The content of infrared technology consists of four main parts: 1. The nature of infrared radiation, which has a heated object emitted by the radiation in the spectrum, intensity and direction of the distribution; radiation propagation characteristics in the medium - reflection, refraction, diffraction and scattering; thermoelectric and photoelectric effects, etc. 2. Infrared components, the development of components, including the radiation source, miniature refrigerator, infrared window materials and filtering photoelectricity, etc. 3. Various infrared elements, components constitute a system of optics, electronics and precision machinery. 4. infrared technology in the military and national economy. It can be seen, infrared technology research involves a wide range of both the target infrared radiation characteristics, background characteristics, and infrared elements, components and systems; both material and application issues.
[Related Technologies] Detection Technology; Precision Guidance Technology; Optoelectronics Technology; Advanced Materials Technology
[Technical Difficulties]
The key to the development of infrared technology lies in the development of infrared materials, infrared equipment, refrigeration, infrared equipment, infrared equipment to the development of longer wavelength bands, the development of infrared focal plane array devices and infrared devices and data processing equipment, such as the combination of.
[Foreign Overview]
Since the British astronomer F?W?Herschel discovered infrared radiation in 1800, the development of infrared technology has experienced nearly two centuries. Since then, infrared radiation and infrared components, components of scientific research and development, but the development is relatively slow, until around 1940 to really appear in the modern infrared technology. At that time, Germany developed into lead sulfide and several kinds of infrared transmissive materials, the use of these elements, components made of some military infrared systems, such as anti-aircraft guns with a guide, coastal ship reconnaissance, ship detection and tracking systems, airborne bomber detector and fire control systems and so on. Some of them reached the stage of laboratory testing, some have been small batch production, but have not had time for practical use. Since then, the United States, Britain, the former Soviet Union and other countries competing for development. Especially the United States, vigorously study the application of infrared technology in the military. At present, the United States will be infrared technology applied to the individual equipment, armored vehicles, aviation and aerospace reconnaissance and surveillance, early warning, tracking and weapons guidance and other areas.
The development of infrared technology is the precursor to the development of infrared detectors. 1800, F.W. Herschel found that infrared radiation is the use of mercury thermometer, which is the most primitive heat-sensitive infrared detectors. 1830 after the development of a temperature difference between the thermocouple of thermal detectors, radiometric calorimetry, etc.. Before 1940, the development of infrared detectors are mainly thermal detectors. 19th century, scientists use thermal infrared detectors, recognize the characteristics of infrared radiation and its laws, proved that infrared and visible light have the same physical properties, comply with the same laws. They are one of the electromagnetic waves, with fluctuation, their propagation speed is the speed of light, wavelength is their characteristic parameter and can be measured. the early 20th century, the measurement of a large number of organic and inorganic substances, absorption, emission and reflection spectra, proved the value of infrared technology in the analysis of substances. 30 s, the first appearance of infrared spectroscopy, and later, it has developed into indispensable instruments in the analysis of substances. In the early 40's, photoelectric infrared detector, lead sulfide infrared detector as a representative of this type of detector, its performance is excellent, reliable structure. 50's, the rapid development of semiconductor physics, so that photoelectric infrared detector to get a new impetus. By the early 1960s, for the 1 ~ 3, 3 ~ 5 and 8 ~ 13 micron three important atmospheric windows have excellent performance infrared detectors. In the same period, solid state physics, optics, electronics, precision machinery and micro-cooler and other aspects of the development of infrared technology in the military and civilian dual-use have been widely used.
From the mid-1960s onwards, the development of infrared detectors and systems reflects the current status of infrared technology and the direction of development.1. Detectors in the range of 1 to 14 micrometers have evolved from unit to multivariate, and from multivariate to focal-plane arrays. The earliest infrared detector is a unit detector, in order to improve the sensitivity and resolution, and later developed into a multivariate line array detector. Multiple line detector successively swept (string sweep) the same target, it output signal-to-noise ratio can be higher than the unit detector n (open square) times, n is the number of elements. If the multiple line detector parallel sweep (flat sweep) target, then you can get a one-dimensional distribution of the target radiation. Line detector-based infrared detection system, mostly installed in the aircraft or satellite remote sensing platform, the platform's forward motion perpendicular to the line column as the second dimension, you can get the distribution of target radiation image. Now, the infrared detector has been developed from multiple to focal plane array, the corresponding system has been realized from the point of detection to the target thermal imaging leap. Infrared thermal imager is one of the most promising devices, representing the development direction of night vision equipment, which replaces the optical machine scanning structure with a focal plane array. At present, long-wave mercury cadmium telluride (HgCdTe) detector face array has reached 640?80 yuan, focal plane array detector laboratory level has reached 256?56 yuan, is expected to reach a million dollars in 2000. 2. infrared detector working band from the near-infrared extended to the far infrared. Early infrared detectors usually work in the near infrared. With the development of infrared technology, infrared detectors have been extended to work in the mid-infrared and far-infrared band, for example, the U.S. Defense Advanced Research Projects Agency put forward a super-spectrum landmine detection program, the purpose of which is to provide a safe and effective way to detect landmines. The program uses the Space Modulated Imaging Fourier Transform Spectrometer (SMIFTS), an infrared sensor, which has been tested on helicopters in the near and mid-wavelength bands, and the next step is planned to extend the working band to the far infrared. Far infrared has become the focus of scientists.3. Lightweight miniaturization. Non-cooling, integrated, large surface array infrared detector direction. The use of low-temperature refrigeration technology, is to improve the sensitivity of the infrared detector device and the signal-to-noise ratio of the output signal, so that it has good performance, but it also makes the infrared detector is large, high cost. In order to achieve miniaturization, it is necessary to reduce the refrigeration equipment and the related power supply, therefore, high-efficiency small coolers and infrared detectors without refrigeration will be the future direction of development. Such as the use of non-cooling work of infrared focal plane array technology, not only can make the system cost reduction of 2 orders of magnitude, but also can make the volume, weight and power consumption will also be greatly reduced. In addition, the use of materials, electronic computers and microelectronics in the latest technology, can make the infrared detector with a certain data processing capabilities of data processing equipment, so that its light integration, large surface array, focal plane direction, in order to improve its performance, to achieve the detection of room temperature targets.4. Infrared detection system from a single band to the development of multi-band. As mentioned earlier: in the atmospheric environment, the target infrared radiation can only be in 1 ~ 3, 3 ~ 5 and 8 ~ 13 micron three atmospheric window to be effectively transmitted. If an infrared detection system can obtain target information in two or more bands, then the system can be more accurate and reliable to obtain more target information, improve the detection effect on the target, reduce the probability of false alarms of the early warning system, improve the system's search and tracking performance, apply more application requirements, and better meet the needs of the military services. At present, the multi-band infrared detection system has been successfully developed, such as France and Sweden jointly developed the "Bonas" end-sensitive submunitions, the use of multi-band infrared detection system to detect the target.
In the development of infrared technology, it is necessary to point out in particular: the emergence of laser in the 1960s greatly affected the development of infrared technology, many important laser devices are in the infrared band, its coherence is easy to move with the electronic technology in the differential reception technology, so that the radar and communications can be realized in the infrared band, and can obtain a higher resolution and greater information capacity. Previously, infrared technology had only been capable of detecting incoherent infrared radiation, and the use of heterodyne receiver technology for infrared detection enabled detection performance to be several orders of magnitude higher than that of power detection. In addition, the need for such applications has led to the emergence of new detector devices.