Spectrometer, Infrared, Fiberoptic
Wednesday, September 20, 2006
A Fiber Optic Infrared Spectrometer has been designed and developed based on a double-pass version of the Schmidt optical system. The optical system is contained in a piece of solid glass (two pieces cemented together), which is mechanically and thermally stable.
A light beam is fed from Fiber Optics into the Spectrometer through a flat entrance surface. The Fiber Optic cable is co-planar with a PbS photodetector array with a blocking filter and displaced a small distance out of the page displacement.
A diffraction grating disperses the light beam angularly according to wavelength and reflects it back through the optical system to the array of PbS photodetectors. The optical system, operating as a camera on the return pass, focuses the light beam wavelength spectrum on the photodetector array. The wavelength display on the photodetector arry is an indication as the function of light beam position.
The diverging light beams are partially collimated by the primary mirror. A narrow stripe at the center of the mirror is left uncoated to prevent reflection of the light beam directly back onto the photodetectors array. The collimated rays are folded 90 degrees by total internal reflection. The light beam then passes out of the optical system, through a corrector surface fully collimating the light beam.
Source: None Available
Reference: N. Page and Mary White, Caltech, Pasadena, CA for NASA’s Jet Propulsion Laboratory
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posted by JD52 @ 8:39 PM,
