METAL THIN-FILM OPTICAL POLARIZERS FOR SPACE APPLICATIONS

WE PROPOSE TO FABRICATE A BROADBAND POLARIZER FOR VISIBLE AND NEAR-INFRARED RADIATION USING A NEW TECHNIQUE RECENTLY DEVELOPED BY THE PRINCIPAL INVESTIGATOR FOR PRODUCING EVAPORATIVELY DEPOSITED METAL THIN FILMS WHICH POLARIZE NORMAL INCIDENCE LIGHT OVER A WIDE ACCEPTANCE ANGLE. NARROW BAND POLARIZERS USING SILVER HAVE BEEN DEMONSTRATED IN THE NEAR INFRARED TO HAVE CONTRAST RATIO K1/K2 IN EXCESS OF 3000 AND EXCELLENT STABILITY IN MILITARY AND SPACE ENVIRONMENTS. THESE POLARIZERS ARE COMPACT SHEET POLARIZERSAND REPLACE PLASTIC DICHROIC SHEETS. THE OBJECTIVE OF THE PROPOSED EFFORT IS USE OF THIN-FILM TECHNIQUES TO DEVELOP VISIBLE AND NEAR-INFRARED POLARIZERS WHICH ARE COMPACT AND CAN BE USED IN A SPACE ENVIRONMENT. AN INVESTIGATION OF FILM MATERIALS, DEPOSITION TECHNIQUES, AND SUBSTRATE MATERIALS WILL BE CONDUCTED TO ACHIEVE POLARIZING IN THE SPECTRAL BAND 400 NM TO 1100 NM. THE STRUCTURE OF THESE POLARIZING THIN METAL FILMS WILL BE EXAMINED AND COMPARED WITH WIRE GRID POLARIZER THEORY AND THTHEORY OF ELECTROMAGNETIC SCATTERING OFF METAL DIPOLES. THEEFFORT WILL INCLUDE INVESTIGATION OF TECHNIQUES FOR IMPROVING COATING DURABILITY, TRANSMISSION, EXTINCTION AND PEAKING PERFORMANCE AT 570 NM TO ACHIEVE CONTRAST RATIO K2/K1 OF 105.