Browse Prior Art Database

Laser Beam Expander and Focusing Lens System

IP.com Disclosure Number: IPCOM000083264D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Dickson, LD: AUTHOR [+4]

Abstract

This system provides a means for expanding and focusing a laser beam which can then be used for scanning purposes. An adjustment on the separation of the lens elements allows loose tolerances on the lens focal lengths.

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Laser Beam Expander and Focusing Lens System

This system provides a means for expanding and focusing a laser beam which can then be used for scanning purposes. An adjustment on the separation of the lens elements allows loose tolerances on the lens focal lengths.

The figure shows a cross-sectional view of the lens assembly. Tapered retaining rings 1 and 2 have two functions -- first, to physically retain the lens elements within the lens housing 3 and second, to mechanically center the lens elements with respect to the center of lens housing 3. This technique allows a loose tolerance on the inside diameter of lens housing 3, and also on the outside diameters of double-concave lens 4 and archromat lens 5. The optical axis of the lens must be centered relative to its outside diameter.

Inner housing 6 slides within outer housing 7 to provide an adjustable axial spacing dimension between lens 4 and lens 5. This allows standard industry tolerances on the lens focal, length with no critical tolerances on the lens housing which relates to the distance between the two seating planes of each lens element. Set screw 8 locks inner housing 6 in place when properly adjusted.

The use of an achromat or doublet lens 5 minimizes spherical aberrations, which is the sole aberration for an on-axis monochromatic object source. In addition, the use of achromat lens 5 allows less critical tolerances on the input beam position, since off-axis aberrations are reduced. The combination of ...