Determining size-of-source effect using the scanning slit method

Abstract

Recently a scanning method for determining the size-of-source effect (SSE) in radiation thermometry was proposed. It was shown that by scanning the radiation thermometer (RT) across a narrow slit with a slit width similar to the spot size of the RT, results comparable to the indirect method can be obtained. However, due to the low signal levels (almost at the noise level) detected by the RT, the method is susceptible to noise. We examine further this scanning method by determining the influence of the relative position of the slit, and slit size on the resulting SSE. We also present a simple model for the radiation propagation relevant to this method. Lastly, we compare the results of the scanning experiments to the conventional direct method for SSE and show that the scanning method is also comparable to the direct method, as long as the parameters of the scanning method (e.g., slit position, slit size) are adjusted properly.