There are two types of temperature sensors; a contact type and a non-contact type.
A contact type temperature sensor is placed into contact with the measured object and measures the temperature when the heat balance is reached. This kind of sensors includes thermocouples, platinum resistance temperature detector (RTD) and thermistors.
Accutherm supplies various thermocouples and platinum resistance temperature detectors.
A non-contact temperature sensor detects infrared radiation emitted from the measured object and measures the temperature from the radiation amount. A radiation temperature sensor belongs to this category.