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Research Article Open Access

Design and fabrication of multilayer dichroic beam splitter

Vemuri SRS Praveen Kumar1, 2, Parinam Sunita1,2, Mukesh Kumar1, Neelam Kumari1,2,
Vinod Karar1, Amit L Sharma1, 2*

 

 

1CSIR-Central Scientific Instruments Organisation, Sector 30C, Chandigarh, 160030, India

2Academy of Scientific & Innovative Research (AcSIR), Sector 30C, Chandigarh, 160030, India

Adv. Mater. Proc., 2017, 2 (6), 398-401

DOI: 10.5185/amp.2017/610

Publication Date (Web):05 June 2017

Copyright © IAAM-VBRI Press

Abstract


Abstract

Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being reflected and transmitted by various interfaces where it is split by percentage of overall intensity or wavelength. In this study, design and fabrication of a dichroic optical beam splitter for filtering of red and green light from a white light source has been presented.  Here, a symmetric dielectric multilayer stack with 15 alternating layers of alumina and silica are deposited on BK-7 glass using e-beam evaporation technique. High and low refractive indices of 1.63 and 1.46 respectively are used with quarter-wave optical thicknesses of layers. The beam splitter is designed for 45˚ angle of incidence using FilmstarTM design software. Transmission spectrum obtained from UV-Vis-NIR double beam spectrophotometer shows reflectance of ~54% at 660 nm (red wavelength region) and transmittance of ~88% at 550 nm (green wavelength region). The coated sample is further subjected to adhesion and hardness test according to MIL standard and no peel off or scratch is observed indicating excellent durability of the coating. The modelled and measured results closely agree with one another over visible spectral regions. Copyright © 2017 VBRI Press.

Keywords


Thin films, optical coatings, beam splitters, optical properties.