What Is An Infrared Detector?

What is an infrared detector? The time constant of the infrared detector. The time constant of the PbS detector is generally 50 to 500 μs, and the time constant of the HgCdTe detector is on the order of 10-6 to 10-8 s. Infrared detectors sometimes detect very weak radiated signals, such as 10-14 W; the output electrical signal is also very small, so a special preamplifier is required.
Time constant: The time constant represents the rate of change of the detector output signal with the incident light signal, τ = 1 / (2πf). The application of photodetectors is mostly concentrated in the infrared band. The reason for choosing the infrared band is no longer redundant here. It is necessary to point out that the emergence of lasers in the 1960s has greatly affected the development of infrared technology, and many important laser devices. Both are in the infrared band.

Its coherence makes it easy to transfer the heterodyne reception technology in electronic technology, enabling both radar and communication to be realized in the infrared band, and to achieve higher resolution and greater information capacity. Prior to this, infrared technology was only able to detect non-coherent infrared radiation, and heterodyne reception technology was used for infrared detection, making detection performance several orders of magnitude higher than power detection. In addition, due to the needs of such applications, new detectors and new radiation transmission methods have emerged, driving infrared technology to a more advanced direction.

Infrared rays can be classified into near-infrared, mid-infrared and far-infrared depending on the wavelength. Near-infrared refers to light waves with a wavelength of 0.75-3 microns, medium red refers to light waves of 3-20 microns, and far infrared refers to bands of 20-1000 microns. However, due to the absorption of infrared light by the atmosphere, only three important window areas are left, that is, 1-3, 3-5 and 8-14 allow infrared radiation to pass. Because of these three windows, it can be applied to many aspects, such as infrared night vision, thermal infrared imaging and so on. Classification of infrared detectors:

According to the working principle, it can be divided into: infrared infrared detector, microwave infrared detector, glass broken infrared detector, vibration infrared detector, laser infrared detector, ultrasonic infrared detector, magnetic switch infrared detector, switch infrared detector, Video motion detection alarms, sound detectors, etc. Light guide type thermal inspection manufacturers indicate that they can be divided into active infrared detectors and passive infrared detectors according to their working methods. Passive infrared detectors are infrared rays that are emitted by the human body or by the outside world. Active infrared detectors are generally directed, infrared fences, etc., and the detector itself emits infrared light.