Large computer generated diffractive optical elements (DOE's) are useful in many applications. Typical sizes of DOE's range from 6 inches up to two meters in diameter. Current state-of-the-art techniques for fabricating these DOE's involve photolithographic processing where photoresist is used as the light sensitive medium and an etchable metal layer is used to form the pattern of the DOE. Handling and costs associated with photolithographic methods become critical issues when the DOE's become large. It is therefore advantageous to have a technique that would not require the photolithographic step in the process. This paper will discuss the instrument and the technique used at the Optical Sciences Center (OSC) for fabricating large computer generated DOE's. A non-photolithographic technique of thermally selective oxidization is used to transfer the DOE pattern onto a metallic film on the substrate. The subsequent etching part of the process takes advantage of the differential etch rates of a non-oxidized and oxidized metal. Figure results indicate the accuracy of using this approach to fabricate DOE's is better than (lambda) /100 rms.

Date Published: 30 September 1994
PDF: 9 pages
Proc. SPIE 2263, Current Developments in Optical Design and Optical Engineering IV, (30 September 1994); doi: 10.1117/12.187993

Published in SPIE Proceedings Vol. 2263:
Current Developments in Optical Design and Optical Engineering IV
Robert E. Fischer; Warren J. Smith, Editor(s)