CN109547718B

CN109547718B - Miniaturized high-gain low-illumination night vision imaging device

Info

Publication number: CN109547718B
Application number: CN201811469603.0A
Authority: CN
Inventors: 张昆林; 靳英坤; 谭何盛; 杨文波; 苏德坦; 朱锦文; 李晓露
Original assignee: North Night Vision Technology Co Ltd
Current assignee: North Night Vision Technology Co Ltd
Priority date: 2018-12-04
Filing date: 2018-12-04
Publication date: 2020-11-27
Anticipated expiration: 2038-12-04
Also published as: CN109547718A

Abstract

The invention discloses a miniaturized high-gain low-illumination night vision imaging device which is mainly used for military helmet night vision devices and similar night vision products used in related industries. The main technical scheme is as follows: the input end of the tube shell is hermetically welded with the input window, and the tail end of the tube shell is hermetically welded with the output end of the CMOS image sensor; the photocathode is plated in the effective area of the inner surface of the input window; the microchannel plate is arranged between the second metal ring and the third metal ring of the tube shell; the CMOS image sensor is welded with the ceramic substrate, and the output end of the CMOS image sensor is connected with the reading circuit board. The invention proves through trying: fundamentally has overcome former device gain phenomenon low, reaches to improve device gain effectively, realizes the miniaturization, adapts to the demand of single night vision products such as military helmet night-vision device.

Description

Miniaturized high-gain low-illumination night vision imaging device

Technical Field

The invention relates to a photoelectric imaging device, in particular to a low-illumination night vision imaging device of a miniaturized high-gain electron bombardment CMOS image sensor, which is mainly used for military helmet night vision devices and similar night vision products used in related industries.

Background

With the development of the CMOS image sensor technology, an electron-bombarded CMOS image sensor (hereinafter, referred to as an electron-bombarded CMOS low-illumination night vision imaging device) is used as a novel low-illumination imaging device, and has important applications in the fields of safety supervision, medicine, scientific research, and the like. In military night vision instruments represented by helmet night vision products, in order to meet the requirements of individual soldiers on night operation, advancing and observation, the night vision instruments need to have good imaging performance under the condition of low illumination, and also need to have small volume and light weightAnd a long service life. The military individual night vision device such as helmet night vision system equipped by the existing low-light image intensifier can basically meet the general use requirement although being used for years by army and related units, but the illumination can only be 10^-3The operation above lx, the low effect of illuminance is worse, for example, the working distance, resolution and the like can not meet the requirements, and simultaneously, the size and the weight are not ideal, so that the lamp is not convenient for individuals such as single soldiers to carry at night, and can not meet the requirements of actual combat and actual conditions.

The imaging principle of the existing electron bombardment CMOS low-illumination night vision imaging device (see figure 1) is as follows: in the tube shell 3, incident light irradiates the surface of the photocathode 2 through the input end 1 to generate photoelectrons, the photoelectrons are accelerated under the action of a high-voltage electric field and strike the CMOS image sensor 4 to generate electron hole pairs and generate more multiplied electrons under the action of an internal bias electric field, the electrons bombard a semiconductor to realize gain, and the electrons are collected by a potential well in the semiconductor and read out by a read-out circuit 5 at the rear end to obtain a required video image. The device has the weight of 57 g, small volume and light weight, but the gain is only about 200-500 times, and obviously, the device cannot be used for low illumination 10^-3The military helmet night vision system operating below lx can only be used for general civil night vision instruments and bioluminescence imaging, which is determined by the performance of CMOS image sensors.

The other kind of electron bombarded CMOS low-illumination night vision imaging device (see figure 2) consists of an input end 1, a photocathode 2, a tube shell 3, a CMOS image sensor 4, a reading circuit 5, a metal ring (electrode) 6 and a magnetic field generator 7, adopts static electricity and magnetic field composite aggregation, utilizes a plurality of electrodes to accelerate photoelectrons, and utilizes the magnetic field generator 7 to focus the photoelectrons on the surface of the CMOS image sensor 4, can obtain high image resolution under the condition of low photoelectron energy, and prolongs the service life of the imaging device. However, the gain is only about 200 times, the use of a plurality of electrodes and magnetic field generators leads to large volume and heavy weight, and the equipped complete machine is difficult to realize miniaturization, so the night vision system is not suitable for a military helmet night vision system, and can only be used for detecting general weak light signals.

Disclosure of Invention

The invention mainly aims to overcome the defect of the conventional electron bombardment CMOS low-illumination night vision imaging device, and designs a miniaturized high-gain low-illumination night vision imaging device, so that the phenomenon of low gain of the conventional device is fundamentally overcome, the gain of the device is effectively improved, the miniaturization is realized, the service life is prolonged, and the device meets the requirements of single night vision products such as military helmet night vision devices and the like.

The main technical scheme of the invention is as follows: the device comprises an input window, a photoelectric cathode, a tube shell, a CMOS image sensor, a reading circuit, a microchannel plate, a getter, a flange plate, a Ni metal film layer, a Cr metal film layer and a ceramic substrate, and has the specific structure that A, a first metal ring at the input end of the tube shell and the input window are hermetically welded through low-temperature indium-tin alloy solder, and a fifth metal ring at the tail end of the tube shell and the flange plate of a signal output end component of the CMOS image sensor are hermetically welded through laser, so that the input window, the tube shell and the signal output end form a closed tubular body; B. wherein the photocathode is plated in the central effective area of the inner surface of the input window, and the photocathode is connected with the Ni and Cr metal film layer at the edge of the input window; C. the microchannel plate is arranged between the second metal ring and the third metal ring of the tube shell through a spring pressing ring; D. welding a getter on the inner wall of the fourth metal ring; E. the distance from the micro-channel plate to the photoelectric cathode is 0.08 mm-0.2 mm, and the distance from the micro-channel plate to the CMOS image sensor is 0.3 mm-0.8 mm; F. the CMOS image sensor is connected with the ceramic substrate in a welding way, and the ceramic substrate is connected with the flange plate in a welding way through glass powder; G. the output end of the CMOS image sensor is connected with the reading circuit.

The invention proves through trying: the invention achieves the aim of fully developing, obtains higher brightness gain, and the gain can reach 10⁵Multiple, 10 times the gain of the original device³Doubling; the night vision device of the military helmet can be arranged at the illumination of 10^-4The working under the condition of lx is lower than the original illumination by less than one order of magnitude; the service life exceeds 5000 hours; in the aspects of volume and weight, the device is smaller and lighter than a low-light-level image intensifier, so that the military helmet night vision device and similar night vision products are easier to realize miniaturization.

Drawings

The following describes in further detail embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a conventional electron-bombarded CMOS low-illumination night vision imaging device.

FIG. 2 is a schematic diagram of another conventional electron-bombarded CMOS low-illumination night-vision imaging device.

Fig. 3 is a schematic structural diagram of the present invention.

Fig. 4 is a structural sectional view of the tube case 3 of the present invention.

Fig. 5 is a schematic diagram illustrating the operation of the present invention.

Fig. 6 is a schematic view of the working principle of the night vision device for the military helmet of the present invention.

Detailed Description

With reference to fig. 3, the main technical solution of the present invention is explained: the invention comprises an input window 1, a photocathode 2, a tube shell 3, a CMOS image sensor 4, a reading circuit 5, a microchannel plate 8, a getter 9, a flange plate 10, a Ni and Cr metal film layer 11 and a ceramic substrate 12, and has the specific structure that A, a first metal ring 3a at the input end of the tube shell 3 and the input window 1 are hermetically welded through a low-temperature indium-tin alloy solder, and a fifth metal ring 3i at the tail end of the tube shell 3 and the flange plate 10 of a signal output end component of the CMOS image sensor 4 are hermetically welded through laser, so that the input window 1, the tube shell 3 and the signal output end form a closed tubular body; B. wherein the photocathode 2 is plated in the central effective area of the inner surface of the input window, and the photocathode 2 is connected with the Ni and Cr metal film layer 11 at the edge of the input window; C. the microchannel plate 8 is arranged between the second metal ring (3c) and the third metal ring (3e) of the tube shell 3 through a spring pressing ring; D. 3g of inner wall of the fourth metal ring is welded with a getter 9; E. the distance between the micro-channel plate 8 and the photocathode 2 is 0.08 mm-0.2 mm, and the distance between the micro-channel plate 8 and the CMOS image sensor 4 is 0.3 mm-0.8 mm; F. the CMOS image sensor 4 is connected with a ceramic substrate 12 in a welding mode, and the ceramic substrate is connected with the flange plate 10 in a welding mode through glass powder; G. the output of the CMOS image sensor 4 is connected to a readout circuit 5.

Referring to fig. 3, the input window 1 is K9 glass with a matte layer, and the edge of the inner surface of the input window 1 is plated with Ni and Cr gold with the thickness of 2000 angstromsA metal film layer 11; the tube shell 3 is a cylindrical shell (see fig. 4) formed by brazing a first ceramic ring 3b, a second ceramic ring 3d, a third ceramic ring 3f and a fourth ceramic ring 3h with a first metal ring 3a, a second metal ring 3c, a third metal ring 3e, a fourth metal ring 3g and a fifth metal ring 3i, wherein five metal rings are electrodes of a device, and the metal material is a valvable alloy; the photocathode 2 is plated in the central effective area (in the area of 85% of the diameter of the input window) of the inner surface of the input window; the photocathode 2 is a potassium, sodium, cesium and antimony multi-alkali photocathode or a negative electron affinity photocathode with higher quantum efficiency; the CMOS image sensor 4 is a purchased standard component, and is a thinned back-illuminated CMOS image sensor, for example, the number is SONY IMX178 LQJ; the input end of the micro-channel plate 8 is plated with Al₂O₃Or SiO₂The film material can reduce the noise of the microchannel plate, the microchannel plate is a standard part and has the specification of 6 mu 0.33, such as a BB plate and the like; the getter 9 is a niobium or titanium strip material; the ceramic substrate 12 is a standard component purchased from the market; the reading circuit 5 is a purchased standard part; the signal output end component of the CMOS image sensor 4 comprises a CMOS image sensor, a ceramic substrate and a flange plate.

Referring to fig. 3, during operation, the voltage applied to the input end of the microchannel plate 8 by the photocathode 2 is not higher than-200V, the voltage applied to the input end of the microchannel plate by the output end of the microchannel plate is 800V, and the voltage applied between the output end of the microchannel plate and the CMOS image sensor 4 is +2kV to 3 kV. The shape of the closed tubular body formed by the input window, the tube shell and the signal output end can be square according to the requirement.

Referring to fig. 5, the working principle of the present invention is: incident photons irradiate the surface of a photocathode 2 to generate photoelectrons, the photoelectrons enter a microchannel plate 8 under the action of voltage acceleration to carry out first multiplication on the electrons, the multiplied electrons enter the CMOS image sensor in an accelerated manner under the action of a high-voltage electric field between the microchannel plate 8 and the CMOS image sensor 4 to bombard and generate electron hole pairs, the high-energy electron hole pairs collide under the action of the electric field to generate more secondary electrons and are collected by a potential well, working voltage is provided for the CMOS image sensor through a reading circuit 5, the multiplied electrons generated by each pixel element generate a larger current signal, the current signal is directly output, and finally, under a logic control program, the images of extremely weak targets can be obtained by collecting photoelectric signals of all the pixel elements.

Referring to fig. 6, the invention is applied to an embodiment of a military helmet night vision device, and the working principle is as follows: the objective lens 13 projects a weak optical image of the target onto the photocathode of the invention 14, the invention converts and enhances the optical image, outputs a video signal to the micro display screen 15, and finally amplifies the video signal through the ocular lens 16, so that the human eye 17 can observe the enhanced target image. The using effect and various main technical indexes of the military helmet night vision device are superior to those of the military helmet night vision device of the existing low-light-level image intensifier equipment. And also for other helmet night vision devices, the structure and the working principle are basically the same, and are not listed.

Referring to fig. 3, the key technology of the invention is analyzed: the invention utilizes the high-gain electronic element micro-channel plate (MCP)8 and the CMOS image sensor 4 to carry out photoelectron multiplication twice to obtain the gain with higher brightness, and the gain of the device can reach 10⁵Multiple (micro-channel plate gain up to 10)³Gain of CMOS image sensor is 10²) Is a gain of 10 of the original device³Doubling; the night vision device of the military helmet can be arranged at the illumination of 10^-4The working under the condition below lx is lower than the original illumination by less than one order of magnitude, so that the working quality is improved; the energy of photoelectrons bombarding the surface of the CMOS image sensor is controlled within the limit of interface radiation damage, and the service life exceeds 5000 hours; in the aspects of volume and weight, the low-light level image intensifier accounts for 70 percent of the low-light level image intensifier, is smaller and lighter than the low-light level image intensifier, and enables similar night vision products such as military helmet night vision devices and the like to be more easily miniaturized.

Claims

1. A miniaturized high-gain low-illumination night vision imaging device is characterized in that: the device comprises an input window (1), a photocathode (2), a tube shell (3), a CMOS image sensor (4), a reading circuit (5), a microchannel plate (8), a getter (9), a flange plate (10), a Ni and Cr metal film layer (11) and a ceramic substrate (12), and has the specific structure that A, a first metal ring (3a) at the input end of the tube shell (3) and the input window (1) are hermetically welded through low-temperature indium-tin alloy solder, and a fifth metal ring (3i) at the tail end of the tube shell (3) and the flange plate (10) of a signal output end component of the CMOS image sensor (4) are hermetically welded through laser, so that the input window (1), the tube shell (3) and the signal output end component form a closed tubular body; B. wherein the photocathode (2) is plated in the central effective area of the inner surface of the input window (1), and the photocathode (2) is connected with the Ni and Cr metal film layer (11) at the edge of the input window; C. the microchannel plate (8) is arranged between the second metal ring (3c) and the third metal ring (3e) of the tube shell (3) through a spring pressing ring; D. a getter (9) is welded on the inner wall of the fourth metal ring (3 g); E. the distance between the micro-channel plate (8) and the photoelectric cathode (2) is 0.08 mm-0.2 mm, and the distance between the micro-channel plate (8) and the CMOS image sensor (4) is 0.3 mm-0.8 mm; F. the CMOS image sensor (4) is connected with the ceramic substrate (12) in a welding mode, and the ceramic substrate is connected with the flange plate (10) in a welding mode through glass powder; G. the output end of the CMOS image sensor (4) is connected with a readout circuit (5).

2. The miniaturized high-gain low-illumination night vision imaging device of claim 1, wherein: the tube shell (3) is a cylindrical shell formed by brazing a first ceramic ring (3b), a second ceramic ring (3d), a third ceramic ring (3f), a fourth ceramic ring (3h), a first metal ring (3a), a second metal ring (3c), a third metal ring (3e), a fourth metal ring (3g) and a fifth metal ring (3 i).

3. The miniaturized high-gain low-illumination night vision imaging device of claim 1, wherein: the photocathode (2) is a multi-alkali photocathode of potassium, sodium, cesium and antimony.

4. The miniaturized high-gain low-illumination night vision imaging device of claim 1, wherein: the input end of the micro-channel plate (8) is plated with Al₂O₃A film material.

5. The miniaturized high-gain low-illumination night vision imaging device of claim 1, wherein: the getter (9) is a niobium strip material.