The Horiba iHR550 is a spectrometer capable of being used as both a monochromator and a spectrograph, i.e. it can be used both for selecting wavelength bands (narrow) or taking an overall spectrum measurement. Its design is of the Czerny-Turner type, which consists of a collimating mirror in front of the entrance slit that collimates onto a diffraction grating turret (that has 3 gratings on it, in this case, controlled by a worm-wheel motor drive) that separates the incident light into its constituent frequencies. A final collimating mirror is then placed between the grating and the exit slit. The light is detected with a thermoelectrically cooled high sensitivity CCD camera. The camera detector also allows spectral images to be taken which are narrow band images of the separated light falling onto the detector.