COMPACT LITTROW-TYPE SCANNING SPECTROGRAPH

摘要

A Littrow-type spectrometer or monochromator using a folded light path to provide a compact optical instrument is disclosed. Light enters the instrument through an inlet aperture on a planar mirror. The aperture is located at the focus of a parabolic collimetor mirror. Collimated light reflected by the parabolic miror is reflected back to the planar mirror, which is positioned at an angle to the collimated light. The light reflected from the planar mirror is directed at a planar grating that produces diffracted light having all the wavelengths input into the system, including light of a selected wavelength, back towards the planar mirror. Light having the selected wavelength is thus caused to fall on the parabolic mirror. The parabolic mirror then focuses the selected wavelength of light ont a light exit aperture that is juxtaposed to the inlet light aperture. The planar grating can be rotatably mounted to scan the input light spectrum.