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Proceedings Paper

Controlling The Groove Depth Of Holographic Gratings
Author(s): Sten Lindau
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Paper Abstract

The diffraction efficiency of a grating depends critically on the groove profile, which in the case of holographic gratings is usually more or less sinusiodal. In order to obtain high efficiency it is thus of great importance to have accurate control of the groove depth during the fabrication process. Usually the groove depth is determined by adjusting the exposure, and then developing the substrate for a fixed time. In this work, a technique is studied where also the development time may be varied in order to obtain the desired groove depth. After interrupting the development, the groove depth of the photo-resist grating, without metallic coating, is determined by measuring the diffraction efficiency in tranmission and comparing it with theoretical efficiencies. Good accuracy is achieved since, in the groove depth range where the efficiency of the final reflection grating has a maximum, the transmission efficiency of the photoresist grating increases rapidly with increasing groove depth. A great advantage is achieved by using a HeNe laser for the efficiency measurements. Since the resist is insensitive to red light, the measurements do not affect the sinusoidal solubility distribution, and the development can be continued to increase the groove depth, if desired.

Paper Details

Date Published: 26 October 1983
PDF: 6 pages
Proc. SPIE 0399, Optical System Design, Analysis, and Production, (26 October 1983); doi: 10.1117/12.935448
Show Author Affiliations
Sten Lindau, The Royal Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 0399:
Optical System Design, Analysis, and Production
Robert E. Fischer; Philip J. Rogers, Editor(s)

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