PDMS has become a frequently used material in the elaboration of optical components such as: variable focal length liquid lenses, optical waveguides, solid elastic lenses, etc. In this work we describe the elaboration of PDMS samples, and we present the physical and optical properties of the material when a variation on its synthesis parameters (mixture ratio of base: curing agent, curing temperature and curing time) is implemented during their elaboration. Tensile and compressive tests were carried out to obtain the corresponding stress-strain curves of the material, and UV-Vis spectroscopy was applied to obtain transmittance and absorbance curves of the samples. A variation of the refractive index of the samples was observed and homogeneity of the samples was studied with the Raman spectra obtained from the samples. Results of the characterization determined the appropriate synthesis parameters for the elaboration of a tunable refractive surface for potential applications in artificial vision.
Tunable lenses have attracted much attention due to their potential applications in such areas like machine vision, laser projection, ophthalmology, etc. In this work we present the design of a tunable opto-mechatronic system capable of focusing and to regulate the entrance illumination that mimics the performance made by the iris and the crystalline lens of the human eye. A solid elastic lens made of PDMS has been used in order to mimic the crystalline lens and an automatic diaphragm has been used to mimic the iris of the human eye. Also, a characterization of such system has been performed with standard values of luminosity for the human eye have been taken into account to calibrate and to validate the entrance illumination levels to the overall optical system.
Mechanical and optical properties of Polydimethylsiloxane (PDMS) have been measured and reported for different applications, however, a full analysis and a compendium of its tension and compression moduli behaviour have not been carried out, nor of its refractive index, for several mixture ratios, temperature and curing time. In this work, samples of PDMS were manufactured and tested to know tension and compression moduli and refractive index as a function of fabrication parameters; Minitab ® , Matlab ® 's Least-squares fitting in Curve Fitting Toolbox™ and genetic algorithms were employed to yield functional dependencies to describe PDMS's behavior. The obtained fitting polynomials are shown to have large agreement with experimental data. Finally, a potential application in the design of a gradient index lens for use in artificial vision is presented.
Abstract-Advances in the development of tunable lenses have produced more compact, simple and lightweight optical systems. There are different types of tunable lenses; among the simplest we can find liquid and solid lenses, which only require a mechanical mount to change the shape of the lenses. We present the analysis and results that were obtained recently from these two types of lenses which have produced an improvement in the quality of images formation as well as some of their future applications.In recent years various types of tunable lenses have been developed and have attracted much attention due to their notable advantages against classical lenses and their potential applications in such areas like ophthalmology, machine vision, microscopy, laser processing, lens cameras phones, etc. due to the possibility of making lighter, simpler and more compact optical devices; such devices are optical systems capable to change their own focal length by modifying some of their physical parameters and this can be achieved by several means [1]. Different technologies are being explored in order to let tunable lenses efficiently respond to a wide variety of stimuli such as mechanical, hydraulic/pneumatic, electromagnetic, photo-thermal, fluid flow and electrochemical [1][2][3][4]. Hydraulically or pneumatically technologies used in tunable liquid lenses commonly include an external pump that introduces a fluid into a lens-shaped elastomer made chamber and induces pressure variations causing a change in its focal length [3][4][5]. It has also been demonstrated that electromagnetic activation, thermal induction, electrochemical effect and changing refraction index are used in tunable lenses [6][7][8][9]. Tunable lenses were also used in a photodetectors array [10]. In this direction, we have developed two types of tunable lenses; the first type is a liquid lens with a variable focal length that consists of a mechanical mount that houses a liquid medium, two elastic membranes, a conduit to removed air from the chamber, a manometer and a system to introduce and remove liquid from the chamber of lens [5]. The liquid pressure on the membranes surfaces causes thickness and curvature changes. A schematic diagram of the system is shown in Fig. 1. To improve the opto-mechanical performance, management and cost of this type of lens, we proposed a different class of mechanical mounts and membranes with different surface profiles to reduce optical aberrations. The process begins with opto-mechanical design, then opto-mechanical analysis and simulation. Using the finite element and ray tracing, software is made to finally manufacture a 3D prototype in order to perform functional tests and a mechanical characterization of
Tunable lenses are optical systems that have attracted much attention due to their potential applications in such areas like ophthalmology, machine vision, microscopy and laser processing. In recent years we have been working in the analysis and performance of a liquid-filled variable focal length lens, this is a lens that can modify its focal length by changing the amount of water within it. Nowadays we extend our study to a particular adaptive lens known as solid elastic lens (SEL) that it is formed by an elastic main body made of Polydimethylsiloxane (PDMS Sylgard 184). In this work, we present the design, simulation and analysis of an adaptive solid elastic lens that in principle imitates the accommodation process of the crystalline lens in the human eye. For this work, we have adopted the parameters of the schematic eye model developed in 1985 by Navarro et al.; this model represents the anatomy of the eye as close as possible to reality by predicting an acceptable and accurate quantity of spherical and chromatic aberrations without any shape fitting. An opto-mechanical analysis of the accommodation process of the adaptive lens is presented, by simulating a certain amount of radial force applied onto the SEL using the finite element method with the commercial software SolidWorks ® . We also present ray-trace diagrams of the simulated compression process of the adaptive lens using the commercial software OSLO ® .
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