Video-frequency light modulator having a wide angular aperture

This paper discusses the 45° ycut ADP modulator. An investigation of the propagation of light through the crystal shows that there is an inherent limitation in the angular aperture of the simple 2-crystal modulator. The inclusion of a halfwave plate between the crystals to improve the temperature stability also enables large angular apertures to be achieved, provided the crystals are correctly aligned. Results of measurements carried out on experimental modulators are presented and a comparison made with the 45° zcut modulator.