Holographic patterning method and tool employing prism coupling

摘要

A holographic lithography tool (110) for generating a light interference pattern used to expose a photosensitive medium (119) employs a refracting prism (121) in the optical path between divergent illuminating beams (127a, 127b). The prism is optically coupled to the photosensitive medium via an index matching fluid (123). By increasing the incident beam angle and the index of refraction, the prism reduces the size of features recorded in the photosensitive material. The divergent illuminating beams are generated by a beam delivery system which preferably employs easily adjustable fiber optic cables (176, 184). Use of the prism coupling technique facilitates use of fiber-optic-compatible wavelengths in the blue region of the spectrum in a variety of applications, such a distributed feedback grating fabrication.