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We investigate the feasibility of multiplexing, employing polarized light, a set o f security encrypted data. The encryption approach is based on the double random pure-phase enciphering method. Phase conjugation operation is conducted in the reconstruction stage with the aid o f a photorefractive crystal which stores the encrypted information. When storing each encrypted image, a polarization change is introduced in the system. This induces decorrelation on the speckle patterns inside the storing medium. We apply this approach for multiple image encryption. We show experimental results that confirm our approach. © 2005 Elsevier B.V . A11 rights reserved. IntroductionIn the optical field there has been constant efforts on both multiplexed [1] and security encrypted [2] data stor age. Securing data in high-capacity storage systems is one of the challenging tasks in order to meet user-requirements in data storage.Optical data storage presents great advantages over tra ditional non-optical storage systems with the potentiality of low cost, high storage capacity, high transfer rate, and hardware-based data encryption. To overcome the difficul ties concerning the storage means for recording photorefractive crystals have been used.There are many methods for multiplexing holograms, e.g., wavelength-, shift-, angle-, and phase-coded multiplexing. Several efforts were performed thanks to the advent of the liquid crystal spatial light modulator (LC SLM). It has opened up the possibility for dynamic control of ampli tude, phase or polarization state of light. The use of LC SLMs for the spatial control of the state of polarization has already been described and experimentally demon strated [3].Several optical systems based on the encryption of information using phase components of wave front have been experimentally demonstrated [4 6], Polarization has been used for the visualization of the decoded information. Two dimensional encoding of the polarization state of light using a parallel aligned liquid crystal SLM has recently been demonstrated [7]. Unnikrishnan et al. [8] experimentally demonstrated an optical encryption system based on polarization encoding to encrypt binary images. The encryption is done by XOR operation between the image and a random code (key to the encrypted image). The XOR operation is done in the polarization domain of coherent light by using two ferroelectric liquid crystal spatial light modulators. The

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Citation: Mira-Agudelo A, TorresSepúlveda W, Barrera JF, et al. Compensation of presbyopia with the light sword lens. Invest Ophthalmol Vis Sci. 2016;57:6870-6877. DOI: 10.1167/iovs.16-19409 PURPOSE. We present the first physiological evaluation of the use of the light sword lens (LSL) for presbyopia compensation. The LSL is an axially asymmetric optical element designed for imaging with extended depth of focus. METHODS.A monocular visual simulator setup is implemented to measure visual acuity (VA). Physiological presbyopia is ''mimicked'' in human subjects by paralysis of the ciliary muscle, using topical application of a muscarinic antagonist. The effect of a contact lens-configured LSL on the mimicked presbyopia visual system is evaluated by measuring VA as a function of target vergence. The ability of the LSL to compensate presbyopia for 2 photopic luminance values was also analyzed. RESULTS.The average VA values for 11 subjects suggest that the LSL can compensate for presbyopia across a wide range of target vergences for which the LSL was designed (À3 to 0 D). However, the proposed corrector element causes a loss of distance VA. The mean logMAR VA in that target vergence range was 0.07. The VA curves also show that luminance does not affect the expected behavior of the LSL-corrected presbyopic eye. CONCLUSIONS.These results indicate that the LSL has significant potential as a visual aid for presbyopia.Keywords: aging changes, ophthalmic optics, presbyopia, vision acuity, visual optics P resbyopia is the decrease in accommodative amplitude of the human visual system that occurs with aging of the eye. 1Although presbyopia is a progressive vision disorder that affects everyone after a certain age, 2 there is no effective way to prevent it. Therefore, over the last 2 decades, important optical investigations have been undertaken to find ways to compensate for this visual condition.Over time, different optical methods to correct presbyopia and restore the ability to recognize both distant and near objects have been proposed.3-6 Some proposals include reading glasses, monovision, residual myopia, multifocal lenses used in glasses, contact lenses, and intraocular lenses. Multifocal intraocular lenses usually are bifocal or trifocal. 7,8 Recent proposals include modifying the topography of the cornea with refractive surgery 4 or inserting a small-aperture (pinhole) implant to artificially reduce the size of the pupil and generate a wider depth of focus. 9Other possible ways to correct presbyopia include varifocal elements based on the Alvarez lenses 10 or programmable lenses based on spatial light modulators, 11,12 which are classified as accommodative lenses. In addition, adjustable lenses that attempt to mimic how the eye lens functions have been designed, 13,14 and changing the optical power by axial displacement of a lens of a fixed focus has also been implanted and tested. 15,16 Despite multiple proposals and scientific advances, there is still no entirely satisfactory way to correct presbyopia. For some p...

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