Principle of Radiation Pyrometers

Principle of Radiation Pyrometers Points : Principle of Radiation Pyrometers, Principle of Radiation Pyrometers, Selective or Partial Radiation Pyrometry, Radiation Receiving Elements Radiation pyrometery measures the radiant heat emitted or reflected by a hot object. Thermal radiation is electromagnetic radiation emitted as a result of temperature. Thermal radiation lies in the wavelength region from above 0.1 to 100µm. practical radiation pyrometers are sensitive to a limited band of radiant energy.

The radiation pyrometers operate on the principle that the energy radiated from a hot body is a function of its temperature. There are two principles for construction of radiation temperature measuring. (i) Total Radiation Pyrometry In this case the total radiant energy from heated body is measured. Radiation pyrometer is intended to receive maximum amount of radiant energy at widest range of wavelengths possible. (ii) Selective or Partial Radiation Pyrometry In this case we may measure the spectral radiant intensity of the radiated energy from the heated body at a given wavelength. Actually it is difficult to build a practical pyrometer that is responsive to radiation of all wavelengths or to spectral radiation of one wavelength. Therefore, practical radiation pyrometers respond to a wide band of radiation of approximately of radiation spectrum. Radiation Receiving Elements The purpose of a radiation-temperature measuring device is to convert the radiant energy into a suitable form for indication of temperature. For this purpose following devices are used:
(i) Vacuum Thermocouple
(ii) Thermopile
(iii) Bolometer
(iv) Photo-electric Transducer