Digital pyrometry in a solar furnace

The brightness temperature and emissivity measurements of an irradiated specimen at the focal point of a solar furnace have been performed by the use of a brightness pyrometer to which an electrical recorder, an oscilloscope and Polaroid camera were attached previously. The use of such a photographic method gave reading errors as ±2K at 3000°C and ±15K at 2000°C.

Therefore, a digital computer system has been coupled with the brightness pyrometer in order to give the higher accuracy in brightness and true temperature measurements and to process a large amount of data. The system consists of A/D converter, central processing unit, graphic display and other transfer units. After an analog signal from the brightness pyrometer was amplified by a dc amplifier, the signal converted into digital form was operated by the digital computer. Conversion errors in the data processing were found to be ±1K at 3000°C and ±7K at 2000°C respectively. The freezing point data by the new system on refractory oxides such as ZrO₂ and Y₂O₃ were presented.