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Proceedings Paper

Thin Film Production With A New Fully Automated Optical Thickness Monitoring System
Author(s): M Lardon; H Selhofer
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Paper Abstract

The increasing demand for complex multilayer optical coatings requires equipment with a completely automated process control system. The new optical thickness monitor GSM 420, which is part of the deposition control system BPU 420 allows the remotely controlled wave-length selection either with a grating monochromator combined with the appropriate order sorting filters or with a set of six narrow bandpass filters. The endpoint detection is based on the digital processing of the signal corresponding to the light intensity after transmission through or reflexion from a testglass located side by side with a quartz crystal microbalance at the center of the coating plant. Turning value monitoring or termination of the process at an arbitrary predetermined point are both possible. Single and multiple layers of silicon dioxide and titanium dioxide and combinations thereof were deposited. Excellent linear correlation between the optical thickness on the test glass and the geometrical layer thickness as measured by the quartz crystal microbalance was observed. The reproducibility for single layers of quarterwave thickness was found to be between ± 0.7 to ± 1.7 % of the center wavelength of the spectral extremum measured on the test glass, depending on wavelength (350 - 3200 nm) and coating material (SiO2 or TiO2 on glass).

Paper Details

Date Published: 13 October 1986
PDF: 5 pages
Proc. SPIE 0652, Thin Film Technologies II, (13 October 1986); doi: 10.1117/12.938351
Show Author Affiliations
M Lardon, Balzers AG (Liechtenstein)
H Selhofer, Balzers AG (Liechtenstein)

Published in SPIE Proceedings Vol. 0652:
Thin Film Technologies II
J. Roland Jacobsson, Editor(s)

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