Encyclopedia > Dichroic

  Article Content


A dichroic material is one in which two opposite polarizations of light travel at different speeds. A thin slab of it can be used to change the polarization of light. If the two polarizations are right and left circular, it rotates linearly polarized light (see circular dichroism); if they are horizontal and vertical, it converts diagonally polarized light to circularly polarized or flips it to the other diagonal.

A slab that delays one polarization by 1/2 wave with respect to the other is a half-wave plate. A circular one rotates polarization by 90 degrees; a linear one flips one diagonal to the other diagonal and exchanges left and right circularly polarized light.

A slab that delays one polarization by 1/4 wave is a quarter-wave plate. A circular one rotates by 45 degrees; a linear one converts diagonal light to circular light and circular light to the other diagonal.

Two pieces of dichroic material with different axis directions can be made into a Wollaston prism. This takes light of two different polarizations and sends them in different directions. With a quarter-wave plate switch, this is used as the detector in quantum cryptography.

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
Kermit the frog

... being green". Kermit's song "Rainbow connection" was also a big hit from The Muppet Movie[?]. In The Muppet Show television series, Kermit was frontman and the ...