Temperature measurement by temperature can be divided into contact and non-contact two categories. Normally, contact Thermometer relatively simple, reliable and high precision; but with the measured medium temperature components require Full contact, takes some time to achieve thermal equilibrium, so there is measured temperature of a delay, while Limited by the high      temperature materials, and can not apply to high temperature measurements. Non-contact temperature measuring instrument is impose the thermal radiation theory to measure the temperature, and temperature measurement devices without contact with the medium, wide temperature range, from the maximum temperature limit, will not undermine the measured object temperature, reaction rate generally faster; but Affected by object's emissive, measuring distance, dust and water vapor and other external factors, has larger measurement error.