Contact and non contact pyrometer are distinguished by the detection method of temperature sensor. The detection part of the contact temperature sensor is in contact with the measured object, and the non-contact temperature sensor and the measured object are not in contact with each other. The non contact pyrometer is mainly infrared thermal imager and single-point infrared thermal imager. Its characteristics are as follows:

1) The contact temperature sensor is also called a thermometer, which achieves thermal equilibrium through conduction or convection, so that the displayed value of the thermometer can directly indicate the temperature of the measured object.

Advantages: The measurement accuracy is high. Within a certain range, the thermometer can also measure the temperature distribution inside the object. But for moving objects, objects with small heat capacity or small size, larger measurement errors will occur. Commonly used thermometers include bimetal thermometers, pressure thermometers, resistance thermometers, thermistors and thermocouples.

Disadvantages: As the heat of the measured object is transferred to the temperature sensor, the temperature of the measured object is reduced. When the heat capacity of the measured object is small, the measurement accuracy is low. Therefore, when the true temperature of the object is measured in this way, the heat capacity of the measured object must be large enough. When using a contact temperature sensor, it is necessary to consider the physical characteristics of the object to be measured. The space limitation of the object to be measured is relatively large, and it is impossible to measure the temperature of an inaccessible object.

2) Non contact pyrometer is also called non-contact temperature measuring instrument, which can be used to measure the surface temperature of moving objects, objects with small heat capacity or rapid temperature changes, and can also be used to measure the temperature distribution of the temperature field.

Advantages: The upper limit of measurement is not limited by the temperature resistance of the temperature sensing element, so there is no limit to the maximum measurable temperature in principle. For high temperatures above 1800°C, non-contact temperature measurement methods are mainly used.

Disadvantages: The temperature measurement results are easily interfered by environmental factors, and it is not easy to achieve long-term continuous measurement of the target.

It can be seen that although there is only one word difference between contact and non contact pyrometer, the principles and characteristics are different, and different measurement methods need to be used in different situations.