title: Measurement of the refractive index of microquantity liquid filled in a capillary and a capillary wall without destruction.
abstract: A method for measuring the refractive index (RI) of a small volume of liquid and a capillary wall is presented in this paper. A transparent capillary filled with liquid is used as a cylindrical positive lens; subsequently, the focal length of the lens is derived through the base of paraxial approximation, which is recorded as a function of the RIs of the liquid and capillary wall. With the RI of a capillary wall known, the RI of the liquid can be obtained by measuring the focal length of the lens, which is characterized by a microquantity liquid, spatial resolution, and easy operation. The RI of the capillary wall can be calculated without ruining the capillary if the capillary is filled with a standard liquid (RI is known), the deviation of which is less than 0.003 RIU. The factors affecting accuracy of the measurement, for instance, the depth of a field (DOF) in a reading microscope system and the outer and inner diameters of a capillary are analyzed, while illustrating that the effective DOF plays an essential role in accurate measurement.
authors.affiliation: Department of Physics, Yunnan University, Kunming, Yunnan 650091, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Pu
mesh_terms: D005898:Glass; D007091:Image Processing, Computer-Assisted; D007753:Laboratories; D008027:Light; D008832:Microchemistry / Q000295:instrumentation* / Q000379:methods; D008853:Microscopy / Q000295:instrumentation* / Q000379:methods; D055620:Optical Phenomena; D055095:Optics and Photonics / Q000295:instrumentation; D012031:Refractometry