an instrument that subjects a photographic material to precisely measured amounts of exposure in monochromatic light that are varied in a definite manner. The spectrosensitograms thus obtained can be measured with a densitometer and are used to construct families of monochromatic characteristic curves and spectral sensitivity curves (seeSENSITOMETRY).
Unlike a sensitometer, a spectrosensitometer includes a spectrograph, which decomposes the radiation from the light source into a spectrum. Glass dispersing prisms are used in spectrosensitometers when the spectral sensitivity of photographic materials is determined in the visible and near-infrared regions; quartz prisms are used for the ultraviolet region. In the USSR, spectrosensitometric experiments with black-and-white photographic materials (GOST [All-Union State Standard] 2818–45) are performed with spectrosensitometers of the ISP-73 type (Figure 1) in the visible region and instruments of the FSR-9 type in the ultraviolet region.