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Proceedings Paper

Off-axis optical elements in integrated injection-molded assemblies
Author(s): Raymond T. Hebert
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Paper Abstract

One of the many benefits of injection-molded plastic optics is the diversity of optical elements that can be incorporated into a design. Aspheres, toroids, irregular apertures and stops, prismatic and diffractive elements are available to the designer with little impact on high- volume production costs. By utilizing off-axis design and total internal reflection (TIR), a series of optical functions can be integrated into an inexpensive, compact unitary structure that can simulate complex conventional optical systems or subsystems. An examples of this philosophy is presented in the form of a fingerprint scanner that includes the entire optical system in a single molded element; accepting radiation from a light-emitting diode, relaying it to an integral fingerpad, and on to a CCD imaging device. The entire structure measures approximately 1 by 3 inches by 1/2 inch thick. It incorporates two off-axis aspheres, three planar TIR surfaces, and two reflective toroids with intermediate aperture stops. The resolution of the system exceeds that of the CCD in center field. The higher-order curvatures of the various elements were played off against one another to minimize distortion resulting from the off-axis design.

Paper Details

Date Published: 1 December 1995
PDF: 6 pages
Proc. SPIE 2600, Design, Fabrication, and Applications of Precision Plastic Optics, (1 December 1995); doi: 10.1117/12.227916
Show Author Affiliations
Raymond T. Hebert, Optimize (United States)

Published in SPIE Proceedings Vol. 2600:
Design, Fabrication, and Applications of Precision Plastic Optics
Alex Ning; Raymond T. Hebert, Editor(s)

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