WAVE PLATE RETARDERS AND METHODS OF MAKING SUCH RETARDERS

摘要

A wave plate retarder 10 comprises two or more birefringent high molecular weight films 11 and 12 arranged with a predetermined angle between their respective optical axes to establish a desired phase difference during transmission through the films 11 and 12 of components of light polarized along orthogonal axes. The predetermined angle may be selected to provide a phase difference of 1 DIVIDED 4 or 1 DIVIDED 2 wavelength of light thus to produce a composite wave plate retarder which functions as a 1 DIVIDED 4 or 1 DIVIDED 2 wave plate regardless of the phase difference of components of light produced by transmission through a single film 11 or 12. As shown, polypropylene films 11, 12 are protected by glass or resin plates 13, 14. Figs. 3, 4 (not shown) show apparatus for measuring the phase difference introduced by single and paired plates. Fig. 1 (not shown) shows the retarder used in a video disc player. IMAGE