Fabricating optical elements using a photoresist formed from contact

Abstract

Gray scale masks used to create optical elements are formed. Desired gray scale patterns may be created by varying the thickness of a light absorbing layer. Such variations in thickness may be created using multiple binary masks. Desired gray scale patterns may also be created on a computer using available software and then imaged onto film or a glass film plate. Direct contact or proximity printing is then used to transfer the true gray scale pattern onto photoresist. The photoresist is then etched, thereby forming the desired pattern therein. All portions of the desired pattern are simultaneously formed in the photoresist. The etched photoresist is then used to photolithographically fabricate either the optical element itself or a master element to be used in injection molding or other replication techniques. The gray scale mask itself may be used repeatedly to generate photoresists. The imaging is particularly useful for forming optical elements having a plurality of arrays of refractive elements.