Inspired by crystalline lenses in human eyes, liquid lenses have a simple yet elegant working principle, and result in compact optical systems. Recent numerical studies showed that membranes with variable thicknesses could affect the lens profile. However, fabrication and assembly of a liquid lens with an inhomogeneous membrane is difficult. There is also a lack of experimental studies about the changes of a lens profile during deformation. In this paper, we provided a new experimental approach for characterizing the performance of a liquid lens with an inhomogeneous membrane. A 2D axisymmetric lens model was built in finite element analysis software to theoretically study the non-linear deformation behavior of the inhomogeneous membrane. Then we provided a new approach to fabricate inhomogeneous membranes using a pre-machined aluminum mold. An optical coherence tomography (OCT) system was used to dynamically measure the changes of a lens profile without contact. Both simulation and the experiments indicated that the variation of the thickness of the membrane could affect the lens profile in a predictable manner. A negative conic constant was achieved when a plano-concave membrane was adopted in a liquid lens. Larger increments of the thickness of the membrane in the radial direction resulted in a larger contribution of a conic constant to the lens profile. The presented study offers guidance for image-quality analysis and optimization of a liquid-lens-based optical system.

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Optical coherence tomography (OCT) has been widely applied to the diagnosis of eye diseases during the past two decades. However, valid evaluation methods are still not available for the clinical OCT devices. In order to assess the axial resolution of the OCT system, standard model eyes with micro-scale multilayer structure have been designed and manufactured in this study. Mimicking a natural human eye, proper Titanium dioxide (TiO 2 ) materials of particles with di®erent concentrations were selected by testing the scattering coe±cient of PDMS phantoms. The arti¯cial retinas with multilayer¯lms were fabricated with the thicknesses from 9.5 to 30 micrometers using spin coating technology. Subsequently, standard OCT model eyes were accomplished by embedding the retina phantoms into the arti¯cial frames of eyes. For ease of measurement processing, a series of model eyes were prepared, and each contained¯lms with three kinds of thicknesses. Considering the traceability and accuracy of the key parameters of the ** Corresponding authors. This is an Open Access article published by World Scienti¯c Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. Vol. 11, No. 3 (2018) standard model eyes, the thicknesses of multilayer structures were veri¯ed using Thickness Monitoring System. Through the experiment with three di®erent OCT devices, it demonstrated the model eyes fabricated in this study can provide an e®ective evaluation method for the axial resolution of an ophthalmic OCT device. Journal of Innovative Optical Health Sciences

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Intrigued by the discovery of the long lifetime in the α-Ta/Al2O3-based Transmon qubit, researchers recently found α-Ta film is a promising platform for fabricating multi-qubits with long coherence time. To meet the requirements for integrating superconducting quantum circuits, the ideal method is to grow α-Ta film on silicon substrate compatible with industrial manufacturing. Here we report the α-Ta film sputter-grown on Si (100) with low-loss superconducting TiNx buffer layer. The pure-phase α-Ta film with a large growth temperature window has good crystalline character. The critical temperature (Tc) and residual resistance ration (RRR) in the α-Ta film grown at 500 oC are higher than that in the α-Ta film grown at room temperature. These results provide crucial experimental clues towards understanding the connection between the superconductivity and the materials' properties in the α-Ta film, and open a new route for producing high-quality α-Ta film on silicon substrate for future industrial superconducting quantum computer.