Littrow spectrometer
A Littrow spectrometer is a spectrometer with only one focussing optic, which simultaneously acts as a collimator for the incident light as well as an objective for the light reflected by the dispersive element. This arrangement was devised by Otto von Littrow (1843–1864), a son of the Austrian astronomer Karl Ludwig von Littrow . Such an arrangement is known as an autocollimation arrangement .
For this purpose, the dispersive element must reflect the light, which is separated according to wavelength, back in the direction of incidence. A reflection grating as well as a prism or transmission grating in front of a plane mirror is possible as a dispersive element . A reflection grating must be rotated in such a way that the diffraction order that is to be observed is reflected back against the direction of incidence. Blaze gratings with a correctly chosen blaze angle are particularly suitable for use in Littrow spectrometers .
So that the reflected light can be detected, the entrance slit and the detector are offset from one another perpendicular to the direction of dispersion.
literature
- Franz Kerschbaum, Isolde Müller: Otto von Littrow and his spectrograph . In: Astronomische Nachrichten Volume 330, Issue 6/2009, pp. 574-577, ISSN 0004-6337
- Berthold Stober: The Mizar test, spectroscopy with a self-made grating spectrograph . In: Stars and Space June 2005, p. 64, ISSN 0039-1263
- Eugene Hecht: optics . 4th revised edition from the English by Dr. Anna Scheitzer. Oldenbourg, Munich Vienna 2005, ISBN 3-486-27359-0 , p. 772
Web links
- spectra-magic.de: Spectrometer concepts and parameters with mapping of the beam path in the Littrow spectrometer