Focal Plane Array Infrared Detector

The focal plane detector is a detector used to image and detect electromagnetic waves of 9-14 μm. Compared with the CCD CMOS image sensor, its photosensitive material, device structure and semiconductor process used are different.

Any object whose temperature is higher than absolute zero (- 273 ℃) can radiate infrared rays. The physical nature of infrared ray is thermal radiation, which is also an electromagnetic wave. Thermal imaging technology converts invisible infrared radiation into visible thermal image and shows the temperature distribution of the target surface.

Infrared radiation is focused by infrared optical lens and converted into electrical signal by the infrared detector. After being processed by the signal processing circuit and image algorithm, the data is output and turns into visible thermal image on the display.

1. Classification of Infrared Focal Plane Arrays
According to the cooling method, infrared focal plane array can be divided into cooled and uncooled thermal imaging detectors. The cooled FPA infrared detector mainly adopts Dewar bottle/quick start throttling refrigerator and Dewar bottle/Stirling cycle refrigerator at present. While the uncooled FPA thermal IR detector works at room temperature. It is the core of uncooled thermal imaging system. The most common heat-sensitive materials include vanadium oxide (Vox) and amorphous silicon (a-Si). Vanadium oxide material is the mainstream choice in the current market; it has a high temperature resistance coefficient, and high thermal sensitivity.

2. Working Principle of Infrared Focal Plane Array
An array of photosensitive elements is arranged on the focal plane array detector. Infrared rays emitted from infinity are imaged on these photosensitive elements of the focal plane array through the optical system. The detector converts the light signal into an electrical signal and performs integral amplification, sampling, output buffer and multiplexing system, and is finally sent to the monitoring system to form an image.

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