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Proceedings Paper

Focus Measurements Using The Star Test Pattern
Author(s): Arthur E. Burgess
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Paper Abstract

The purpose of the paper is to describe a method of focal spot size measurement. A two dimensional smeared filament image focus model is presented. The model contains four adjustable parameters but average values for the two smearing parameters are sufficient. The two remaining scaling parameters can be determined from MTF minima frequencies. "Equivalent" size descriptors such as RMS equivalent rectangle or the noise equivalent aperture can be calculated using the focus model parameters. The use of the star test pattern to obtain these parameters is described. Results for nine foci are compared with pin hole camera measurements. Star pattern size measurements for 76 focal spots are presented and compared to nominal size. A majority of the foci exceed tolerance in at least one direction.

Paper Details

Date Published: 23 December 1976
PDF: 8 pages
Proc. SPIE 0096, Application of Optical Instrumentation in Medicine V, (23 December 1976); doi: 10.1117/12.965395
Show Author Affiliations
Arthur E. Burgess, University of B.C. (Canada)

Published in SPIE Proceedings Vol. 0096:
Application of Optical Instrumentation in Medicine V
Robert K. Cacak; Paul L. Carson; Gregory Dubuque; Joel E. Gray; William R. Hendee; Raymond P. Rossi; Arthur Haus, Editor(s)

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