<title>Spectral radiance source for vacuum ultraviolet calibrations</title>

Abstract

A working standard extended source of spectral radiance has been assembled and calibrated for use in the 150-to 260-nm region. The assembly consists of a 10-kw, argon arc lamp mounted to irradiate a 4-in. diam diffuser. The reflected energy from the diffuser is utilized as a calibration source. The procedure for calibrating the spectral radiance of the diffuser is reviewed. Traceability is accomplished by the use of a standard vacuum photodiode. The total uncertainty in the calibration ofthe source is estimated to be 15 percent.