CN211148967U

CN211148967U - Infrared light diffusion sheet

Info

Publication number: CN211148967U
Application number: CN201922313549.7U
Authority: CN
Inventors: 杨萌; 戴付建; 赵烈烽
Original assignee: Ningbo Sunny Olai Technology Co ltd
Current assignee: Ningbo Sunny Olai Technology Co ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-07-31
Anticipated expiration: 2029-12-20

Abstract

The utility model provides an infrared light diffusion piece. The infrared light diffusion sheet includes: a substrate comprising a plurality of layer structures, each layer structure being arranged one above the other; the micro-lenses are arranged on the exposed surface of at least one layer structure at intervals, the height direction of the micro-lenses is the same as the stacking direction of the layer structures, and the refractive index of each layer structure is gradually reduced towards the direction close to the micro-lenses. The utility model provides a have the problem that high order diffraction easily appears among the prior art.

Description

Infrared light diffusion sheet

Technical Field

The utility model relates to an optical imaging equipment technical field particularly, relates to an infrared diffusion piece.

Background

In the fields such as AR and VR which need 3D optical sensing, a scene must be illuminated by a light source with a certain spatial distribution and time distribution, and the distance from each position in the scene to the light source, that is, the depth, is restored according to the change of the spatial distribution and time distribution of the reflected light of the scene, so that the obtained depth map is the basis for various AR and VR applications.

The wavelength of light emitted by a light source is preferably in the infrared region in the range of 800-1000nm to reduce the interference of visible light due to the characteristics of the solar spectrum in the environment, the light source generally uses a VSCE L laser or an array thereof, and the emitted coherent light passes through a DOE to form a spot pattern with a certain spatial distribution, or passes through a light diffusion sheet to form a uniform light pattern with a uniform spatial distribution but modulated in terms of phase, time, and the like.

That is, the prior art is prone to higher order diffraction.

SUMMERY OF THE UTILITY MODEL

A primary object of the present invention is to provide an infrared light diffusing sheet, which solves the problem of high-order diffraction in the prior art.

In order to achieve the above object, the present invention provides an infrared light diffusion sheet, including: a substrate comprising a plurality of layer structures, each layer structure being arranged one above the other; the micro-lenses are arranged on the exposed surface of at least one layer structure at intervals, the height direction of the micro-lenses is the same as the stacking direction of the layer structures, and the refractive index of each layer structure is gradually reduced towards the direction close to the micro-lenses.

Further, the refractive index of the micro-lenses is smaller than the refractive index of the layer structure.

Further, the refractive index of the material of each layer structure for light having a wavelength in the range of 850nm to 1010 nm is greater than 1.4 and less than 1.8.

Further, the thickness of each layer structure is greater than or equal to 0.05 mm and less than or equal to 0.3 mm.

Further, the abbe numbers of the material of the substrate and the material of the microlens are greater than 40.

Further, a plurality of microlenses form a periodic array, and the microlenses are arranged at equal intervals.

Further, the distance between two adjacent microlenses is greater than or equal to 1 micrometer and less than or equal to 20 micrometers.

Further, the distance between two adjacent microlenses is smaller than the length of the microlens.

Further, the height of the microlens is smaller than the length of the microlens.

Further, the height of the micro lens is more than or equal to 1 micron and less than or equal to 50 microns; the length of the micro lens is greater than or equal to 5 micrometers and less than or equal to 200 micrometers.

By applying the technical scheme of the utility model, the infrared light diffusion sheet comprises a substrate and a micro lens, the substrate comprises a plurality of layer structures, and the layer structures are arranged in an overlapping way; the micro-lenses are arranged on the exposed surface of at least one layer structure at intervals, the height direction of the micro-lenses is the same as the stacking direction of the layer structures, and the refractive index of each layer structure is in gradient change towards the direction close to the micro-lenses.

The plurality of layer structures are arranged on the substrate, the refractive indexes among the plurality of layer structures are in gradient distribution, and the exit angle of the infrared light diffusion sheet is increased or reduced through the change of the refractive indexes among the layer structures, so that high-order diffraction or high-frequency components caused by the micro lens are reduced. Meanwhile, on the premise of meeting the requirements of different exit angles, the change of the micro lens is reduced as much as possible, and the exit angle is changed by changing the change of the substrate, so that the infrared light diffusion sheet is suitable for the laser with a specific divergence angle.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic view of the overall structure of an infrared light diffusion sheet according to an alternative embodiment of the present invention; and

FIG. 2 shows an angled view of the IR diffuser of FIG. 1;

fig. 3 is a schematic diagram showing a positional relationship between the microlens and the layer structure in fig. 1.

Wherein the figures include the following reference numerals:

10. a substrate; 11. a layer structure; 20. a microlens.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In the present application, where the contrary is not intended, the use of directional words such as "upper, lower, top and bottom" is generally with respect to the orientation shown in the drawings, or with respect to the component itself in the vertical, perpendicular or gravitational direction; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.

In order to solve the problem that high-order diffraction easily appears in the prior art, the utility model provides an infrared light diffusion piece.

As shown in fig. 1 to 3, the infrared light diffusion sheet includes a substrate 10 and microlenses 20, the substrate 10 including a plurality of layer structures 11, the layer structures 11 being disposed one on another; the number of the microlenses 20 is multiple, the microlenses 20 are arranged on the exposed surface of at least one layer structure 11 at intervals, the height direction of the microlenses 20 is the same as the stacking direction of the layer structures 11, and the refractive index of each layer structure 11 is gradually reduced towards the direction close to the microlenses 20.

By providing the plurality of layer structures 11 on the substrate 10, the refractive indices between the plurality of layer structures 11 are distributed in a gradient manner, and the exit angle of the infrared light diffusion sheet is increased or decreased by the change in the refractive index between the respective layer structures 11, thereby reducing the high-order diffraction or high-frequency components caused by the microlenses 20. Meanwhile, on the premise of meeting the requirements of different exit angles, the change of the micro lens is reduced as much as possible, and the exit angle is changed by changing the change of the substrate, so that the infrared light diffusion sheet is suitable for the laser with a specific divergence angle.

It should be noted that the gradient difference between two adjacent layer structures 11 is greater than 0.05. Of course, the gradient difference between two adjacent layer structures 11 may be 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, etc.

Alternatively, the refractive index of each layer structure 11 decreases gradually towards the microlenses 20, the refractive index of the microlenses 20 being smaller than the refractive index of the layer structure 11. The exit angle of the infrared light diffusion sheet is increased by the change of the refractive index between the respective layer structures 11, thereby reducing high-order diffraction or high-frequency components caused by the microlenses.

In the specific embodiment shown in fig. 3, the infrared light diffuser has a three-layer structure 11. Of course, the number of layer structures 11 can be increased or decreased as desired, for example, the exit angle of the infrared light diffusing sheet can be changed by only increasing or decreasing the number of layer structures 11 without changing the arrangement of the microlenses 20 and the laser configuration. Furthermore, adjusting the exit angle by the layer structure 11 in the substrate 10 may also mitigate the effects of higher order diffraction.

It should be noted that, in the present application, the infrared light diffusion sheet is rectangular, the length of one set of opposite side edges in the infrared light diffusion sheet is greater than or equal to 2 mm and less than or equal to 4 mm, and the length of the other set of opposite side edges in the infrared light diffusion sheet is greater than or equal to 3 mm and less than or equal to 6 mm. The arrangement is convenient for the infrared light diffusion sheet to be suitable for the TOF module.

Of course, the refractive index of each layer structure 11 gradually increases toward the microlens 20, and the refractive index of the microlens 20 is larger than that of the layer structure 11. This arrangement can reduce the exit angle of the infrared light diffusing sheet by the change in the refractive index between the layer structures 11 to accommodate lasers requiring a small exit angle.

In the present embodiment, the refractive index of the material of each layer structure 11 for light having a wavelength in the range of 850nm to 1010 nm is greater than 1.4 and less than 1.8. The arrangement is such that light is greatly deflected when entering each layer structure 11, so as to be reflected and scattered inside the infrared light diffusion sheet, thereby increasing the uniformity of emergent light of the infrared light diffusion sheet. The material of the substrate 10 may be various types of optical glass, preferably optical glass having an abbe number of more than 50. The abbe number of the material of the layer structure 11 may be 55, 60, 65, 70, 80, etc. The refractive index of the material of the layer structure 11 for light having a wavelength in the range of 850nm to 1010 may be 1.45, 1.50, 1.55, 1.6, 1.7, 1.73, 1.75, 1.78, etc.

In the present embodiment, the thickness of each layer structure 11 is 0.05 mm or more and 0.3 mm or less. The arrangement can ensure the structural strength of the infrared light diffusion sheet, so that the infrared light diffusion sheet can be stably used. Furthermore, limiting the thickness of the layer structure 11 to a range of 0.05 mm to 0.3 mm can ensure miniaturization of the substrate, so that the infrared light diffusion sheet is suitable for a small lens.

It should be noted that the thickness of each layer structure 11 may be the same in this embodiment, which facilitates the manufacturing of the layer structure 11. Of course, the thicknesses of the layers of the structure 11 may be different, so as to meet different diffusion requirements, and the thickness of each layer of the structure 11 may be designed according to actual use requirements. Alternatively, the thickness of the layer structure 11 may be 50um, 55um, 60um, 65um, 70um, 75um, 80um, 85um, 90um, 100um, etc.

In the present embodiment, the abbe numbers of the material of the substrate 10 and the material of the microlens 20 are larger than 40. Having the abbe number of the material of the substrate 10 and the microlenses 20 greater than 40 reduces dispersion and distortion of the image exiting through the infrared light diffuser.

In the present embodiment, the plurality of microlenses 20 form a periodic array, and the microlenses 20 are arranged at equal intervals. The microlenses 20 are periodically arranged, so that the infrared light diffusion sheets can be conveniently manufactured, the consistency of the infrared light diffusion sheets in the mass production process can be increased, and the difference between the produced infrared light diffusion sheets can be reduced.

As shown in fig. 1 to 2, the microlens is square in the present embodiment, but is not limited to the square. The microlens 20 may be a hemisphere, an aspherical curved surface, a free curved surface, a saddle, a pillar, or any other shape as long as it has a shape or a change in refractive index that enables a change in the optical path difference of transmitted light.

The periodic array may be fabricated by micro-fabrication techniques such as imprinting, photolithography, and electron beam exposure, and is preferably fabricated in a large area using a template and then diced. In the case of imprinting, the substrate 10 is first coated with the microlenses 20, then the temperature is raised to soften the material of the microlenses 20, the mold is pressed against the microlenses 20 to form a two-dimensional periodic array or the reverse of the two-dimensional periodic array, and finally the pattern is transferred to the glass substrate by pattern transfer through plating or direct etching. In the case of photolithography, after a photosensitive dielectric such as PMMA is coated on the substrate 10, exposure is performed by irradiating a laser beam with a flood film or directly by a spatially encoded laser beam, and finally the exposed portion is removed by a developing solution, leaving a pattern.

In the present embodiment, the distance between two adjacent microlenses 20 is greater than or equal to 1 micrometer and less than or equal to 20 micrometers. The diffraction effect can be reduced by the arrangement, and the difficulty of mass production can be reduced.

In the present embodiment, the distance between two adjacent microlenses 20 is smaller than the length of the microlenses 20. This arrangement ensures a density of the microlenses 20, and thus makes the light emitted from the infrared light diffusing sheet more uniform.

Note that, in the present application, the length of the microlens 20 refers to the maximum length of the microlens 20 parallel to the substrate 10, and the height of the microlens 20 refers to the maximum height in the direction perpendicular to the substrate 10.

In the present embodiment, the height of the microlens 20 is smaller than the length of the microlens 20.

In the present embodiment, the height of the microlens 20 is 1 micron or more and 50 microns or less; the length of the microlens 20 is 5 micrometers or more and 200 micrometers or less. The length of the microlens 20 is 5 micrometers or more and 200 micrometers or less. This arrangement enables the infrared light diffusion sheet to achieve high transmittance and high diffraction efficiency.

In order to achieve a balance between high transmittance and high diffraction efficiency and a suitable exit angle, the relationship between the size of the microlenses 20 and the pitch of the adjacent microlenses 20 should be optimized, and reducing the height of the microlenses 20 is advantageous in reducing the manufacturing difficulty. Therefore, the height H of each microlens 20, the length D of each microlens 20, and the spacing D between two adjacent microlenses 20 satisfy: h < D, D < D.

Preferably, H < D/2, D < D/2.

In the present application, high transmittance means transmittance of more than 90%, and high diffraction efficiency means diffraction efficiency of more than 70%. The diffraction efficiency is defined as the proportion of the portion of the emitted light field with more than 10% of the central energy of the emitted light field to the energy of the emitted light field used. A suitable exit angle is an exit angle greater than 60 degrees. The exit angle is defined as the spatial angle of the distribution of the exiting light field in the X and Y directions.

Optionally, the infrared light diffusion sheet further includes an antireflection film on a surface of the substrate 10 on a side opposite to the microlenses 20; and/or the infrared light diffusion sheet further includes a filter on a surface of the substrate 10 on a side opposite to the microlens 20. The reflection of light on the infrared light diffusion sheet can be reduced by arranging the antireflection film on the infrared light diffusion sheet, the light transmission amount of the infrared light diffusion sheet is increased, the light transmittance of the infrared light diffusion sheet is further increased, and meanwhile, stray light can be reduced by the antireflection film. The filter plate can allow infrared light to pass through, and influence of other light on the infrared light is reduced. And the antireflection film and the filter are provided on the surface of the substrate 10 on the side opposite to the microlens 20, so that the influence of the antireflection film and the filter on the dielectric layer can be reduced, and the microlens 20 can stably operate. The antireflection film may include common materials such as silicon nitride, silicon dioxide, titanium dioxide, and aluminum oxide. Organic polymers may also be included.

It should be noted that the filter in this embodiment is preferably an infrared narrow-band filter, and of course, the type of the filter may be set according to the requirement of the light to be filtered actually.

In this embodiment, the infrared light diffusion sheet may be provided with a functional film for preventing static electricity, preventing cracks, and increasing hardness. In order to protect the periodic microlenses 20 on the microlenses 20, these functional films are preferably arranged on the surface of the substrate 10 on the side opposite to the microlenses 20.

Note that the antireflection film, the functional film, and the like described above may also be provided between two adjacent layer structures 11.

In the present embodiment, only the microlenses 20 contain a dielectric material.

It is obvious that the above described embodiments are only some of the embodiments of the present invention, and not all of them. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in sequences other than those illustrated or described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An infrared light diffusing sheet, comprising:

a substrate (10), said substrate (10) comprising a plurality of layer structures (11), each of said layer structures (11) being arranged one above the other;

the number of the micro lenses (20) is multiple, the micro lenses (20) are arranged on the exposed surface of at least one layer structure (11) at intervals, the height direction of the micro lenses (20) is the same as the stacking direction of the layer structures (11), and the refractive index of each layer structure (11) is gradually reduced towards the direction close to the micro lenses (20).

2. An infrared light diffuser sheet according to claim 1, wherein the refractive index of the microlenses (20) is smaller than the refractive index of the layer structure (11).

3. An infrared light diffuser sheet according to claim 1, wherein the refractive index of the material of each layer structure (11) for light having a wavelength in the range of 850nm to 1010 nm is greater than 1.4 and less than 1.8.

4. The infrared light diffuser sheet according to claim 1, wherein the thickness of each layer structure (11) is 0.05 mm or more and 0.3 mm or less.

5. The infrared light diffuser sheet according to any one of claims 1 to 4, characterized in that the Abbe number of the material of the substrate (10) and of the material of the microlenses (20) is greater than 40.

6. The infrared light diffusion sheet according to any one of claims 1 to 4, wherein a plurality of the microlenses (20) form a periodic array, and each of the microlenses (20) is arranged at equal intervals.

7. The infrared light diffusion sheet according to claim 6, wherein the distance between two adjacent microlenses (20) is greater than or equal to 1 micrometer and less than or equal to 20 micrometers.

8. The infrared light diffuser sheet according to claim 6, wherein the distance between two adjacent microlenses (20) is less than the length of the microlenses (20).

9. The infrared light diffuser sheet according to any one of claims 1 to 4, characterized in that the height of the microlenses (20) is smaller than the length of the microlenses (20).

10. The infrared light diffusion sheet according to any one of claims 1 to 4,

the height of the micro lens (20) is more than or equal to 1 micron and less than or equal to 50 microns;

the length of the micro lens (20) is greater than or equal to 5 micrometers and less than or equal to 200 micrometers.