Infrared thermometer filter

As the temperature increases, the radiation peak shifts to the left along the short wave direction, satisfying Wien's displacement theorem. The peak wavelength is inversely proportional to the absolute temperature T. This formula tells us why high-temperature thermometers work in short waves, while low-temperature thermometers work in long waves. When the temperature of an object is above absolute zero, due to the presence of internal thermal motion, electromagnetic waves will continue to radiate to the surrounding area, containing 0.75 μ m~100 μ m; Infrared light of m. His biggest characteristic is that the radiation energy emitted by an object has a maximum value at a given temperature and wavelength. This material is called a blackbody (acrylic optical window), with a reflection coefficient of 1. If the reflection coefficient of other materials is less than 1, it is called a gray body. Because the spectral radiation power P (λ T) and absolute temperature T of a blackbody satisfy Planck's measurements. The results indicate that at absolute temperature T, the unit area of a blackbody is at wavelengthλ The radiated power at is P (λ T).

The higher the temperature, the stronger the radiation energy of the object, which is the starting point of infrared radiation theory and the design basis of single band infrared thermometers.

The rate of change of shortwave radiation energy with temperature is greater than that of longwave radiation energy, indicating that shortwave thermometers have higher signal-to-noise ratio (sensitivity) and strong anti-interference ability. It is particularly important for thermometers to operate at peak wavelengths as much as possible, especially in the case of low temperature small targets.

Characteristics of infrared thermometer

1. Non contact measurement: It does not require contact with the surface or interior of the measured temperature field, so it will not interfere with the measured temperature field.

2. Wide measurement range: Due to non-contact temperature measurement, the thermometer is not in a high or low temperature field, but works at room temperature or under conditions allowed by the thermometer. Generally speaking, negative tens of degrees can be measured to over 3000 degrees.

3. Fast temperature measurement: fast response time.

4. High precision: Infrared temperature measurement, as a contact type temperature measurement, does not damage the temperature distribution of the object itself, resulting in high measurement accuracy.

5. High sensitivity: As long as the temperature change of the object is small, the radiation energy will undergo significant changes, making it easy to measure. It can measure the temperature of a micro temperature field.

6. As well as temperature measurement and temperature distribution measurement of moving or rotating objects, it is safe to use and has a long service life.

The principle of infrared thermometer:

The infrared filter thermometer consists of a photodetector, optical system, signal processing, signal amplifier, display output, etc. The radiation lines of the feedback source and the measured object are modulated by a modulator and input into the infrared detector. The inverse amplifier amplifies the difference between the two signals to control the temperature of the feedback source, so that the spectral radiation of the feedback source is the same as that of the target.