title: Alternative method for measuring the full-field refractive index of a gradient-index lens with normal incidence heterodyne interferometry.
abstract: A linearly/circularly polarized heterodyne light beam coming from a heterodyne light source with an electro-optic modulator in turn enters a modified Twyman-Green interferometer to measure the surface plane of a GRIN lens. Two groups of periodic sinusoidal segments recorded by a fast complementary metal-oxide semiconductor camera are modified, and their associated phases are derived with the unique technique. The data are substituted into the special equations derived from the Fresnel equations, and the refractive index can be obtained. When the processes are applied to other pixels, the full-field refractive-index distribution can be obtained similarly. Its validity is demonstrated.
authors.affiliation: Department of Photonics and Institute of Electro-Optical Engineering, National Chiao-Tung University, 1001 Ta-Hsueh Road, Hsinchu 30050, Taiwan.
authors.forename: Yen-Liang
authors.initials: YL
authors.lastname: Chen
authors.forename: Hung-Chih
authors.initials: HC
authors.lastname: Hsieh
authors.forename: Wang-Tsung
authors.initials: WT
authors.lastname: Wu
authors.forename: Wei-Yao
authors.initials: WY
authors.lastname: Chang
authors.forename: Der-Chin
authors.initials: DC
authors.lastname: Su
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D007368:Interferometry / Q000295:instrumentation* / Q000379:methods*; D007909:Lenses; D008027:Light; D012031:Refractometry / Q000379:methods*; D015203:Reproducibility of Results