Optical element and optical module

Abstract

The present application discloses an optical element and an optical module, which relate to the field of optical technology. The optical element comprises a transparent substrate, an array microlens layer and a Fresnel lens layer, wherein the array microlens layer and the Fresnel lens layer are stacked on the transparent substrate, or the array microlens layer and the Fresnel lens layer are respectively located on opposite sides of the transparent substrate, wherein the Fresnel lens layer is used to adjust the exit angle of the incident light beam, and the random array microlens layer is used to homogenize the light beam emitted by the Fresnel lens layer. The light beam direction and light intensity distribution can be adjusted, and the occupied space can be reduced.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular, to an optical element and an optical module. Background Art

[0002] In most optical systems, the light emitted by the light source often needs to adjust the divergence angle and intensity distribution of the light beam. When adjusting the light beam emitted by the light source, the collimating lens is often used to collimate the light beam with a larger divergence angle into a light with a smaller divergence angle, and the microlens array is often used to shape the light beam into a specific intensity distribution.

[0003] In the prior art, in the application of light beam adjustment and shaping, the microlens array often causes diffraction fringes to appear in the shaped light spot due to the interference and diffraction of the small lens units. On the other hand, the shaping effect of the microlens on the light beam is often affected by the divergence angle of the incident light and the light intensity distribution of the incident light, and the effect is poor at a larger incident divergence angle. In addition, when adjusting and shaping the light beam, multiple sets of optical elements need to be coordinated, which increases the space occupied and is not conducive to the miniaturization of the product. Summary of the invention

[0004] The purpose of the present application is to provide an optical element and an optical module that can adjust the direction of a light beam and the distribution of light intensity and reduce the occupied space.

[0005] The embodiment of the present application is implemented as follows:

[0006] According to one aspect of an embodiment of the present application, an optical element is provided, comprising a transparent substrate, an array microlens layer and a Fresnel lens layer, wherein the array microlens layer and the Fresnel lens layer are stacked on the transparent substrate, or the array microlens layer and the Fresnel lens layer are respectively located on two opposite sides of the transparent substrate, wherein the Fresnel lens layer is used to adjust the exit angle of an incident light beam, and the array microlens layer is used to homogenize the light beam emitted by the Fresnel lens layer.

[0007] Optionally, the array microlens layer includes microlenses distributed along the same plane, and the microlenses at different positions have different shapes and sizes.

[0008] Optionally, the light-transmitting surface of the microlens includes any one of a concave surface, a convex surface or a wavy curved surface.

[0009] Optionally, adjacent microlenses are closely fitted, and the distance between geometric centers of adjacent microlenses is 1 um-200 um.

[0010] Optionally, the height of the microlens is 1um-100um.

[0011] Optionally, when the array microlens layer and the Fresnel lens layer are stacked on the transparent substrate, the refractive index n of the array microlens layer is 1 The refractive index n of the Fresnel lens layer 2 The difference between them is: |n 1 -n 2 |≥0.2.

[0012] Optionally, a spacing layer is further provided between the array microlens layer and the Fresnel lens layer, and the refractive index n of the array microlens layer is 1 The refractive index n of the spacer layer 3 The difference between them is: |n 1 -n 3 |≥0.2, and the refractive index n of the Fresnel lens layer 2 The refractive index n between the spacer layer 3 The difference is: |n 2 -n 3 |≥0.2.

[0013] Optionally, the Fresnel lens layer includes a stepped Fresnel structure, and the height h of the stepped Fresnel structure is 1 is 0.1um-10um, or, the Fresnel lens layer includes a continuous Fresnel structure, and the height h of the continuous Fresnel structure is 2 1um-100um.

[0014] Optionally, the transparent substrate, the array microlens layer and the Fresnel lens layer are made of any one of glass, resin or plastic.

[0015] Another aspect of the embodiments of the present application provides an optical module, comprising an optical element as described in any one of the above, and a light-emitting module, wherein the optical element is located on an outgoing light path of the light-emitting module.

[0016] The beneficial effects of the embodiments of the present application include:

[0017] The optical element and optical module provided in the embodiments of the present application use a Fresnel lens layer to collimate the light beam, or to make the light beam emerge at a specific angle, so that the direction of the light beam can be flexibly adjusted as needed. After the light beam emerges from the Fresnel lens layer, it is shaped and homogenized by the array microlens layer, and is less affected by the coherence of the light beam, which is beneficial to improving the quality of the light beam after it emerges from the optical element. By combining the Fresnel lens layer and the array microlens layer, the functions of adjusting the direction of the light beam and the light intensity distribution can be achieved at the same time, thereby improving the light beam adjustment capability, and occupying less space, which is beneficial to the miniaturization of the optical module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 One of the structural schematic diagrams of the optical element provided in the embodiment of the present application;

[0020] Figure 2 The second structural schematic diagram of the optical element provided in the embodiment of the present application;

[0021] Figure 3 The third structural schematic diagram of the optical element provided in the embodiment of the present application;

[0022] Figure 4 A fourth structural schematic diagram of an optical element provided in an embodiment of the present application;

[0023] Figure 5 A schematic diagram of the structure of an array microlens layer provided in an embodiment of the present application;

[0024] Figure 6 One of the schematic diagrams of a light beam transmitted through an optical element provided in an embodiment of the present application;

[0025] Figure 7 The second schematic diagram of the transmission of a light beam through an optical element provided in an embodiment of the present application;

[0026] Figure 8 A cross-sectional distribution diagram of a light spot passing through a conventional lens assembly provided in an embodiment of the present application;

[0027] Fig. 9 A cross-sectional distribution diagram of a light spot passing through an optical element provided in an embodiment of the present application;

[0028] Fig.10 A schematic diagram of the structure of an optical module provided in an embodiment of the present application.

[0029] Icons: 100 - optical element; 105 - light source; 110 - transparent substrate; 120 - array microlens layer; 122 - microlens; 130 - Fresnel lens layer; 140 - spacer layer; 200 - optical module; 210 - light emitting module. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] Please refer to Figure 1 , Figure 2 and Figure 3 The embodiment of the present application provides an optical element 100, including a transparent substrate 110, an array microlens layer 120 and a Fresnel lens layer 130, wherein the array microlens layer 120 and the Fresnel lens layer 130 are stacked on the transparent substrate 110, or the array microlens layer 120 and the Fresnel lens layer 130 are respectively located on two opposite sides of the transparent substrate 110, wherein the Fresnel lens layer 130 is used to adjust the exit angle of an incident light beam, and the array microlens layer 120 is used to homogenize the light beam emitted by the Fresnel lens layer 130.

[0035] Specifically, the Fresnel lens layer 130 is used to adjust the exit angle of the incident light beam, which includes not only collimating the light beam so that the light beam is emitted in parallel, but also flexibly adjusting the exit direction of the light beam so that the light beam is emitted at a specific angle. In actual applications, the light source 105 incident on the Fresnel lens layer 130 is not a simple point light source 105 or a surface light source 105. For example, the light source 105 is irradiated to the Fresnel lens layer 130 after passing through the lens imaging system. The above method may cause the incident angle and position relationship of the main light ray to be irregularly distributed at different positions of the Fresnel lens layer 130. At this time, the structural form of the Fresnel lens layer 130 can still be set according to the incident angle of the main light ray so that the light beam is emitted in parallel, or the light beam can be emitted at a specific angle as needed, so as to achieve the desired shaping effect.

[0036] After passing through the Fresnel lens layer 130, the light beam enters the array microlens layer 120 to homogenize the light beam emitted by the Fresnel lens layer 130. The array microlens layer 120 is a random microlens 122 array, which can avoid the problem of not being able to eliminate diffraction well due to the use of a periodic structure.

[0037] In addition, the array microlens layer 120 can be implemented by a combination of laser direct writing and embossing, or by a combination of grinding light and melting. It can be understood that the Fresnel lens layer 130 can be made by a combination of mask lithography and etching, or by a combination of grinding lithography and embossing, or by a combination of laser direct writing and embossing. By adopting the above method, the optical element 100 is an integrated structure, which is conducive to improving the stability of the structure and can reduce the occupied space compared with discrete optical modules. The alignment accuracy of the Fresnel lens layer 130 and the array microlens layer 120 can be increased by adding alignment marks.

[0038] like Figure 2 and Figure 3 As shown, when the array microlens layer 120 and the Fresnel lens layer 130 are stacked on the transparent substrate 110, the array microlens layer 120 can be in contact with the transparent substrate 110, or the Fresnel lens layer 130 can be in contact with the transparent substrate 110. The embodiment of the present application does not impose any specific restrictions on this. In practical applications, it is only necessary to make the light beam pass through the Fresnel lens layer 130 first.

[0039] The optical element 100 provided in the embodiment of the present application uses the Fresnel lens layer 130 to collimate the light beam, or to make the light beam emerge at a specific angle, so that the direction of the light beam can be flexibly adjusted as needed. After the light beam is emitted from the Fresnel lens layer 130, it is shaped and homogenized by the array microlens layer 120, and is less affected by the coherence of the light beam, which is beneficial to improving the quality of the light beam after being emitted by the optical element 100. By combining the Fresnel lens layer 130 and the array microlens layer 120, the functions of adjusting the direction of the light beam and the light intensity distribution can be achieved at the same time, thereby improving the light beam adjustment capability, and occupying a smaller space, which is beneficial to the miniaturization of the optical module 200 (such as a TOF transmitter, a laser projection module, etc.).

[0040] like Figure 5 As shown, the array microlens layer 120 includes microlenses 122 distributed along the same plane, and the shapes and sizes of the microlenses 122 at different positions are different.

[0041] Specifically, the microlenses 122 in the embodiment of the present application are random microlenses 122, that is, the parameters of the microlenses 122 at different positions are different. For example, the lens height, lens diameter, lens curvature, lens pitch, etc. of the microlenses 122 can be flexibly set as needed. In other words, the shapes and sizes of the microlenses 122 at different positions are different. This can reduce the coherence of the light beam to a certain extent, thereby reducing the speckle effect, thereby maintaining the desired shape and uniformity at a specific distance, and further improving the quality of the shaped spot. It should be noted that the array form and specific parameters of the microlenses 122 can be flexibly set according to actual needs. In actual applications, different design parameters can be determined according to the size of the optical element 100 and the divergence angle of the output light beam and the final desired divergence angle of the output light beam.

[0042] In an optional embodiment of the present application, the light-transmitting surface of the microlens 122 includes any one of a concave surface, a convex surface or a wavy curved surface.

[0043] Specifically, the light-transmitting surfaces of the microlenses 122 may all adopt a concave structure, i.e., a concave lens; or may all adopt a convex structure, i.e., a convex lens; or may adopt a wavy surface to achieve different optical properties. It is understandable that the light-transmitting surfaces of the microlenses 122 may also adopt a combination of a concave surface, a convex surface, or a wavy surface, as long as the required uniform light effect can be ensured, and the embodiments of the present application do not impose specific restrictions on this.

[0044] like Figure 5 As shown, in an optional embodiment of the present application, adjacent microlenses 122 are closely fitted together, and the distance between the geometric centers of adjacent microlenses 122 is 1 um-200 um.

[0045] Specifically, since the adjacent microlenses 122 are closely fitted and have no gaps, in order to make the adjacent microlenses 122 have no overlapping parts, the microlenses 122 have irregular boundary shapes. When the light beam passes through the microlenses 122, the parameters of different microlenses 122 are different to achieve the purpose of light homogenization. In addition, the above-mentioned placement makes the array microlens layer 120 a seamless structure, which is beneficial to avoid the light leakage problem caused by the spacing between the microlenses 122, and is beneficial to improve the light homogenization performance of the optical element 100 when it is used. According to the different parameters of different microlenses 122, the spacing between the geometric centers of adjacent microlenses 122 is also different. In order to ensure the homogenization quality of the light beam, in the preferred embodiment of the present application, the spacing between the geometric centers of adjacent microlenses 122 is 1um-200um. For example, the spacing between the geometric centers of adjacent microlenses 122 can be set to 1um, 50um, 100um or 200um, etc.

[0046] In an optional embodiment of the present application, the height of the microlens 122 is 1 um-100 um.

[0047] Specifically, by setting the height of the microlens 122 to different heights, it is beneficial to generate a phase difference when the height of the microlens 122 is distributed within a certain range. This is to utilize the phase difference to improve the problems of uneven brightness and color caused by diffraction, thereby improving the quality of light beam homogenization. In a preferred embodiment of the present application, the height of the microlens 122 is 1um-200um. For example, the height of the microlens 122 can be set to 1um, 50um, 100um or 200um, etc.

[0048] like Figure 2 and Figure 3 As shown, in an optional embodiment of the present application, when the array microlens layer 120 and the Fresnel lens layer 130 are stacked on the transparent substrate 110, the refractive index n of the array microlens layer 120 is 1 The refractive index n of the Fresnel lens layer 130 is 2 The difference between them is: |n 1 -n 2 |≥0.2.

[0049] Specifically, the material forming the array microlens layer 120 may have a relatively high refractive index, and the material forming the Fresnel lens layer 130 may have a relatively low refractive index. Alternatively, the material forming the array microlens layer 120 may have a relatively low refractive index, and the material forming the Fresnel lens layer 130 may have a relatively high refractive index, which is not specifically limited in the present embodiment. 1 -n 2|≥0.2, it is conducive to ensuring better optical performance. It should be noted that the use of different refractive indices is to ensure the stability of the optical properties of the array microlens layer 120 and the Fresnel lens layer 130. If materials with the same refractive index are used, it can be considered that the array microlens layer 120 and the Fresnel lens layer 130 form the same structure and no longer have their own optical properties. Therefore, the refractive index between the array microlens layer 120 and the Fresnel lens layer 130 needs to be different.

[0050] like Figure 4 As shown, in an optional embodiment of the present application, a spacer layer 140 is further provided between the array microlens layer 120 and the Fresnel lens layer 130. In this case, the refractive index n of the array microlens layer 120 is 1 The refractive index n of the spacer layer 140 is 3 The difference between them is: |n 1 -n 3 |≥0.2, and the refractive index n of the Fresnel lens layer 130 2 The refractive index n between the spacer layer 140 3 The difference is: |n 2 -n 3 |≥0.2.

[0051] It can be understood that different refractive indices are used to ensure the stability of the optical characteristics of the array microlens layer 120 and the Fresnel lens layer 130. When a spacing layer 140 is further provided between the array microlens layer 120 and the Fresnel lens layer 130, the refractive indices of the array microlens layer 120 and the Fresnel lens layer 130 may be the same or different, and the embodiment of the present application does not impose any specific limitation on this.

[0052] like Figure 2 As shown, the Fresnel lens layer 130 includes a stepped Fresnel structure, and the height h of the stepped Fresnel structure is 1 0.1um-10um.

[0053] Specifically, when a stepped Fresnel structure is used, a multi-step structure such as a 2-step, 4-step or 8-step structure may be used. Generally, the height of each step is equal, and a structure of unequal heights may also be set as required. In specific applications, it can be flexibly set as required, wherein the height h of the stepped Fresnel structure is 1 It can be set to 0.1um, 0.5um, 4um or 10um according to actual needs.

[0054] like Figure 1 As shown, the Fresnel lens layer 130 includes a continuous Fresnel structure, and the height h of the continuous Fresnel structure is 2 1um-100um.

[0055] Specifically, the continuous Fresnel structure can be composed of multiple surface sections divided from a spherical surface, an aspherical surface, etc., or can be composed of multiple surface sections divided from a free-form surface. The sawtooth heights of the continuous Fresnel structure can be equal or unequal, and can be flexibly set as needed. For example, the height h of the continuous Fresnel structure is 2 It can be set to 1um, 10um, 20um, 50um or 100um, etc.

[0056] like Figure 6 As shown, it is a schematic diagram of a light beam in an embodiment of the present application being emitted in parallel after passing through the Fresnel lens layer 130, that is, the light beam is collimated. In practical applications, the optical element 100 of the present application directs the light source 105 toward the Fresnel lens layer 130, wherein the light source 105 may be any one of a light emitting diode (LED), a semiconductor laser (LD), and a vertical cavity surface emitting laser (VCSEL). The above form is adopted to realize that the light beam is collimated by the Fresnel lens layer 130 and then emitted after being shaped and homogenized by the array microlens layer 120. Among them, the Fresnel lens layer 130 may adopt a stepped Fresnel structure or a continuous Fresnel structure.

[0057] like Figure 7 As shown, it is a schematic diagram of adjusting the angle of the light beam to be emitted as needed after passing through the Fresnel lens layer 130 in an embodiment of the present application. In this form, after the light source 105 emits light toward the Fresnel lens layer 130, the light beam direction is adjusted by the Fresnel lens layer 130, and then the light beam is shaped and homogenized by the array microlens layer 120 before being emitted, so as to realize a variety of light beam adjustment forms.

[0058] Depend on Figure 6 and Figure 7It can be seen from the structural form of the optical element 100 and the light beam propagation form in the embodiment that the Fresnel lens layer 130 of the present application can not only play a collimating role, but also flexibly adjust the direction of the light beam. When the direction of the light beam needs to be adjusted, after the refraction of the Fresnel lens layer 130, the refracted light is no longer emitted in parallel, but the angles of the refracted light at different positions are different, and then the diffusion of the array microlens layer 120 makes the main light angles of the emitted light in different fields of view different. In practical applications, the direction of the emitted light can be flexibly modulated according to the requirements of the subsequent optical system. When adjusting the direction of the light beam, the incident light angle at different positions of the optical element 100 and the required exit light angle at different positions can be determined first, and the free surface solution method is used to first solve a whole free surface, and then the surface is divided into a Fresnel lens layer 130 of multiple surface types. It is also possible to first determine the incident angle and the exit angle at different positions, and then directly adjust the structural form of the Fresnel structure at each position to achieve flexible regulation of the incident light beam.

[0059] For example, when a conventional lens group (a combination of light source 105 and microlens array) is used for testing, assuming that the divergence angle of light source 105 is ±13°, the luminous area of ​​light source 105 is 100um×100um, and the distance between light source 105 and microlens array is 0.9mm, the cross-sectional distribution of the light spot is measured as follows: Figure 8 When the optical element 100 of the present application is tested, the above light source 105 is also used for testing, and the focal length of the Fresnel lens is set to 0.9 mm. At this time, the cross-sectional distribution of the measured light spot is as follows: Fig. 9 As shown. Figure 8 and Fig. 9 By comparison, it can be seen that the optical element 100 of the present application can make the edge of the output light spot sharper, the window efficiency higher, and the light uniformity effect better without adding additional elements.

[0060] In an optional embodiment of the present application, the material of the transparent substrate 110 , the array microlens layer 120 , and the Fresnel lens layer 130 includes any one of glass, resin, or plastic.

[0061] Specifically, the transparent substrate 110, the array microlens layer 120 and the Fresnel lens layer 130 are transparent materials of the applied wavelength band. In this way, when the light source 105 emits light of different wavelength bands, the transmittance of the transparent substrate 110, the array microlens layer 120 and the Fresnel lens layer 130 is matched with the wavelength band, which is conducive to improving the utilization rate of light.

[0062] In addition, the transparent substrate 110 in the embodiment of the present application mainly plays a role of bearing support, and the thickness of the transparent substrate 110 is 0.1 mm-5 mm. For example, the thickness of the transparent substrate 110 can be set to 0.1 mm, 1 mm, 3 mm or 5 mm.

[0063] like Fig.10 As shown, the embodiment of the present application also discloses an optical module 200, including the optical element 100 in the aforementioned embodiment, and a light-emitting module 210, wherein the optical element 100 is located on the light path of the light-emitting module 210. The optical module 200 includes the same structure and beneficial effects as the optical element 100 in the aforementioned embodiment. The structure and beneficial effects of the optical element 100 have been described in detail in the aforementioned embodiment, and will not be repeated here.

[0064] It should be noted that the light-emitting module 210 in the embodiment of the present application can be a single light source, or a module composed of a light source and a lens, a reflector or an aperture, so as to meet the application requirements of different scenarios.

[0065] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical element, characterized in that: The invention comprises a transparent substrate, an array microlens layer and a Fresnel lens layer, wherein the array microlens layer and the Fresnel lens layer are stacked on the transparent substrate, wherein the Fresnel lens layer is used to adjust the exit angle of the incident light beam, and the array microlens layer is used to homogenize the light beam emitted from the Fresnel lens layer. A spacing layer is further arranged between the array microlens layer and the Fresnel lens layer, and the light beam is incident on the array microlens layer after being acted upon by the Fresnel lens layer, so as to homogenize the light beam emitted from the Fresnel lens layer 130. The difference between the refractive index n1 of the array microlens layer and the refractive index n3 of the spacing layer is: |n1-n3|≥0.2, and the difference between the refractive index n2 of the Fresnel lens layer and the refractive index n3 of the spacing layer is: |n2-n3|≥0.2, and the array microlens layer and the Fresnel lens layer can be transparent materials of the same refractive index in the application band.

2. The optical element according to claim 1, characterized in that The array microlens layer includes microlenses distributed along the same plane, and the microlenses at different positions have different shapes and sizes.

3. The optical element according to claim 2, characterized in that The light-transmitting surface of the microlens includes any one of a concave surface, a convex surface or a wavy curved surface.

4. The optical element according to claim 2, characterized in that The adjacent micro lenses are closely fitted, and the distance between the geometric centers of the adjacent micro lenses is 1um-200um.

5. The optical element according to any one of claims 2 to 4, characterized in that: The height of the microlens is 1um-100um.

6. The optical element according to claim 1, characterized in that The Fresnel lens layer includes a stepped Fresnel structure, and a height h1 of the stepped Fresnel structure is 0.1um-10um; or, the Fresnel lens layer includes a continuous Fresnel structure, and a height h2 of the continuous Fresnel structure is 1um-100um.

7. The optical element according to any one of claims 1 to 4, characterized in that: The transparent substrate, the array microlens layer and the Fresnel lens layer are made of any one of glass, resin or plastic.

8. An optical module, characterized in that: It comprises the optical element as described in any one of claims 1 to 7, and a light-emitting module, wherein the optical element is located on the outgoing light path of the light-emitting module.

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