Objective prism

An objective prism is a flat optical prism that is placed in front of a telescope objective in order to simultaneously image a spectrum of all the stars shown . It is also occasionally used in astrographs , where the spectra are only a few millimeters long due to the relatively short focal length.

The great advantage of quickly obtaining a large number of spectra is offset by the disadvantages that they are short, show only a few details and that neighboring star spectra can overlap. But even if only the clearest spectral lines can be seen, at least the approximate spectral class can be determined from the light distribution within the short spectrum .

literature

• Zimmermann / Weigert: Lexicon of Astronomy . Heidelberg 1999, p. 276 and 396 f .