Christiansen filter

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A Christiansen filter is an optical filter that has a maximum transmittance for a certain wavelength .

At the end of the 19th century, the Danish physicist Christian Christiansen investigated the relationship between body surfaces and their heat emission . For experiments, he embedded crushed window glass in a mixture of organic liquids with approximately the same refractive index . The experiment showed that with the same refractive index ratio between the two phases (glass - liquid), the glass becomes transparent, but the glass and liquid have a color. Christiansen recognized that the dispersion of light is the cause of this iridescent effect.

The liquid and the crushed glass only have the same refraction ratio at a certain wavelength. This one wavelength transmits the mixture of immersion liquid and glass powder unhindered, the other colors of the spectrum, on the other hand, are bent according to the wave optics and deflected in different spatial directions.

While you can only go through z. B. Sodium flame monochromatic light could produce, Christiansen recognized the possibilities, by means of the named after him Christiansen filter to produce monochromatic light outside the visible spectrum.

A change in the wavelength which this dispersion filter lets through can take place by changing the concentration of the organic liquid, by changing the temperature or by varying the pressure, all of which result in a change in the refractive index of the liquid.

Individual evidence

  1. ↑ a b Christian Christiansen: Investigations into the optical properties of finely distributed bodies - first communication. In: Annual Review of Physical Chemistry , No. 23 , pp. 298–306, 1884
    Christian Christiansen: Investigations into the optical properties of finely distributed bodies - second communication. In: Annual Review of Physical Chemistry , No. 24 , pp. 439-446, 1885
  2. ↑ CV Raman: The theory of the Christiansen experiment. Proc. Ind. Acad. Sci., Vol. 29, pp. 381-390, 1949
  3. ↑ VI Shelyubskii: A new method for determining and controlling the homogeneity of glass (orig. Russian: Nowy metod opredelenija i kontrolja odnorodnosti stekla). Glass and Ceramics (Steklo i Keramika), vol. 17, pp. 17-22, 1960
  4. ↑ T. Sakaino, M. Yamane, A. Makishima, and S. Inoue: An improved method for measuring the homogeneity of glass by Shelyubskii´s method. Glass Technol., Vol. 19, pp. 69-74, 1978

literature

  • J. Braunbeck: Optical properties of liquid-soaked porous solids. Acta Physica Austriaca 15, 99 (1962)
  • RP Heidrich: Experimental homogeneity tests on technical glasses with the Cristiansen filter. Dissertation. Clausthal University of Technology, 1999.
  • RP Heidrich, GH Frischat: Optimizing the Christiansen-Shelyubskii method and its comparison with industrial control methods for homogeneity determination of glasses. Glass tech. Ber. Glass Sci. Technol., Vol. 72, pp. 197-203, 1999.