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31 January 2013 Application of fiber spectrometers for etch depth measurement of binary computer-generated holograms
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Proceedings Volume 8759, Eighth International Symposium on Precision Engineering Measurement and Instrumentation; 875959 (2013) https://doi.org/10.1117/12.2014603
Event: International Symposium on Precision Engineering Measurement and Instrumentation 2012, 2012, Chengdu, China
Abstract
Novel spectrophotometric method of computer-generated holograms depth measurement is presented. It is based on 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 a phase depth of the grooves by factor of 2 and measure more precisely shallow phase gratings. Diffraction binary structures with depth from several hundreds to thousands nanometers could be measured by the method. Measurement uncertainty is mainly defined by following parameters – shifts of the spectrum maximums that are occurred 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 can ensure 0.25-1% error for desktop spectrophotometers. However fiber spectrometers are more convenient for creation of real measurement system with scanning measurement of large area computer-generated holograms which are used for optical testing of aspheric optics. Especially diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. Experimental system for characterization of binary computer-generated holograms was developed using spectrophotometric unit of confocal sensor CHR-150 (STIL SA).
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
V. P. Korolkov, A. S. Konchenko, and A. G. Poleshchuk "Application of fiber spectrometers for etch depth measurement of binary computer-generated holograms", Proc. SPIE 8759, Eighth International Symposium on Precision Engineering Measurement and Instrumentation, 875959 (31 January 2013); https://doi.org/10.1117/12.2014603
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