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Proceedings Paper

Microforging technique for rapid low-cost fabrication of lens array molds
Author(s): C. R. Forest; M. A. Saez; I. W. Hunter
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Paper Abstract

Interest in micro-optical components for applications ranging from telecommunications to life sciences has driven the need for accessible, low-cost fabrication techniques. Most micro-lens fabrication processes are unsuitable for applications requiring 100% fill factor, diameters around 1 mm, and scalability to large areas with millions of lenses. We report on a flexible, low-cost mold fabrication technique that utilizes a combination of milling and microforging. The technique involves first performing a rough cut with a ball-end mill. Final shape and sag height are then achieved by pressing a sphere of equal diameter into the milled divot. Using this process, we have fabricated molds for rectangular arrays of 1-10,000 lenses with apertures of 0.25-1.6 mm, sag heights of 3-130 &mgr;m, inter-lens spacings of 0.25-2 mm, and fill factors of 0-100%. Mold profiles have roughness and figure error of 68 nm and 354 nm, respectively, for 100% fill factor, 1 mm aperture lenses. The required forging force was modeled as a modified open-die forging process and experimentally verified to increase nearly linearly with surface area. The process is easily adapted to lenticular arrays. Limitations include milling machine range and accuracy.

Paper Details

Date Published: 14 May 2007
PDF: 4 pages
Proc. SPIE 10316, Optifab 2007: Technical Digest, 1031614 (14 May 2007); doi: 10.1117/12.717838
Show Author Affiliations
C. R. Forest, Massachusetts Institute of Technology (United States)
M. A. Saez, Massachusetts Institute of Technology (United States)
I. W. Hunter, Massachusetts Institute of Technology (United States)

Published in SPIE Proceedings Vol. 10316:
Optifab 2007: Technical Digest
James J. Kumler; Matthias Pfaff, Editor(s)

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