CN217982098U - Liquid crystal polarization camera system based on micro-lens array - Google Patents

Abstract

The application discloses a liquid crystal polarization camera system based on a micro-lens array. The system comprises: the micro-lens array is arranged in parallel relative to the liquid crystal polarizing film and comprises a plurality of micro-lens units which are regularly arranged, each micro-lens unit corresponds to each focal plane unit on the liquid crystal polarizing film, light is split into a plurality of beams after being incident to the micro-lens array, the beams penetrate through the liquid crystal polarizing film and are respectively focused on the image sensor, the beams penetrate through the micro-lens array to be split and focused on the corresponding liquid crystal polarizing film, the liquid crystal polarizing film is filtered in four-angle polarization directions, the four-angle polarization units serve as a macro-polarization unit and are sequentially distributed on the whole liquid crystal polarizing film, the linearly polarized light after being filtered is received by a camera image sensing device, and the collected light field information is reconstructed to obtain a polarization image. The integrated circuit has the advantages of simple structure, high integration level, small volume, low cost and the like.

Description

A Liquid Crystal Polarization Camera System Based on Microlens Array

technical field

The application belongs to the technical field of optical imaging, and in particular relates to a liquid crystal polarization camera system based on a microlens array.

Background technique

In addition to acquiring the light intensity, spectrum, and space information of the beam reflected by the object, polarization imaging technology can also acquire the polarization state information of the beam, which can improve the information dimension of the image, so that the image can reflect more detailed information of the object itself. At present, polarization cameras mainly use polarization elements to integrate with image sensing equipment, which has the problems of large size, low integration, and high cost.

Utility model content

In order to solve the aforementioned problems of large size and low integration of the polarization camera, the present application proposes a liquid crystal polarization camera system based on a microlens array. The system is also effective in reducing costs.

In order to achieve the above object, the application adopts the following technical solutions:

A kind of liquid crystal polarization camera system based on microlens array, it is characterized in that, comprises:

A microlens array, a liquid crystal polarizing film, and an image sensor, the microlens array and the liquid crystal polarizing film are relatively parallel to each other,

The microlens array includes a plurality of regularly arranged microlens units, and each of the microlens units corresponds to each focal plane unit on the liquid crystal polarizing film,

After the light is incident on the microlens array, it is split into multiple beams, passes through the liquid crystal polarizing film and focuses on the image sensor respectively.

Preferably, the liquid crystal polarizing film is bonded (seamlessly bonded) to the image sensor. The bonding state between the liquid crystal polarizing film and the image sensor can reduce the crosstalk of the filtered light beam during transmission to the image sensor, which can reduce the possibility of the image sensor obtaining wrong information.

Preferably, the microlens unit is a plano-convex lens. The structure can focus the light beam, and at the same time, its processing is relatively labor-saving and the thickness is thinner.

Preferably, the image sensor is arranged at the focal length of the microlens array. This can reduce the overall size of the polarization camera.

Preferably, the liquid crystal polarizing film includes a plurality of polarizing picture elements, which correspond to the microlens units one by one,

When the microlens array splits the incident light, it will focus on the corresponding pixel units respectively, so that the light distribution can be made uniform.

Preferably, the focal length of the microlens unit satisfies the formula condition

Where, f is the focal length of the microlens, N is the refractive index of the microlens, and R is the radius of curvature of the microlens.

Preferably, the liquid crystal polarizing film includes four polarizing units that are sequentially arranged and spliced with different polarization angles and focal planes, and the image sensor receives the light field information that has been split and polarized and filtered by the liquid crystal polarizing film for image reconstruction.

Preferably, in the microlens array-based liquid crystal polarization camera system, the polarization units on each of the focal planes correspond to the pixel units on the image sensor one-to-one, so that each pixel unit can only obtain polarization information in one direction .

Preferably, in the liquid crystal polarization camera system based on the microlens array, the light beam after polarization filtering is transmitted to the pixel unit of the image sensor, and the image sensor will acquire a single polarization information and spectral information, and reconstruct the acquired light field information structure.

Preferably, the microlens array includes a transparent substrate, and a plurality of regularly arranged microlens units are arranged on the side of the substrate away from the image sensor.

Beneficial effect

Compared with the prior art, the microlens array-based liquid crystal polarization camera system proposed in this application is a system integrating the microlens array, liquid crystal polarizing film and camera image sensor, and the light beam is split through the microlens array Focusing on the corresponding liquid crystal polarizing film, the liquid crystal polarizing film filters the polarization directions of four angles, and the polarizing units of the four angles are used as a macro polarizing unit, and the entire liquid crystal polarizing film is arranged in sequence, and the filtered linearly polarized light is The image sensor system of the camera receives and reconstructs the collected light field information to obtain a polarization image. It has the advantages of simple structure, high integration, small volume and low cost. The disadvantages of high cost and low integration of the original polarization camera are avoided.

Description of drawings

The accompanying drawings are used to provide an understanding of the technical solutions of the present disclosure, and constitute a part of the specification, and are used together with the embodiments of the present disclosure to explain the technical solutions of the present disclosure, and do not constitute limitations to the technical solutions of the present disclosure. The shape and size of each component in the drawings do not reflect the real scale, and the purpose is only to illustrate the content of the present application.

1 is a schematic diagram of a liquid crystal polarization camera system based on a microlens array according to an embodiment of the present application;

In Fig. 2, a is a schematic diagram of the microlens array of the embodiment of the present application, and b is a schematic diagram of the microlens unit of the embodiment of the present application;

FIG. 3 is a partial schematic diagram of a four-angle polarizing element in an embodiment of the present application;

4 is a schematic diagram of the assembly of a microlens array, a liquid crystal polarizing film, and an image sensor according to an embodiment of the present application;

Where: 301 is a natural light source, 302 is a microlens array, 303 is a liquid crystal polarizing film, 304 is an image sensor, 305 is a microlens unit, and 306 is a four-angle linear polarization unit.

detailed description

The above solution will be further described below in conjunction with specific embodiments. It should be understood that these examples are used to illustrate the present application and not limit the scope of the present application. The implementation conditions adopted in the examples can be further adjusted as the conditions of specific manufacturers, and the implementation conditions not indicated are usually the conditions in routine experiments.

Unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present disclosure shall have the common meanings understood by those skilled in the art to which the present application belongs. "First", "second" and similar words used in the embodiments of the present disclosure do not indicate any sequence, quantity or importance, but are only used to distinguish different components. "Comprising" or "comprising" and similar words mean that the elements or items appearing before the word include the elements or items listed after the word and their equivalents, without excluding other elements or items. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Herein, "electrically connected" includes the case where constituent elements are connected together through an element having some kind of electrical function. The "element having some kind of electrical action" is not particularly limited as long as it can transmit and receive electrical signals between connected components. "Up", "Down", "Left", "Right" and so on are only used to indicate the relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

In the present application, the orientations or positional relationships indicated by the terms "upper", "lower", "inner", "middle", etc. are based on the orientations or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

This application proposes a liquid crystal polarization camera system based on a microlens array, including: a microlens array, a liquid crystal polarizing film, and an image sensor;

Wherein, the microlens units in the microlens array are plano-convex lenses, and each lens corresponds to each focal plane unit on the polarizing element. After the natural light is incident on the microlens array, it is split into multiple beams and focused onto the image sensor. The liquid crystal polarizing film is made of liquid crystal and dichroic dyes, and it is a polarizing film with four polarization angles and focal planes, which is seamlessly bonded to the image sensor. The image sensor receives the beam-splitting and polarization-filtered light field information for image reconstruction, and the image sensor is placed at the focal length of the microlens array. The working mechanism of the system: the microlens array, liquid crystal polarizing film, and image sensor are placed in parallel, the liquid crystal polarizing film is bonded to the image sensor, and the integrated module of the liquid crystal polarizing film and the image sensor is placed at the focal length of the microlens array. When the external natural light enters and passes through the microlens array, the natural light will be divided into many beams and transmitted to each pixel of the image sensor respectively, and the corresponding liquid crystal polarizing film in front of the image sensor will filter it to obtain a single polarization information and then transmit it to On the image sensor, it is received, and finally the collected light field information is reconstructed to obtain an image. In this embodiment, the integration of the microlens array, the liquid crystal polarizing film and the image sensor can improve the integration degree of the polarization camera and reduce the volume and cost of the polarization camera. The camera imaging system uses a CMOS camera, which has the characteristics of low power consumption, high integration and fast response speed. Each electrical component can be integrated on one chip and has multiple charge-voltage converters and row-column switch controls. Its readout speed is fast. Imaging devices such as CCD can also be used according to actual needs.

其中f是微透镜焦距，N为微透镜折射率，R为微透镜曲率半径。微透镜阵列可采用平凸结构，该结构能对光束起聚焦的作用，同时其加工相对省力，厚度更薄。Microlens array module: The microlens array not only has the functions of focusing and imaging that traditional lenses have, but also has the characteristics of small unit size and high integration, and can form different optical systems to achieve what is difficult to achieve with traditional optical devices. Function. Microlenses adjust incoming light so that it is focused on a single pixel, which reduces crosstalk between light rays. The microlens unit structure adopts a plano-convex structure, and the microlens array corresponds to the polarization pixels on the liquid crystal polarizing film one by one. When the microlens array splits the incident light, it will focus on the corresponding units respectively, which can make the light distribution uniform. . Among them, the focal length of the microlens satisfies the formula condition

Where f is the focal length of the microlens, N is the refractive index of the microlens, and R is the radius of curvature of the microlens. The microlens array can adopt a plano-convex structure, which can focus the light beam, and at the same time, its processing is relatively labor-saving and its thickness is thinner.

Liquid crystal polarizing film module: liquid crystal, dichroic dye and photo-alignment agent are used as materials for the liquid crystal polarizing film. Among them, four focal planes with different polarization angles are used for patterning. The polarization units on the focal plane correspond to the pixels on the image sensor one by one, and each pixel can only obtain polarization information in one direction. The bonding state between the liquid crystal polarizing film and the image sensor can reduce the crosstalk of the filtered light beam during transmission to the image sensor, which can reduce the possibility of the image sensor obtaining wrong information. The photo-alignment agent for preparing the liquid crystal polarizing film adopts SD1 molecule. SD1 has the characteristics of rewriting and writing, which can improve the error tolerance rate of the preparation, and its alignment exposure energy is low, and the alignment effect is good.

Image sensor module: The polarization-filtered light beam is transmitted to the pixel unit of the image sensor, and the image sensor will obtain a single polarization information and spectral information, and reconstruct the obtained light field information. The image sensor is placed at the focal length of the microlens array, and the focal length of the microlens array is small, which can reduce the overall volume of the polarization camera. The camera imaging system uses a CMOS camera, which has the characteristics of low power consumption, high integration and fast response speed. Each electrical component can be integrated on one chip and has multiple charge-voltage converters and row-column switch controls. Its readout speed is fast. Imaging devices such as CCD can also be used according to actual needs.

Next, the microlens array-based liquid crystal polarization camera system proposed by the present application will be described with reference to the accompanying drawings 1-4.

The liquid crystal polarization camera system based on a microlens array includes a natural light source 301 , a microlens array 302 , a liquid crystal polarizing film 303 , an image sensor 304 , a microlens unit 305 and a four-angle linear polarization unit 306 . Wherein, the beam split and focused by the natural light source 301 incident on the microlens array 302 is filtered by the liquid crystal polarizing film 303 and transmitted to the image sensor 304 to acquire information.

The three interfaces of the microlens array 302 , the liquid crystal polarizing film 303 and the image sensor 304 are parallel, wherein the image sensor 304 is placed at the focal length f of the microlens array 302 , and the liquid crystal polarizing film 303 and the image sensor 304 are bonded together.

The microlens array 302 includes a plurality of microlens units 305, and its structure adopts a plano-convex structure.

The macro-pixel unit of the liquid crystal polarizing film 302 is a four-angle linear polarization unit 306, which adopts four different angles. In this example, a CMOS camera is used, where the resolution of the camera is 2448×2048, and the pixel unit size is 3.45 μm×3.45 μm. The polarizing units of the liquid crystal polarizing film 303 correspond to the pixel units one by one, so its size is 3.45 μm×3.45 μm, and the number of polarizing units is 2448×2048. The four polarized pixel units adjacent to the upper, lower, left, and right sides of the liquid crystal polarizing film are a macro pixel unit, that is, the number of macro pixel units is 1224×1024, and the polarization directions are 0°, 45°, 90° and 135° respectively. The microlens unit 305 (see figure b in FIG. 2 ) of the microlens array 302 (see figure a in FIG. 2 ) needs to be focused to the corresponding polarization unit, and the size is also set to 3.45 μm×3.45 μm, and the number of microlens units 305 is 2448 ×2048, the refractive index of the microlens unit is 1.49, and its focal length f is 1.02mm, that is, the distance between the microlens array 302 and the image sensor is 1.02mm.

In this embodiment, the liquid crystal polarizing film 303 is prepared by using SD1 spin-coating exposure orientation, and then spin-coating liquid crystal and dichroic dye solution to guide the arrangement of liquid crystal and dichroic dye. After the light beam passes through the microlens array 302 , an adjusted light beam can be obtained. The light beam will pass through a single polarized pixel unit and will not be incident on other pixel units, thereby avoiding light crosstalk. After the adjusted light beam passes through the liquid crystal polarizing film 303, linearly polarized light with a single polarization direction can be obtained, and the light field information is obtained after being transmitted to the pixel unit of the image sensor 304 through the RGB filter, and the polarization is obtained after internal data processing and image reconstruction. image.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those familiar with this technology to understand the content of the present application and implement it accordingly, and not to limit the protection scope of the present application. All equivalent changes or modifications made according to the spirit of the present application shall fall within the protection scope of the present application.

Claims (10)

1. A liquid crystal polarization camera system based on microlens array, is characterized in that, comprises: A microlens array, a liquid crystal polarizing film, and an image sensor, the microlens array and the liquid crystal polarizing film are relatively parallel to each other, The microlens array includes a plurality of regularly arranged microlens units, and each of the microlens units corresponds to each focal plane unit on the liquid crystal polarizing film, After the light is incident on the microlens array, it is split into multiple beams, passes through the liquid crystal polarizing film and focuses on the image sensor respectively. 2. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The liquid crystal polarizing film is attached to the image sensor. 3. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The microlens unit is a plano-convex lens. 4. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The image sensor is configured at the focal length of the microlens array. 5. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The liquid crystal polarizing film includes a plurality of polarizing picture elements, which correspond to the microlens units one by one, When the microlens array splits the incident light, it will focus on the corresponding pixel units respectively, so that the light distribution can be made uniform. 6. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The focal length of the microlens unit satisfies the formula condition

Where, f is the focal length of the microlens, N is the refractive index of the microlens, and R is the radius of curvature of the microlens. 7. the liquid crystal polarization camera system based on microlens array as described in any one in claim 1-6, it is characterized in that, The liquid crystal polarizing film includes four sequentially arranged polarization units spliced with different focal planes, and the image sensor receives the light field information after beam splitting and polarization filtering of the liquid crystal polarizing film for image reconstruction. 8. the liquid crystal polarization camera system based on microlens array as claimed in claim 7, is characterized in that, The polarization units on each of the focal planes are in one-to-one correspondence with the pixel units on the image sensor, so that each pixel unit can only obtain polarization information in one direction. 9. the liquid crystal polarization camera system based on microlens array as claimed in claim 8, is characterized in that, The polarization-filtered light beam is transmitted to the pixel unit of the image sensor, and the image sensor will obtain a single polarization information and spectral information, and reconstruct the obtained light field information. 10. the liquid crystal polarization camera system based on microlens array as claimed in claim 1, is characterized in that, The microlens array includes a transparent substrate, and a plurality of regularly arranged microlens units are arranged on the side of the substrate away from the image sensor.

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