High-performance tunable filter.

The tuning performance of a liquid-crystal, electro-optically tunable, Lyot filter is described. This filter is widely tunable across the visible region up to a wavelength of approximately 630 nm and has very high performance characteristics that are preserved over the entire tuning range. These include a narrow passband of 0.1 nm, a large-aperture performance of at least 30 mm, a wide field of view of ?8.5 degrees , and the ability to be tuned to an accuracy that is one tenth of the linewidth of the passband. Possible applications for such a filter include remote sensing, multispectral sensing, and laser environmental and underwater monitoring.