HN22 SHEET POLARIZER, AN INEXPENSIVE INFRARED RETARDER

The popular sheet polarizer, Polaroid HN22, has been measured to be a nearly half-wave retarder in the 3.6-5.4-mu m spectral band with a tra nsmittance of approximately 20%. Tuning of the retardance value betwee n 60 degrees and 260 degrees has been demonstrated by tilting of the H N22 sheet with respect to the incident beam. The material's availabili ty, relatively large aperture, large field of view, and low cost make it an excellent candidate for use as an infrared retarder for systems operating in this wave band. Thus HN22 may be employed as an inexpensi ve half-wave linear retarder and used for rotating the plane of polari zation as well as for conversion between circular polarization states. (C) 1997 Optical Society of America.