Study of the system responsivity to measure the blackbody's temperature by optical pyrometry from 1200 K to 1570 K

Abstract

This work presents a method that has been recently adopted in our laboratory to determine the temperatures of blackbody sources in the range of 1200–1570 K. The system uses a Double Monochromator System (DMS) based on a grating and a prism as dispersion elements. The detection element was a silicon photodiode (Si-MMA), over which the spectral range from 800 nm to 900 nm has been used. Between the blackbody source and the DMS was placed an optical system consists of two convergent lenses. The system responsivity “G ” was determined by the transmission factor of the optical system and the transmission factor of the DMS and the photodiode responsivity. The obtained results showed that the relative uncertainty of the system responsivity “G ” varied from 0.3% to 1.12%. This in turn resulted in a corresponding uncertainty in temperature of about 2.2 K and 4.5 K (k = 1) over the evaluated temperature range. Although this uncertainty level was significantly high compared to those obtained by many other national metrology institutes, it was considered as a step forward in our laboratory to measure high temperatures.