A copper disk pyrheliometer has been designed and constructed that utilizes a new methodology to measure solar radiation. By operating the shutter of the instrument and measuring the heating and cooling rates of the sensor at the very moment when the sensor is at the same temperature, the solar radiation can be accurately determined with these rates. The method is highly accurate and is shown to be totally independent of the loss coefficient in the measurement. The pyrheliometer has been tested using a standard irradiance lamp in the laboratory. The uncertainty of the instrument is identified to be ±0.61%. Field testing was also conducted by comparing data with that of a calibrated (Eppley) Normal Incidence Pyrheliometer. This paper spells out details of the construction and testing of the instrument; the analysis underlying the methodology was also covered in detail. Because of the high accuracy, the instrument is considered to be well suited for a bench standard for measurement of solar radiation.
© 1983 Optical Society of America
C. K. Hsieh and X. A. Wang, "Copper disk pyrheliometer of high accuracy," Appl. Opt. 22, 107-114 (1983)