Phase mask with amplitude structure prodn. - by photolithography and evapn. avoids justification problems

摘要

Prodn. of a phase mask with amplitude structure for an optical memory or for masks for optical symbols is carried out by photolithographic and evapn. techniques. An amplitude structure (I) is produced photolithographically on a substrate and then the negative of a phase structure (II) is imprinted, accurately positioned, in a photoresist layer (III) placed over (I). The negative is then coated with an optical retarding layer (IVe of definite thickness and the positive of (II) is obtd. by dissolving out the resist of the negative structure. Problems of justification and imaging occurring with separate phase and amplitude masks are obviated. Pref. (I) is a Cr pattern. (IV) has the same thickness over its entire area and consists of Ce oxide.