Infrared thermal imaging devices and systems have been used as military equipment for reconnaissance, surveillance, observation, tracking, aiming and navigation. enterXinshiAfter the generation, the military of various countries put forward higher requirements for thermal imaging technology in the face of the new situation of modern war and future information war. It is hoped that the infrared thermal imaging devices and systems manufactured in the future will have better performance, such as smaller volume and lighter weight, higher resolution and sensitivity, longer working range and lower price. Therefore, in order to extend the service life of the first generation of infrared thermal imaging devices and systems, Europe and the United States are currently using advanced technology to transform the first generation of infrared thermal imaging devices and systems. At the same time, we will continue to develop new products of the second generation thermal imaging technology and expand its application scope.

Improvement of the first generation thermal imaging device

selfSince the end of 1980s, the United States, Britain and other European and American countries have been actively adopting new technologies to develop more advanced refrigerators, scanners, processing circuits and detectors for the first generation of infrared thermal imaging devices and systems in order to further improve their performance and extend their service life. At the same time, infrared focal plane array detector and new processing circuit are used to modify the first generation thermal imager to improve its performance to the level of the second generation thermal imager.

1. Britain improved Sprite detector

In order to improve the thermal sensitivity and spatial resolution of thermal imaging system in Britain, the original Sprite detector has been improved as follows:(1) using liquid phase epitaxial growth technology to grow high-quality N-type HgCdTe materials to manufacture high-sensitivity detectors; (2) Extend the cutoff wavelength of the detector from 11 microns to 13 microns, so that it has the highest thermal sensitivity to normal temperature targets; (3) The 7.5 ~ 13 micron antireflection film and high efficiency cut-off filter installed on the window of the detector dewar bottle are redesigned to prevent noise; (4) The detector with new geometry is adopted to improve the spatial resolution. The improved detector is called Turbo Sprite detector, and its performance is greatly improved compared with the original Sprite detector. In addition, Britain has also improved many Class II TICM thermal imagers by using the optical system of deformation detector.

2. The United States adopted new technology to refit a generation of thermal cameras.

The United States fromAt the beginning of 1992, it was decided to refit its AN/TAS series first-generation thermal imager with the 288× 4 yuan array of the French company Su Fallati, and replace the original electronic components with new electronic components. At the same time, a new imaging optical system was designed. The demonstration of the modified AN/TAS series first-generation thermal imager shows that the distance of detecting and identifying the target is farther than that of the original AN/TAS-4A, and the video image produced is of high quality. The performance of the weapon system can be further improved by refitting the first generation thermal imager used in the weapon system with the 288× 4 yuan array detector of Su Fallati Company.

In order to refit the thermal imager based on American universal component detector, American Digital Imaging Company developed a processing electronic device which can be connected with various staring focal plane arrays. The device includes three circuit boards and a small buffer board, which can replace the original post-amplifier circuit board in the general component thermal imager. The processing electronics can be combined with Martin Company 256.× 256 yuan InSb, PTSI and HgCdTe quantum well devices are connected into improved components, which are used to modify various models of the first generation of general-purpose component thermal imager.

3. Sweden adopts advanced optical system and scanning device to develop intelligent forward-looking infrared device.

AGMA Sweden has developed THV 1000 intelligent forward-looking infrared device by using advanced optical system, scanner components, analog-to-digital converter and special software, and its performance exceeds that of the current forward-looking infrared device in the army. The optical system used in the device consists of a field lens, two cylindrical lenses and a focusing lens, which can form the change ratio of images, make the performance of Sprite detector * * * * *, provide the same geometric resolution for horizontal and vertical directions, and eliminate stray light from the shell. The scanner module used is a new polyhedral reflection scanning module called LK-4, and its detection performance is almost three times that of ordinary scanning system, and it is obviously better than that achieved by using focal plane array system. This scanner assembly can also be installed in other infrared systems.

Development of the second generation thermal imaging technology

The second generation infrared thermal imaging technology was developed in 1990s to better adapt to military applications. Focal plane array technology is its core technology, and its main structural forms are 4n scanning array and n scanning array.X m staring array. Refrigerated InSb and HgCdTe detectors are a mature infrared imaging technology in the field of medium and short wave infrared applications, and are playing a huge role in military applications. According to the needs of some military and aerospace applications, it is still one of the main development projects. While continuously developing new products, in order to further improve the resolution and sensitivity of the above two types of infrared material detectors, research is being done to expand the array size and increase the number of pixels.

1. The United States launched military STAR SAFIRE.

Foresight infrared system company adopts high-performance320×240 yuan infrared focal plane array and more effective Stirling cooler were used to produce Starsafire, the replacement product of AAQ-22 airborne thermal imaging system of the US Army, in the spring of 1998. The product adopts InSb staring focal plane array, and the working band is 3 ~ 5 microns. Its characteristics are: small size and low power consumption; The array can be moved in two directions electronically and mechanically to improve the resolution; The resolution similar to that of 640× 480 yuan array can be obtained. Very strong stable elements and sliding rings are adopted, and the elements can resist damaging impact, vibration and high/low temperature; A large number of digital signal processors and Intel Pentium processors are used, which greatly improves the image processing and system management capabilities. Now the US military has decided to equip more than 20 kinds of fixed-wing aircraft and helicopters with this product, such as the P-3 maritime patrol aircraft of the US Navy, the C-130 transport aircraft of the Air Force, and the UH-1N, HH-6, S-61 and 76 helicopters of the Army/National Guard.

2. Large InSb and HgCdTe focal plane arrays come out.

The research on enlarging the array size and increasing the number of pixels isA new development trend of InSb and HgCdTe focal plane arrays. American Raytheon Company has been committed to the research and development of large InSb focal plane arrays. In the second half of 1999, the company plans to display its first large InSb focal plane array product with 2052× 2052 elements, and the output of the array is four times that of the previous array with 1024× 1024 elements. It will be first used for astronomical observation. Rockwell Company of the United States is engaged in the research and development of large-scale HgCdTe focal plane array, and is currently developing a large-scale HgCdTe focal plane array with the working band of 0.9 ~ 2.5 micron near infrared 2000× 2000 yuan. The sensitivity of the array is the highest at 60K, and the dark current is less than 0.1 electron/second, and the readout noise is less than 2.5 electrons. The infrared image quality of the array is similar to that of the Hubble telescope when it is used in the current super telescope. In addition, the company will also develop a 4000× 4000 yuan large-scale HgCdTe focal plane array for a new generation of space telescopes planned to be launched by NASA in 2008. The spectrum sensitivity range will be expanded from 2.5 microns to 5 microns, and its sensitivity is as high as 0.005 K when optimized for traditional imaging.

At present, the key technology to be solved in the fabrication of the above two kinds of large focal plane arrays is large crystal.Film growth technology.