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Two dimensional array of AR-coated diffractive microlenses fabricated by thin film deposition

 
: Pawlowski, E.; Engel, H.; Ferstl, M.; Furst, W.; Kuhlow, B.

Roychoudhuri, C. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Miniature and micro-optics. Fabrication and system applications II : 19 - 20 July 1992, San Diego, California
Bellingham/Wash.: SPIE, 1993 (SPIE Proceedings Series 1751)
ISBN: 0-8194-0924-3
S.13-21
Conference "Miniature and Micro-Optics. Fabrication and System Applications" <2, 1992, San Diego/Calif.>
Englisch
Konferenzbeitrag
Fraunhofer HHI ()
antireflection coatings; diffraction gratings; electron beam lithography; integrated optics; lenses; optical workshop techniques; photolithography; sputter deposition; sputtered coatings; two dimensional arrays; antireflection coated diffractive microlenses; thin film deposition; fresnel zone microlenses; antireflection layers; ion-beam-sputter deposition technique; thickness; reflection-wideband-monitoring system; circular aperture; focal lengths; wavelength; blazed profile; stepped profiles; photolithographic technology; spot-sizes; diffraction limited values; diffraction efficiency; eight level structure; 0.63 micron; 1.52 micron

Abstract
Two dimensional arrays of Fresnel zone microlenses were fabricated and coated with antireflection layers by ion-beam-sputter deposition technique. The thickness of the layers was controlled by a reflection-wideband-monitoring system with high accuracy. The lenses have a circular aperture of 2 mm and focal lengths of 70 mm and 20 mm for the wavelength of 0.63 mu m and focal lengths of 29 mm, 8 mm and 5.7 mm for the wavelength of 1.52 mu m. The blazed profile in each zone was approximated by an eight level profile. Such stepped profiles were recorded with several masks, written with e-beam and with photolithographic technology. The measurements reveal that the spot-sizes of the fabricated microlenses are close to the diffraction limited values, and the diffraction efficiency for the eight level structure is 83 %.

: http://publica.fraunhofer.de/dokumente/N-13616.html