Improvements in birefringent filters. 6: Analog birefringent elements.

A 100-mA analog birefringent element has been built from a polarizing wide field solid Michelson interferometer. The analog element behaves on-axis identically to a crystal element but has the field characteristics of a wide field Michelson. It is demonstrated that by proper choice of glasses for the arms of the Michelson the wide field condition can hold over a large spectral and large temperature range. Most important, proper choice of arm materials allows minimization of the wavelength sensitivity to temperature. A reduction of a factor of 10(2)-10(3) compared to birefringent crystals can be achieved.