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Proceedings Paper

Chirped lens-array LED spot-array generator with individually colored spots
Author(s): Peter Schreiber; Peter Dannberg; Frank Wippermann
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Paper Abstract

State-of-the-art high brightness LEDs offer optical powers of about one watt and span a wide wavelength range - clearly outperforming usual single mode laser diodes. Thus, LEDs excel in applications where beam quality - the main advantage of lasers - is not the decisive criteria and/or speckle are critical. For a LED illuminated spot array generator a pupil splitting design approach with a lens-array is presented. Contrary to usual laser diode spot array generators with diffractive beamsplitters this design enables individually colored spots, suppresses unwanted speckle and increases beam quality with increasing spot number. Design rules and scaling laws are established, then the resulting system is analyzed with respect to useful transmission, beam quality and chromatic aberrations. We realized a 21x21 spot array generator with 40°x40° FOV using a simple plano-convex lens as projection optics. A chirped lens array with varying focal widths and pre-distorted lenslet positions corrects field curvature and distortion of the projection optics. Additional buried apertures and color filters suppress unwanted straylight and enable individually colored spots, respectively. The lens array is fabricated by replication of reflow master structures into polymer on glass.

Paper Details

Date Published: 13 May 2010
PDF: 8 pages
Proc. SPIE 7716, Micro-Optics 2010, 771617 (13 May 2010); doi: 10.1117/12.854415
Show Author Affiliations
Peter Schreiber, Fraunhofer Institute for Applied Optics and Precision Mechanics (Germany)
Peter Dannberg, Fraunhofer Institute for Applied Optics and Precision Mechanics (Germany)
Frank Wippermann, Fraunhofer Institute for Applied Optics and Precision Mechanics (Germany)

Published in SPIE Proceedings Vol. 7716:
Micro-Optics 2010
Hugo Thienpont; Peter Van Daele; Jürgen Mohr; Hans Zappe, Editor(s)

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