Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers. Specim manufactures and sells imaging spectrographs, hyperspectral cameras and systems. He also built several imagers and spectrographs for the 1.8-meter Perkins telescope. Michelson spectrographs are capable of very high spectral resolution observations of very bright sources. This has significant advantages for spectrographs and other heavy instruments typically used at research observatories. Early spectrographs employed banks of prisms that split light into a broad spectrum. Distinguishable on high resolution wideband spectrographs, the wave amplitude grows linearly then switches to non-linear. IRTF also hosts a number of visitor instruments, usually thermal infrared spectrographs. Both cameras were equipped with slitless spectrographs. Otto Struve proposed in 1952 the use of powerful spectrographs to detect distant planets. Examples of fiber-fed spectrographs include the planet-hunting spectrographs HARPS or ESPRESSO. Radial velocity follow-up is performed with high-precision spectrographs, namely SOPHIE, HARPS and HIRES. The first spectrographs used photographic paper as the detector. This would mean a large step forward over current radial-velocity spectrographs like ESO's HARPS. He made spectrographs of the atmospheres of Jupiter, Saturn, and Uranus.