Partial polarizer filter

摘要: A birefringent filter module comprises, in seriatum, an entrance polarizer, a first crystal responsive to optical energy exiting the partial polarizer second and exit polarizer. The crystals have fast axes disposed ± 45° from high transmitivity direction of Preferably, has length 1/2 that is nine times as great low direction. To provide tuning, polarizations entering leaving are varied by either rotating polarizers, or sandwiching polarizers between pairs half wave plates rotated relative polarizers. plurality modules may be cascaded. for (n+1) 2/3 n.