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Proceedings Paper

Multi-layer dielectric thin-film optical filters for beam folding applications
Author(s): Mukesh Kumar; Neelam Kumari; P. Krishna Rao; Vinod Karar; S. V. Ramagopal; Amit L. Sharma
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Paper Abstract

Multi-layer reflective thin film filters optimized for oblique incidence angles were deposited on glass substrates using Electron Beam evaporation technique with in situ thickness monitoring. The present study involves deposition and optical characterization of 5 layered multi-layer structures of TiO2-Al2O3 and TiO2-SiO2 having different thicknesses for varied wavelength ranges in the visible region. Three TiO2-SiO2 multi-layer thin film filters were deposited having peak reflectance at 480 nm, 540 nm and 675 nm respectively corresponding to light sources in the blue, green and red wavelength regions. Similarly, a TiO2-Al2O3 multi-layer was fabricated having peak reflectance of around 64% at 610nm. These filters were deposited at an elevated temperature of 250° C in an oxygenated reactive environment for better adhesion, mechanical strength and proper stoichiometry. Reflectance measurements of these multi-layer filters at oblique incidence angles reveal high reflectance of around 70 ~ 75% with a reasonably broad reflection band which can have wide applications in beam steering, shaping and folding applications in various complex optical systems facing constrained space and weight requirements.

Paper Details

Date Published: 15 June 2015
PDF: 5 pages
Proc. SPIE 9654, International Conference on Optics and Photonics 2015, 96540F (15 June 2015); doi: 10.1117/12.2181776
Show Author Affiliations
Mukesh Kumar, Central Scientific Instruments Organisation (India)
Academy of Scientific & Innovative Research (India)
Neelam Kumari, Central Scientific Instruments Organisation (India)
Academy of Scientific & Innovative Research (India)
P. Krishna Rao, Central Scientific Instruments Organisation (India)
Vinod Karar, Central Scientific Instruments Organisation (India)
Academy of Scientific & Innovative Research (India)
S. V. Ramagopal, Central Scientific Instruments Organisation (India)
Academy of Scientific & Innovative Research (India)
Amit L. Sharma, Central Scientific Instruments Organisation (India)
Academy of Scientific & Innovative Research (India)


Published in SPIE Proceedings Vol. 9654:
International Conference on Optics and Photonics 2015
Kallol Bhattacharya, Editor(s)

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