Rapid measurement of liquid diffusion coefficients for different concentrations based on compound liquid-core cylindrical lenses and the finite element method.

Liquid diffusion coefficients are usually concentration-dependent (D(C)), and current methods for measuring the D(C) relationship suffer from long measurement times and large repetitive experimental workloads. This paper consequently proposes a new method for rapid measurement of D(C), which can eliminate the need to measure uncalibrated diffusion coefficients corresponding to concentration by comparing the theoretical concentration distribution of diffusion solution obtained by the finite element method and the experimental concentration distribution. The core diffusion and imaging setup is a compound liquid-core cylindrical lens, which can offer the advantages of high refractive index resolution and imaging quality, guaranteeing the accurate measurement concentration distribution.

Design and fabrication of a focus-tunable liquid cylindrical lens based on electrowetting.

In this study, a focus-tunable liquid cylindrical lens based on electrowetting was designed and fabricated. The cylindrical cavity usually used in common electrowetting zoom spherical lenses was replaced by a 20 mm × 10 mm × 8 mm cuboid cavity, in which the interface of two liquids formed a toroid owing to the electrowetting effect. The proposed liquid cylindrical lens can serve as either a converging or diverging lens with the response time under 110 ms by changing the supplied voltage.

Design of spherical aberration free liquid-filled cylindrical zoom lenses over a wide focal length range based on ZEMAX.

A systematic design idea for liquid-filled cylindrical zoom lenses with ideal imaging quality over a wide focal length range is introduced in detail. The PWC method is used to calculate the initial structure parameters of the zoom lenses, and the optical design software ZEMAX is used to eliminate the spherical aberration at different focal lengths. Lenses named SLCL-Doublet are finally designed, which are formed by a symmetric liquid-core cylindrical lens (SLCL) filled with variable refractive index (RI) liquid and a doublet cylindrical lens capable of significantly weakening the spherical aberration.

A novel visualization technique for measuring liquid diffusion coefficient based on asymmetric liquid-core cylindrical lens.

A visualization and quantification optical method for measuring binary liquid diffusion coefficient (D) based on an asymmetric liquid-core cylindrical lens (ALCL) is introduced in this paper. Four groups of control experiments were performed to verify the influences of diffusing substance category, concentration and temperature on diffusion process, and the measured D values were well consistent with data measured by Holographic interferometry and Taylor dispersion methods. The drifting of the diffusion image recorded by CCD reflects the diffusion rate visually in an easily understandable way.

Asymmetric liquid-core cylindrical lens used to measure liquid diffusion coefficient.

We design and fabricate an asymmetric liquid-core cylindrical lens (ALCL), which is used to measure the binary liquid diffusion coefficient (D). Acting as both diffusion cell and key imaging element, ALCL is of the function to measure the refractive index (RI) of liquid filled in its core in the way of spatial resolution. Comparing the ALCL with a symmetric liquid-core cylindrical lens (SLCL), the spherical aberration is reduced from about 300 μm (SLCL) to less than 5 μm (ALCL) when the RI of filled liquid is near 1.

New method to measure liquid diffusivity by analyzing an instantaneous diffusion image.

A novel optical method was applied to measure the binary liquid diffusion coefficient (D) quickly. Equipped with an asymmetric liquid-core cylindrical lens (ALCL), the spatially resolving ability of the ALCL in measuring refractive index of liquid was utilized to obtain the gradient distribution of the liquid concentration along diffusive direction. Based on Fick's second law, the D value was then calculated by analyzing diffusion images.