1. Contact type
The detection part of the contact temperature sensor has good contact with the measured object, also known as a thermometer. The thermometer achieves thermal equilibrium through conduction or convection, so that the value of the thermometer can directly indicate the temperature of the measured object.
2. Non-contact
Its sensitive components do not touch each other with the measured object, and it is also called a non-contact temperature measuring instrument. This kind of instrument can be used to measure the surface temperature of moving objects, small targets and objects with small heat capacity or rapid temperature changes (transient), and can also be used to measure the temperature distribution of the temperature field.
The most commonly used non-contact temperature measuring instrument is based on the basic law of black body radiation and is called a radiation temperature measuring instrument. All kinds of radiation temperature measurement methods can only measure the corresponding luminosity temperature, radiation temperature or colorimetric temperature. Only the temperature measured for a black body (an object that absorbs all radiation and does not reflect light) is the true temperature. If you want to determine the true temperature of an object, you must correct the surface emissivity of the material. The surface emissivity of the material not only depends on the temperature and wavelength, but also on the surface state, coating film and microstructure, so it is difficult to accurately measure.
The advantage of the non-contact temperature sensor is that the upper limit of measurement is not limited by the temperature resistance of the temperature sensing element, so there is no limit in principle to the maximum measurable temperature.
