A projector and surface structured light system

Abstract

The present application discloses a projector and a surface structured light system. The projector disclosed in the present application includes a digital micromirror module and a projection lens, wherein the digital micromirror module includes a pixel array, wherein the pixel array includes a plurality of micromirror units, wherein the plurality of micromirror units are arranged in a matrix according to a preset pixel pitch, and there is a gap between adjacent micromirror units, wherein the width of the gap is less than the pixel pitch; wherein the projection lens includes a plurality of lenses, wherein the spherical aberration combination of the plurality of lenses enables the maximum resolution of the projection lens to be R line pairs / mm, wherein R=1 / (2*pixel pitch). The projector of the present application eliminates DMD gaps in the projected image and improves the accuracy of three-dimensional reconstruction.

Description

Technical Field

[0001] The present application relates to the field of 3D imaging technology, and in particular to a projector and a surface structured light system. Background Art

[0002] With the development of virtual reality technology, 3D printing technology, and unmanned flight / driving technology, the industry has developed a large number of 3D imaging technologies, and the surface structured light system composed of a camera and a projector is one of them.

[0003] When measuring an object using a surface structured light system, a projector is used to project phase-shifted sinusoidal stripes onto the surface of the object being measured. The camera collects a 2D stripe image on the object being measured. The corresponding image coordinates are obtained based on the relationship between the image coordinates and phase of the stripes captured by the camera. The world coordinates of the object being measured are calculated based on the corresponding projector image coordinates, thereby completing the three-dimensional reconstruction of the object being measured. At present, the phase shift algorithm is one of the most widely used and stable methods for calculating absolute phase in industry. However, since trigonometric functions are used when calculating the phase, phase wrapping (or truncation) will occur, such as Figure 1 In order to restore the continuous phase, the wrapped phase must be unfolded, that is, phase unwrapping, as shown in Figure 2 Phase unwrapping is an integration process, which reconstructs the continuous phase distribution by comparing the truncated phase values ​​(between -π and +π) of two adjacent pixels and adding (or subtracting) integer multiples of 2π.

[0004] The projector needs to project an energy gradient image (encoded image) onto the object to be measured. As one of the current mainstream projection technologies, the core component of the projector using the digital light processor (DLP) is the digital micromirror device (DMD), or DMD chip. The DMD chip is a matrix composed of multiple micromirror units, each of which is equivalent to a small mirror. There are gaps (gaps) between adjacent mirrors in the DMD chip. The gaps cannot reflect light, forming corresponding dark areas in the projected pattern, resulting in unnecessary discontinuities in the depth information, which will cause errors in the phase wrapping solution, and have a great impact on the overall image algorithm. It may lead to poor correspondence between the three-dimensional reconstructed image and the object to be measured, that is, the measurement accuracy of the surface structured light system is reduced; or the algorithm can specifically identify or eliminate the depth discontinuity caused by the gap, but in this case the algorithm will be very complicated, which will correspondingly lead to an increase in system hardware costs or system overhead. Summary of the invention

[0005] One of the purposes of the present application is to provide a projector to solve the technical problem in the prior art that the accuracy of three-dimensional reconstruction is reduced due to gaps between micromirror units.

[0006] A projector provided in an embodiment of the present application includes a digital micromirror module and a projection lens, wherein the digital micromirror module includes a pixel array, wherein the pixel array includes a plurality of micromirror units, wherein the plurality of micromirror units are arranged in a matrix according to a preset pixel pitch, and there is a gap between adjacent micromirror units, wherein the width of the gap is less than the pixel pitch; wherein the projection lens includes a plurality of lenses, wherein the spherical aberration combination of the plurality of lenses enables the maximum resolution of the projection lens to be R line pairs / mm, wherein R=1 / (2*pixel pitch).

[0007] In some embodiments, the pixel array is an orthogonal pixel array.

[0008] In some embodiments, the pixel array is a diamond-shaped pixel array.

[0009] In some embodiments, the micromirror unit is a square, the pixel pitch is the distance between the centers of two adjacent micromirror units, and the gap is between two adjacent sides of the two adjacent micromirror units.

[0010] In some embodiments, the pixel pitch is a distance between two opposite sides of the micromirror unit, and the gap is between two adjacent sides of the two adjacent micromirror units.

[0011] In some embodiments, the pixel pitch is 0.76 micrometers and the highest resolution is 65 line pairs / mm.

[0012] In some embodiments, the cumulative spherical aberration coefficient of the projection lens is 0.001792.

[0013] In some embodiments, the plurality of lenses include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are arranged in sequence from the object side to the imaging side.

[0014] In some embodiments, the object side spherical aberration coefficient of the first lens is 0.000017, and the image side spherical aberration coefficient of the first lens is 0.000001; the object side spherical aberration coefficient of the second lens is 0.000113, and the image side spherical aberration coefficient of the second lens is -0.001767; the object side spherical aberration coefficient of the third lens is 0.000001; the object side spherical aberration coefficient of the fourth lens is -0.001163, and the image side spherical aberration coefficient of the fourth lens is -0.001163. The side spherical aberration coefficient is 0.003884; the object side spherical aberration coefficient of the fifth lens is -0.000012, and the image side spherical aberration coefficient of the fifth lens is 0.000877; the object side spherical aberration coefficient of the sixth lens is -0.000177, and the image side spherical aberration coefficient of the sixth lens is 0.000021; the spherical aberration coefficient of the object side of the glass plate is -0.000008, and the spherical aberration coefficient of the image side of the glass plate is 0.000005.

[0015] In some embodiments, the object side surface radius of the first lens is 52.3 mm, and the image side surface radius of the first lens is -671.7 mm; the object side surface radius of the second lens is 10.9 mm, the image side surface radius of the second lens is 5.7 mm, and the thickness of the second lens is 3.91 mm; the object side surface radius of the third lens is -29.2 mm, and the thickness of the third lens is 3.02 mm; the image side surface radius of the fourth lens is -8.2 mm, and the thickness of the fourth lens is 9.56 mm; the object side surface radius of the fifth lens is -772.2 mm, the image side surface radius of the fifth lens is -28.4 mm, and the thickness of the fifth lens is 9.71 mm; the object side surface and image side surface radius of curvature of the sixth lens are both infinite, and the thickness of the sixth lens is 26.62 mm.

[0016] In some embodiments, the projection lens also includes an aperture, which is located between the second lens and the third lens, the distance between the second lens and the first lens is 18.67 mm, the distance between the second lens and the aperture is 1.1 mm, the aperture is adjacent to the third lens, the third lens and the fourth lens form a cemented lens, the distance between the fourth lens and the fifth lens is 6.64 mm, the distance between the fifth lens and the sixth lens is 4.29 mm, and the distance between the sixth lens and the glass plate is 1 mm.

[0017] Another object of the present application is to provide a surface structured light system, which includes a projector for projecting a coded image onto an object to be measured and a camera for photographing the coded image on the surface of the object to be measured, wherein the projector includes a digital micromirror module and a projection lens, the digital micromirror module includes a pixel array, the pixel array includes a plurality of micromirror units, the plurality of micromirror units are arranged in a matrix according to a preset pixel pitch, and there is a gap between adjacent micromirror units, and the width of the gap is less than the pixel pitch; the projection lens includes a plurality of lenses, and the spherical aberration combination of the plurality of lenses makes the maximum resolution of the projection lens R line pairs / mm, where R=1 / (2*pixel pitch).

[0018] According to the surface structured light system of the embodiment of the present invention, a certain spherical aberration is retained in the projection lens so that the maximum resolution of the projection lens is equal to the pixel pitch of the micromirror unit, so that the image formed by the reflected light of the micromirror unit with the pixel pitch size can be clearly projected through the projection lens, while the gap between the micromirror units smaller than the pixel pitch cannot be clearly projected, so that the depth information discontinuity caused by the gap between the micromirror units can be eliminated in the projected image, so as to more accurately reflect the depth information of the object being measured, which is beneficial to the accuracy of three-dimensional reconstruction, and does not require complex algorithms to identify the depth discontinuity caused by the gap, thereby reducing system overhead and reducing the overall cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the scheme in the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of phase wrapping is shown;

[0021] Figure 2 A schematic diagram of phase unwrapping is shown;

[0022] Figure 3 This is a schematic diagram of the system structure of a surface structured light system according to an embodiment of the present application;

[0023] Figure 4 is a simplified schematic diagram of a digital micromirror module of a projector according to one embodiment of the present application;

[0024] Figure 5 is a simplified schematic diagram of a digital micromirror module of a projector according to another embodiment of the present application;

[0025] Figure 6 is a schematic diagram of a projection lens of a projector according to an embodiment of the present application;

[0026] Figure 7 yes Figure 6 Schematic diagram of light propagation of the projection lens shown;

[0027] Figure 8 is a spot diagram of a projection lens according to an embodiment of the present application;

[0028] Fig. 9 is a schematic diagram of the MTF of the projection lens according to the embodiment of the present application;

[0029] Fig.10 is a schematic diagram of field curvature and distortion curves of a projection lens according to an embodiment of the present application;

[0030] Fig.11 It is a schematic diagram comparing the fringe pattern projected by the projection lens for the surface structured light system according to the embodiment of the present application with the fringe pattern of the projection lens in the prior art. DETAILED DESCRIPTION

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned figures are used to distinguish different objects, not to describe a specific order or technical meaning. The "connection" and "connection" mentioned in this application, unless otherwise specified, include direct and indirect connections (connections).

[0032] Please see Figure 3 , is a schematic diagram of the system structure of a surface structured light system of an embodiment of the present application. The surface structured light system 100 of this embodiment includes a camera 1 and a projector, wherein the projector is used to project a coded image onto the object O to be measured. In one example, the coded image can be a black and white vertical stripe pattern. The camera 1 is used to capture the coded image of the surface of the object O to be measured. Since the object O to be measured is a three-dimensional structured object, the coded image projected onto the surface of the object O to be measured will be distorted due to the concavity and convexity of the object surface, and the distorted black and white stripe image is equivalent to being highly modulated by the object to be measured, and the height information can be inferred from the phase difference of the black and white stripe image. According to the obtained height information, the object to be measured can be reconstructed in three dimensions.

[0033] The projector includes a digital micromirror module 7 and a projection lens 10, as well as a projection light source 2 and an optical system 5. In one example, the projection light source 2 projects white light, and the optical system 5 includes components such as a color filter wheel, a condensing lens, and a correction lens. The optical system generates light of multiple colors from the light source, and the multi-color light is reflected by the digital micromirror module 7, and then the image is projected onto the object O to be measured through the projection lens 10.

[0034] Please see again Figure 4 , is a simplified schematic diagram of a digital micromirror module of a projector according to an embodiment of the present application. The digital micromirror module 7 can specifically be a DMD chip, which includes a pixel array composed of a plurality of micromirror units 70, wherein the plurality of micromirror units 70 are arranged in a matrix according to a preset pixel pitch P, and there is a gap 72 between adjacent micromirror units 70. In this example, the pixel array is a diamond pixel array, and specifically, each micromirror unit 70 includes four sides, wherein the diagonal of the micromirror unit 70 is perpendicular or parallel to the edge of the DMD chip, or the micromirror unit 70 is arranged in a diagonal form relative to the edge of the DMD chip. The pixel pitch P is the distance between the centers C of two adjacent micromirror units 70, and the gap 72 is between two adjacent sides of the two adjacent micromirror units 70.

[0035] Please see again Figure 5 , is a simplified schematic diagram of a digital micromirror module of a projector according to another embodiment of the present invention. Figure 4 The diamond pixel array shown, Figure 5 The pixel array of the embodiment is an orthogonal pixel array. As another example, the pixel pitch L can also define the distance between two opposite sides of the micromirror unit 80, the gap 82 is between two adjacent sides of the two adjacent micromirror units 80, and the width S of the gap 82 is less than the pixel pitch P or L.

[0036] As an example, the pixel pitch P in each embodiment of the present application is 0.76 micrometers.

[0037] Please continue to see Figure 6 and Figure 7 , Figure 6 is a schematic diagram of a projection lens 10 of a projector according to an embodiment of the present application, Figure 7 yes Figure 6Schematic diagram of light propagation of the projection lens shown. In the present application, the projection lens 10 includes a plurality of lenses, and the spherical aberration combination of the plurality of lenses makes the resolution of the projection lens equal to or less than R line pairs / mm, where R=1 / 2*pixel pitch. As an example, the projection lens 10 includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15 and a sixth lens 16, wherein the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15 and the sixth lens 16 are arranged in sequence from the object side to the imaging side, and the object side is the side close to the DMD chip.

[0038] Table 1

[0039] Serial number Surface type Radius of curvature thickness Material Semi-caliber 0 STANDARD unlimited 128 38.41777 1 STANDARD 52.38406 3.369862 H-ZF6 11.43824 2 STANDARD -671.747 18.67953 10.98364 3 STANDARD 10.96342 3.911182 H-ZF88GT 2.991948 4 STANDARD 5.774316 1.10036 1.776939 5 STANDARD unlimited 0.5 0.867795 6 STANDARD -29.2767 3.029967 H-ZF52 1.622462 7 STANDARD 9.652582 9.557575 H-ZPK2A 2.526568 8 STANDARD -8.2387 6.641666 5.453507 9 STANDARD -772.201 9.712886 H-ZLAF75A 6.960409 10 STANDARD -28.453 4.295354 7.810455 11 STANDARD unlimited 26.62 H-ZLAF2A 7.485325 12 STANDARD unlimited 1 6.583656 13 STANDARD unlimited 0.65 EAGLEXG 6.521732 14 STANDARD unlimited 0.302025 6.495286 15 STANDARD unlimited 0 5.976584

[0040] In the embodiment shown in Table 1, the radius of curvature of the object side surface of the first lens 11 (serial number 1 in Table 1) is 52.3 millimeters (mm), the radius of curvature of the image side surface is -671.7 mm, and the thickness thereof can be about 3.36 mm. The material model H-ZF6 or similar optical glass can be selected; the radius of curvature of the object side surface of the second lens 12 is 10.9 mm, the radius of curvature of the image side surface is 5.7 mm, and the thickness thereof can be about 3.91 mm. The material model H-ZF88GT or similar optical glass can be selected; the radius of curvature of the object side surface of the third lens 13 is -29.2 mm, and the thickness can be selected to be about 3.02 mm. The material model H-ZF52 or similar optical glass can be selected; the fourth lens 14 The fourth lens 14 and the third lens 13 form a cemented lens, the curvature radius of the cemented surface is 9.6mm, the curvature radius of the image side surface of the fourth lens 14 is -8.2mm, the thickness is about 9.56mm, and the material model H-ZPK2A or similar optical glass can be used; the curvature radius of the object side surface of the fifth lens 15 is -772.2mm, the curvature radius of the image side surface is -28.4mm, and the thickness is about 9.71mm, and the material model H-ZLAF75A or similar optical glass can be used; the curvature radius of the object side surface of the sixth lens 16 is infinite (that is, the object side surface is a flat surface), the curvature radius of the image side surface is infinite, and the thickness can be selected to be about 26.62mm, and the material model H-ZLAF2A or similar optical glass can be used.

[0041] The other parameters of the projection lens 10 can be specifically referred to in Table 1. For example, the projection lens 10 also includes an aperture located between the second lens 12 and the third lens 13 (corresponding to the plane numbered 5 in Table 1), and the thickness of the aperture is 0.5 mm. The projection lens 10 can further include a glass plate 20, which is located on the side of the image side of the sixth lens 16, and the thickness of the glass plate 20 can be selected to be 0.65 mm. The distance between the first lens 11 and the object plane (numbered 0 in Table 1) is 128 mm; the distance between the second lens 12 and the first lens 11 is about 18.67 mm, the distance between the second lens 12 and the aperture is about 1.1 mm, the aperture is close to the third lens 13, the distance between the fourth lens 14 and the fifth lens 15 is about 6.64 mm, the distance between the fifth lens 15 and the sixth lens 16 is about 4.29 mm, and the distance between the sixth lens 16 and the glass plate 20 is about 1 mm. The aperture sizes of the lenses or elements included in the projection lens 10 can be found in the “semi-aperture” column of Table 1, and will not be described in detail here.

[0042] Through the parameter design of the projection lens 10 of the embodiment of Table 1, the Dessel aberration coefficients shown in Table 2 can be obtained. In Table 2, SPHA, COMA, ASTI, and FCUR represent spherical aberration, coma, astigmatism, and field curvature, respectively. The specific values ​​of the spherical aberrations of the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15, and the sixth lens 16 can be known from Table 2. Specifically, the spherical aberration coefficient of the object side of the first lens 11 is 0.000017, and the spherical aberration coefficient of the image side is 0.000001; the spherical aberration coefficient of the object side of the second lens 12 is 0.000113, and the spherical aberration coefficient of the image side is -0.001767; the spherical aberration coefficient of the object side of the third lens 13 is 0.000001 ; The spherical aberration coefficient of the fourth lens 14 on the object side is -0.001163, and the spherical aberration coefficient of the image side is 0.003884; the spherical aberration coefficient of the fifth lens 15 on the object side is -0.000012, and the spherical aberration coefficient of the image side is 0.000877; the spherical aberration coefficient of the sixth lens 16 on the object side is -0.000177, and the spherical aberration coefficient of the image side is 0.000021; the spherical aberration coefficient of the object side of the glass plate 20 is -0.000008, and the spherical aberration coefficient of the image side is 0.000005. The cumulative spherical aberration coefficient of the projection lens 10 is 0.001792. Similarly, the coma, astigmatism, and field curvature of each lens can be obtained from Table 1, which will not be described in detail here.

[0043] Table 2

[0044]

[0045]

[0046] In this embodiment, the projection lens 10 is optically designed to have a certain spherical aberration. The existence of the spherical aberration blurs and eliminates the discontinuity of image depth information in the projected image caused by the gap between the micromirror units. At the same time, the image information reflected by the micromirror unit itself can be clearly projected.

[0047] Please see Figure 8 to Figure 10 , respectively, are the point diagram, MTF diagram and distortion curve diagram obtained by the projection lens of the aforementioned embodiment of the present application according to the parameters of Table 1 and Table 2. Among them, the first figure in the upper left corner of the point diagram is a diffuse image formed by imaging a point light source in the central field of view (with the image field position as the center). Although only black is represented in the figure, those skilled in the art can know that the figure is a comprehensive point diagram of multi-wavelength light, such as three-color light imaging. In addition to the first figure in the upper left corner above, the other figures represent imaging situations in different fields of view or different positions of the image field. Fig. 9 It can be seen from the MTF curve shown that when the OTF value (Optical Transfer Function) is about 0.03, the resolution of the projection lens 10 is R=1 / (2*pixel pitch)=1 / (2*0.0076mm)=about 65 line pairs / mm (lp / mm), that is, the maximum resolution of the projection lens 10 is 65 line pairs / mm, and the single pixel represented by the micromirror units 70 and 80 of the size represented by the pixel pitch can be resolved, so that the image reflected by each micromirror unit 70 and 80 can be clearly projected, while the gaps between the micromirror units smaller than the pixel pitch cannot be clearly resolved, and the corresponding fine black lines originally caused by the gaps in the projected image are blurred or replaced by gradient grayscale, so that the depth information implied in the projected image is reduced. The abnormal discontinuity, please refer to Fig.11 ,in Fig.11 The left picture, Fig.11 (a) shows a real shot of a fringe pattern projected by a projection lens in the prior art, and the right side shows Fig.11 (b) is a real picture showing the stripe pattern projected by the projector of the embodiment of the present application. It can be seen from the left picture that there are some fine black lines in the large white stripe area. These black lines are caused by the DMD gap (that is, the micromirror unit gap), while in the right picture, it can be clearly seen that the black lines in the large white stripe area have been eliminated. Fig.10 The field curvature and distortion curves of the projection lens 10 of the projector of the present application are shown.

[0048] The surface structured light system 100 of the embodiment of the present invention designs the specific spherical aberration of the projection lens 10 so that the maximum resolution of the projection lens 10 is equal to the pixel pitch of the micromirror unit, so that the image formed by the reflected light of the micromirror unit with the pixel pitch size can be clearly projected through the projection lens, while the gap between the micromirror units smaller than the pixel pitch cannot be clearly projected, so that the depth information discontinuity caused by the gap between the micromirror units can be eliminated in the projected image, so as to more accurately reflect the depth information of the object being measured, which is beneficial to the accuracy of three-dimensional reconstruction, and does not require complex algorithms to identify the depth discontinuity caused by the gap, thereby reducing system overhead and reducing the overall cost of the system.

[0049] It should be understood that the precise numerical examples involving numerical values ​​in the embodiments of the present application should not be used to limit the scope of the present application, and reasonable parameter numerical changes and numerical change combinations based on the concept of the present application are within the scope of protection.

[0050] This document is described with reference to various exemplary embodiments. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of this document. For example, various operating steps and components for performing the operating steps may be implemented in different ways (e.g., one or more steps may be deleted, modified, or incorporated into other steps) depending on the specific application or considering any number of cost functions associated with the operation of the system.

[0051] Although the principles of this invention have been shown in various embodiments, many modifications of structures, arrangements, proportions, elements, materials and components particularly suitable for specific environments and operational requirements can be used without departing from the principles and scope of this disclosure. The above modifications and other changes or modifications will be included in the scope of this invention.

[0052] The foregoing specific description has been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure. Therefore, the consideration of the present disclosure will be illustrative rather than restrictive, and all these modifications will be included in its scope. Similarly, the advantages, other advantages and solutions to the problems of various embodiments have been described above. However, the benefits, advantages, solutions to the problems and any elements that can produce these, or solutions that make them more clear should not be interpreted as critical, necessary or necessary. The term "include" and any other variants used in this article are all non-exclusive inclusions, so that the process, method or device including the list of elements includes not only these elements, but also includes other elements that are not explicitly listed or do not belong to the process, method, system or device. In addition, the term "coupled" and any other variants used in this article refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections and / or any other connections.

[0053] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the invention. Therefore, the scope of the invention should be determined from the following claims.

Claims

1. A projector, characterized in that: include: A digital micromirror module, wherein the digital micromirror module comprises a pixel array, wherein the pixel array comprises a plurality of micromirror units, wherein the plurality of micromirror units are arranged in a matrix according to a preset pixel pitch, and there is a gap between adjacent micromirror units, wherein the width of the gap is smaller than the pixel pitch; A projection lens, wherein the projection lens comprises a plurality of lenses, the spherical aberration combination of the plurality of lenses enables the maximum resolution of the projection lens to be R line pairs / mm, wherein R=1 / (2*pixel pitch), the plurality of lenses comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a glass plate, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the glass plate are arranged in sequence from the object side to the imaging side, the object side spherical aberration coefficient of the first lens is 0.000017, the image side spherical aberration coefficient of the first lens is 0.000001; the object side spherical aberration coefficient of the second lens is 0.000113, The image side spherical aberration coefficient of the second lens is -0.001767; the object side spherical aberration coefficient of the third lens is 0.000001; the object side spherical aberration coefficient of the fourth lens is -0.001163, and the image side spherical aberration coefficient of the fourth lens is 0.003884; the object side spherical aberration coefficient of the fifth lens is -0.000012, and the image side spherical aberration coefficient of the fifth lens is 0.000877; the object side spherical aberration coefficient of the sixth lens is -0.000177, and the image side spherical aberration coefficient of the sixth lens is 0.000021; the spherical aberration coefficient of the object side of the glass plate is -0.000008, and the spherical aberration coefficient of the image side of the glass plate is 0.000005, The object side surface of the first lens has a curvature radius of 52.3 mm, and the image side surface of the first lens has a curvature radius of -671.7 mm; the object side surface of the second lens has a curvature radius of 10.9 mm, the image side surface of the second lens has a curvature radius of 5.7 mm, and the thickness of the second lens is 3.91 mm; the object side surface of the third lens has a curvature radius of -29.2 mm, and the thickness of the third lens is 3.02 mm; the image side surface of the fourth lens has a curvature radius of -8.2 mm, and the thickness of the fourth lens is 9.56 mm; the object side surface of the fifth lens has a curvature radius of -772.2 mm, the image side surface of the fifth lens has a curvature radius of -28.4 mm, and the thickness of the fifth lens is 9.71 mm; the object side surface and image side surface radii of curvature of the sixth lens are both infinite, and the thickness of the sixth lens is 26.62 mm.

2. The projector according to claim 1, characterized in that The pixel array is an orthogonal pixel array or a diamond pixel array.

3. The projector according to claim 1, characterized in that: The micromirror unit is a square, the pixel pitch is the distance between the centers of the two adjacent micromirror units, or the pixel pitch is the distance between two opposite sides of the micromirror unit; the gap is between two adjacent sides of the two adjacent micromirror units.

4. The projector according to claim 1, characterized in that: The projection lens also includes an aperture, which is located between the second lens and the third lens, the distance between the second lens and the first lens is 18.67 mm, the distance between the second lens and the aperture is 1.1 mm, the aperture is adjacent to the third lens, the third lens and the fourth lens form a cemented lens, the distance between the fourth lens and the fifth lens is 6.64 mm, the distance between the fifth lens and the sixth lens is 4.29 mm, and the distance between the sixth lens and the glass plate is 1 mm.

5. The projector according to claim 1, characterized in that: The pixel pitch is 0.76 micrometers and the highest resolution is 65 line pairs / mm.

6. The projector according to any one of claims 1 to 5, characterized in that: The cumulative spherical aberration coefficient of the projection lens is 0.001792.

7. A surface structured light system, comprising a projector for projecting a coded image onto a measured object and a camera for photographing the coded image on the surface of the measured object, characterized in that: The projector is the projector described in any one of claims 1 to 5.

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