Thermal-radiation detector measurement

Total Radiation Pyrometers In total radiation pyrometers, the thermal radiation is detec ted over a large range of wavelengths from the objec t at high temperature. The detector is normally a thermopile, which is built by connec ting several thermocouples in series to increase the temperature measurement range. The pyrometer is calibrated for black bodies, so the indicated temperature Tp should be converted for non-black body temperature. 

The system consists of a water cooled ring adapter with purge air supply (Figure 29) and of a control and evaluation unit. The laser beam with an excitation wavelength of 1064 nm is focused in the measurement volume by a light fiber and the enhanced thermal radiation is captured by an appropriate detector head perpendicularly. It can be applied directly in the raw exhaust without dilution up to exhaust gas peak temperatures of 700°C. Its sensitivity (3 (ig/m3) and variability for realtime (20 Hz) soot characterizing in different applications is shown. 

Most IR spectrometers used in analytical laboratories measure absorption spectra using thermal radiation sources with detectors at room temperature or at a lower temperature. 

The intensity of the selected radiation is measured by devices in which the radiation either interacts with the materials in the detector (e.g., electron release, thermal heating) or generates induced currents due to the electromagnetic field of the radiation. 

More generally, the term refers to any device used to sense or measure the amount or kind of radiation or substance in an analytical system. The term is also used to refer to any device that can respond to a particular signal or substance and provide qualitative or quantitative information about it, e.g., electrochemical detectors in HPLC, thermal conductivity detectors in GC, etc. 

The heated sample emits thermal radiation, which is used for temperature determination. The spectrum collected was measured in the wavelength range 515-820 nm corresponding to the range of maximal quantum efficiency of our CCD detector. To determine the temperature we fitted the Planck formula with a wavelength independent emissivity to the measured spectrum. The Planck formula [10] contains the temperature and the wavelength dependence of the thermal radiation intensity /bb( j of the black body (BB) ... 

---