Spectrometer, Infrared, Miniature
Wednesday, September 20, 2006
A Miniature Infrared Spectrometer has been designed and developed where light beam enters the Spectrometer through a rectangular hole in a baffle and strikes an off-axis parabolic mirror. The mirror images the field of view onto an entrance slit. The slit is followed in an optical train by four side-by-side concave Laser-ruled holographic diffraction gratings. Each grating is independently adjustable and optimized for a 2,000-A portion of the overall-A wavelength range. Each grating is corrected for aberrations and acts as a dispensing, focusing, and field-flattening optical element combined into one.
The portion of the spectrum from each grating is focused onto one of four strips on a 40-mm-diameter photocathode mounted on the faceplate of an image intensifier. Half the faceplate is coated with S1 photocathode material (sensitive primarily in the near infrared); the other half is coated with S20 photocathode material (sensitive primarily in the visible). The output of the image intensifier is coupled and minified by a Fiber Optic taper onto an 11.4-by-8.8-mm CCD array. Peltier devices cool the photocathode and the CCD.
The optical system of the spectrometer is moderately fast, aperture about 1/6 of the focal length. The instrument has a dynamic range of 10.5. The Spectrometer is 37 cm by 37 cm by 48 cm.
Source: NASA Tech Briefs
Reference: Marsha R. Torr, NASA, Marshall Space Center, Houston, Texas
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posted by JD52 @ 8:41 PM,
