Broadly speaking, an optical spectrometer consists of an entrance slit, a diffraction grating or prism, a detector, and routing optics. ZEISS Spectroscopy offers high-quality, robust, customer-driven spectrometer modules. Various optical design and detector options allow for OEM solutions tailored to your exact needs. An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument. The VIRTIS imaging spectrometer built for ESA's Rosetta cometary mission is a versatile instrument that is also well-suited to Venus observations. The discovery of the near-IR windows in the atmosphere of Venus from ground-based observations in the 1980s showed that the surface of the planet can be. An optical spectrometer is a kind of instrumentation used to measure the spectrum of light.