Recent Developments in Monochromatic Birefringent Filters

Optical birefringent filters are used in various fields of science and technology. Applications in astronomy are very well known from the work of Lyot in 1933. They are used now for tuning dye lasers and figure 1 shows a three element Lyot filter in a dye laser resonator. If the inclinations of the plates are chosen to be equal to the Brewster angle, no polarizers are necessary. Turning the filter around the XX’ axis perpendicular to the plates results in a continuous change of the peak transmission wavelength.