A detector that works according to the principle of photoconductive effect is called photoconductive detector. As a bulk effect of semiconductor materials, photoconductive effect does not need to form a pn junction. The stronger the light, the smaller the resistivity of photoconductive materials, so photoconductive materials are also called photoresistors. Impurity-free photoresistors generally work at room temperature and are suitable for detecting visible light and near-infrared radiation, while impurity-containing photoresistors usually work at low temperature and are often used for detecting far-infrared radiation.
(2) Application in Camera Tube The photoconductive material is one of the most widely used photoelectric conversion materials in camera tube at present. Compared with the camera tube using external photoelectric effect, the photoconductive camera tube has the outstanding advantages of small volume, light weight, simple structure and high sensitivity. At present, it has been widely used in industrial monitoring system. (1) infrared night vision equipment (thermal imager)
Through the light guide material, the infrared light in the thermal imager can be converted into visible light, that is, the infrared image can be converted into visible light image, so that combatants can observe the battlefield situation at night. This process is divided into two steps: first, the infrared radiation signal is converted into an electrical signal by using an infrared conductivity detector sensitive to infrared radiation, and the signal size is proportional to the intensity of infrared radiation; Secondly, the electrical signal is displayed on the TV screen through the TV imaging system.
Thermal imager is the highest level of the development of contemporary night vision technology, which is widely used in all kinds of infrared observation instruments, infrared thermal sights, periscope instruments on tanks, rangefinders with lights, fire control systems and tracking systems, and has the advantages of good concealment, strong anti-interference, high resolution and all-weather.
(2) Guidance device in missile system and early warning device in anti-missile system.
Infrared conductance camera tube is the eye of infrared guided missile. Many military targets (aircraft, tanks, warships, etc. ) are equipped with high-power engines, and the power part of the engine is a powerful infrared radiation source, which can form the target control signal of infrared guided missiles. After the missile receives the signal, it drives the control system of the missile through processing, and with the help of infrared conductance camera tube, it constantly corrects the flight direction of the missile, approaches the target and destroys it. The key to intercept missiles with missiles lies in the accurate and timely detection and tracking of targets by sensors. The infrared conductance detector made of light guide material has fast response speed, high sensitivity and high response rate to infrared light. It can be installed on early warning aircraft or early warning satellites, and can accurately and timely detect and track the infrared radiation of the enemy missile tail flame. It is an important part of the early warning device of the anti-missile system. Infrared light conductance guidance detection technology has the advantages of being less susceptible to interference, high positioning accuracy, simple structure and low cost, and can detect ultra-low altitude targets, but it is greatly affected by meteorological conditions, and radar cooperation is often needed to learn from each other. At present, many surface-to-air missiles are radar infrared dual-mode guided missiles. Interestingly, photoconductive effect has also been applied to stealth technology. Application of (1) in production and life
In production and life, photoresistors can be used in various automatic control devices and optical detection equipment, such as automatic feeding, automatic door devices, navigation lights, street lamps, emergency automatic lighting, automatic water supply and water stop devices, production safety devices, smoke fire alarm devices, automatic camera adjustment, electronic computers and input devices of medical instruments (such as photoelectric pulse meters and electrocardiographs). In addition, it can also be used in household appliances such as electronic musical instruments and televisions.
(2) Application in education and teaching.
In education and teaching, photoconductive camera tube can be widely used in the supervision and management evaluation of school education and teaching. Photoconductive materials are used in scanners, copiers and projectors, which brings convenience to school teaching and people's daily study and communication.
(3) Application in scientific research
In scientific research, infrared light conductance can be used for surface temperature remote sensing, nondestructive testing, meteorological remote sensing, geoscience remote sensing and so on.
In a word, photoconductive sensing and remote sensing technology are very important for automatic control and electromechanical integration. The development of detection and sensing technology is inseparable from high-performance photoelectric device materials. In the future, high-performance photoconductive materials with faster response speed, better response efficiency, higher sensitivity and wider response frequency will be the main development direction of photoconductive technology research.
To sum up, mankind has entered the information age, and semiconductor and microelectronics technology is undoubtedly one of the core technologies of the information society. Looking ahead, in the revolution of optoelectronic technology, photoconductive materials will play an important role in the fields of optics, integrated optoelectronics and molecular electronics. In terms of language and image recognition, the development of artificial intelligence to make judgments in complex situations, neural network and simulation of human brain, semiconductor microelectronics and optoelectronics will remain the main contents of the future scientific and technological revolution. Photoconductive materials, as the basic components of continuous performance optimization, will have a great future.