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.

We present a null-screen design for testing the shape quality of the reflecting surface of a parabolic trough solar collector (PTSC). This technique is inexpensive, the whole surface is tested at once, and it is easy to implement. For this, we propose the design of a flat null-screen perpendicular to the optical axis of the PTSC in such a way that it allows testing of the full aperture; we compute the caustic associated with the reflected light rays on the desired surface and analyze the parameters that determine the null-screen dimensions. Additionally, we perform a numerical simulation to analyze the accuracy of the method by introducing random displacement errors into the measured data. Accuracies $>0.35mrad$ were found to evaluate the quality of surfaces with this method. The errors in the determination of the coordinates of the centroids of the reflected images must be measured with an accuracy $>0.5pixels$, and the errors in the coordinates of the spots of the null-screen must be $<0.5mm$.

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

There has been a considerable recent increase in the use of variable focal length lenses (VFLLs), especially as microlenses in photographic objectives, endoscopes, microscope objectives, etc. One distinguishing feature of these VFLLs is the presence of a mechanism whereby the shape of the lens and its geometrical parameters can be changed. A new type of variable focal length lens is introduced made from elastic material. It is placed inside a mechanical mount where radial forces can be applied to its perimeter. We also present the optomechanical design and the measurement of wavefront aberrations to the third and fifth order of a solid elastic lens (SEL). A point-diffraction interferometer is used as a wavefront sensor to test changes of the lens. Geometrical changes in the lens produce changes in the aberrations. Finally, the aberrations found in the SEL (without any application of stress) are compared with aberrations obtained by means of numerical ray trace. Some experimental results are also shown.

We present a simple method to evaluate the curved surface of a plano–convex aspheric lens using an incoherent light source. We implement an exact ray trace to obtain analytical expressions for designing a set of geometric objects, placed within a plane, to produce by refraction a regular array of either circles or straight lines in the plane of detection when the optical system under test works in accordance with the nominal design. An innovative geometrical test is implemented to calibrate the position of each element involved in the measurement system. As part of the calibration process, we considered that the camera lens can be affected by the distortion aberration; therefore, we proposed a straightforward method to compensate for the defects introduced in the experimental images. Finally, we used the measured values of the slopes to recover the shape of the surface under test using an iterative algorithm; as a result, we obtained the geometric parameters describing the surface with a percentage error less than 1.7%.