Circular Polarizers

International Polarizer's circular polarizer converts unpolarized light to circularly polarized light. Circular polarizers are composite structures consisting of a linear polarizer and a quarter wave retarder. The retarder axis is oriented at 45 degrees with respect to the polarizer axis. As incident light passes through the composite it is converted to circularly polarized light. After reflection the light returns, passing through the retarder a second time. The net result is that the plane of polarization is rotated 90 degrees with respect to the original orientation. The linear polarizer then blocks the return light. This eliminates reflections. (See top diagram) On the other hand, light originating from behind the circular polarizer passes through it only one time and is not blocked. If a display is placed behind a circular polarizer, reflections from the surface of the display are eliminated but characters on the display are seen clearly. In fact, their contrast is enhanced.	Light passes through a circular polarizer, is reflected by a mirror, and is blocked on its return path.
Standard circular polarizers are constructed with quarter wave retarders for 550 nm, the center of the visible region. The retardance value is 138 nm. Custom circular polarizers can be supplied with wave retarders at other wavelengths. The reflection from a front surface mirror can be reduced by a circular polarizer. (See middle diagram.) The mirror itself has a reflectivity of 92%. The circular polarizer reduces this to 0.5%.	The Circular Polarizer panel is a parallelogram 16.5" x 39"
The circular polarizers can be mounted on or between glass or plastic sheets, if desired. The sheets can accept anti reflection coating. Circular polarizers are offered as panels in the shape of a parallogram 17 inch x 39.4 inch (1 meter) x 0.040 inch. The usable width is 16.5 inches. One edge is cut at 45 degrees with respect to the other edge. (See lower diagram.) The panels are available with or without a pressure sensitive adhesive for easy laminating to other substrates.	Reflected light is eliminated by the CP