A light diffuser

Abstract

The present invention relates to a light diffuser, comprising a plurality of randomly positioned microlenses spliced ​​into a microlens array, wherein the curved surface of each microlens is random, and the random curved surface of the microlens includes a random curved surface center position, a random curved surface Z-axis height, a random curved surface size, and a random curved surface rotation angle. The light diffuser of the present invention has no stripes in its light spot, and can improve the accuracy of 3D imaging.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial intelligence three-dimensional imaging, and in particular relates to a light diffuser. Background Art

[0002] At present, the main ways to achieve 3D imaging in the fields of 3D sensing, face recognition, machine vision, autonomous driving, etc. are binocular, structured light and TOF technologies. Among them, binocular has low precision, structured light has complex structure and high imaging cost. TOF has gradually become the mainstream of 3D imaging due to its high enough precision and low cost. The microlens units of the existing TOF light diffuser are the same and their positions are arranged in a periodic or random arrangement, which has the problem of stripes in the illumination spot and complex imaging algorithm. Summary of the invention

[0003] The purpose of the present invention is to solve the above problem and provide a light diffuser to solve the problem of light spots having stripes.

[0004] To achieve the above-mentioned purpose, the present invention provides a light diffuser, comprising a plurality of randomly positioned microlenses spliced ​​into a microlens array, wherein the curved surface of each microlens is random, and the random curved surface of the microlens includes a random curved surface center position, a random curved surface Z-axis height, a random curved surface size, and a random curved surface rotation angle.

[0005] According to one aspect of the present invention, the coordinates of the center position of the surface are (x, y), and the coordinates of the center position of the surface (x, y) randomly fall within an area of ​​L*W, and -L / 2≤x≤L / 2, -W / 2≤y≤W / 2, wherein the value range of L is 1μm-1mm, and the value range of W is 1μm-1mm.

[0006] According to one aspect of the present invention, the Z-axis height of the curved surface is H, and the Z-axis height H is the distance from the highest point to the lowest point of the Z-axis of the curved surface, satisfying 0<H<1mm.

[0007] According to one aspect of the present invention, the random rotation angle of the surface itself includes the random rotation angle alpha of the surface itself, the random rotation angle beta of the surface itself and the random rotation angle gamma of the surface itself;

[0008] Alpha is the rotation angle of the center axis of the surface around the x-axis, beta is the rotation angle of the center axis of the surface around the y-axis, and gamma is the rotation angle of the center axis of the surface around the z-axis.

[0009] According to one aspect of the present invention, the value ranges of the Alpha, the beta and the gamma are all -90°-90°.

[0010] According to one aspect of the present invention, the size of the microlens curved surface randomly satisfies: the minimum circumscribed circle diameter of the microlens is R, 0<R<1mm.

[0011] According to one aspect of the present invention, the refractive index of the microlens is N, satisfying 1<N<5.

[0012] According to one aspect of the present invention, the surfaces of the microlenses are all free surfaces, satisfying:

[0013]

[0014]

[0015] The light diffuser of the present invention can realize the random position of each microlens by randomly setting the center position of each microlens curved surface, and combine the random setting of the Z-axis height of each microlens, the random setting of the curved surface size, and the random setting of the curved surface's own rotation angle, and then splice them into a microlens array, so that light redistribution is achieved through geometric refraction optics, and light spot interference fringes are eliminated, making the illumination effect more uniform, meeting the detection light requirements, and improving 3D imaging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram showing the structure of a light diffuser according to an embodiment of the present invention;

[0017] Figure 2 A schematic diagram showing a random diagram of the center position of the microlens curved surface of the light diffuser according to the present invention;

[0018] Figure 3 Schematically showing a random diagram of the height of the microlens curved surface along the Z axis of the light diffuser according to the present invention;

[0019] Figure 4 A schematic diagram showing a random rotation angle alpha of a microlens curved surface of a light diffuser according to the present invention;

[0020] Figure 5 Schematically showing a random diagram of the rotation angle beta of the microlens surface of the light diffuser according to the present invention;

[0021] Figure 6 Schematically showing a random diagram of the rotation angle gamma of the microlens surface of the light diffuser according to the present invention;

[0022] Figure 7 A random diagram schematically showing the size of the microlens curved surface of the light diffuser according to the present invention;

[0023] Figure 8 Schematically showing one embodiment of a microlens array of a light diffuser according to the present invention;

[0024] Fig. 9 Schematically showing a second embodiment of the microlens array of the light diffuser according to the present invention;

[0025] Fig.10 Schematically showing a third embodiment of the microlens array of the light diffuser according to the present invention;

[0026] Fig.11 Schematically showing a fourth embodiment of the microlens array of the light diffuser according to the present invention;

[0027] Fig.12 A fifth embodiment of the microlens array of the light diffuser according to the present invention is schematically shown;

[0028] Fig.13 A sixth embodiment of the microlens array of the light diffuser according to the present invention is schematically shown;

[0029] Figure 14-16 The light spot diagram of the light diffuser according to the present invention is schematically shown. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0033] like Figure 1 As shown, the light diffuser of the present invention includes a plurality of randomly positioned microlenses spliced ​​into a microlens array, and the curved surface of each microlens is random, and the random curved surface of the microlens includes random curved surface center position, random curved surface Z-axis height, random curved surface size, and random curved surface rotation angle.

[0034] The light diffuser of the present invention can realize the random position of each microlens by randomly setting the center position of each microlens curved surface, and combine the random setting of the Z-axis height of each microlens, the random setting of the curved surface size, and the random setting of the curved surface's own rotation angle, and then splice them into a microlens array, so that light redistribution is achieved through geometric refraction optics, and light spot interference fringes are eliminated, making the illumination effect more uniform, meeting the detection light requirements, and improving 3D imaging accuracy.

[0035] Combination Figure 1 , Figure 2 As shown, in the present invention, the coordinates of the center position of the curved surface of each microlens are set to (x, y), and the coordinates of the center of the curved surface (x, y) randomly fall within the area of ​​L*W, and -L / 2≤x≤L / 2, -W / 2≤y≤W / 2. In the present invention, the value range of L is 1μm-1mm, and the value range of W is 1μm-1mm. In this way, by randomly setting the center position of the microlens curved surface, the random setting of multiple microlens positions is achieved, which is conducive to eliminating interference diffraction fringes and making the lighting effect more uniform.

[0036] like Figure 3 As shown, in the present invention, the Z-axis height of the curved surface of each microlens is H, and the Z-axis height H is the distance from the highest point to the lowest point of the Z-axis of the curved surface, satisfying 0<H<1mm. Such a setting is also conducive to eliminating interference diffraction fringes through the random height of the curved surface, making the lighting effect more uniform.

[0037] Combination Figure 4-6 As shown, the random rotation angle of the microlens surface of the present invention includes the random rotation angle alpha of the surface, the random rotation angle beta of the surface and the random rotation angle gamma of the surface. Wherein Alpha is the rotation angle of the center axis of the surface around the x-axis, beta is the rotation angle of the center axis of the surface around the y-axis, and gamma is the rotation angle of the center axis of the surface around the z-axis. In the present invention, the value ranges of Alpha, beta and gamma are all -90°-90°. In other words, the center axis of the microlens surface of the present invention can be randomly set in the range of 0-90° in a clockwise or counterclockwise direction around the x-axis, y-axis and z-axis. In this way, the random setting of the center axis of the microlens surface around the x-axis, y-axis and z-axis can also eliminate interference diffraction fringes, make the illumination more uniform, and improve the 3D imaging effect.

[0038] like Figure 7 As shown, the circle in the figure is the circumscribed circle of the microlens. In the present invention, the size of the curved surface of the microlens is random, satisfying the diameter R of the circumscribed circle of the microlens, 0<R<1mm. The random size of the curved surface of the microlens is also conducive to eliminating the interference diffraction stripes of the light spot, making the illumination more uniform and improving the 3D imaging effect.

[0039] In the present invention, the refractive index of the microlens is N, which satisfies 1<N<5. By controlling the refractive index and the curvature of the surface, the optical distribution in the required direction can be obtained according to the law of refraction, thereby obtaining illumination of a certain target.

[0040] In the present invention, the surfaces of the microlenses are all free-form surfaces, satisfying:

[0041]

[0042]

[0043] When the coefficients Cj are all positive, the free-form surface is a biconvex free-form surface, and the microlens is a biconvex microlens;

[0044] When the coefficients Cj are all negative, the free-form surface is a biconcave free-form surface, and the microlens is a biconcave microlens;

[0045] The free-form surface is not an aspherical surface, and has a high degree of freedom. Generally, in order to simplify the design, the free-form surface is usually designed to be quadrant symmetrical. However, the non-quadrant symmetrical free-form surface designed based on this principle is also within the protection scope of this application. The light diffuser of the present invention makes the surface of the microlens a free-form surface, so that the free-form surface can eliminate phase difference, has a high degree of freedom, and can achieve any optical lighting distribution. At the same time, the free-form surface has a smooth transition, which increases the manufacturing feasibility.

[0046] The light diffuser of the present invention has different forms of microlens arrays formed according to the above parameter settings. Figure 8-13 As shown, they respectively represent diagrams of a microlens array with periodic microlens positions, a microlens array with random microlens positions, a microlens array with periodic microlens positions and random gamma, a microlens array with random microlens positions and random gamma, a microlens array with periodic lens positions, random gamma and random curved surface size, and a microlens array with random lens positions, random gamma and random curved surface size.

[0047] like Figure 14-16 As shown, the light diffuser of the random microlens array of the present invention has a light spot pattern that is dark in the middle and bright around, and has a smooth curve transition, which is beneficial to improving the 3D imaging accuracy and simplifying the imaging algorithm.

[0048] In addition, the light diffuser of the present invention can be realized by processes such as embossing, injection molding, and machining. Plastic injection molding is a method of plastic products, in which molten plastic is injected into a plastic product mold under pressure, and then cooled and molded to obtain various desired plastic parts. The materials used for optical products are usually PC or PMMA. The microlenses mainly produced by this process are relatively large in size, generally above the millimeter level.

[0049] Nanoimprint technology is a new type of micro-nano processing technology. This technology achieves ultra-high resolution through mechanical transfer and is expected to replace traditional photolithography in the future and become an important processing method in the field of microelectronics and materials. Nanoimprint technology is a technology that transfers the micro-nano structure on the template to the material to be processed with the assistance of photoresist. Nanoimprint technology is divided into three steps.

[0050] The first step is to process the template. Generally, electron beam etching and other methods are used to process the required structure on silicon or other substrates as a template. Since the diffraction limit of electrons is much smaller than that of photons, the resolution can be much higher than that of photolithography.

[0051] The second step is the transfer of the pattern. Apply photoresist to the surface of the material to be processed, and then press the template on its surface to transfer the pattern to the photoresist by applying pressure. Note that the photoresist cannot be completely removed to prevent the template from directly contacting the material and damaging the template.

[0052] The third step is substrate processing. Use ultraviolet light to solidify the photoresist, remove the template, and use an etching solution to etch away the photoresist that was not completely removed in the previous step, exposing the surface of the material to be processed. Then use chemical etching to process it. After completion, remove all the photoresist and finally obtain a high-precision processed material.

[0053] Since the processing of nanoimprint technology does not use visible light or ultraviolet light to process patterns, but uses mechanical means to transfer patterns, this method can achieve very high resolution. The highest reported resolution can reach 2 nanometers. In addition, the template can be used repeatedly, which undoubtedly greatly reduces the processing cost and effectively shortens the processing time. Therefore, nanoimprint technology has the technical advantages of ultra-high resolution, easy mass production, low cost, and high consistency, and is considered to be a processing method that is expected to replace existing photolithography technology.

[0054] The mechanical processing method is to process the microlens structure on the mold by a machine tool, or it can be processed on a transparent material by laser marking.

[0055] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A light diffuser, characterized in that: A plurality of randomly positioned microlenses are spliced ​​into a microlens array, wherein the curved surface of each microlens is random, and the random curved surface of the microlens includes a random curved surface center position, a random curved surface Z-axis height, a random curved surface size, and a random curved surface rotation angle; The coordinates of the center position of the surface are (x, y), and the coordinates of the center position of the surface (x, y) randomly fall within the area of ​​L*W, and -L / 2≤x≤L / 2, -W / 2≤y≤W / 2, where the value range of L is 1μm-1mm, and the value range of W is 1μm-1mm; The Z-axis height of the curved surface is H, and the Z-axis height H is the distance from the highest point to the lowest point of the Z-axis of the curved surface, satisfying 0<H<1mm; the random rotation angle of the curved surface itself includes the random rotation angle alpha of the curved surface itself, the random rotation angle beta of the curved surface itself and the random rotation angle gamma of the curved surface itself; Alpha is the rotation angle of the center axis of the surface around the x-axis, beta is the rotation angle of the center axis of the surface around the y-axis, and gamma is the rotation angle of the center axis of the surface around the z-axis; The value ranges of the Alpha, the beta and the gamma are all -90° to 90°.

2. The light diffuser according to claim 1, characterized in that The size of the microlens curved surface randomly satisfies: the minimum circumscribed circle diameter of the microlens is R, 0<R<1mm.

3. The light diffuser according to claim 1, characterized in that The refractive index of the microlens is N, which satisfies 1<N<5.

4. The light diffuser according to claim 1, characterized in that The surfaces of the microlenses are all free surfaces, satisfying: 。

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