Browse Prior Art Database

Lens System for Optical Encoder

IP.com Disclosure Number: IPCOM000078144D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Heiling, GM: AUTHOR [+3]

Abstract

This lens system images a relatively small source of light into multiple parallel bars in the image plane. With this configuration, utilization of the available energy is enhanced since no masking is required. A light source 1, such as a light-emitting diode, is positioned on the axis of a thick lens system 2 having a spherical lens surface 3 and a cylindrical lens surface 4.

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Lens System for Optical Encoder

This lens system images a relatively small source of light into multiple parallel bars in the image plane. With this configuration, utilization of the available energy is enhanced since no masking is required. A light source 1, such as a light-emitting diode, is positioned on the axis of a thick lens system 2 having a spherical lens surface 3 and a cylindrical lens surface 4.

Light which is characterized by axial ray 5 provides a bar of light 6 in the image plane 7. Because of the ratio of the magnifications of the lens system, the width of the image of source 1 is increased. The image is expanded in the direction of arrow 8, because of the combination of spherical lens 3 and cylindrical lens 4.

Due to the thickness of lens system 2 and reflecting surfaces 9 and 10, light from source 1 may take alternate paths characterized by the single-bounce ray 11 and the double-bounce ray 12. Symmetrical rays 11a and 12a combine to provide a plurality of parallel illuminated bars in the image plane. The system operates as if the effective sources 1a, 1b, 1c and 1d were also illuminating the image plane.

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