - splitting film for S - polarized light ≤ 2%, and the average transmittance for P - polarized light ≥ 94%, having excellent optical properties.

[0014] The H-LaK7 material has good processability, with a hardness FA value of 76, making it more suitable for planar processing. The H-LaK7 has a high ultraviolet light transmittance and is suitable for the photocuring gluing process. At the same time, the film layer of the beam splitter film is thinner, which is more conducive to the transmission of ultraviolet light, enabling rapid photocuring and improving processing efficiency.

[0015] In terms of cost, the H-Lak7 material is slightly more expensive, but the film layer of the beam splitter film is thinner, the production time is shorter, and it basically does not increase the comprehensive cost. At the same time, it has better performance and a higher cost performance.

[0016] In some embodiments, the film layer structure of the first beam splitter film is as follows: starting from the side of the first base layer, it includes Ta layers and SiO layers alternately stacked in sequence, with a total of 23 layers. The layer thicknesses starting from the side of the first base layer are 27.65nm, 285.08nm, 110.67nm, 220.28nm, 92.28nm, 179.06nm, 85.37nm, 206.95nm, 67.32nm, 129.51nm, 2 O 5 layers and SiO 2 layers, with a total of 23 layers. The layer thicknesses starting from the side of the first base layer are 27.65nm, 285.08nm, 110.67nm, 220.28nm, 92.28nm, 179.06nm, 85.37nm, 206.95nm, 67.32nm, 129.51nm,

[0017] 53.63nm, 228.66nm, 69.04nm, 109.92nm, 51.9nm, 108.58nm, 56.85nm, 103.03nm,

[0018] 51.27nm, 87.08nm, 53.44nm, 96.43nm, 34.18nm.

[0019] In some embodiments, the first base layer has a triangular prism or quadrangular prism structure. A triangular prism has two parallel and congruent triangular bases, and three quadrilateral side faces connecting these bases. A quadrangular prism has two parallel and congruent quadrilateral bases, and four quadrilateral side faces connecting these bases. Among them, the quadrilateral can be a rectangle, a parallelogram, or a square.

[0020] In some embodiments, the first beam splitter film is formed on at least one side surface of the triangular prism or quadrangular prism.

[0021] In some embodiments, the first base layer is a right triangular prism, that is, it has two parallel and congruent triangular bases, and the side faces connecting these bases are all rectangles or squares.

[0022] In some embodiments, the first base layer is a right triangular prism and has two parallel and congruent right triangular bases. The first beam splitter film is formed on the side surface connecting the hypotenuses of the two right triangular bases.

[0023] In some embodiments, the right triangle base is an equilateral right triangle base.

[0024] In some embodiments, the right-angled side length of the equilateral right triangle base is 0.5 - 1 mm, and the distance between the equilateral right triangle bases is 14 - 16 mm.

[0025] In some embodiments, the first base layer has a quadrangular prism structure and has two parallel and congruent rectangular bases. A group of side faces connecting the long sides of the bases are rectangles, and the first polarization splitting film is formed on the surface of one of these rectangular side faces.

[0026] In some embodiments, in the first base layer, a group of side faces connecting the short sides of the bases are parallelograms with an acute angle of 45°.

[0027] In some embodiments, in the first base layer, the length of the base is 14 - 16 mm, the width is 0.5 - 1 mm, and the distance between the bases is 0.5 - 1 mm.

[0028] An embodiment of the second aspect of the present utility model relates to a polarization splitting plate, including the above-mentioned polarization splitting prism.

[0029] Due to the characteristics of the above-mentioned polarization splitting prism, the polarization splitting plate has better optical characteristics and processability.

[0030] In some embodiments, the polarization splitting plate includes: a glued quadrangular prism, including a plurality of first polarization splitting prisms glued in sequence. The first polarization splitting prism has a second base layer. The second base layer has a quadrangular prism structure. A second polarization splitting film is formed on one side face of the second base layer. The second polarization splitting film of one first polarization splitting prism is glued to the opposite side surface of the second polarization splitting film of the adjacent first polarization splitting prism. The same-side bases of the second base layer and the other group of side faces connecting the bases are respectively located in the same plane;

[0031] A second polarization splitting prism, having a third base layer in the shape of a right triangular prism. A third polarization splitting film is formed on one side face of the third base layer. The third polarization splitting film is glued to the opposite side surface of the second polarization splitting film on the outermost side of the glued quadrangular prism;

[0032] A third polarization splitting prism, having a fourth base layer in the shape of a right triangular prism. One side face of the fourth base layer is glued to the second polarization splitting film on the outermost side of the glued quadrangular prism;

[0033] The materials of the second base layer, the third base layer, and the fourth base layer are all H-Lak7 optical glass. The film layer structures of the second beam splitter film starting from the second base layer side and the third beam splitter film starting from the third base layer side are the same as the film layer structure of the first beam splitter film starting from the first base layer side defined above; the glued four-prism, the second polarization beam splitter prism, and the third polarization beam splitter prism are glued to form a cuboid structure.

[0034] In some embodiments, there are 16 first polarization beam splitter prisms.

[0035] In some embodiments, the polarization beam splitter plate further includes 8 half-wave plates. One bottom surface of one side of the second base layer is the incident surface, and the other bottom surface is the exit surface. The 8 half-wave plates are respectively located on the exit surface side of the 8 first polarization beam splitter prisms in the glued four-prism, and there is one first polarization beam splitter prism between adjacent two half-wave plates. When linearly polarized light passes through a half-wave plate, its phase will be delayed by half a wavelength, and thus the polarization direction of the light can be adjusted to better adapt to the working angle. The material of the half-wave plate can be quartz crystal, resin material, etc., and the thickness is, for example, 0.05 - 0.2 mm.

[0036] In some embodiments, the half-wave plate is glued and connected to the first polarization beam splitter prism.

[0037] In some embodiments, a first antireflection film is provided on the incident surface side of the polarization beam splitter plate, and a second antireflection film is provided on the surface of the polarization beam splitter plate opposite to the incident surface.

[0038] In some embodiments, the thicknesses of the first antireflection film and the second antireflection film are independently 250 - 300 nm. The antireflection film is used to reduce the reflection of light and improve the light transmittance. The material of the antireflection film can be Ta 2 O 5 film and SiO 2 film deposited alternately, or TiO 2 film and SiO 2 film deposited alternately. Non-limiting examples of the total number of film layers are: 5 - 9 layers, specifically, it can be 5 layers, 6 layers, 7 layers, 8 layers, or 9 layers. The thickness of each layer can be selected according to the experience in the art. For example, when it is Ta 2 O 5 film and SiO 2 film (a total of 6 layers), non-limiting examples of the layer thicknesses are, in sequence: 11.3 nm, 42.31 nm, 45.36 nm, 8.41 nm, 69.75 nm, 87.72 nm; if it is TiO 2 film and SiO 2When the film (a total of 6 layers), non-limiting examples of the layer thickness are, in sequence: 13.62 nm, 32.69 nm, 52.91 nm, 10 nm, 37.95 nm, 89.65 nm.

[0039] In some embodiments, in the first polarization beam splitter prism, the bottom surface of the second base layer is rectangular, a group of side surfaces connecting the long sides of the bottom surface are rectangular, and the second beam splitting film is formed on the surface of one of the rectangular side surfaces.

[0040] In some embodiments, in the first polarization beam splitter prism, a group of side surfaces connecting the short sides of the bottom surface are parallelograms with an acute angle of 45°.

[0041] In some embodiments, in the first polarization beam splitter prism, the length of the bottom surface is 14 - 16 mm, the width is 0.5 - 1 mm, and the distance between the bottom surfaces is 0.5 - 1 mm.

[0042] In some embodiments, in the second polarization beam splitter prism, the bottom surface of the third base layer is an isosceles right triangle, and the third beam splitting film is formed on the surface of the side surface connecting the hypotenuse of the bottom surface.

[0043] In some embodiments, the right-angled side length of the isosceles right triangle is 0.5 - 1 mm, and the distance between the bottom surfaces is 14 - 16 mm.

[0044] The third aspect embodiment of the present utility model relates to a preparation method of the above polarization beam splitter prism, including: alternately depositing the Ta 2 O 5 layer and the SiO 2 layer on the surface of the first base layer to form the first beam splitting film, and obtaining the polarization beam splitter prism.

[0045] This method has high production efficiency, and the polarization beam splitting effect of the prepared polarization beam splitter prism is good.

[0046] In some embodiments, the method for forming the first beam splitting film is electron beam evaporation and RF ion source assisted deposition. Coating with an RF ion source and a heating method can ensure spectral stability while ensuring the firmness of the film layer. The specific deposition process is a well-known technology, and the coating quality and film layer thickness can be adjusted through coating temperature, atmosphere, pressure, evaporation rate, etc.

[0047] In some embodiments, before forming the first beam splitting film, it further includes cleaning and polishing the first base layer.

[0048] It can be understood that the above preparation method of the polarization beam splitter prism can be used to prepare the polarization beam splitter prism of the above embodiments. Therefore, for the specific structure of the prepared polarization beam splitter prism, refer to the embodiments of the above polarization beam splitter prism.

[0049] The fourth aspect of the present utility model relates to a method for preparing a polarization beam splitter plate, which includes the steps of:

[0050] Alternately deposit Ta 2 O 5 layers and SiO 2 layers on the surface of the fifth base layer to obtain a coated base layer; sequentially bond multiple coated base layers, where the coated surface of one of the coated base layers is bonded to the other side opposite to the coated surface of the adjacent coated base layer to obtain a plywood; cut the plywood to obtain multiple polarization beam splitter plates; wherein, the material of the fifth base layer is H-Lak7 optical glass, and the coating structure of the coated base layer starting from the fifth base layer side is the same as the film layer structure of the first beam splitting film starting from the first base layer side defined above.

[0051] It can be understood that in the above method for preparing a polarization beam splitter plate, the fifth base layer corresponds to the first base layer of the aforementioned polarization beam splitting prism, and different positions of the fifth base layer in the plywood also correspond to the positions of the second base layer, the third base layer, and the fourth base layer in the aforementioned embodiments of the polarization beam splitter plate, with only the difference in size. Thus, the polarization beam splitter plate including the second base layer, the third base layer, and the fourth base layer can be obtained by further cutting.

[0052] This method has high production efficiency, and the polarization beam splitting effect of the prepared polarization beam splitter plate is good.

[0053] In addition, the following method can also be used to prepare a polarization beam splitter plate: after coating the surface of the fifth base layer, first make a polarization beam splitting prism of the target size (cutting, grinding, etc. can be performed), and bond multiple polarization beam splitting prisms to obtain a polarization beam splitting plate, that is, this method is to first cut and make small-sized prisms and then bond them. Compared with this method, bonding into a large plate first and then cutting can obtain multiple polarization beam splitter plates with fewer bonding times and improve processing efficiency.

[0054] In some embodiments, the cutting is multi-stage cutting.

[0055] The H-Lak7 material has good processability and is suitable for planar processing. Large-sized base layers can be used and the target size can be obtained through multi-stage cutting, further improving processing efficiency. For example, for two-stage cutting, if n intermediate plates are formed by the first-stage cutting and each intermediate plate is refined into m by the second-stage cutting, then n×m polarization beam splitter plates can be obtained.

[0056] In some embodiments, the method for depositing Ta 2 O 5 layers and SiO 2 layers is electron beam evaporation and RF ion source assisted deposition, referring to the formation method of the aforementioned first beam splitting film.

[0057] In some embodiments, the cutting is performed using an internal circular cutting machine and / or an external circular cutting machine. Among them, if multi-stage cutting is adopted, the external circular cutting machine can be used for the final stage cutting, and the internal circular cutting machine can be used for other grading cuttings.

[0058] In some embodiments, before plating the Ta 2 O 5 layer and the SiO 2 layer, the method further includes cleaning and polishing the fifth base layer.

[0059] In some embodiments, the method for preparing the polarization beam splitter further includes: after the cutting, performing polishing and cleaning.

[0060] In some embodiments, the gluing is segmented gluing, that is, first gluing some of the coated base layers into sub-components, and then gluing all the sub-components into a whole. The gluing generally uses ultraviolet light (UV) curable adhesives. The segmented gluing reduces the laminated thickness of the previous stage curing, which is beneficial to light penetration and can improve the overall curing efficiency.

[0061] In some embodiments, the gluing is an evenly divided three-stage gluing. For example, when a total of 18 coated base layers need to be glued, it is divided into 3 segments, with 6 layers in each segment glued into sub-blocks separately, and then the 3 sub-blocks are glued together.

[0062] In some embodiments, the gluing adopts positive and negative deviation matching gluing according to the thickness deviation of the coated base layer to offset part of the tolerance and reduce the cumulative dimensional error. Considering reasonable errors, the thickness deviation of the coated base layer can be a positive deviation or a negative deviation. When selecting the coated base layers for combined gluing, try to make the positive and negative deviations of all the coated base layers cancel each other out as much as possible to effectively reduce the dimensional error of the finished product.

[0063] In some embodiments, the gluing uses a UV curable optical adhesive. The optical adhesive is suitable for optical or optoelectronic products, and has the characteristics of high transparency, stable refractive index, high purity, good durability, and little influence on optical performance. The UV curable optical adhesive has a fast curing rate and high production efficiency.

[0064] In some embodiments, the polarization beam splitter has an incident surface and an exit surface. The method for preparing the polarization beam splitter further includes: forming a first antireflection film on the incident surface, pasting a 1 / 2 wavelength plate on a partial area of the exit surface, and forming a second antireflection film on the surface on the side where the 1 / 2 wavelength plate is located.

[0065] In some embodiments, the method for forming the first antireflection film and / or the second antireflection film is electron beam evaporation and RF ion source assisted deposition.

[0066] It can be understood that the above method for preparing a polarization beam splitter can be used to prepare the polarization beam splitter of the above embodiments. Therefore, for the specific structure of the polarization beam splitter, refer to the above embodiments of the polarization beam splitter. According to the structure of the polarization beam splitter, it is easy to select a suitable material for gluing and obtain the target product by cutting.

[0067] A fifth aspect embodiment of the present invention relates to a projector, including the above polarization beam splitter prism or the above polarization beam splitter.

[0068] In some embodiments, the projector includes an LCOS (liquid crystal on silicon) projector or an LCD (liquid crystal display) projector.

[0069] A sixth aspect embodiment of the present invention relates to a head-up display, including the above polarization beam splitter prism or the above polarization beam splitter.

[0070] In some embodiments, the head-up display includes a vehicle-mounted head-up display.

[0071] A seventh aspect embodiment of the present invention relates to the application of the above polarization beam splitter prism or the above polarization beam splitter in a projector or a head-up display.

[0072] In this article, when referring to a numerical range, it includes the end values and any subset range within the range. "A plurality" means two or more, and "above" includes the base number. For example, two or more includes two.

[0073] The additional aspects and advantages of the present invention will be partly given in the following description, partly become apparent from the following description, or be understood through the practice of the present invention.

[0074] Description of the Drawings in the Specification

[0075] Figure 1 Top view schematic diagram of the polarization beam splitter of Example 1 along the incident plane.

[0076] Figure 2 Side view of the polarization beam splitter of Example 1.

[0077] Figure 3 Spectral curve of the polarization beam splitter of Example 1.

[0078] Figure 4 Spectral curve of the polarization beam splitter of Comparative Example 1.

[0079] Reference Signs:

[0080] First polarization beam splitter prism 110; second beam splitting film 111; second polarization beam splitter prism 120; third beam splitting film 121;

[0081] Third polarization beam splitter prism 130; 1 / 2 wavelength plate 140; First antireflection film 150; Second antireflection film 160. Detailed implementation mode

[0082] The embodiments of the present invention will be described in detail below. The embodiments are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0083] In the following examples and comparative examples, the relevant raw materials are described as follows:

[0084] Glue: UT20, a UV-curable optical adhesive, purchased from Sekisui Fuller Co., Ltd., Japan.

[0085] M2 film: The coating raw material is Merck M2 coating material.

[0086] The coating processes of the second beam splitting film and the third beam splitting film are electron beam evaporation and RF ion source assisted deposition. The process parameters are as follows: the working temperature is 200 °C, the working gas is oxygen, and the gas flow rate is 65 sccm; the starting pressure is 8.0×10 -4 Pa; Ta 2 O 5 material and SiO 2 material are melted to alternately evaporate the two materials. Ta 2 O 5 Evaporation rate: 0.25 nm / second; SiO 2 Evaporation rate: 0.8 nm / second.

[0087] The coating processes of the first antireflection film and the second antireflection film are electron beam evaporation and RF ion source assisted deposition. The process parameters are as follows: the working temperature is 60 °C, the working gas is oxygen, and the gas flow rate is 85 sccm; the starting pressure is 8.0×10 -4 Pa; Ta 2 O 5 material and SiO 2 material are melted to alternately evaporate the two materials. Ta 2 O 5 Evaporation rate: 0.25 nm / second; SiO 2 Evaporation rate: 0.8 nm / second. The deposition thicknesses are successively: 11.3 nm, 42.31 nm, 45.36 nm, 8.41 nm, 69.75 nm, 87.72 nm.

[0088] 1 / 2 wavelength plate: thickness 0.156 mm, model WA-280T, resin material, purchased from Nippon Kayaku Co., Ltd., Japan.

[0089] Unless otherwise specified, the raw materials or equipment involved are all conventional raw materials or equipment that can be purchased commercially.

[0090] Example 1

[0091] In this example, a polarizing beam splitter was prepared, and its structure is as shown in Figure 1-2 . The polarizing beam splitter in this example includes 16 first polarization beam splitting prisms 110 that are glued together in sequence. The first polarization beam splitting prism has a second base layer made of H-Lak7 material and having a quadrangular prism structure. The upper and lower bottom surfaces of the second base layer are rectangles (length 15.3 ± 0.15 mm, width 0.92 ± 0.02 mm), and the distance between the bottom surfaces is 0.92 ± 0.02 mm. One set of side surfaces connecting the long sides of the bottom surfaces are rectangles, and the other set of side surfaces connecting the short sides of the bottom surfaces are parallelograms with an acute angle of 45°.

[0092] On one rectangular side surface of the second base layer, a second beam splitting film 111 is deposited. The second beam splitting film 111 includes Ta 2 O 5 layers and SiO 2 layers that are alternately stacked in sequence for a total of 23 layers. The film thicknesses starting from the second base layer side are shown in Table 1 in sequence. Among them, the thickness error of the Ta 2 O 5 layer is controlled within ±1 nm, and the thickness error of the SiO 2 layer is controlled within ±2 nm:

[0093] Table 1 Beam Splitting Film Structure of Example 1

[0094] Film layer material Thickness of each layer (nm) <![CDATA[Ta 2 O 5 > 27.65 <![CDATA[SiO 2 > 285.08 <![CDATA[Ta 2 O 5 > 110.67 <![CDATA[SiO 2 > 220.28 <![CDATA[Ta 2 O 5 > 92.28 <![CDATA[SiO 2 > 179.06 <![CDATA[Ta 2 O 5 > 85.37 <![CDATA[SiO 2 > 206.95 <![CDATA[Ta 2 O 5 > 67.32 <![CDATA[SiO 2 > 129.51 <![CDATA[Ta 2 O 5 > 53.63 <![CDATA[SiO 2 > 228.66 <![CDATA[Ta 2 O 5 > 69.04 <![CDATA[SiO 2 > 109.92 <![CDATA[Ta 2 O 5 > 51.9 <![CDATA[SiO 2 > 108.58 <![CDATA[Ta 2 O 5 > 56.85 <![CDATA[SiO 2 > 103.03 <![CDATA[Ta 2 O 5 > 51.27 <![CDATA[SiO 2 > 87.08 <![CDATA[Ta 2 O 5 > 53.44 <![CDATA[SiO 2 > 96.43 <![CDATA[Ta 2 O 5 > 34.18 Total thickness 2508.18

[0095] The second beam splitting film 111 of one first polarization beam splitting prism 110 is glued to the other rectangular side surface opposite to the second beam splitting film 111 on another first polarization beam splitting prism 110, so that the bottom surfaces on the same side of the second base layer and the parallelogram side surfaces on the same side are respectively located in the same plane, forming a glued quadrangular prism.

[0096] The second polarization beam splitting prism 120 has a third base layer made of H-Lak7 material and having a right triangular prism structure. The two bottom surfaces of the third base layer are isosceles right triangles with a right side length of 0.92 ± 0.02 mm, and the distance between the bottom surfaces is 15.3 ± 0.15 mm. On the side surface connecting the hypotenuses of the two bottom surfaces, a third beam splitting film 121 is provided. The film layer structure and film thickness of the third beam splitting film 121 starting from the third base layer side are the same as those of the second beam splitting film 111 (Table 1). The third beam splitting film 121 is glued to the outermost rectangular side surface of the glued quadrangular prism that does not have the second beam splitting film 111.

[0097] The third polarization beam splitting prism 130 has a fourth base layer made of H-Lak7 material and in a right triangular prism structure. The two bottom surfaces of the fourth base layer are equilateral right triangles with a right side length of 0.92 ± 0.02 mm, and the distance between the bottom surfaces is 15.3 ± 0.15 mm. The side surface connecting the hypotenuses of the two bottom surfaces is glued to the outermost second beam splitting film 111 of the glued four-prism. The glued four-prism, the second polarization beam splitting prism 120, and the third polarization beam splitting prism 130 are glued to form a cuboid structure.

[0098] Through the design of the substrate and the beam splitting film, the thickness of the film layer is greatly reduced. The total thickness of the unilateral beam splitting film is about 2500 nm, which is significantly lower than the film system (about 9000 nm) adapted to the conventional B270 or BK7 substrates. With a thin film layer, the substrate is not easily deformed and is easier to glue, reducing appearance defects such as bubbles and splashes. More importantly, better optical performance is obtained. The applicable wavelength range is 425 nm - 650 nm, and the air incident angle is 0 ± 8°, which is better than the industry's conventional technical indicators: 450 - 650 nm, air incident 0° ± 5°. All characteristics of the beam splitting film meet: AOI = 0°, λ = 425 nm - 650 nm, Ts,ave ≤ 0.1%, Tp,ave ≥ 97%; AOI = 0° ± 8°, λ = 430 nm - 650 nm, Ts,ave ≤ 2%, Tp,ave ≥ 94%; AOI represents the air incident angle, λ is the incident wavelength, Ts,ave represents the average transmittance of S light, and Tp,ave represents the average transmittance of P light.

[0099] Method for testing the average transmittance: Use a spectrophotometer (model PHOTON RT, manufacturer Essent Optics), set the test mode of the spectrophotometer to transmittance T%, select P light and S light, set the wavelength range from 380 to 780 nm, and the transmittance range from 0 to 100%, and perform the instrument baseline calibration; after the calibration is completed, place the polarization beam splitting plate, with the polarization beam splitting plate and the light receiver in a vertical state, and select to start the test; after the test is completed, export the test data.

[0100] The H-LaK7 material has good processability, and the hardness FA value is 76, which is more suitable for planar processing. The H-LaK7 has a high ultraviolet light transmittance and is suitable for the light-curing gluing process. At the same time, the thin film layer of the beam splitting film is more conducive to the transmission of ultraviolet light, realizing rapid light curing and improving the processing efficiency. In terms of cost, because the film layer of the beam splitting film is thinner, it offsets the cost pressure of H-Lak7, basically does not increase the comprehensive cost, and has better performance and higher cost performance.

[0101] In one embodiment, a 1 / 2 wavelength plate 140 (with one side as the exit surface and the opposite side as the incident surface) is coated on the bottom surface on the same side of any outermost first, third, fifth, seventh, ninth, eleventh, thirteenth, and fifteenth first polarization beam splitting prisms 110. It is used to introduce a phase delay of half a wavelength to the passing polarized light, so as to adjust the polarization direction of the light and better adapt to the working angle. The material of the 1 / 2 wavelength plate 140 can be quartz crystal, and the fixing method can be bonding. The characteristics of the 1 / 2 wavelength plate meet the requirements: AOI = 0° ± 10°, reflectance Rave ≤ 0.5% @ 425nm - 650nm, retardation: λ / 2 @ 425nm - 650nm, retardation error: λ / 500.

[0102] A first anti-reflection film 150 is deposited on the incident surface side of the polarization beam splitting plate, and a second anti-reflection film 160 is deposited on the exit surface side of the polarization beam splitting plate. The first anti-reflection film 150 and the second anti-reflection film 160 are used to reduce the reflection of light and improve the light transmittance. The material, thickness of each layer, and deposition process are as described above. All anti-reflection films meet the requirements: AOI = 0° ± 8°, λ = 425nm - 650nm, Rave ≤ 0.5%.

[0103] Embodiment 2

[0104] This embodiment provides a method for preparing the polarization beam splitting plate of Embodiment 1, including the steps:

[0105] S1. Provide a rectangular fifth base layer.

[0106] S2. After the fifth base layer is cleaned and polished, Ta layers and SiO layers in Table 1 are alternately coated on one surface to obtain a coated substrate. The coating method is electron beam evaporation and RF ion source assisted deposition, and the process is as described above. In terms of operation, clean baffles, bottom plates, cover plates, etc. are replaced before each furnace coating to facilitate the control of the coating appearance. 2 O 5 layer and SiO 2 layer, and the coating method is electron beam evaporation and RF ion source assisted deposition, and the process is as described above. In terms of operation, clean baffles, bottom plates, cover plates, etc. are replaced before each furnace coating to facilitate the control of the coating appearance.

[0107] S3. The coated substrates are sequentially bonded using glue. The coated surface or its opposite surface of the coated substrate is the bonding surface, and all coated surfaces face the same direction, so that the bonding interface contains only one layer of coating. A total of 6 coated substrates are glued together at a time to obtain a sub-block. During gluing, the thickness deviation of the coated base layer is detected, and positive and negative deviations are combined for gluing to cancel out the overall deviation as much as possible (for example, among 6 layers of plates, 3 plates with a thickness tolerance of -0.01mm and 3 plates with a thickness tolerance of +0.01mm are combined, and one positive and one negative are selected for gluing to cancel out the cumulative error). During gluing, constant pressure control is performed to improve the consistency of the bonding thickness.

[0108] S4. Perform the first UV curing on the sub-blocks in step S3, and then glue the 3 sub-blocks according to the same rule (the coated surface or its opposite surface is the bonding surface, and all coated surfaces face the same direction, so that the bonding interface only contains one layer of coating), and perform UV curing to obtain a 18-layer plywood board.

[0109] S5. Cut the plywood board in step S4 (the cutting direction is not parallel to the bonding interface direction, such as perpendicular or intersecting, ensuring that the total number of layers remains 18 layers, corresponding to the second base layer, the third base layer, and the fourth base layer) to obtain a plurality of polarization beam splitters with the structure shown in Embodiment 1.

[0110] Specifically, to prepare the polarization beam splitter of Embodiment 1, control the size of the plywood board to be appropriately larger than the polarization beam splitter (which can be achieved by adjusting the size of the fifth substrate and / or the stacking direction), so as to be able to obtain a plurality of polarization beam splitters with the same structure through cutting. When stacking at a certain angle (such as 45°), an auxiliary reference block can be used for positioning. When cutting at a certain angle (such as 45°), a 45° cutting jig can be used in combination to fix the tool spacing, and the size is detected after cutting to improve the stability of the cutting quality. The cutting can use an internal circular cutting machine or an external circular cutting machine. Specifically, an external circular cutting machine can be used for the final cutting, and an internal circular cutting machine can be used for other grading cuts.

[0111] The H-Lak7 material has good processability and is suitable for planar processing. Glue large-sized substrates and then cut and subdivide them to the target size to improve processing efficiency. After cutting, cleaning and polishing can be performed to reduce surface contaminants and defects.

[0112] In one embodiment, it further includes the steps:

[0113] S6: Take one side bottom surface of the polarization beam splitter as the incident surface and the other side bottom surface as the exit surface, and alternately deposit Ta 2 O 5 films and SiO 2 films on the incident surface side of the polarization beam splitter, the same as the first antireflection film 150 in Embodiment 1.

[0114] S7: Bond a plurality of 1 / 2 wavelength plates 140 on the exit surface side of the polarization beam splitter with glue;

[0115] S8: Alternately deposit Ta 2 O 5 films and SiO 2 films on the exit surface side of the polarization beam splitter, the same as the second antireflection film 160 in Embodiment 1.

[0116] It can be understood that in steps S6 - S8, the number and position of the 1 / 2 wavelength plates 140, and the positions of the first antireflection film 150 and the second antireflection film 160 are determined with reference to Embodiment 1.

[0117] Comparative Example 1

[0118] For the existing polarization beam splitter plate, the structure refers to Embodiment 1, with the difference being that the second base layer, the third base layer, and the fourth base layer are made of B270 glass. The film layer structure and thickness of the second beam splitting film starting from the second base layer side and the film layer structure and thickness of the third beam splitting film starting from the third base layer side are shown in Table 2 in sequence (wherein, the thickness error of the M2 layer is controlled within ±1 nm, and the thickness error of the SiO 2 layer is controlled within ±2 nm). The coating process is electron beam evaporation and RF ion source assisted deposition, and the process parameters are as follows: the working temperature is 250 °C, the working gas is oxygen, and the gas flow rate is 85 sccm; the starting pressure is 8.0×10 -4 Pa; the coating materials are melted by the thermal energy of the electron beam to alternately evaporate the two materials. The evaporation rate of M2: 0.3 nm / second; the evaporation rate of SiO 2 : 0.8 nm / second.

[0119] Table 2 Beam Splitting Film Structure of Comparative Example 1

[0120]

[0121]

[0122] The beam splitting film parameters of Comparative Example 1 are as follows: AOl = 0°, λ = 425 nm - 650 nm, Ts,ave ≤ 2%, Tp,ave ≥ 96%; AOl = 0° ± 8°, λ = 430 nm - 650 nm, Ts,ave ≤ 3%, Tp,ave ≥ 94%. The spectral curves of the polarization beam splitter plates of Embodiment 1 and Comparative Example 1 are shown in Figure 3 and Figure 4 .

[0123] It can be seen that the polarization separation effect of the beam splitting film of Comparative Example 1 is significantly inferior to that of Embodiment 1, and the coating design curve fluctuates greatly, resulting in the inability to meet the requirements for the theoretical design values of the transmittance of P-light and S-light at 0° ± 5°. The beam splitting film of Embodiment 1 has a high ultraviolet light transmittance, a smoother coating design curve, and the theoretical design values of P-light and S-light at 0° ± 5° can meet the requirements, and the applicable wavelength band is wider.

[0124] In addition, due to the thin thickness (about 2500 nm) of the beam splitting film in Embodiment 1, good surface finish, easy gluing, the appearance risk is reduced. The beam splitting film of Comparative Example 1 has a thickness of about 9000 nm, thick film layers, large stress, easy to generate bubbles during gluing, and easy to appear pockmarks on the appearance. The B270 material is prone to deliquescence and easy to generate delamination risk, and is inferior to Embodiment 1 in terms of optical performance, appearance, and use strength.

[0125] In view of the performance advantages of the polarization beam splitter of this embodiment, it can better meet the usage requirements of optoelectronic products such as projectors or head-up displays, and can be applied to products such as LCOS projectors, LCD projectors or in-vehicle head-up displays.

[0126] The above has described the present utility model in detail in conjunction with the embodiments. However, the present utility model is not limited to the above embodiments, and various changes can be made without departing from the gist of the present utility model within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A polarization beam splitter prism, characterized in that: include: The first base layer is made of H-Lak7 optical glass; A first spectroscopic film is formed on at least one side of the first substrate, wherein the film structure of the first spectroscopic film is as follows: from the first substrate side, it includes 23 layers of Ta2O5 layers and SiO2 layers alternately stacked in sequence, and the layer thicknesses are 26.65-28.65nm, 283.08-287.08nm, 109.67-111.67nm, 218.28-222.28nm, 91.28-93.28nm, 177.06-181.06nm, 84.37-86.37nm, 204.95-208.95nm, 66.32 ~68.32nm, 127.51~131.51nm, 52.63~54.63nm, 226.66~230.66nm, 68.04~70.04nm, 107.92~111.92nm, 50.9~52.9nm, 106.58~11 0.58nm, 55.85~57.85nm, 101.03~105.03nm, 50.27~52.27nm, 85.08~89.08nm, 52.44~54.44nm, 94.43~98.43nm, 33.18~35.18nm.

2. The polarization beam splitter according to claim 1, characterized in that: The first base layer has a triangular prism structure or a quadrangular prism structure; and / or, the film structure of the first spectroscopic film is: starting from the first base layer side, it includes 23 layers of Ta2O5 layers and SiO2 layers alternately stacked in sequence, and the layer thicknesses are 27.65nm, 285.08nm, 110.67nm, 220.28nm, 92.28nm, 179.06nm, 85.37nm, 206.95nm, 67.32nm, 129.51nm, 53.63nm, 228.66nm, 69.04nm, 109.92nm, 51.9nm, 108.58nm, 56.85nm, 103.03nm, 51.27nm, 87.08nm, 53.44nm, 96.43nm, and 34.18nm in sequence from the first base layer side.

3. A polarization beam splitter, characterized in that: Comprising the polarization beam splitter prism as claimed in claim 1 or 2.

4. The polarization beam splitter according to claim 3, characterized in that: The polarization beam splitter comprises: A glued quadrangular prism, comprising a plurality of first polarization beam splitting prisms glued in sequence, wherein the first polarization beam splitting prism has a second base layer, the second base layer has a quadrangular prism structure, a second beam splitting film is formed on one side surface of the second base layer, the second beam splitting film of one of the first polarization beam splitting prisms is glued to the other side surface opposite to the second beam splitting film of the adjacent first polarization beam splitting prism, and the bottom surface on the same side of the second base layer and another group of side surfaces connected to the bottom surface are respectively located in the same plane; A second polarizing beam splitter prism, comprising a third base layer of a right triangular prism, a third beam splitter film being formed on one side of the third base layer, and the third beam splitter film being glued to a surface of the outermost side of the glued quadrangular prism opposite to the second beam splitter film; A third polarization beam splitter prism, comprising a fourth base layer of a right triangular prism, wherein one side surface of the fourth base layer is glued to the outermost second beam splitter film of the glued quadrangular prism; The materials of the second base layer, the third base layer and the fourth base layer are all H-Lak7 optical glass, and the film layer structure of the second prismatic film from the second base layer side and the film layer structure of the third prismatic film from the third base layer side are the same as the film layer structure of the first prismatic film from the first base layer side defined in claim 1; The glued quadrangular prism, the second polarization beam splitting prism and the third polarization beam splitting prism are glued together to form a rectangular parallelepiped structure.

5. The polarization beam splitter according to claim 4, characterized in that: The number of the first polarization beam splitting prisms is 16.

6. The polarization beam splitter according to claim 4, characterized in that: In the first polarization beam splitter prism, the bottom surface of the second base layer is a rectangle, a group of side surfaces connecting the long sides of the bottom surface are rectangles, the second beam splitting film is formed on one of the rectangular side surfaces, and a group of side surfaces connecting the short sides of the bottom surface are parallelograms with an acute angle of 45°; And / or, in the first polarization beam splitter prism, the length of the bottom surface is 14-16 mm, the width is 0.5-1 mm, and the distance between the bottom surfaces is 0.5-1 mm; And / or, in the second polarization splitter prism, the bottom surface of the third base layer is an equilateral right triangle, and the third splitter film is formed on the side surface connecting the hypotenuse of the bottom surface. Optionally, the right angle side length of the equilateral right triangle is 0.5 to 1 mm, and the distance between the bottom surfaces is 14 to 16 mm.

7. The polarization beam splitter according to claim 4, characterized in that: The polarization beam splitter plate also includes 8 1 / 2 wavelength plates, one side bottom surface of the second base layer is the incident surface, and the other side bottom surface is the exit surface, the 8 1 / 2 wavelength plates are respectively located on one side of the exit surface of the 8 first polarization beam splitter prisms in the glued quadrangular prism, and a first polarization beam splitter prism is spaced between two adjacent 1 / 2 wavelength plates.

8. The polarization beam splitter according to claim 7, characterized in that: A first anti-reflection film is disposed on one side of the incident surface of the polarization beam splitter, and a second anti-reflection film is disposed on a surface of the polarization beam splitter opposite to the incident surface; Optionally, the thickness of the first anti-reflection film and the second anti-reflection film are independently 250-300 nm.

9. A projector, characterized in that: It comprises the polarization beam splitter prism as claimed in claim 1 or 2, or the polarization beam splitter plate as claimed in any one of claims 3-8.

10. A head-up display, characterized in that: It comprises the polarization beam splitter prism as claimed in claim 1 or 2, or the polarization beam splitter plate as claimed in any one of claims 3-8.

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