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Proceedings Paper

Precision, Post-Objective, Two-Axis, Galvanometer Scanning
Author(s): Kurt Pelsue
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Paper Abstract

Using a laser beam and galvanometer scanners with mirrors in an orthogonal configuration is a simple, low cost way to scan an X-Y flat field in a raster or vector mode. The major drawback in the method has been the geometric distortions inherent in two-axis, flat-field scanning, primarily pincushion, tangent, and focus errors of the imaged beam on the field. Until now the problem has been resolved by pre-objective scanning in which a corrective lens is placed between the scanners and the field. Use has been limited, however, to small fields (20 cm) where corrective lenses are practical. Accurate corrections with multiple wavelengths are difficult, if not impossible. Small fields with large radii also have been used to minimize geometric errors, but long focus distances create a number of optical problems. General Scanning now has a post-objective scanning system which solves these problems in virtually any field size or scan radius configuration. By positioning simple lenses and dynamic focusing before the scanners, a post-objective scanning system is created. In this system, the scanning and focus servos are under precise control of a digital correction computer. This paper discusses the theory of correction and the hardware available, as well as the implementation and performance, of a post-objective scanning system.

Paper Details

Date Published: 20 September 1982
PDF: 9 pages
Proc. SPIE 0390, High Speed Read/Write Techniques for Advanced Printing and Data Handling, (20 September 1982); doi: 10.1117/12.935036
Show Author Affiliations
Kurt Pelsue, General Scanning, Inc. (United States)

Published in SPIE Proceedings Vol. 0390:
High Speed Read/Write Techniques for Advanced Printing and Data Handling
Leo Beiser, Editor(s)

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