A device which enables visual observation and evaluation of optical spectra (usually confined to the visible spectral region).
Source:
PAC, 1995, 67, 1725. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-IX. Instrumentation for the spectral dispersion and isolation of optical radiation (IUPAC Recommendations 1995)' on page 1729 (https://doi.org/10.1351/pac199567101725)