PURPOSE: To obtain a random phase plate of large size which has superior phase precision by using a film or sheet of plastic which have areas with different refractive indexes at random.
CONSTITUTION: The random phase plate is made of the film or sheet 1 of plastic which has areas 2, 2', 2"Whaving different refractive indexes. This film or sheet 1 is manufactured by blending ≥2 kinds of polymers which differ in refractive index and molding them by an extrusion flow drawing method, etc., into a film having parts with different refracting indexes in a mosaic shape, or treating the drawn film locally and physically by a heat treatment, solvent treatment, etc., and thus forming the drawn film which varies in refractive index. The size of teach area with a different refractive index is about 10-6W10-2mm2, preferably, 10-4W10mm2.
KUBOZONO TATSUYA
OISHI YOZO
