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Proceedings Paper

Influence of the machine vision lens on the accuracy in contactless 2D metrology
Author(s): Norbert Schuster; Thomas Schoenheit
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Paper Abstract

A model for quick estimation of the accuracy of the contactles 2D-measurement is developed. Perspective errors of entocentric lenses and distortion errors of entocentric and telecentric lenses are respected. The perspective error starts from the standard deviation of the working distance. The distortion contribution starts from the often publicized maximal distorint value in percent. The distorint contribution is divided in two parts: the size part considers the variation from calibration width and to width to measure, the field part considers the psoition variation of the piece under test in the field of view. Two graphs show typical and generally valuable functions. The superimpose of differnet contributions is realized as sum of quadrates. Due to this, the result can be interprted as the standard deviation of a contactless measured width. All results have the dimension pixel. Three examples are presented. The first one shows the accuracy limits in a typical machine vision application using different entocentric lenses. The second one discusses an entocentric lens measuring differnet object sizes. The third one uses a telecentric lens at same measuring condition. Here, the estimated accuracy is ten times higher.

Paper Details

Date Published: 18 October 2002
PDF: 11 pages
Proc. SPIE 4902, Optomechatronic Systems III, (18 October 2002); doi: 10.1117/12.467251
Show Author Affiliations
Norbert Schuster, Vision & Control GmbH (Germany)
Thomas Schoenheit, Vision & Control GmbH (Germany)

Published in SPIE Proceedings Vol. 4902:
Optomechatronic Systems III
Toru Yoshizawa, Editor(s)

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