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Proceedings Paper

Telecentric zoom lens used in metrology applications
Author(s): Stephanie Bloch; Ellis I. Betensky
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Paper Abstract

A 10:1 telecentric zoom lens has been designed for metrology purposes. In addition to the specifications for high quality imaging, and less than 0.5 percent distortion throughout the range of magnification, the system has to fit within a predetermined mechanical space, and allow for coaxial illumination inserted directly into the optical axis in the space after the objective lens. This combination of specifications eliminates the possibility of using a conventional zoom lens type, primarily because the entrance pupil requirement would necessarily place the aperture stop where both size and aberrations could not be controlled. The design described includes a reimaging relay lens between the collimating objective and the zoom lens. The use of this reimaging relay lens allows for full correction of all of the aberrations, including distortion, and satisfies the mechanical requirements because the entrance pupil position for the zooming groups can be nearly ideally located. Because the coaxial illumination is a source of unwanted surface reflections from the objective lens, the objective lens must have a minimum number of air-glass surfaces. A cemented triplet including an aspherical surface satisfies this requirement.

Paper Details

Date Published: 14 December 2001
PDF: 11 pages
Proc. SPIE 4487, Zoom Lenses III, (14 December 2001); doi: 10.1117/12.450419
Show Author Affiliations
Stephanie Bloch, Optical Gaging Products, Inc. (United States)
Ellis I. Betensky, Consultant Optical Designer (Canada)

Published in SPIE Proceedings Vol. 4487:
Zoom Lenses III
Iain A. Neil; Takanori Yamanashi, Editor(s)

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