Measurement of refractive index and liquid diffusion coefficient based on focal plane imaging method

Liquid-core cylindrical lens (LCL) is glued together by two cylindrical lenses, translucent liquid with refractive index n is injected into the liquid core, based on focal plane imaging method, the refractive index n has a one-to-one dependence on the focal length f of the LCL, n= f(n). Two kind of LCL, symmetrical liquid-core cylindrical lens (SLCL) and asymmetrical liquid-core cylindrical lens (ALCL) had been designed and fabricated, the refractive index measurement accuracy is superior to 0.0002 RIU. Based on the refractive index spatial measurement capability of ALCL, the equivalent refractive index thin layer movement method for rapidly and accurately measuring the diffusion coefficient D under the infinite dilution condition was applied to measure an aqueous CaCl2 solution at temperature of 303 K, and the result D were simulated and verified by ray tracing method. Comparing with the traditional method, this method has the advantages of visualization of diffusion process, strong anti-interference capability, rapid measurement, which can be widely used in medical, chemical, biological, environmental protection or other fields.