Spectrophotometer for Both Transmissivity and Reflectivity Measurement in the Region from the Near Infrared to the Ultraviolet

Abstract

When multiple internal reflections are taken into account, low-absorption (high-transmissivity) measurement must be corrected with the reflectivity. With this in mind, a spectrophotometer for both transmissivity and reflectivity measurement has been developed. It covers measurement from the near infrared to the ultraviolet (1.1 to 6.2 eV). Since the spectrophotometer aims at especially high transmissivity measurement, it requires low stray light, fine adjustment of the optical system and low-noise electronics. This paper discusses its principle, its performance and the method of correction for effective operation. The spectrophotometer can measure the transmissivity T from 0.0004 to 0.998 and the reflectivity R from 0.0005 to 0.998 in the spectral region from 1.1 to 5.1 eV, and T from 0.003 to 0.995 and R from 0.0008 to 0.995 in the region from 5.2 to 6.2 eV.