Analyses the basic principle of infrared sensor we all know that no matter what objects are emit electromagnetic radiation, and infrared sensors is using this principle, once the temperature of the object changes, so it radiates the wavelength of the electromagnetic wave will also change, and the change of the wavelength shift into the change of temperature, and realized the purpose of temperature measurement.Mainly consists of optical system, infrared sensor components and conversion circuit. And its optical system according to the structure of the different can be roughly divided into transmission type and reflection type. The two and test components can be roughly divided into thermal detecting element and photoelectric detecting element. The most is a thermistor temperature sensor application. Thermistors it primarily by infrared radiation will result in higher temperature, resistance will change at this moment, and then by converting circuit and then into electrical signal output. The photoelectric detecting element is the most commonly used optical sensor.Then the basic principle of infrared sensors work is not too complicated: 1, the target under test. We are according to the infrared radiation characteristics of the target under test then set for infrared system. 2, the atmospheric attenuation. Infrared radiation of the target under test through the earth's atmosphere, so at this time due to gas molecule and all sorts of all sorts of gas sol particles scattering and absorption, will cause the infrared source emits infrared radiation attenuation. 3, the optical receiver. The goal of this receiver is part of the infrared radiation is transmitted to infrared sensors at the same time. That is a 1 in the radar antenna.4, according to the sensor detection mechanism is different, it can be roughly divided into heat detector and the two photon detector.