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What is the basic theory of the far infrared thermometer?
- 2019-03-14-

In 1672, it was discovered that sunlight (white light) was composed of various colors of light, and at the same time, Newton reached the conclusion that monochromatic light is simpler in nature than white light. Using a spectroscopic prism, the sunlight (white light) is decomposed into red, orange, yellow, green, cyan, blue, purple and other monochromatic lights. In 1800, when British physicist FW Hussell studied various colored lights from a thermal perspective, he discovered infrared rays. When he was studying the heat of various colored lights, he intentionally blocked the only window of the dark room with a dark plate, and opened a rectangular hole in the plate, and a beam splitting prism was installed in the hole. When sunlight passes through a prism, it is broken down into colorful light bands, and a thermometer is used to measure the heat contained in the different colors in the light band. In order to compare with the ambient temperature, Husserl used several thermometers near the colorful light band as a comparison thermometer to determine the ambient temperature. During the experiment, he occasionally found a strange phenomenon: a thermometer placed outside the light band with red light was higher than the indicated value of other indoor temperatures. After repeated tests, this so-called high-temperature area is always located outside the red light at the edge of the light band. Therefore, he announced that in addition to visible light, the radiation announced by the sun also had a "hot line" that was invisible to the human eye. This invisible "hot line" was located outside the red light and was called infrared. Infrared is an electromagnetic wave, which has the same essence as radio waves and visible light. The discovery of infrared is a leap for human beings to know nature. It has opened up a new and vast journey to the research, use and opening up of the field of infrared technology.

Infrared has a wavelength between 0.76 and 100 μm. According to the wavelength plan, it can be divided into four categories: near infrared, mid infrared, far infrared thermometer , and extreme far infrared. Its orientation in the continuous spectrum of electromagnetic waves is between radio waves and visible light. Area. Infrared radiation is a kind of extensive electromagnetic wave radiation that exists in the natural world. It is based on the random movement of molecules and atoms of any object under normal circumstances, and it continuously radiates thermal infrared energy, and the movement of molecules and atoms The more intense, the greater the radiated energy, and conversely, the less the radiated energy.

Objects with a temperature above a certain zero degree will radiate infrared rays due to their own molecular motion. After the infrared detector converts the power signal radiated by the object into an electrical signal, the output signal of the imaging device can be completely one-to-one corresponding to the spatial distribution of the surface temperature of the scanned object. Corresponding thermogram of the surface heat distribution. Using this method, it is possible to realize long-distance thermal state image imaging and temperature measurement of targets and analysis and judgment.