Open AccessScanned conical illumination as a probe of electro-optic retro-reflection
Author(s) -
Ali S. Alshomrany,
Zoom Nguyen,
Joseph E. Maclennan,
Noel A. Clark
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.018383
Subject(s) - optics , materials science , refractive index , fresnel equations , numerical aperture , angle of incidence (optics) , liquid crystal , reflection (computer programming) , interference (communication) , total internal reflection , optoelectronics , physics , wavelength , channel (broadcasting) , electrical engineering , computer science , programming language , engineering
We describe a prototype element for use in probing electro-optic retro-reflection in sensor applications, illuminating a planar-aligned nematic liquid crystal electro-optic cell with convergent light having a single, tunable angle of incidence (tunable conical illumination). This illumination is generated using a 100X, high numerical aperture, long working-distance microscope objective under conditions of extreme spherical aberration. The electro-optic effect observed is multiple-beam optical interference between polarized reflections from the two bounding plates of the cell, rendered tunable with voltage-controlled refractive index changes induced by molecular reorientation of the liquid crystal. Characterization of the reflectivity vs. angle of incidence and applied voltage enables identification of conditions of high-contrast, low power, electro-optic reflectivity control applicable to fiber optics.