Any object in nature above absolute temperature (-273 degrees Celsius) radiates heat (electromagnetic waves) outwards. There are long and short electromagnetic waves. Waves with a wavelength range of 760nm-1mm are called infrared waves, which cannot be seen by the naked eye. The higher the temperature of the object, the greater the radiated energy will be.
Infrared thermalgraphy is to sense infrared waves through special materials, then convert the infrared waves into electrical signals, and then convert the electrical signals into image signals.
Since the special material for infrared sensing is also affected by the external temperature, the sensor (detector) must be processed at low and constant temperature, or corrected by algorithm, when making the infrared thermal imaging movement.
The technology of low-temperature and constant-temperature treatment of sensors (detectors, special materials) is called cooling far-infrared. The technique of correcting the data collected by the sensor through algorithms is called uncooled far-infrared. This technology requires a large number of algorithms to correct the data retrieved by the detector, and some also require baffle correction. The baffle is to place a black isothermal object in front of the sensor to perform temperature compensation and dead pixel removal on the sensor.
The main principle of the far-infrared sensor: the material that senses infrared wavelengths (may contain resistive materials depending on the material) is enclosed in a box that is always connected to a fixed current. When the infrared wavelength of the material receives infrared waves, it will change the entire box resistance, so that the voltage passing through the box will change, and the voltage from the sensor at the back end (the specific use of steady current or voltage regulation has not been studied) is adjusted to the corresponding Y(YUV).
The infrared sensor is always working from production to outlast regardless of whether it is powered or not. Because the heat-sensitive material is constantly receiving infrared waves from the outside, the infrared device should be stored as far as possible, and not to high-temperature objects. If it is exposed long time to a high-temperature object (here refers to the temperature of the object itself, regardless of the distance, such as the sun), it may permanently deform, and the sensor will no longer be sensitive.
The production process and material characteristics of infrared sensors will result in poor sensor anti-interference ability and insufficient data collection accuracy. So each pixel needs to be corrected (salt and pepper noise, Gaussian noise, vertical stripes, horizontal stripes, etc.), and then determine the value of Y. Therefore, the infrared thermography applications have not yet reached the chip level, and the global infrared thermalgraphy technology is still at the FPGA stage. Once the internal logic of the chip is produced, it cannot be adjusted, and data correction is generally not done on the software. Software correction will cause two problems. One is that the efficiency cannot keep up with. The other is that the efficiency leads to high overall power consumption and high cost, which is not worth it.