The internal structure of the infrared camera

The internal structure of the infrared camera

As a typical mechatronics device, infrared thermal imager can accomplish such a powerful thermal imaging function because of its internal components. In simple terms, the internal components of an infrared thermal imager are composed of four major parts, namely an optical system, an infrared detector, a signal processing system and a display recording system. The following will make a detailed functional explanation of these four parts.

Optical system

The main function of this system is to receive the infrared radiation emitted by the target object, usually two focal points. The main function of the first focus is to place the modulator; the main function of the second focus is to place the detector. In order to ensure the accuracy of the temperature measurement results, it is necessary to use a modulator to input the temperature reference object in the form of a fixed frequency. During the reverse process of the scan, the optical path needs to be quickly inserted, and the corresponding optical path should be completely blocked. The first focus in China plays an important functional role. In the optical system, the aperture stop is usually not set separately, so the aperture should be enlarged as much as possible. After a certain aperture stop, even if the aperture angle does not change much, the signal energy received by the optical system will be decrease very much. Ensuring the stability of the aperture angle can effectively improve the temperature measurement accuracy of the infrared camera.

2. Infrared detector

After the optical system receives the infrared radiation emitted by the measuring object, the radiation energy will be concentrated on the focal plane of the detector to form a rough outline, and then the detector will integrate and differentiate the radiation information. The detector is the core component of the infrared thermal imager. To avoid the interference of thermal noise and noise on the measurement results, so that the detection rate and signal-to-noise ratio of the detector are greatly improved, the detector needs to be kept in a low temperature environment at all times. Using the cooling method as the basis for division, the focal plane can be divided into two types: one is a cooled detector; the other is an uncooled detector.

3. Signal processing system

Under normal circumstances, the signal received by the detector is extremely weak, only reaching the level of microvolts. Therefore, in order to better reflect the small temperature difference, the received signal needs to be converted and amplified. The main function of the signal processing circuit is to limit the bandwidth of the low-level signal received by the detector, perform amplification processing, and then output the signal to the display or control system.

4. Display recording system

The imaging of the infrared camera is to transmit the amplified video signal to the TV picture tube, and then display the infrared image of the target object. This imaging method is very common in production and life. When the CRT has only two colors, black and white, the black and white in the picture indicates that the temperature of the target object is different; when the CRT is in color, the radiation signal will undergo a series of processing such as encoding and layering, and finally the display will display the color image of the target object. For the temperature image output by the infrared camera, it is worth noting that the color in the image does not reflect the actual color of the target object, but the temperature distribution of the object, which can be called a false color thermal image. Normally, red and yellow indicate higher temperatures, and blue and purple indicate lower temperatures.