Showing papers on "Lens (optics) published in 2011"

Eyepiece with uniformly illuminated reflective display

Abstract: An eyepiece includes a mechanical frame adapted to secure a lens and an image source facility above the lens. The image source facility includes an LED, a planar illumination facility and a reflective display. The planar illumination facility converts a light beam from the LED received on a side of the planar illumination facility into a top emitting planar light source, uniformly illuminates the reflective display, and is substantially transmissive to allow reflected light to pass through towards a beam splitter. The beam splitter is positioned to receive the image light and to reflect a portion onto a mirrored surface. The mirrored surface is positioned and shaped to reflect the image light into an eye of a user of the eyepiece thereby providing an image within a field of view, the mirrored surface further adapted to be partially transmissive within an area of image reflectance.

Bioinspired Tunable Lens with Muscle-Like Electroactive Elastomers

Abstract: Optical lenses with tunable focus are needed in several fields of application, such as consumer electronics, medical diagnostics and optical communications. To address this need, lenses made of smart materials able to respond to mechanical, magnetic, optical, thermal, chemical, electrical or electrochemical stimuli are intensively studied. Here, we report on an electrically tunable lens made of dielectric elastomers, an emerging class of “artificial muscle” materials for actuation. The optical device is inspired by the architecture of the crystalline lens and ciliary muscle of the human eye. It consists of a fluid-filled elastomeric lens integrated with an annular elastomeric actuator working as an artificial muscle. Upon electrical activation, the artificial muscle deforms the lens, so that a relative variation of focal length comparable to that of the human lens is demonstrated. The device combined optical performance with compact size, low weight, fast and silent operation, shock tolerance, no overheating, low power consumption, and possibility of implementation with inexpensive off-the-shelf elastomers. Results show that combing bioinspired design with the unique properties of dielectric elastomers as artificial muscle transducers has the potential to open new perspectives on tunable optics.

Automatic focus improvement for augmented reality displays

Abstract: An augmented reality system provides improved focus of real and virtual objects. A see-through display device includes a variable focus lens a user looks through. A focal region adjustment unit automatically focuses the variable focus lens in a current user focal region. A microdisplay assembly attached to the see-through display device generates a virtual object for display in the user's current focal region by adjusting its focal region. The variable focus lens may also be adjusted to provide one or more zoom features. Visual enhancement of an object may also be provided to improve a user's perception of an object.

Ergonomic head mounted display device and optical system

Abstract: This invention concerns an ergonomic optical see-through head mounted display device with an eyeglass appearance. The see-through head-mounted display device consists of a transparent, freeform waveguide prism for viewing a displayed virtual image, a see-through compensation lens for enabling proper viewing of a real-world scene when combined together with the prism, and a miniature image display unit for supplying display content. The freeform waveguide prism, containing multiple freeform refractive and reflective surfaces, guides light originated from the miniature display unit toward a user's pupil and enables a user to view a magnified image of the displayed content. A see-through compensation lens, containing multiple freeform refractive surfaces, enables proper viewing of the surrounding environment, through the combined waveguide and lens. The waveguide prism and the see-through compensation lens are properly designed to ergonomically fit human heads enabling a wraparound design of a lightweight, compact, and see-through display system.

Fast two-layer two-photon imaging of neuronal cell populations using an electrically tunable lens

Abstract: Functional two-photon Ca(2+)-imaging is a versatile tool to study the dynamics of neuronal populations in brain slices and living animals. However, population imaging is typically restricted to a single two-dimensional image plane. By introducing an electrically tunable lens into the excitation path of a two-photon microscope we were able to realize fast axial focus shifts within 15 ms. The maximum axial scan range was 0.7 mm employing a 40x NA0.8 water immersion objective, plenty for typically required ranges of 0.2-0.3 mm. By combining the axial scanning method with 2D acousto-optic frame scanning and random-access scanning, we measured neuronal population activity of about 40 neurons across two imaging planes separated by 40 μm and achieved scan rates up to 20-30 Hz. The method presented is easily applicable and allows upgrading of existing two-photon microscopes for fast 3D scanning.

Plasmonic Luneburg and Eaton lenses

Abstract: Plasmonics takes advantage of the properties of surface plasmon polaritons, which are localized or propagating quasiparticles in which photons are coupled to the quasi-free electrons in metals. In particular, plasmonic devices can confine light in regions with dimensions that are smaller than the wavelength of the photons in free space, and this makes it possible to match the different length scales associated with photonics and electronics in a single nanoscale device. Broad applications of plasmonics that have been demonstrated to date include biological sensing, sub-diffraction-limit imaging, focusing and lithography and nano-optical circuitry. Plasmonics-based optical elements such as waveguides, lenses, beamsplitters and reflectors have been implemented by structuring metal surfaces or placing dielectric structures on metals to manipulate the two-dimensional surface plasmon waves. However, the abrupt discontinuities in the material properties or geometries of these elements lead to increased scattering of surface plasmon polaritons, which significantly reduces the efficiency of these components. Transformation optics provides an alternative approach to controlling the propagation of light by spatially varying the optical properties of a material. Here, motivated by this approach, we use grey-scale lithography to adiabatically tailor the topology of a dielectric layer adjacent to a metal surface to demonstrate a plasmonic Luneburg lens that can focus surface plasmon polaritons. We also make a plasmonic Eaton lens that can bend surface plasmon polaritons. Because the optical properties are changed gradually rather than abruptly in these lenses, losses due to scattering can be significantly reduced in comparison with previously reported plasmonic elements.

Scattering lens resolves sub-100 nm structures with visible light.

Abstract: The smallest structures that conventional lenses are able to optically resolve are of the order of 200 nm. We introduce a new type of lens that exploits multiple scattering of light to generate a scanning nanosized optical focus. With an experimental realization of this lens in gallium phosphide we imaged gold nanoparticles at 97 nm optical resolution. Our work is the first lens that provides a resolution better than 100 nm at visible wavelengths.

Displayed content vision correction with electrically adjustable lens

Abstract: This disclosure concerns an interactive, head-mounted eyepiece with an electrically adjustable liquid lens that adjusts a focus of the displayed content for the user. The electrically adjustable lens may be of the type wherein the lens is moved back and forth with a small worm drive. Alternatively, the electrically adjustable lens may be of the type that uses two liquids, a conducting liquid and a non-conducting liquid. The liquid lens may instead be a tunable liquid crystal cell, in which a non-uniform magnetic field is used to shape the liquid crystal and adjust a focus for the user.

Dynamically tunable hemispherical electronic eye camera system with adjustable zoom capability

Abstract: Imaging systems that exploit arrays of photodetectors in curvilinear layouts are attractive due to their ability to match the strongly nonplanar image surfaces (i.e., Petzval surfaces) that form with simple lenses, thereby creating new design options. Recent work has yielded significant progress in the realization of such “eyeball” cameras, including examples of fully functional silicon devices capable of collecting realistic images. Although these systems provide advantages compared to those with conventional, planar designs, their fixed detector curvature renders them incompatible with changes in the Petzval surface that accompany variable zoom achieved with simple lenses. This paper describes a class of digital imaging device that overcomes this limitation, through the use of photodetector arrays on thin elastomeric membranes, capable of reversible deformation into hemispherical shapes with radii of curvature that can be adjusted dynamically, via hydraulics. Combining this type of detector with a similarly tunable, fluidic plano-convex lens yields a hemispherical camera with variable zoom and excellent imaging characteristics. Systematic experimental and theoretical studies of the mechanics and optics reveal all underlying principles of operation. This type of technology could be useful for night-vision surveillance, endoscopic imaging, and other areas that require compact cameras with simple zoom optics and wide-angle fields of view.

Wideband Planar Microwave Lenses Using Sub-Wavelength Spatial Phase Shifters

Abstract: We present a new technique for designing low-profile planar microwave lenses. The proposed lenses consist of numerous miniature spatial phase shifters distributed over a planar surface. The topology of each spatial phase shifter (SPS) is based on the design of a class of bandpass frequency selective surfaces composed entirely of sub-wavelength, non-resonant periodic structures. A procedure for designing the proposed lenses and their constituting spatial phase shifters is also presented in the paper. This design procedure is applied to two different planar lenses operating at X-band. Each lens is a low-profile structure with an overall thickness of 0.08λ0 and uses sub-wavelength SPSs with dimensions of 0.2λ0 × 0.2λ0, where λ0 is the free-space wavelength at 10 GHz. These prototypes are fabricated and experimentally characterized using a free-space measurement system and the results are reported in the paper. The fabricated prototypes demonstrate relatively wide bandwidths of approximately 20%. Furthermore, the lenses demonstrate stable responses when illuminated under oblique angles of incidence. This feature is of practical importance if these lenses are to be used in beam-scanning antenna applications.

Lens-free optical tomographic microscope with a large imaging volume on a chip

Abstract: We present a lens-free optical tomographic microscope, which enables imaging a large volume of approximately 15 mm3 on a chip, with a spatial resolution of < 1 μm × < 1 μm × < 3 μm in x, y and z dimensions, respectively. In this lens-free tomography modality, the sample is placed directly on a digital sensor array with, e.g., ≤ 4 mm distance to its active area. A partially coherent light source placed approximately 70 mm away from the sensor is employed to record lens-free in-line holograms of the sample from different viewing angles. At each illumination angle, multiple subpixel shifted holograms are also recorded, which are digitally processed using a pixel superresolution technique to create a single high-resolution hologram of each angular projection of the object. These superresolved holograms are digitally reconstructed for an angular range of ± 50°, which are then back-projected to compute tomograms of the sample. In order to minimize the artifacts due to limited angular range of tilted illumination, a dual-axis tomography scheme is adopted, where the light source is rotated along two orthogonal axes. Tomographic imaging performance is quantified using microbeads of different dimensions, as well as by imaging wild-type Caenorhabditis elegans. Probing a large volume with a decent 3D spatial resolution, this lens-free optical tomography platform on a chip could provide a powerful tool for high-throughput imaging applications in, e.g., cell and developmental biology.

Zoom lens system, interchangeable lens device, and camera system

Abstract: This zoom lens system is provided with: a first lens group that has negative power; a second lens group that has positive power; a third lens group that has negative power; and a fourth lens group that has positive power. During zooming, the first lens group, second lens group, and third lens group move along the optical axis. During focusing, the third lens group moves along the optical axis. The zoom lens system satisfies the conditions: 2.5 ≤ | (1 - (β 3T ) 2 ) × (β 4T ) 2 | ≤ 7.0 and 0.5 ≤ Bf W /f W ≤ 4.0 (β 3T being the lateral magnification of the third lens group at an infinite object distance at the telephoto end; β 4T the lateral magnification of the fourth lens group at an infinite object distance of the telephoto end; Bf W the back focus of the entire system at the wide angle end; and f W the focal length of the entire system at the wide angle end).

Photographing optical lens assembly

Abstract: This invention provides a photographing optical lens assembly, from an object side to an image side in order, comprising a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a concave image-side surface, a third lens element with positive refractive power, a fourth lens element with negative refractive power having a concave image-side surface, both the two surfaces of the fourth lens thereof being aspheric. And an aperture stop is positioned between the first element and the second lens element. There are four lens elements with refractive power in the lens assembly.

Characterization of high-resolution diffractive X-ray optics by ptychographic coherent diffractive imaging

Abstract: We have employed ptychographic coherent diffractive imaging to completely characterize the focal spot wavefield and wavefront aberrations of a high-resolution diffractive X-ray lens. The ptychographic data from a strongly scattering object was acquired using the radiation cone emanating from a coherently illuminated Fresnel zone plate at a photon energy of 6.2 keV. Reconstructed images of the object were retrieved with a spatial resolution of 8 nm by combining the difference-map phase retrieval algorithm with a non-linear optimization refinement. By numerically propagating the reconstructed illumination function, we have obtained the X-ray wavefield profile of the 23 nm round focus of the Fresnel zone plate (outermost zone width, Δr = 20 nm) as well as the X-ray wavefront at the exit pupil of the lens. The measurements of the wavefront aberrations were repeatable to within a root mean square error of 0.006 waves, and we demonstrate that they can be related to manufacturing aspects of the diffractive optical element and to errors on the incident X-ray wavefront introduced by the upstream beamline optics.

Image capturing lens assembly

Abstract: This invention provides an image capturing lens assembly in order from an object side to an image side comprising: a first lens group has only one first lens element with a positive refractive power, and a second lens group in order from the object side to the image side comprising: a second lens element with a negative refractive power, a third lens element, a fourth lens element and a fifth lens element; while a distance between an imaged object and the image capturing lens assembly changes from far to near, focusing is performed by moving the first lens group along the optical axis and a distance between the first lens group and an image plane changes from near to far. By such arrangement and focusing adjustment method, good image quality is achieved and less power is consumed.

Fluidic lens with reduced optical aberration

Abstract: A fluidic optical device may include a first optical surface that includes an deformable material and a second optical surface that includes a rigid material. An optical fluid disposed between first and second optical surfaces and an actuator is disposed in communication with first optical surface. Activation of actuator results in a deformation of first optical surface and displacement of optical fluid. The deformation and displacement result in a change in an optical property of the device. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Design and measurements of a broadband two-dimensional acoustic lens

Abstract: We describe the design, fabrication, and measurement of a 2D broadband gradient index acoustic lens in air. The index of refraction is tuned by controlling the dimensions of acoustic metamaterial unit cell inclusions designed through numerical simulations. The lens was fabricated in plastic through rapid prototyping stereolithography, and measurements of the sound field show good agreement with the theoretical lens performance. The broadband performance of the lens is confirmed for frequencies ranging from 1.5 kHz to 4.5 kHz.

Camera lens structures and display structures for electronic devices

Abstract: A camera may be mounted under a display in an electronic device. The display may include a polarizer layer, a color filter layer, and a thin-film-transistor layer. A layer of material such as a glass insert may be attached to an edge of the display. Openings may be formed in the layers of the display and the insert to accommodate the camera. A sleeve structure may be mounted within an opening. The camera may include lens structures formed from a stack of lens elements. One or more layers of the display may be interposed within the lens structures. The glass insert may be mounted within a notch in the color filter layer and thin-film transistor layer or along a straight edge of the color filter layer and thin-film transistor layer. The edge of the color filter layer may be recessed with respect to form a mounting shelf for the insert.

Contact lenses in the management of keratoconus.

Abstract: The range of contact lens modalities currently available for the successful optical correction of keratoconus is greatly expanded. We review lens types currently available for the nonsurgical management of keratoconus, including rigid gas-permeable (GP) lenses, intralimbal lenses, corneoscleral lenses, scleral lenses, hybrid lenses, and piggyback lenses. In this review, we discuss the contemporary range of available lens types and the circumstances in which they are best used.

Head-mounted display apparatus employing one or more fresnel lenses

Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a Fresnel lens system (115) supported by the frame (107). The HMD (100) can employ a reflective optical surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107), with the Fresnel lens system (115) being located between the image display system (110) and the reflective optical surface (120). The Fresnel lens system (115) can include at least one curved Fresnel lens element (820). Fresnel lens elements (30) for use in HMDs are also disclosed which have facets (31) separated by edges (32) which lie along radial lines (33) which during use of the HMD pass through a center of rotation (34) of a nominal user's eye (35) or through the center of the eye's lens (36) or are normal to the surface of the eye's cornea.

Lenses for Circular Polarization Using Planar Arrays of Rotated Passive Elements

Abstract: A planar array of passive lens elements can be phased to approximate the effect of a curved dielectric lens. The rotational orientation of each element can provide the required phase shift for circular polarization. The array elements must be designed so that the hand of circular polarization changes as the electromagnetic wave passes through the lens. An element is presented that is based on an aperture-coupled microstrip patch antenna, and two lenses are designed. Each lens has a diameter of 254 mm and contains 349 elements. The elements have identical dimensions but the rotational orientation of each element is selected to provide a specific lens function. The first lens is designed to collimate radiation from a feed horn into a beam pointing 20° from broadside. At 12.9 GHz the aperture efficiency is 48%. The second lens acts as a Wollaston-type prism. It splits an incident wave according to its circular polarization components.

Symmetric lenses

Abstract: Lenses--bidirectional transformations between pairs of connected structures--have been extensively studied and are beginning to find their way into industrial practice. However, some aspects of their foundations remain poorly understood. In particular, most previous work has focused on the special case of asymmetric lenses, where one of the structures is taken as primary and the other is thought of as a projection, or view. A few studies have considered symmetric variants, where each structure contains information not present in the other, but these all lack the basic operation of composition. Moreover, while many domain-specific languages based on lenses have been designed, lenses have not been thoroughly explored from an algebraic perspective.We offer two contributions to the theory of lenses. First, we present a new symmetric formulation, based on complements, an old idea from the database literature. This formulation generalizes the familiar structure of asymmetric lenses, and it admits a good notion of composition. Second, we explore the algebraic structure of the space of symmetric lenses. We present generalizations of a number of known constructions on asymmetric lenses and settle some longstanding questions about their properties---in particular, we prove the existence of (symmetric monoidal) tensor products and sums and the non-existence of full categorical products or sums in the category of symmetric lenses. We then show how the methods of universal algebra can be applied to build iterator lenses for structured data such as lists and trees, yielding lenses for operations like mapping, filtering, and concatenation from first principles. Finally, we investigate an even more general technique for constructing mapping combinators, based on the theory of containers.

Imager with multiple sensor arrays

Abstract: An imager array may be provided as part of an imaging system The imager array may include a plurality of sensor arrays (eg, also referred to as lenslets or optical elements) Each sensor array may include a plurality of sensors (eg, pixels) associated with a lens The sensor arrays may be oriented, for example, substantially in a plane facing the same direction and configured to detect images from the same scene (eg, target area) Such images may be processed in accordance with various techniques to provide images of electromagnetic radiation The sensor arrays may include filters or lens coatings to selectively detect desired ranges of electromagnetic radiation Such arrangements of sensor arrays in an imager array may be used to advantageous effect in a variety of different applications

The effect of two-zone concentric bifocal spectacle lenses on refractive error development and eye growth in young chicks.

Abstract: Purpose To characterize the effects on refractive error development and eye growth in young chicks of two-zone concentric lens designs, which differentially affect the defocus experiences of central and peripheral retinal regions. Methods Monocular defocusing lenses were worn for 5 days from 17 days of age. Four two-zone concentric lens designs (overall optical zone diameter, 10 mm) combining plano with either -5- or +5-D power were used. Lens designs were as follows: (1) +5 D center (+5C), (2) +5 D periphery (+5P), (3) -5 D center (-5C), and (4) -5 D peripheral (-5P), with plano in periphery for all C-designs and in the center for P-designs. Five central zone diameters (CZDs) were tested, ranging from 2.5 to 6.5 mm in 1-mm increments. Plano, +5- and -5-D single-vision (SV) lenses were used as the control. A minimum of six birds were included in each lens group. Results For the two-zone lenses, the P designs (i.e., peripheral defocus) had greater effects than the C designs (i.e., central defocus) on both on-axis eye growth and refractions. All but the 6.5-mm CZD +5P lens induced larger changes than the +5SV lens. The +5C lenses with CZD less than 5.5 mm had little effect. The two-zone -5-D lenses had less effect than the -5SV lens, and only the 6.5-mm CZD lens of the -5C series had a significant effect. Conclusions The results demonstrate that peripheral defocus can influence both peripheral and central refractive development. The inhibitory effect on axial eye growth of the +5P lenses opens the possibility that appropriately designed concentric lenses may control the progression of human myopia.

Methods and lenses for correction of chromatic aberration

Abstract: The subject invention provides lenses, and methods for designing and manufacturing these lenses, with reduced chromatic aberration. Advantageously, these lenses are specifically designed to correct chromatic aberration that results as multichromatic light passes through the lenses.

A Review of Electrically Tunable Focusing Liquid Crystal Lenses

Abstract: Electrically tunable focusing liquid crystal (LC) lenses are reviewed in this paper. The distribution of the orientations of LC directors which is controlled by electric fields results in a distribution of refractive indices of LC directors. The incident light can be modulated by the electrically tunable lens-like phase difference of the LC lens. We introduce the basic operating principles of LC lenses and discuss the structures of LC lenses. The major challenges of LC lenses are also discussed. We believe this paper provides a guideline for basic understanding of LC lenses.

Super multi-view display with a lower resolution flat-panel display.

Abstract: A lenticular-type super multi-view (SMV) display normally requires an ultra high-resolution flat-panel display. To reduce this resolution requirement, two or more views are generated around each eye with an interval smaller than the pupil diameter. Cylindrical lenses constituting a lenticular lens project a group of pixels of the flat-panel display to generate a group of viewing zones. Pixel groups generating left and right viewing zones through the same cylindrical lens are partitioned to separate the two zones. The left and right pixel groups for different cylindrical lenses are interlaced horizontally. A prototype SMV display is demonstrated.

Dynamic Changeable Focus Contact And Intraocular Lens

Abstract: A contact lens or an intraocular lens include an electronic component and a dynamic optic, where the dynamic optic is configured to provide a first optical power and a second optical power, where the first and the second optical power are different. The dynamic optic may comprise a fluid lens.