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Monitoring of overmodulation effect in high efficient generally slanted transmission gratings produced in photopolymers
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SYSNO ASEP 0469352 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Monitoring of overmodulation effect in high efficient generally slanted transmission gratings produced in photopolymers Author(s) Vojtíšek, Petr (UFP-V) RID
Květoň, M. (CZ)
Richter, I. (CZ)Article number 1015115 Source Title Proceedings of SPIE 10151, Optics and Measurement International Conference 2016, OAM 2016 Proceedings, 10151. - Bellingham : SPIE, Society of Photo-Optical Instrumentation Engineers, 2016 / Kovačičinová J. - ISSN 0277-786X - ISBN 978-1-5106-0753-8 Number of pages 10 s. Publication form Print - P Action OAM 2016, Optics and Measurement International Conference 2016 Event date 11.10.2016 - 14.10.2016 VEvent location Liberec Country CZ - Czech Republic Event type WRD Language eng - English Country US - United States Keywords photopolymer ; overmodulation ; two-wavelength measurement ; multiple-wavelength measurement Subject RIV JI - Composite Materials R&D Projects LO1206 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support UFP-V - RVO:61389021 UT WOS 000393154700041 EID SCOPUS 85012904346 DOI https://doi.org/10.1117/12.2256488 Annotation In our laboratory, we use for fabrication of volume phase diffraction gratings a photopolymer recording material Bayfol HX. It is an extremely effective recording material; a high value of the refractive index modulation is obtained already during a holographic exposure. The value of this refractive index modulation influences the diffraction properties (e.g. efficiency) of the recorded gratings and, in the case of transmission gratings, the growth of this modulation beyond the optimal value leads to an effect of so called overmodulation. This effect is, in the most cases, unwanted as it causes the decrease of the diffraction efficiency from its maximum value (practically close to 100%). The analysis whether the grating is over- or under- modulated is relatively difficult as the value of the refractive index modulation can’t be measured directly and it is evaluated from the measurement of the diffraction efficiency. However, the obtained value can be often incorrect due to the overmodulation effect. In this contribution, we would like to extend (to include any arbitrary slanted transmission gratings) and discuss a simple measurement method for the determination of the correct value of the refractive index modulation based on a multiple/two-wavelength measurement of a diffraction efficiency of transmission gratings. The theoretical idea of this method and also experimental results obtained on photopolymer Bayfol HX will be presented. From practical point of view, this approach help us mainly for correct adjustment of exposure parameters to reach efficient gratings Workplace Institute of Plasma Physics Contact Vladimíra Kebza, kebza@ipp.cas.cz, Tel.: 266 052 975 Year of Publishing 2017
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