Squeeze rings

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With the help of bear moss spores , corona was generated around a lamp
Schematic diagram for central observation of Queteletschen rings: the left by a pinhole incident plane wave is reflected by a surface mirror (right), and a wavelength-dependent scattering at a location on the mirror layer of dust. An observer (below) sees the interference rings with different brightnesses and colors centered around the optical axis in an inclined, partially transparent mirror (middle).

Quételet rings are colored, more or less arcuate phenomena in the scattering of light at contaminated, specular arise surfaces. They are named after the astronomer Adolphe Quetelet , who observed and explained their formation, but are also known as Whewell's rings after the scientist William Whewell . Occasionally, the term Newtonian dust rings is also found , as Isaac Newton discovered these phenomena at the end of the 17th century without being able to interpret or explain them.

Squeeze rings arise from the simultaneous reflection and scattering of coherent light, when the interfering rays travel different distances depending on the viewing angle within the coherence length of the light, acquire an angle-dependent phase position and thus intensify or extinguish each other. With white light sources, the light is also split into its spectral components because of the wavelength-dependent diffraction . The closer the light source is to the observer, the greater the distance between the virtual rings and the more clearly they emerge. The lines that only appear to lie on the reflecting surface shift with the moving observer.

Such rings can also be observed in nature as corons in the atmosphere under certain conditions .

Photographs

Schematic diagram for eccentric observation of Queteletschen rings (respectively strips): the left by a pinhole incident plane wave is reflected by a surface mirror (right), and a wavelength-dependent scattering at a location on the mirror layer of dust. Due to the interference of the rays, an observer sees different brightnesses and colors depending on the viewing direction

Eccentric photographs of a camera focused to infinity of squeezed rings on a talc- dusted mirror (50 centimeters in diameter) set up five meters away at various lateral distances of a small incandescent lamp (visible in the images as a bright white spot):

  • Light source directly on the camera lens

  • Light source approximately 10 centimeters from the camera lens

  • Light source about 25 centimeters from the camera lens

  • Light source about 50 centimeters from the camera lens

Squeeze rings can, for example, also be observed in sunlight on slightly contaminated water surfaces.

Individual evidence

  1. ↑ Karl Exner : About the Newtonian dust rings
  2. ↑ Joachim Schlichting: Color wreaths on dusty waters (PDF; 581 kB), Physics in our time, Wiley-VCH Verlag, 35th year (2004), number 2, pages 86 to 89

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