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.

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.

A polymer that has been used for the development of optical components and has had a significant impact is polydimethylsiloxane (PDMS) due to its remarkable mechanical and optical properties and easy handling. We present a practical and straightforward technique for designing and manufacturing a tunable graded index, graphical input (GRIN)-type lenses, and tunable lenses with a homogeneous refractive index made of PDMS. Implementing a biconical surface profile in a tunable plane-convex lens is proposed for elaborating both a homogeneous refractive index lens and a multilayered GRIN-type lens with a constant increased variation of 0.014 on its refractive index. Likewise, we introduce a mechanical mounting system that aims to modify their curvatures and therefore their focal lengths through mechanical stimuli applied on the lenses. Simulations of the optomechanical behavior and optical characterization of the lenses are also presented.

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. Full Text: PDF References N. Nguyen, "Micro-optofluidic Lenses: A review", Biomicrofluidics 4, 031501-1 (2010). CrossRef U. Levy, R. Shamai, "Tunable optofluidic devices", Microfluidics and Nanofluidics 4, 97 (2008). CrossRef G. R. Xiong et al. "Liquid microlens with tunable focal length and light transmission", Appl. Phys. Lett. 92, 241119 (2008). CrossRef A. Weber and H. Zappe, IEEE/ASME JMEMS 17, 1218 (2008). A. Santiago-Alvarado et al. "Simulating the functioning of variable focus length liquid-filled lenses using the finite element method (FEM)", Optik, 124, 1003 (2013). CrossRef B. Malouin et al. "Electromagnetic liquid pistons for capillarity-based pumping", Lab. Chip 11, 393 (2011). CrossRef W. Wang and J. Fang, "Design, fabrication and testing of a micromachined integrated tunable microlens", J. Micromech. Microeng 16, 1221 (2006). CrossRef C. López, C. Lee and A. Hirsa, "Electrochemically activated adaptive liquid lens", Appl. Phys. Lett. 87, 134102 (2005). CrossRef N. Nam-Trung, "Micro-optofluidic Lenses: A review", BIOMICROFLUIDICS 4,031501 (2010). CrossRef I. Jung et al. "Dynamically tunable hemispherical electronic eye camera system with adjustable zoom capability", Proc. Natl. Acad. Sci. 108, 1788 (2011). CrossRef A. Cruz-Félix, A. Santiago-Alvarado, IJESIT 3, 563 (2014). R. Kingslake, Lens Design Fundamental, (New York, Academic Press 1978). A. Santiago Alvarado et al. Jour. of Phys: Conf. Series 274 (2011). A. Santiago Alvarado et al. "Measurement of aberrations of a solid elastic lens using a point-diffraction interferometer", Opt. Eng. 49, 123401 (2010). CrossRef 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. Full Text: PDF References N. Nguyen, "Micro-optofluidic Lenses: A review", Biomicrofluidics 4, 031501-1 (2010). CrossRef U. Levy, R. Shamai, "Tunable optofluidic devices", Microfluidics and Nanofluidics 4, 97 (2008). CrossRef G. R. Xiong et al. "Liquid microlens with tunable focal length and light transmission", Appl. Phys. Lett. 92, 241119 (2008). CrossRef A. Weber and H. Zappe, IEEE/ASME JMEMS 17, 1218 (2008). A. Santiago-Alvarado et al. "Simulating the functioning of variable focus length liquid-filled lenses using the finite element method (FEM)", Optik, 124, 1003 (2013). CrossRef B. Malouin et al. "Electromagnetic liquid pistons for capillarity-based pumping", Lab. Chip 11, 393 (2011). CrossRef W. Wang and J. Fang, "Design, fabrication and testing of a micromachined integrated tunable microlens", J. Micromech. Microeng 16, 1221 (2006). CrossRef C. López, C. Lee and A. Hirsa, "Electrochemically activated adaptive liquid lens", Appl. Phys. Lett. 87, 134102 (2005). CrossRef N. Nam-Trung, "Micro-optofluidic Lenses: A review", BIOMICROFLUIDICS 4,031501 (2010). CrossRef I. Jung et al. "Dynamically tunable hemispherical electronic eye camera system with adjustable zoom capability", Proc. Natl. Acad. Sci. 108, 1788 (2011). CrossRef A. Cruz-Félix, A. Santiago-Alvarado, IJESIT 3, 563 (2014). R. Kingslake, Lens Design Fundamental, (New York, Academic Press 1978). A. Santiago Alvarado et al. Jour. of Phys: Conf. Series 274 (2011). A. Santiago Alvarado et al. "Measurement of aberrations of a solid elastic lens using a point-diffraction interferometer", Opt. Eng. 49, 123401 (2010). CrossRef

In this research, we present a prototype optical system that offers significant advances in detecting hydrochloric acid (HCl) and ammonia (NH3) vapors. The system utilizes a natural pigment sensor based on Curcuma longa that is securely attached to a glass surface support. Through extensive development and testing with HCl (37% aqueous solution) and NH₃ (29% aqueous solution) solutions, we have successfully demonstrated the effectiveness of our sensor. To facilitate the detection process, we have developed an injection system that exposes C. longa pigment films to the targeted vapors. The interaction between the vapors and the pigment films triggers a distinct color change, which is then analyzed by the detection system. By capturing the transmission spectra of the pigment film, our system allows a precise comparison of these spectra at different concentrations of the vapors. Our proposed sensor exhibits remarkable sensitivity, allowing the detection of HCl at a concentration of 0.009 ppm using only 100 µL (2.3 mg) of pigment film. In addition, it can detect NH₃ at a concentration of 0.03 ppm with a 400 µL (9.2 mg) pigment film. Integrating C. longa as a natural pigment sensor in an optical system opens up new possibilities for detecting hazardous gases. The simplicity and efficiency of our system, combined with its sensitivity, make it an attractive tool in environmental monitoring and industrial safety applications.