Optoelectronic sensor and detection device

Abstract

The application discloses an optoelectronic sensor and a detection device, and applies to the technical field of optoelectronic detection, and comprises a pixel array; the pixel array comprises a plurality of pixels arranged in an array, the pixel array comprises N1 pixels arranged along an x direction and N2 pixels arranged along a y direction; when scanning y by x, one column of N1 pixels is turned on each time; wherein the x and y directions are perpendicular; the light receiving surface of each pixel is provided with a plurality of anisotropic microstructures, the microstructures form a one-dimensional grating along the y direction to diffract light in the y direction; the microstructures have an inclination angle for reducing reflection of light to the x direction. The microstructure makes the light reflected by the metal layer only propagate along the x direction towards the yz plane, so as to ensure that there is no signal crosstalk in the y direction; and in the x direction, the crosstalk in the x direction does not affect the final read value due to the one-dimensional scanning mode, thereby solving the interference caused by the crosstalk phenomenon.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to a photoelectric sensor and a detection device. Background Technology

[0002] A Time-of-Flight (TOF) camera is an active optical system that transmits a laser pulse to a target object, which is then detected by a photodetector at the receiver. The depth information of the target is calculated using the time of flight. For a single-exposure, single-emission TOF camera, reflected light from the photodetector pixels is reflected again by the receiver elements and incident on other pixels, causing crosstalk and resulting in ranging errors in some pixels. This directly affects the system's ranging performance. While anti-reflective structures in the detector pixels can reduce reflectivity to zero, line scanning only eliminates crosstalk in one direction, and point scanning significantly reduces the frame rate. Currently, these methods are not effective in solving the crosstalk problem in TOF systems.

[0003] Therefore, how to provide a photoelectric sensor that can effectively solve the crosstalk phenomenon is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a photoelectric sensor that can effectively solve the interference caused by crosstalk; another purpose of this invention is to provide a detection device that can effectively solve the interference caused by crosstalk.

[0005] To address the aforementioned technical problems, the present invention provides a photoelectric sensor, comprising a pixel array;

[0006] The pixel array includes multiple pixels arranged in an array, comprising N1 pixels arranged along the x-direction and N2 pixels arranged along the y-direction; when scanning along the x-direction y-direction, a column of N1 pixels is opened for each scan; wherein the x and y directions are perpendicular;

[0007] Each pixel has multiple anisotropic microstructures on its light-receiving surface. These microstructures form a one-dimensional grating along the y-direction to diffract light in the y-direction. The microstructures have a tilt angle that reduces light reflection in the x-direction.

[0008] Each pixel also includes a light-absorbing layer and a metal layer on the non-light-receiving surface of the pixel. The microstructure has a low refractive index and the absorption layer has a high refractive index.

[0009] Optionally, the microstructure includes: a triangular prism array, the triangular prism array comprising a plurality of triangular prisms with parallel axes, the axes of the triangular prisms being parallel to the x-direction.

[0010] Optionally, the triangular prism is an asymmetrical right-angled triangular prism, with one right-angled face of the prism located in the xy plane and the other right-angled face located in the xz plane; the inclined face of the prism and the right-angled face in the xz plane form the inclination angle.

[0011] Optionally, the triangular prism is embedded in the light-absorbing layer, and the surface of the light-absorbing layer facing the light-receiving surface covers the triangular prism.

[0012] Optionally, the microstructure includes a volume grating located on the light-receiving surface of the pixel, and the material forming the volume grating is formed into an inclined structure along the yz plane, wherein the angle between the inclined structure and the y direction is the inclination angle.

[0013] Optionally, the material forming the volume grating may include two materials with different refractive indices.

[0014] Optionally, when the Bragg condition is satisfied: 2psin(θ)=λ / n, where p is the period, θ is the tilt angle, n is the average refractive index of the material, and λ is the working wavelength, the volume grating will have the minimum reflection of light in the xz plane.

[0015] The present invention also provides a detection device, including a photoelectric sensor as described in any of the preceding claims.

[0016] The present invention provides a photoelectric sensor comprising a pixel array; the pixel array includes multiple pixels arranged in an array, including N1 pixels arranged along the x-direction and N2 pixels arranged along the y-direction; when scanning along the x-direction and y-direction sequentially, one column of N1 pixels is opened in each scan; wherein the x and y directions are perpendicular; each pixel's light-receiving surface is provided with multiple anisotropic microstructures, the microstructures forming a one-dimensional grating along the y-direction to diffract light in the y-direction; the microstructures have a tilt angle to reduce light reflection in the x-direction; each pixel also includes a light-absorbing layer and a metal layer on the non-light-receiving surface of the pixel, the microstructures having a low refractive index and the absorption layer having a high refractive index.

[0017] The microstructure ensures that light reflected by the metal layer will only propagate along the x-direction towards the yz plane, thus preventing crosstalk in the y-direction. In the x-direction, due to the one-dimensional scanning method, crosstalk will not affect the final read value, thereby solving the interference caused by crosstalk.

[0018] The present invention also provides a detection device, which has the same beneficial effects as described above, and will not be described in detail here. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the crosstalk phenomenon in existing area array TOF cameras that perform one-time transmission and one-time exposure.

[0021] Figure 2 This is a schematic diagram of one-dimensional partition scanning in the prior art;

[0022] Figure 3 This is a schematic diagram of the microstructure array in a photoelectric sensor provided in an embodiment of the present invention;

[0023] Figure 4 This is a cross-sectional view of a photoelectric sensor in the yz plane provided in an embodiment of the present invention;

[0024] Figure 5 This is a cross-sectional view of a photoelectric sensor provided in an embodiment of the present invention in the xz plane;

[0025] Figure 6 This is a schematic diagram of a photoelectric sensor provided in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of another photoelectric sensor provided in an embodiment of the present invention.

[0027] In the figure: 1. Microstructure, 2. Light absorption layer, 3. Metal layer, 4. Volume grating. Detailed Implementation

[0028] The core of this invention is to provide a photoelectric sensor. Please refer to [link / reference]. Figure 1 , Figure 1 This diagram illustrates the crosstalk phenomenon in existing area array TOF cameras that perform one-shot, one-exposure operations. (See also...) Figure 1 In this type of detector chip, each pixel is turned on at the same time. Therefore, the reflected light from the pixel surface will be reflected by the module's receiving element and then incident on other pixels a second time. The secondary or even multiple reflected signals are mixed with the received signals, causing crosstalk. Figure 1 Crosstalk pixels are affected by secondary reflected light from the received signal pixels, impacting the actual signal readout of that pixel. In area scan mode, if crosstalk is not suppressed, it can cause crosstalk in specific pixels across the entire area scan.

[0029] Please refer to Figure 2 , Figure 2This diagram illustrates a one-dimensional partitioned scanning technique. One-dimensional partitioned scanning can eliminate crosstalk effects in one dimension. In each scan, only a specific rectangular area of ​​the photodetector pixel array is exposed, while pixels in other areas remain inactive and do not read signal light. In this case, even if a receiving pixel emits light, the secondary reflection light hitting the non-exposed area will not affect the actual signal of that pixel; only the secondary reflection light hitting the exposed area will affect the actual signal light of that pixel. Therefore, this partitioned scanning method can improve crosstalk effects in one direction, but it is ineffective against crosstalk effects in the other direction.

[0030] The photoelectric sensor provided by this invention includes a pixel array; the pixel array includes multiple pixels arranged in an array, including N1 pixels arranged along the x-direction and N2 pixels arranged along the y-direction; when scanning along the x-direction and y-direction sequentially, one column of N1 pixels is opened in each scan; wherein the x and y directions are perpendicular; each pixel's light-receiving surface is provided with multiple anisotropic microstructures, the microstructures forming a one-dimensional grating along the y-direction to diffract light in the y-direction; the microstructures have a tilt angle to reduce light reflection in the x-direction; each pixel also includes a light-absorbing layer and a metal layer on the non-light-receiving surface of the pixel, the microstructures have a low refractive index and the absorption layer has a high refractive index.

[0031] The microstructure ensures that light reflected by the metal layer will only propagate along the x-direction towards the yz plane, thus preventing crosstalk in the y-direction. In the x-direction, due to the one-dimensional scanning method, crosstalk will not affect the final read value, thereby solving the interference caused by crosstalk.

[0032] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please refer to Figures 3 to 6 , Figure 3 This is a schematic diagram of the microstructure array in a photoelectric sensor provided in an embodiment of the present invention; Figure 4 This is a cross-sectional view of a photoelectric sensor in the yz plane provided in an embodiment of the present invention; Figure 5 This is a cross-sectional view of a photoelectric sensor provided in an embodiment of the present invention in the xz plane; Figure 6 This is a schematic diagram of a photoelectric sensor provided in an embodiment of the present invention.

[0034] See Figures 3 to 5In this embodiment of the invention, the photoelectric sensor includes a pixel array; the pixel array includes a plurality of pixels arranged in an array, including N1 pixels arranged along the x-direction and N2 pixels arranged along the y-direction; when scanning along the x-direction y-direction, a column of N1 pixels is opened in each scan; wherein the x and y directions are perpendicular; each pixel's light-receiving surface is provided with a plurality of anisotropic microstructures 1, the microstructures 1 forming a one-dimensional grating along the y-direction to diffract light in the y-direction; the microstructures 1 have a tilt angle to reduce light reflection in the x-direction; each pixel also includes a light-absorbing layer 2 and a metal layer 3 on the non-light-receiving surface of the pixel, the microstructures 1 having a low refractive index and the absorption layer having a high refractive index.

[0035] The aforementioned pixel array is a structure for a photoelectric sensor to acquire light signals. This pixel array includes multiple pixels arranged in an array, each capable of independently acquiring light signals and converting them into electrical signals. In this embodiment, each pixel includes a light absorption layer 2 for absorbing light signals and converting them into electrical signals. A metal layer 3 is disposed on the non-light-receiving surface of the pixel, which reflects light, thus creating crosstalk. Specific pixel structures can be found in existing technologies and will not be elaborated upon here.

[0036] In this embodiment, multiple anisotropic microstructures 1 are disposed on the light-receiving surface of each pixel. Firstly, these microstructures 1 are disposed on the light-receiving surface of each pixel, and these microstructures 1 must be anisotropic. Anisotropy means that the microstructure 1 selectively reflects light in all directions, rather than diverging in all directions. Specifically, the microstructure 1 forms a one-dimensional grating along the y-direction to diffract light in the yz-plane. That is, when reflected light passes through the microstructure 1, the reflected light in the yz-plane will produce a significant diffraction effect, so there will be no crosstalk in the x-direction. Combined with the anisotropy of the microstructure 1, the microstructure 1 confines the reflected light to the yz-plane. In this embodiment, based on the yz cross-sectional view, it can be seen that the microstructure 1 has a one-dimensional grating structure in the yz-plane and exhibits a significant diffraction effect. Based on the xz cross-sectional view, it can be seen that the microstructure 1 has translation invariance in the xz-plane and exhibits no diffraction effect.

[0037] In this embodiment, the microstructure 1 has a tilt angle that reduces the reflection of light in the xz plane. Although this structure will generate crosstalk in the x direction, this embodiment specifically performs a one-dimensional scan column by column along the x direction, thus avoiding the influence of crosstalk in the x direction on the signal.

[0038] Specifically, the anisotropic microstructure 1 described above enables reflected light to be essentially concentrated in the yz plane, significantly reducing reflected light in the xz plane. Additionally, this anisotropic microstructure 1 can improve the light absorption capability of the photodetector by scattering incident light, thereby increasing the effective optical path length of light in the absorbing material and also reducing the overall reflectivity. Specifically, the anisotropic reflective effect can be adjusted by changing the tilt angle and array period of the microprisms.

[0039] See Figure 6 By combining the above pixel structure with a one-dimensional pixel scanning method, crosstalk across the entire pixel surface can be completely eliminated. When a pixel receiving a signal emits signal light, due to the anisotropic pixel structure, the reflected light will only appear in a plane perpendicular to the exposed area. Therefore, the secondary reflected light will only hit the non-exposed area, and the secondary reflected light in the exposed area will be greatly attenuated, thus not affecting the real signal light of the pixels in the exposed area.

[0040] In this embodiment, the refractive index of microstructure 1 needs to be lower than that of the absorption layer. When reflected light propagates from the light absorption layer 2 to microstructure 1, it is equivalent to propagating from a high-refractive-index medium to a low-refractive-index medium, thus satisfying the total internal reflection condition. This causes the reflected light to be reflected back to the light absorption layer 2 for absorption due to total internal reflection, thereby effectively improving the absorption efficiency of the light absorption layer 2. The specific materials of microstructure 1 and light absorption layer 2 are not specifically limited in this embodiment, as long as the above relationship is satisfied.

[0041] This application specifically provides two different microstructures 1. In this embodiment, the microstructure 1 may specifically include: a triangular prism array, the triangular prism array including a plurality of triangular prisms with parallel axes, the axes of the triangular prisms being parallel to the x-direction.

[0042] Specifically, the microstructure 1 described above can be a triangular prism structure. The triangular prism itself is anisotropic and has a surface that forms the aforementioned tilt angle. In this embodiment, multiple triangular prisms are arranged parallel to each other along the y-direction to form a one-dimensional grating, and the axial direction of the triangular prisms is set parallel to the x-direction. For reflected light, due to the arrangement of the one-dimensional grating, the triangular prisms will propagate the light along their axial direction, thereby forming a significant diffraction effect in the y-direction that restricts the propagation of reflected light, while there is no diffraction effect in the x-direction that allows the light to propagate. In this embodiment, the size of each triangular prism in the above triangular prism array is not specifically limited, but depends on specific circumstances, such as the wavelength of light that the light absorption layer 2 can absorb.

[0043] Specifically, in this embodiment, the aforementioned triangular prism is typically an asymmetrical right-angled triangular prism, with one right-angled face in the xy-plane and the other right-angled face in the xz-plane; the inclined face of the triangular prism forms the tilt angle with the right-angled face in the xz-plane. At this time, the axis of the triangular prism is set along the x-direction, one right-angled face is parallel to the surface of the light-absorbing layer 2, and the other right-angled face is perpendicular to the surface of the light-absorbing layer 2. The inclined face of the triangular prism forms the tilt angle with the right-angled face in the xz-plane, i.e., with the surface of the light-absorbing layer 2. This inclined face can reduce light reflection in the x-direction.

[0044] Furthermore, in this embodiment, the aforementioned triangular prism can be embedded in the light-absorbing layer 2, with the surface of the light-absorbing layer 2 covering the triangular prism on the side facing the light-receiving surface. Of course, in this case, the triangular prism is only embedded in the surface layer of the light-absorbing layer 2 to increase the absorption of light by the light-absorbing layer 2.

[0045] The photoelectric sensor provided in this embodiment of the invention has a microstructure 1 that ensures that light reflected by the metal layer 3 will only propagate in the yz plane, so as to ensure that no signal crosstalk will be generated in the x direction.

[0046] The specific structure of the photoelectric sensor provided by this invention will be described in detail in the following embodiments.

[0047] Please refer to Figure 7 , Figure 7 This is a schematic diagram of another photoelectric sensor provided in an embodiment of the present invention.

[0048] Unlike the embodiments described above, the embodiments of the present invention further define the content of microstructure 1 based on the embodiments described above. The remaining details have been described in detail in the embodiments described above and will not be repeated here.

[0049] See Figure 7 In this embodiment of the invention, the microstructure 1 includes a volume grating 4 located on the light-receiving surface of the pixel. The material forming the volume grating 4 forms an inclined structure along the yz plane, and the angle between the inclined structure and the y direction is the inclination angle.

[0050] The volume grating 4 is a grating formed by alternating changes in refractive index along a certain direction in three-dimensional space; that is, the volume grating 4 is composed of a material with a uniformly varying refractive index. In this embodiment, the volume grating 4 needs to be formed as a one-dimensional grating along the y-direction, while simultaneously forming a tilt angle to reduce light reflection in the x-direction. Therefore, the material forming the volume grating 4 needs to form a tilted structure along the yz plane, meaning that the morphology of the volume grating 4 mapped onto the yz plane exhibits a tilted structure to achieve the aforementioned effect. The alternating arrangement of the aforementioned tilted structures can form a one-dimensional grating along the y-direction and create the aforementioned tilt angle.

[0051] Specifically, in this embodiment, the materials forming the volume grating 4 include two materials with different refractive indices, which are alternately arranged in the volume grating 4. Black represents one material, and white represents the other, with the refractive index of the black material being higher than that of the white material. When the period, refractive index distribution, and grating vector tilt angle of the volume grating 4 approximately satisfy the Bragg condition, its diffraction efficiency is highest, resulting in the most significant anisotropy of reflection and the best crosstalk suppression effect. That is, in this embodiment, when the Bragg condition is satisfied: 2psin(θ) = λ / n, where p is the period, θ is the tilt angle, n is the average refractive index of the material, and λ is the working wavelength, the volume grating 4 exhibits minimal reflection of light in the xz plane. The aforementioned n is the average refractive index of the two materials forming the volume grating 4. If n1 is the refractive index of the black material and n2 is the refractive index of the white material, then n is the average of n1 and n2. When the volume grating 4 satisfies the above condition, the reflection of light in the xz plane by the volume grating 4 can be further reduced, ensuring less crosstalk in the x-direction. In this embodiment, the degree of anisotropy of the reflection effect can be controlled by adjusting the structural parameters of the microstructure 1. Specifically, crosstalk suppression can be achieved by selecting the parameters of the volume grating 4 to satisfy the Bragg condition, that is, by adjusting the p period and θ tilt angle to improve the crosstalk effect.

[0052] The photoelectric sensor provided in this embodiment of the invention uses a volume grating 4 as a microstructure 1, which ensures that light reflected by the metal layer 3 will only propagate in the yz plane, so as to prevent signal crosstalk in the xz plane.

[0053] This invention also provides a detection device, which includes a photoelectric sensor as described in any of the above embodiments. The remaining structures of the detection device can be found in the prior art and will not be described in detail here.

[0054] Since the detection device provided in this embodiment specifically uses the aforementioned photoelectric sensor, which can effectively solve the interference caused by crosstalk, the detection device provided in this embodiment can also avoid the interference caused by crosstalk and ensure high-quality imaging.

[0055] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0056] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0057] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0058] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The photoelectric sensor and detection device provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A photoelectric sensor, characterized in that, Including pixel arrays; The pixel array includes multiple pixels arranged in an array, comprising N1 pixels arranged along the x-direction and N2 pixels arranged along the y-direction; when scanning along the x-direction y-direction, a column of N1 pixels is opened for each scan; wherein the x and y directions are perpendicular; Each pixel's light-receiving surface is provided with multiple anisotropic microstructures, which form a one-dimensional grating along the y-direction to diffract light in the y-direction; the microstructures have a tilt angle to reduce light reflection in the x-direction; Each pixel also includes a light-absorbing layer and a metal layer on the non-light-receiving surface of the pixel. The microstructure has a low refractive index and the absorption layer has a high refractive index.

2. The photoelectric sensor according to claim 1, characterized in that, The microstructure includes a triangular prism array, which comprises a plurality of triangular prisms with parallel axes, the axes of which are parallel to the x-direction.

3. The photoelectric sensor according to claim 2, characterized in that, The triangular prism is an asymmetrical right-angled triangular prism, with one right-angled face in the xy plane and the other right-angled face in the xz plane; the inclined face of the triangular prism and the right-angled face in the xz plane form the inclination angle.

4. The photoelectric sensor according to claim 2, characterized in that, The triangular prism is embedded in the light-absorbing layer, and the surface of the light-absorbing layer facing the light-receiving surface covers the triangular prism.

5. The photoelectric sensor according to claim 1, characterized in that, The microstructure includes a volume grating located on the light-receiving surface of the pixel, and the material forming the volume grating is formed into an inclined structure along the yz plane, the angle between the inclined structure and the y direction being the inclination angle.

6. The photoelectric sensor according to claim 5, characterized in that, The materials forming the volume grating include two materials with different refractive indices.

7. The photoelectric sensor according to claim 5, characterized in that, When the Bragg condition is satisfied: 2psin(θ)=λ / n, where p is the period, θ is the tilt angle, n is the average refractive index of the material, and λ is the working wavelength, the volume grating minimizes the reflection of light in the xz plane.

8. A detection device, characterized in that, Including the photoelectric sensor as described in any one of claims 1 to 7.

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