title: Scanning focused refractive-index microscopy.
abstract: We present a novel scanning focused refractive-index microscopy (SFRIM) technique to obtain the refractive index (RI) profiles of objects. The method uses a focused laser as the light source, and combines the derivative total reflection method (DTRM), projection magnification, and scanning technique together. SFRIM is able to determine RIs with an accuracy of 0.002, and the central spatial resolution achieved is 1 µm, which is smaller than the size of the focal spot. The results of measurements carried out on cedar oil and a gradient-refractive-index (GRIN) lens agree well with theoretical expectations, verifying the accuracy of SFRIM. Furthermore, using SFRIM, to the best of our knowledge we have extracted for the first time the RI profile of a periodically modulated photosensitive gelatin sample. SFRIM is the first RI profile-resolved reflected light microscopy technique that can be applied to scattering and absorbing samples. SFRIM enables the possibility of performing RI profile measurements in a variety of applications, including optical waveguides, photosensitive materials and devices, photorefractive effect studies, and RI imaging in biomedical fields.
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Teng-Qian
authors.initials: TQ
authors.lastname: Sun
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Xiao-Wan
authors.initials: XW
authors.lastname: Wang
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Zhi-Chao
authors.initials: ZC
authors.lastname: Deng
authors.affiliation: Advanced Technology Institute, Nankai University, Tianjin 300071, China.
authors.forename: Jian-Chun
authors.initials: JC
authors.lastname: Mei
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Wen-Yuan
authors.initials: WY
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Chun-Ping
authors.initials: CP
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of physics and TEDA Applied Physics School, Nankai University, Tianjin 300071, China.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Tian