Spectrophotometer with two separate light paths - has flat and concave mirrors on either side of diffraction grating

摘要

The spectro-photometer includes a spectrograph (1) with an input plate (2) with a number of slot openings (3) connected by fibre-optic conductors (13,14) to a standard light source (15). Inside the spectrograph are flat and concave mirrors (5,6,7,8), two on the input side and two on the output side of a grid (9). The output light beams emerge as two separate spectra from an outlet opening (4) through a masking plate (17) to an optical detector (16), an interface (18) and a data processor (19). In use, one of the spectra is used for measurement and the other is a reference. The effect of the mask is to cut out the higher orders of the spectra. The grid typically has a spacing of 150 lines per mm and is suitable for a light wave-length range of 400 to 700 mm.