HIGH-QUALITY BREWSTERS ANGLE POLARIZER FOR BROAD-BAND INFRARED APPLICATION

We have designed and constructed a linear polarizer for use with visib le and infrared radiation. The broadband polarizer consists of four ge rmanium plates arranged In st chevron geometry. Input radiation is inc ident near Brewster's angle for the first plate such that the reflecte d beam is preferentially s-wave polarized. This reflected beam is stee red subsequently to the successive plates, always intersecting near Br ewster's angle. The beam polarization at the output of the device is a lmost completely s-wave polarized. The ratio of the the paraxial flux of the nearly extinguished p-wave polarized light to the s-wave polari zed light transmitted through the device is found to be less than 10(- 5) for laser illumination at wavelengths af 0.638, 1.32, 3.39, and 10. 6 mu m. Calculations predict that extinction ratios less than 10(-5) a re achievable over the wavelength range from 0.4 mu m to beyond 500 mu m. Alternative design geometries involving fewer plates are also desc ribed along with their advantages and disadvantages.