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Proceedings Paper

Influence of temperature gradients on the performance of ZnSe lenses
Author(s): R. J. Tangelder; Leo H. J. F. Beckmann; Johan Meijer
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Paper Abstract

Focus shift of lenses used in high power laser machining systems is a serious problem. Unavoidable energy absorption in lenses combined with cooling at the outer rims causes radial thermal gradients and ensuing optical distortion. An existing ray tracing program was adjusted to compute the influence of stationary radial temperature profiles on the performance of lenses. Three effects were taken into account: a change of the lens thickness and curvatures caused by thermal expansion, an alteration of the angles of refraction at both air-lens- interfaces, and a curved light path through the lens. The last two effects are caused by the thermally induced radial refractive index gradient. Major consequence is a shortening of the focal length. Reasonable agreement was obtained between measurements of the focal lengths of ZnSe-lenses and theoretical predictions based on measured power absorption.

Paper Details

Date Published: 15 April 1993
PDF: 9 pages
Proc. SPIE 1780, Lens and Optical Systems Design, (15 April 1993); doi: 10.1117/12.142816
Show Author Affiliations
R. J. Tangelder, Univ. of Twente (Netherlands)
Leo H. J. F. Beckmann, Univ. of Twente (Netherlands)
Johan Meijer, Univ. of Twente (Netherlands)


Published in SPIE Proceedings Vol. 1780:
Lens and Optical Systems Design

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