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Proceedings Paper

Characterization of gradient index optical components using experimental ray tracing
Author(s): Tobias Binkele; Rebecca Dylla-Spears; Michael A. Johnson; David Hilbig; Mahmoud Essameldin; Thomas Henning; Friedrich Fleischmann
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Paper Abstract

New methods enabling the production of custom-tailored Gradient Index (GRIN) optical components brings the next challenge to the lens manufacturers. Simultaneously, for testing these optics, metrology has to evolve to accommodate new optics. In this paper, we describe how Experimental Ray Tracing (ERT) can be used to test GRIN optics produced using additive manufacturing. To evaluate this technique, we compare the results to those obtained using Phase Shifting Diffraction Interferometry (PSDI). The common way of lens manufacturers to verify their products is the measurement of the surface, e.g. using surface profilers or reflective interferometry. Determination of optical performance solely from surface topography includes the assumption of a completely homogeneous structure inside the lens. Since GRIN lenses introduce material inhomogeneity on purpose, these measurement techniques exceed their limits, as surface measurement techniques cannot see the material structure inside the lens. To overcome this problem, we propose the measurement of GRIN lenses using ERT. This reference free measurement technique measures the device under test in transmission. A narrow laser beam is introduced into the device under test (DUT) at a known position. By measuring the direction of the beam behind the DUT, its optical function at this position can be determined. Evaluating these local measurements to an optical powermap over the full aperture, details of the inside structure of the DUT can be seen. The results of the proposed measurement technique show good agreement with the results from measurements using PSDI. However, differences can be seen between the two techniques. Therefore, the results of both measurement techniques are evaluated and compared and the advantages and disadvantages of both techniques are presented.

Paper Details

Date Published: 4 March 2019
PDF: 10 pages
Proc. SPIE 10925, Photonic Instrumentation Engineering VI, 109250D (4 March 2019); doi: 10.1117/12.2511072
Show Author Affiliations
Tobias Binkele, Hochschule Bremen Univ. of Applied Sciences (Germany)
Rebecca Dylla-Spears, Lawrence Livermore National Lab. (United States)
Michael A. Johnson, Lawrence Livermore National Lab. (United States)
David Hilbig, Hochschule Bremen Univ. of Applied Sciences (Germany)
Mahmoud Essameldin, Hochschule Bremen Univ. of Applied Sciences (Germany)
Thomas Henning, Hochschule Bremen Univ. of Applied Sciences (Germany)
Friedrich Fleischmann, Hochschule Bremen Univ. of Applied Sciences (Germany)

Published in SPIE Proceedings Vol. 10925:
Photonic Instrumentation Engineering VI
Yakov G. Soskind, Editor(s)

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