Measuring temperatures in a high concentration solar simulator – Demonstration of the principle

Abstract

A new single color pyrometric method for samples heated radiatively via an artificial light source is presented. The method allows separation of the external radiation reflected by a sample from its thermal emission as the intensity of arc lamps, commonly used in high concentration solar simulators, can be electrically modulated at frequencies well above the thermal response (ω≫1/τth) of the sample. Thus, the external radiation reflected off the sample can be measured separately using a phase sensitive detection scheme at the modulation frequency of the light source. In addition, a composite signal consisting of the thermal emission with the reflected external radiation superimposed is detected. This signal is obtained by observing the sample with a mechanical chopper operating at a different frequency placed in the observation path. The composite signal is measured simultaneously with identical optics and detector. The thermal emission of the sample can then be extracted as the difference of the two measured signals after suitable calibration. The working principle of the method and its calibration is explained and the performance of the method is demonstrated using its implementation on a lab scale.