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Diffraction Grating Oscillator

IP.com Disclosure Number: IPCOM000085867D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Mathisen, ES: AUTHOR

Abstract

Certain types of spectrophotometers use diffraction gratings to disperse a wide-band light beam into a spectra. A slit is located in front of a detector and allows the spectra to be analyzed by passing only a relatively narrow bandwidth of the spectra at any given time. To sweep the entire spectra, it is common to move either the diffraction grating or the slit.

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Diffraction Grating Oscillator

Certain types of spectrophotometers use diffraction gratings to disperse a wide-band light beam into a spectra. A slit is located in front of a detector and allows the spectra to be analyzed by passing only a relatively narrow bandwidth of the spectra at any given time. To sweep the entire spectra, it is common to move either the diffraction grating or the slit.

In attempting to increase the rate at which the spectra could be scanned, the manner in which the movement is effected becomes complex not only because of the increased scanning rate but also because of the need to maintain or improve the accuracy and resolution of the instrument. Shown in the drawing is a mechanical oscillator that is coupled to a diffraction grating so as to provide high speed and accurate scanning.

As shown in the drawing, polychromatic light from a source 1 is imaged by lens 2 on a slit 3. The light beam passing through the slit 3 is reflected from a mirror 4 onto a diffraction grating 5. The resultant spectra is reflected from a mirror 6 onto a slit 7 that allows a narrow bandwidth portion to fall upon a photodetector 8, such as a photomultiplier tube. Grating 5 is mounted upon a shaft 9 that is oscillated causing grating 5 to oscillate within limits, so that the spectra produced thereby is swept past slit 7 allowing an analysis to be made of the components of the spectra.

To accomplish the oscillation of grating 5, a continuously driven constant- speed...