Design of Wide Band Tunable Birefringent Filters with Liquid Crystals

We demonstrate LC tunable fllters designed for integration into biomedical optical imaging systems and can be utilized to many other areas. Two types of tunable fllters with wide dynamic range are presented based on a stack of birefringent plates similar to Lyot based con- flguration. Modiflcation of sets of Lyot fllters controlled by difierent sets of external electric fleld allowed us to eliminate unwanted orders. In a difierent approach integration of an additional thin liquid crystal cell (retarder) between crossed polarizers to eliminate one order of the Lyot fllter. Another conflguration proposed uses a sequence of retarders each between crossed polarizers but with increasing thickness following an arithmetic sequence.

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