Quality control of injection molded eyewear by non-contact deflectometry

A. Speck; B. Zelzer; A. Langenbucher; T. Eppig

doi:10.2971/jeos.2014.14027

Journal of the European Optical Society - Rapid publications, Vol 9 (2014)

Quality control of injection molded eyewear by non-contact deflectometry

A. Speck, B. Zelzer, A. Langenbucher, T. Eppig

Abstract

Occupational eye wear such as safety spectacles are manufactured by injection molding techniques. Testing of the assembled safety spectacle lenses in transmission is state of the art, but there is a lack of surface measurement systems for occupational safety lenses. The purpose of this work was to validate a deflectometric setup for topography measurement, detection of defects and visualization of the polishing quality, e.g. casting indentations or impressions, for the production process of safety spectacles. The setup is based on a customized stereo phase measuring deflectometer (PMD), equipped with 3 cameras with f’1,2 = 16 mm and f’3 = 8.5 mm and a specified measurement uncertainty of ± 3 μm. Sixteen plastic lenses and 8 corresponding injection molds from 4 parallel cavities were used for validation of the deflectometer. For comparison an interferometric method and a reference standard (< λ/10 super polished) was used. The accuracy and bias with a spherical safety spectacle sample was below 1 μm, according to DIN ISO 5725-2.2002-12. The repeatability was 2.1 μm and 35.7 μm for a blind radius fit. In conclusion, the PMD technique is an appropriate tool for characterizing occupational safety spectacle and injections mold surfaces. With the presented setup we were able to quantify the surface quality. This can be useful and may optimize the quality of the end product, in addition to standardized measuring systems in transmission.

Full Text: PDF

Citation Details

Cite this article

References

International Standard, ”Personal eye-protectors - Specifications,” ISO 4849–1981 (1981).

American National Standard, ”Occupational and educational personal eye and face protection devices - spectacles,” ANSI Z 87.1 (2003).

Deutsches Institut für Normung e.V., ”Personal eye protection - specifications,” DIN EN 166 (2001).

Deutsches Institut für Normung e.V., ”Personal eye protection - optical test methods,” DIN EN 167 (2001).

International Standard, ”Personal eye-protectors - Optical test methods,” ISO 4854–1981 (1981).

T. Eppig, K. Zoric, A. Speck, B. Zelzer, J. Götzelmann, D. Nagengast and A. Langenbucher, ”Wave-front analysis of personal eye protection,” Opt. Express 20, 17806–17815 (2012).

A. Speck, B. Zelzer, M. Speich, R. Börret, A. Langenbucher, and T. Eppig, ”Deflectometric analysis of high volume injection molds for production of occupational eye wear,” Z. Med. Phys. 23, 314– 323 (2013) .

B. Zelzer, A. Speck, A. Langenbucher, and T. Eppig, ”Theoretical model for design and analysis of protectional eyewear,” Z. Med. Phys. 23, 120–128 (2013).

J. Kaminski, M. Knauer, and G. Häusler, ”Calculating curvatures from discrete slope data,” in Lehrstuhl für Optik - Annual Report 2003, M. Eberler, and G. Gardavsky, eds., 31 (Chair of Optics, University of Erlangen-Nuremberg, 2003).

M. Knauer, and J. Kaminski, ”Measurement of eye glasses with phase measuring deflectometry,” in Lehrstuhl für Optik - Annual Report 2003, M. Eberler, and G. Gardavsky, eds., 30 (Chair of Optics, University of Erlangen-Nuremberg, 2003).

M. Knauer, J. Kaminski and G. Häusler, ”Absolute phase measuring deflectometry,” DGaO Proceedings 105, A15 (2004).

C. Horneber, M. Knauer, and G. Häusler, ”Phase Measuring Deflectometry: a new method to measure reflecting surfaces,” Proc. SPIE 5457, 366–376 (2004).

R. Seßner, ”Direction coded Deflectometry by telecentricity,” (doctoral thesis, Friedrich-Alexander-University Erlangen-Nuremberg, 2009).

M. Knauer, and K. Veit, ”Vermessung spiegelnder Oberflächen - eine Aufgabe der optischen 3D-Sensorik,” Photonik 4, 62–64 (2004).

M. Speich, and R. Börret, ”Mould fabrication for polymer optics,” J. Europ. Opt. Soc. Rap. Public. 6, 11050 (2011).

M. Speich, R. Börret, A. K. M. DeSilva, D. K. Harrison, and W. Rimkus, ”Precision Mold Manufacturing for Polymer Optics,” Mater. Manuf. Process. 28, 529–533 (2013).

A. Speck, B. Zelzer, M. Kannengießer, A. Langenbucher, and T. Eppig, ”Inspection of freeform intraocular lens topography by phase measuring deflectometric methods,” Appl. Opt. 52, 4279– 4286 (2013).

Deutsches Institut für Normung e.V., ”EN-Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method,” DIN ISO 5725-2.2002-12 (2002).