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Optical Engineering

Etch depth mapping of phase binary computer-generated holograms by means of specular spectroscopic scatterometry
Author(s): Victor P. Korolkov; Alexander Konchenko; Vadim V. Cherkashin; Nikolay G. Mironnikov; Alexander G. Poleshchyk
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Paper Abstract

Detailed analysis of etch depth map for phase binary computer-generated holograms intended for testing aspheric optics is a very important task. In particular, diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. We offer a simplified version of the specular spectroscopic scatterometry method. It is based on the spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase the phase depth of the grooves by a factor of 2 and measure more precisely shallow phase gratings. Measurement uncertainty is mainly defined by the following parameters: shifts of the spectrum maximums that occur due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method we describe can ensure 1% error. However, fiber spectrometers are more convenient for scanning measurements of large area computer-generated holograms. Our experimental system for characterization of binary computer-generated holograms was developed using a fiber spectrometer.

Paper Details

Date Published: 26 April 2013
PDF: 7 pages
Opt. Eng. 52(9) 091722 doi: 10.1117/1.OE.52.9.091722
Published in: Optical Engineering Volume 52, Issue 9
Show Author Affiliations
Victor P. Korolkov, Institute of Automation and Electrometry (Russian Federation)
Alexander Konchenko
Vadim V. Cherkashin, Institute of Automation and Electrometry (Russian Federation)
Nikolay G. Mironnikov, Institute of Automation and Electrometry (Russian Federation)
Alexander G. Poleshchyk, Institute of Automation and Electrometry (Russian Federation)

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