阅读说明：本技术 一种光电成像传感器 (Photoelectric imaging sensor ) 是由 赵照 于 2020-05-15 设计创作，主要内容包括：本发明公开了一种光电成像传感器,包括滤光层和成像单元,滤光层由若干个滤光单元组成,每个滤光单元包括四个滤光区,四个滤光区分别允许通过红光、绿光、蓝光和宽光谱光；成像单元用于接收穿过滤光层的光线并进行成像,包括可见光成像单元和单光子成像单元,允许通过红光、绿光和蓝光的滤光区与可见光成像单元对应,允许通过宽光谱光线的滤光区与单光子成像单元对应,单光子成像单元用于接收透过宽光谱滤光区的弱光信号并将弱光信号高倍数放大处理生成图像。本发明基于被测场景环境,可以生成彩色图像或黑白夜视图像；单光子成像单元接收弱光信号并将信号高倍数放大达到光电探测灵敏范围生成图像,有效提高了传感器的灵敏度、信噪比和清晰度。(The invention discloses a photoelectric imaging sensor, which comprises a filter layer and an imaging unit, wherein the filter layer consists of a plurality of filter units, each filter unit comprises four filter zones, and the four filter zones allow red light, green light, blue light and wide spectrum light to pass through respectively; the imaging unit is used for receiving light rays penetrating through the filter layer and imaging, and comprises a visible light imaging unit and a single photon imaging unit, wherein the filter regions allowing red light, green light and blue light to pass correspond to the visible light imaging unit, the filter regions allowing wide-spectrum light rays to pass correspond to the single photon imaging unit, and the single photon imaging unit is used for receiving weak light signals penetrating through the wide-spectrum filter regions and amplifying the weak light signals at high times to generate images. The invention can generate a color image or a black-and-white night vision image based on the detected scene environment; the single photon imaging unit receives the weak light signal and amplifies the signal by high times to reach the photoelectric detection sensitivity range to generate an image, so that the sensitivity, the signal-to-noise ratio and the definition of the sensor are effectively improved.)

1. A photoelectric imaging sensor is characterized by comprising a filter layer and an imaging unit, wherein the filter layer consists of a plurality of filter units, each filter unit comprises four filter zones, and the four filter zones allow red light, green light, blue light and wide spectrum light to pass through respectively; the imaging unit is used for receiving light rays penetrating through the filter layer and imaging, and comprises a visible light imaging unit and a single photon imaging unit, wherein filter areas allowing red light, green light and blue light to correspond to the visible light imaging unit, the filter areas allowing wide-spectrum light to correspond to the single photon imaging unit, and the single photon imaging unit is used for receiving weak light signals penetrating through the wide-spectrum filter areas and amplifying the weak light signals at high times to generate images.

2. The photoelectric imaging sensor according to claim 1, wherein the single photon imaging unit comprises a packaging tube shell and an optical window, the packaging tube shell and the optical window are combined to form a vacuum sealed cavity, a photosensitive cathode and a single photon imaging circuit are arranged in the vacuum sealed cavity, the photosensitive cathode grows on the lower surface of the optical window, the single photon imaging circuit is arranged on the opposite surface of the photosensitive cathode, and photoelectrons released by the photosensitive cathode move to the single photon imaging circuit under the action of an external high voltage.

3. The optoelectronic imaging sensor of claim 2, wherein the single photon imaging circuit comprises a high voltage protection circuit, an acquisition circuit, an amplification circuit, an ADC circuit and an interface circuit, and is fabricated using standard CMOS processes.

4. The optoelectronic imaging sensor of claim 2, wherein the photo-sensing cathode is fabricated using one or more of Si, Ge, GaAs, InGaAsP, InGaAs, or InAs/GaAsSb class II superlattices in a MEMS process.

5. The optoelectronic imaging sensor of claim 2, wherein the vertical distance of the photo-sensing cathode from the single photon imaging circuitry is greater than 1 mm.

6. The optoelectronic imaging sensor of claim 2, wherein the single photon imaging unit is packaged in wafer level, ceramic or metal high vacuum, and the vacuum degree of the vacuum sealed cavity is 1x10^-3Pa or above.

7. The optoelectronic imaging sensor of claim 2, wherein the single photon imaging circuit is fabricated by using MEMS technology to grow photon reflecting walls and electron absorbing wells.

8. The optoelectronic imaging sensor of claim 2, wherein a getter is further disposed within the vacuum-sealed cavity for maintaining a vacuum within the cavity.

9. The optoelectronic imaging sensor according to any one of claims 1 to 8, further comprising a polarizing layer, wherein the polarizing layer is composed of a plurality of polarizing units, the polarizing units are arranged in a two-row and two-column matrix by four polarizing plates with different polarization angles, each polarizing plate corresponds to a filter unit, and the filter layer is located between the polarizing layer and the imaging unit or the polarizing layer is located between the filter layer and the imaging unit.

10. The optoelectronic imaging sensor of claim 9, wherein the angles of the polarization axes of the four polarizers are 0 degrees, 45 degrees, 90 degrees, and 135 degrees, respectively.

Technical Field

The invention relates to the technical field of photoelectric detection, in particular to a photoelectric imaging sensor.

Background

With the increasing importance of society to the security protection field, the application range that it relates increases gradually, and different users also put forward more higher requirements to its relevant equipment and technique simultaneously. The image sensor is used as a core component of a camera and a monitoring device, and has a decisive influence on the quality of images of shot scenes. The demand of users for security monitoring application often requires that a monitoring camera can work continuously for 24 hours, and clear, visual and accurate images must be acquired even at night or in a very weak light environment.

The image sensor utilizes the photoelectric conversion function of the photoelectric device. The light image on the light sensing surface is converted into an electric signal in corresponding proportion to the light image. In contrast to the photosensitive elements of "point" light sources such as photodiodes, phototransistors, etc., image sensors are functional devices that divide the light image on their light-receiving surface into many small cells and convert it into usable electrical signals. The image sensor has the characteristics of small volume, light weight, high integration level, high resolution, low power consumption, long service life, low price and the like, and is widely applied. With the upgrading of user applications, the market needs higher-sensitivity imaging sensors, solving novel applications such as low illumination, large dynamic, wide spectrum, etc.

The single photon detection technology is a weak light detection technology, amplifies photoelectron signals excited by a single photon or a small number of photons, and identifies and extracts extremely weak photoelectron signals through technologies such as pulse discrimination, accumulation and the like, so that the ultra-sensitivity limit of photoelectric detection is reached. The single photon detection technology has wide application in the fields of high-resolution spectral measurement, nondestructive substance analysis, high-speed phenomenon detection, precision analysis, atmospheric pollution detection, bioluminescence, radiation detection, high-energy physics, astronomical photometry, optical time domain reflection, quantum key distribution systems and the like. The detector for single photon detection mainly comprises a photomultiplier tube (PMT), an Avalanche Photodiode (APD), a Single Photon Avalanche Diode (SPAD), a silicon photomultiplier tube (SIPM), an enhanced photodiode (IPD), an electron multiplying CCD (EMCCD), a scientific sCMOS and the like. However, the existing single photon detectors have certain limitations, such as low quantum efficiency of PMT in an infrared band, large volume and easy interference of an external magnetic field; APD has the disadvantages of low gain, high noise, complex peripheral control circuit and thermoelectric refrigeration circuit.

Disclosure of Invention

The invention aims to provide a photoelectric imaging sensor which is compatible with visible light and low-light night vision imaging, has the performances of large dynamic range, high resolution, high sensitivity, wide detection spectrum range and the like, and has the following specific technical scheme:

a photoelectric imaging sensor comprises a filter layer and an imaging unit, wherein the filter layer consists of a plurality of filter units, each filter unit comprises four filter zones, and the four filter zones allow red light, green light, blue light and wide spectrum light to pass through respectively; the imaging unit is used for receiving light rays penetrating through the filter layer and imaging, and comprises a visible light imaging unit and a single photon imaging unit, wherein filter areas allowing red light, green light and blue light to correspond to the visible light imaging unit, the filter areas allowing wide-spectrum light to correspond to the single photon imaging unit, and the single photon imaging unit is used for receiving weak light signals penetrating through the wide-spectrum filter areas and amplifying the weak light signals at high times to generate images.

Furthermore, the single photon imaging unit comprises a packaging tube shell and an optical window, the packaging tube shell and the optical window are combined to form a vacuum sealed cavity, a photosensitive cathode and a single photon imaging circuit are arranged in the vacuum sealed cavity, the photosensitive cathode grows on the lower surface of the optical window, the single photon imaging circuit is arranged on the opposite surface of the photosensitive cathode, and photoelectrons released by the photosensitive cathode move to the single photon imaging circuit under the action of an external high voltage.

Furthermore, the single photon imaging circuit comprises a high-voltage protection circuit, an acquisition circuit, an amplification circuit, an ADC circuit and an interface circuit, and is prepared by adopting a standard CMOS process.

Preferably, the photosensitive cathode is made of one or more of Si, Ge, GaAs, InGaAsP, InGaAs or InAs/GaAsSb II type superlattice by MEMS process.

Preferably, the vertical distance between the photosensitive cathode and the single photon imaging circuit is more than 1 mm.

Preferably, the single photon imaging unit is packaged by adopting wafer level, ceramic or metal high vacuum, and the vacuum degree of the vacuum sealed cavity is 1x10^-3Pa or above.

Furthermore, a photon reflecting wall and an electron absorption trap are processed and grown on the single photon imaging circuit by adopting an MEMS (micro electro mechanical system) process.

Further, a getter is arranged in the vacuum sealing cavity and used for maintaining the vacuum degree in the cavity.

Furthermore, the photoelectric imaging sensor also comprises a polarizing layer, wherein the polarizing layer is composed of a plurality of polarizing units, the polarizing units are formed by arranging four polarizing plates with different polarizing angles into a matrix with two rows and two columns, each polarizing plate corresponds to one filtering unit, and the filtering layer is positioned between the polarizing layer and the imaging unit or the polarizing layer is positioned between the filtering layer and the imaging unit.

Preferably, the angles of the polarization axes of the four polarizing plates are 0 degree, 45 degree, 90 degree and 135 degree, respectively.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, four filter regions of red, green and blue and a broad spectrum are arranged, the red, green and blue filter regions correspond to a visible light imaging unit, the broad spectrum filter region corresponds to a single photon imaging unit, a color image or a black and white night vision image is generated, and based on a detected scene environment and a user selection mode, color or low-light night vision imaging is supported;

(2) the single photon imaging unit receives the weak light signal which penetrates through the wide spectrum light filter area, amplifies the weak light signal at high times to reach a photoelectric detection sensitivity range to generate an image, and effectively improves the sensitivity, the signal-to-noise ratio and the definition of the sensor;

(3) the invention is based on MEMS technology to package the photosensitive cathode and the single photon imaging circuit in high vacuum, has high integration level and obviously reduces the volume of the sensor; the photosensitive cathode can be made of various materials, and the electromagnetic wave with the wave band of 300nm-14um can be received by changing different materials, so that the spectral response range is wide.

Drawings

FIG. 1 is an exploded schematic view of one embodiment of the present invention;

FIG. 2 is a schematic diagram of a filter unit according to the present invention;

FIG. 3 is a schematic diagram of a single photon imaging unit according to the present invention;

FIG. 4 is a schematic diagram of a single photon imaging circuit in accordance with the present invention;

FIGS. 5a and 5b are exploded schematic views of another embodiment of the present invention;

fig. 6 is a schematic structural view of a polarizing unit in the present invention.

Detailed Description

The following detailed description of the embodiments and specific operations of the present invention will be made with reference to fig. 1 to 6, but the scope of the present invention is not limited to the following examples.

The invention discloses a photoelectric imaging sensor, which comprises a filter layer 1 and an imaging unit 2, wherein as shown in fig. 1, the filter layer 1 consists of a plurality of filter units 11, each filter unit 11 comprises four filter regions 111, and the four filter regions 111 allow red light, green light, blue light and wide spectrum light to pass through and are respectively named as R, G, B, BR filter regions as shown in fig. 2. The imaging unit 2 is configured to receive light passing through the filter layer 1 and perform imaging, and includes a visible light imaging unit 21 and a single photon imaging unit 22 (filled portion in fig. 1). The filter regions allowing red light, green light and blue light to pass correspond to the visible light imaging unit 21, i.e. the visible light imaging unit receives the light filtered by the red, green and blue filter regions to generate a color image, and such an imaging method is commonly used in bright light scenes in daytime. The filter area allowing the light with the wide spectrum to pass through corresponds to the single photon imaging unit 22, where the wide spectrum includes a visible light band and an invisible light band, the filter area allowing the light with the wide spectrum may also be a filter area allowing a specific band, such as a filter area allowing an infrared band to pass through, and the filter area with the wide spectrum and the single photon imaging unit are used in a low-light night vision scene, and the single photon imaging unit 22 receives a low-light signal passing through the filter area with the wide spectrum and amplifies the low-light signal by a high factor to achieve a photoelectric detection sensitivity range to generate a black-and-white image. The four filter regions may be integrally formed, or the four filter regions may be combined together by gluing or the like to form one filter unit.

The invention can select a daytime mode or a night vision mode based on the use scene of a user, the daytime mode and the night vision mode can be realized by respectively arranging switches on the visible light imaging unit and the single photon imaging unit, and the selection of different modes can be realized according to the on-off of the user use scene selection switch. In different scene modes, the visible light imaging unit 21 or the single photon imaging unit 22 generates corresponding images. When the using scene is daytime strong light, the switch on the visible light imaging unit is closed, the switch on the single photon imaging unit is opened, and the visible light imaging unit receives light passing through the red, green and blue filter regions to generate a color image. When the scene of use is low-light night vision, a switch on the visible light imaging unit is disconnected, a switch on the single photon imaging unit is closed, the single photon imaging unit receives a weak light signal penetrating through the wide spectrum light filtering area and amplifies the weak light signal to reach a photoelectric detection sensitivity range to generate a black-and-white image, a user can select to close the switch on the visible light imaging unit under the low-light night vision scene, the visible light imaging unit and the single photon imaging unit work simultaneously, and a color night vision image is generated through image fusion. It should be noted that, in a low-light night vision scene, whether the visible light imaging unit works or not needs to be selected according to the actual situation of the field, and when the noise introduced by opening the visible light imaging unit is large, only the single photon imaging unit is selected to work to generate a black-and-white image.

Specifically, the single photon imaging unit includes a package 221 and an optical window 222, as shown in fig. 3, the package 221 and the optical window 222 form a vacuum-sealed cavity, and the optical window 222 is used for projecting optical signals. The vacuum sealed cavity is internally provided with a photosensitive cathode 223 and a single photon imaging circuit 224, the photosensitive cathode 223 grows on the lower surface of the optical window 222, the single photon imaging circuit 224 is arranged on the opposite surface of the photosensitive cathode 223, and photoelectrons released by the photosensitive cathode 223 move to the single photon imaging circuit 224 under the action of an external high voltage. The photosensitive cathode 223 is made of one or more of Si, Ge, GaAs, InGaAsP, InGaAs or InAs/GaAsSb II type superlattice by MEMS process. By replacing different materials, the photosensitive cathode 223 can realize the reception of electromagnetic waves with wave bands of 300nm-14um, so the spectral response range of the invention is wide. The vertical distance between the photosensitive cathode 223 and the single photon imaging circuit 224 is greater than 1mm, and the setting distance between the photosensitive cathode 223 and the single photon imaging circuit 224 is different according to the difference of bias voltage.

In the present invention, the single photon imaging circuit 224 is used for receiving the optoelectronic signal, and processing and outputting the signal, as shown in fig. 4, and specifically comprises a high voltage protection circuit, an acquisition circuit, an amplification circuit, an ADC circuit and an interface circuit, and is prepared by a standard CMOS process. After single or a plurality of photons enter the photosensitive cathode 223 through the optical window 222, a photoelectric effect is triggered to generate photoelectrons, the photoelectrons are accelerated to fly to the pixel structure anode (namely, the acquisition anode) on the acquisition circuit under the action of a high-voltage electric field, a large number of electron-hole pairs are generated inside the acquisition circuit under the bombardment of high-energy electrons, so that the photoelectron signals are amplified in high times, and then the photoelectron signals are processed by the amplification circuit and the ADC circuit, so that the signal-to-noise ratio, the sensitivity and the definition are integrally and effectively improved, and the interface circuit is used for. The whole single-photon imaging circuit is in an ultrahigh vacuum working state.

In order to maintain the vacuum degree in the cavity, one or more getters 225 are further disposed in the vacuum-sealed cavity, and preferably, the getters 225 are film-type getters and can be adhered to the lower surface of the optical window 222.

The single photon imaging unit is packaged by adopting wafer level, ceramic or metal high vacuum, and the vacuum degree of a vacuum sealed cavity is 1x10^-3Pa or above. The photosensitive cathode is prepared by adopting an MEMS (micro-electromechanical system) process, the single photon imaging circuit is prepared by adopting a standard CMOS (complementary metal oxide semiconductor) process, the whole body is packaged in a wafer level, ceramic or metal high vacuum mode, the integration level is high, and the volume of the product is obviously reduced compared with that of a traditional product.

The light is a transverse wave, light vectors may have various vibration states in a two-dimensional space perpendicular to the propagation direction of the light, and in order to enhance the difference between a disguised/invisible target and a background and improve the target detection and identification capability of the photoelectric sensor, the photoelectric imaging sensor is further provided with a polarization layer 3, as shown in fig. 5a and 5b, the polarization layer 3 is composed of a plurality of polarization units 31, the polarization units 31 are formed by arranging four polarizing plates 311 with different polarization angles into a matrix with two rows and two columns, for example, the angles of the polarization axes of the four polarizing plates are respectively 0 degree, 45 degrees, 90 degrees and 135 degrees, and are arranged into a matrix with two rows and two columns, as shown in fig. 6. Each polarizing plate 311 corresponds to one filter unit 11, the filter layer 1 is located between the polarizing layer 3 and the imaging unit 2 or the polarizing layer 3 is located between the filter layer 1 and the imaging unit 2, and in the actual use process, the positions of the filter layer 1 and the polarizing layer 3 can be flexibly set according to needs. In addition, when the filter layer 1 is located between the imaging unit 2 and the polarization layer 3, since the polarization layer 1 often uses metal gratings arranged at intervals, and the location of the polarization layer 3 between the imaging unit 2 and the filter layer 1 causes uneven placement of the filter layer 1, it is preferable to choose to dispose the filter layer 1 between the polarization layer 3 and the imaging unit 2, so that the filtering effect is good. The imaging unit 2 receives the polarized light passing through the corresponding filter region 111 and having different polarization angles, so that the polarized light with four different polarization angles in the shot scene can be obtained, and the utilization range of the shot scene is improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.