Nonmechanical bifocal zoom telescope.
ABSTRACT We report on a novel zoom lens with no moving parts in the form of a switchable Galilean telescope. This zoom telescope consists of two flat liquid-crystal diffractive lenses with apertures of 10mm that can each take on the focal lengths of -50 and +100cm, with a spacing of 50cm and, hence, a zoom ratio of 4x. The lenses are driven using a low-voltage ac source with 1.6V and exhibit millisecond switching times. The spectral characteristic of this diffractive zoom system is evaluated for light sources of various bandwidths. Potential applications for this technology include a zoom lens with no moving parts for camera phones and medical imaging devices.
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ABSTRACT: Materials that have subwavelength structure can add degrees of freedom to optical system design that are not possible with bulk materials. We demonstrate two lenses that are composed out of lithographically patterned arrays of elliptical cross-section silicon nanowires, which can dynamically reconfigure their imaging properties in response to the polarization of the illumination. In each element, two different focusing functions are polarization encoded into a single lens. The first nanowire lens has a different focal length for each linear polarization state, thereby realizing the front end of a nonmechanical zoom imaging system. The second nanowire lens has a different optical axis for each linear polarization state, demonstrating stereoscopic image capture from a single physical aperture.Nano Letters 09/2011; 11(10):4299-303. · 13.03 Impact Factor
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ABSTRACT: We present a theoretical method for analyzing the first-order optics of stabilized zoom lenses with two focal-length-variable elements. The zoom equations are established through the use of the Gaussian brackets method. This is done because the optical power of the focal-length-variable elements varies during the zooming process. The first and second derivatives and the Hessian matrix of the zoom equations with respect to the Gaussian parameters are determined using the equations. These parameters could represent the sensitivity of the zoom ratio of the system to changes in the corresponding system variables. We select the initial values of these system variables, i.e. the magnification of the focal-length-variable element and the structure parameters of the fixed lens group, to be close to the steepest gradient direction. Here the sensitivity of the system focal length is high with respect to variations in the zoom variables. This process leads to an increase in the zoom ratio of the zoom system. The results show successful four-group stabilized zoom lens designs with 2:1 and 5:1 zoom ratios, using two deformable mirrors as focal-length-variable elements. This system, with the inherent characteristics of a steepest gradient, could miniaturize zoom systems.Optics Express 03/2013; 21(6):7758-67. · 3.55 Impact Factor
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ABSTRACT: An electrically controllable liquid crystal (LC) microlens with polymer crater, which is simply prepared by droplet evaporation, has been previously proposed as a focusing device possessing excellent characteristics in optical performance, especially for the capability of tunable focal lengths. As the alignment layer on the crater surface cannot be effectively rubbed, non-uniformly symmetrical electric fields in the LC lenses usually induce disclination lines during operation. In this paper, a polymer surface stabilization technique is applied to successfully prevent disclination lines and greatly improve the performance of the LC microlens with the polymer crater.Optics Express 02/2014; 22(4):4620-7. · 3.55 Impact Factor