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We present a new accommodative intraocular lens based on a two-element varifocal Alvarez lens. The intraocular lens consists of (1) an anterior element combining a spherical lens for refractive power with a cubic surface for the varifocal effect, and (2) a posterior element with a cubic surface only. The focal length of the IOL lens changes when the superimposed refractive elements shift in opposite directions in a plane perpendicular to the optical axis. The ciliary muscle will drive the accommodation by a natural process of contraction and relaxation. Results of ray-tracing simulations of the model eye with the two-element intraocular lens are presented for on-axis and off-axis vision. The configuration of the lens is optimized to reduce refractive errors as well as effects of misalignment. A prototype with a clear aperture of ~5.7 mm is manufactured and evaluated in air with a Shack-Hartmann wave-front sensor. It provides an accommodation range of ~4 dioptres in the eye at a ~0.75-mm lateral displacement of the optical elements. The experimentally measured on-axis optical performance of the IOL lens agrees with the theoretically predicted performance.

An approximate analytical expression is derived for the two-dimensional incoherent optical transfer function (OTF) of an imaging system invariant to second-order aberrations. The system broadband behavior resulting from a third-order phase mask in its pupil plane is analyzed by using the two-dimensional stationary phase method. This approach does not require mathematical separability of the pupil function and can be applied to any pupil shape. The OTF is found to be a well-defined and smooth function at all nonzero spatial frequencies when the phase mask function includes third-order mixed terms in the pupil coordinates.

We present a new technique for light scanning by use of viscoelastic-based deformable phase diffraction gratings. Mechanical stretching of the grating permits control of its spatial period, and thus the orders of diffraction can be spatially deflected. In the experiments the viscoelastic gratings with triangular and rectangular profiles have been characterized at = 633 nm. It is demonstrated that the reversible elongation can exceed 20% of the initial length. For the triangular profile grating, the diffraction angle of the first order changed from 6.6°to 5.4°while the diffraction efficiency remained almost constant at ϳ17%. Dynamic scanning of a laser beam at frequencies of ϳ1 kHz is demonstrated by use of electromechanically driven viscoelastic gratings. © 2005 Optical Society of America OCIS codes: 050.1950, 050.2770, 120.5800, 160.2750, 230.1360 Diffraction phase gratings are traditionally used for light deflection and splitting. They have a number of applications in spectroscopy, holography, interferometry, fiber-optic interconnects, light scanners, etc. 1,2There has been a growing interest in phase gratings in the past few years brought about by the gratings' essential advantages for ultrafast laser applications.Compared with an ordinary beam splitter, a phase grating permits the generation of passively phaselocked pulse pairs and ensures high phase stability. 3,4Another important advantage is that it produces diffraction orders with wave fronts that are not tilted relative to the incident beam. 5Optics that employ controllable diffraction elements are of interest for laser beam scanning and deflection. These elements have been used in many applications, including laser treatment of materials, projector systems, and light shutters. Most known devices make use of acousto-optical, electrooptical, magneto-optical, or hybrid spatial light modulators. [6][7][8] In this Letter we report on new low-cost transmission diffraction elements with the possibility of controlling their parameters by mechanical deformation. Diffraction gratings with rectangular and triangular profiles are produced by replication from master molds by the use of a two-component viscoelastic silicone elastomer (Sylgard 184, Dow Corning Corporation). We fabricated a master with a rectangular profile by etching an aluminum layer deposited on to a silicone chip.9 One-level gray-tone lithography was employed to make the triangular profile master. 10,11The newly prepared elastomer is deposited in the master mold and then is cured at 60°C for ϳ8 h until complete polymerization occurs. The viscoelastic elastomer has low optical losses, perfect homogeneity, and parameter stability. It can be reversibly elongated by 40% of its initial length.12 This property permits the creation of deformable optical elements.The resultant viscoelastic deformable (VD) gratings perfectly replicate the relief of the master molds. 12 To facilitate smooth and controllable stretching of the VD samples in experiments we glued the gratings onto the clamps of an optical moun...

We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low-and high-ohmic electrodes, respectively. Adaptive correction of ocular aberrations is achieved by changing the amplitude and the frequency of the applied control voltage. The convex-shaped glass substrates provide the required initial focusing power of the lens. A loop antenna mounded on the rim of the lens delivers an amplitude-modulated radio-frequency control signal to the integrated rectifier circuit that drives the liquid-crystal modal corrector. In vitro measurements of a 5-mm clear aperture prototype with an initial focusing power of +12.5 diopter, remotely driven by a radio-frequency control unit at ~6 MHz, were carried out using a Shack-Hartmann wavefront sensor. The lens based on a 40-μm thick liquid-crystal layer allows for an adjustable defocus of 4 waves, i. e. an accommodation of ~2.51 dioptres at a wavelength of 534 nm, and correction of spherical aberration coefficient ranging from -0.8 to 0.67 waves. Frequency-switching technique was employed to increase the response speed and eliminate transient overshoots in aberration coefficients. The full-scale settling time of the adaptive modal corrector was measured to be ~4 s.