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Proceedings Paper

Model for symmetric and asymmetric vignetting in beam position measurement
Author(s): Lawrence B. Brown
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Paper Abstract

Laser alignment systems frequently use position sensitive detectors such as CCD arrays and lateral or segmented photodiodes. Nonlinear properties of the detector elements and optical aberrations are usually important design considerations, but the effect of small amounts of vignetting is often neglected. This can be an important factor in achieving highly accurate beam position measurement, especially for systems which work at long ranges or use expanded beams. In cases where the size of the optical aperture must be minimized due to cost considerations, it can be difficult to choose the optimum clear aperture diameter without lengthy analysis. Sometimes, simple rules of thumb based upon “X times the 1/e2 diameter will work fine, but the designer still needs to know how “X” relates to precise instrument performance in order to rationally choose a value for it. The objective of this paper is to provide a thorough description of the tools needed by the electro-optical engineer in order to solve these kinds of problems. Analytical and numerical methods are outlined which simulate truncation and its effect on both the point spread function and the center of energy. Algorithms are described for computing simple vignetting geometries and results are presented for a variety of sample cases showing the magnitude of the effects. Limitations of the theory are also listed in order to determine its applicability to other kinds of systems. Application as both a design simulation tool and a real-time software compensation system is suggested.

Paper Details

Date Published: 25 September 1997
PDF: 12 pages
Proc. SPIE 3130, Lens Design, Illumination, and Optomechanical Modeling, (25 September 1997); doi: 10.1117/12.284065
Show Author Affiliations
Lawrence B. Brown, Brown Optronics Corp. (United States)

Published in SPIE Proceedings Vol. 3130:
Lens Design, Illumination, and Optomechanical Modeling
R. Barry Johnson; Robert E. Fischer; R. Barry Johnson; Richard C. Juergens; Richard C. Juergens; Paul R. Yoder Jr.; Warren J. Smith; Paul R. Yoder Jr., Editor(s)

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