Showing papers on "Lens (optics) published in 2012"

Aberration-free ultrathin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces.

Abstract: The concept of optical phase discontinuities is applied to the design and demonstration of aberration-free planar lenses and axicons, comprising a phased array of ultrathin subwavelength-spaced optical antennas. The lenses and axicons consist of V-shaped nanoantennas that introduce a radial distribution of phase discontinuities, thereby generating respectively spherical wavefronts and nondiffracting Bessel beams at telecom wavelengths. Simulations are also presented to show that our aberration-free designs are applicable to high-numerical aperture lenses such as flat microscope objectives.

Dual-polarity plasmonic metalens for visible light

Abstract: Surface topography and refractive index profile dictate the deterministic functionality of a lens. The polarity of most lenses reported so far, that is, either positive (convex) or negative (concave), depends on the curvatures of the interfaces. Here we experimentally demonstrate a counter-intuitive dual-polarity flat lens based on helicity-dependent phase discontinuities for circularly polarized light. Specifically, by controlling the helicity of the input light, the positive and negative polarity are interchangeable in one identical flat lens. Helicity-controllable real and virtual focal planes, as well as magnified and demagnified imaging, are observed on the same plasmonic lens at visible and near-infrared wavelengths. The plasmonic metalens with dual polarity may empower advanced research and applications in helicity-dependent focusing and imaging devices, angular-momentum-based quantum information processing and integrated nano-optoelectronics.

A super-oscillatory lens optical microscope for subwavelength imaging

Abstract: The maximum imaging resolution in classical optics is limited to approximately the wavelength of light used, and subwavelength resolution can only be achieved by advanced imaging schemes. The appeal of the super-oscillatory lens optical microscope described here is that it enables subwavelength imaging with, in principle, unlimited resolution using a modified conventional microscope. The past decade has seen an intensive effort to achieve optical imaging resolution beyond the diffraction limit. Apart from the Pendry–Veselago negative index superlens1, implementation of which in optics faces challenges of losses and as yet unattainable fabrication finesse, other super-resolution approaches necessitate the lens either to be in the near proximity of the object or manufactured on it2,3,4,5,6, or work only for a narrow class of samples, such as intensely luminescent7,8 or sparse9 objects. Here we report a new super-resolution microscope for optical imaging that beats the diffraction limit of conventional instruments and the recently demonstrated near-field optical superlens and hyperlens. This non-invasive subwavelength imaging paradigm uses a binary amplitude mask for direct focusing of laser light into a subwavelength spot in the post-evanescent field by precisely tailoring the interference of a large number of beams diffracted from a nanostructured mask. The new technology, which—in principle—has no physical limits on resolution, could be universally used for imaging at any wavelength and does not depend on the luminescence of the object, which can be tens of micrometres away from the mask. It has been implemented as a straightforward modification of a conventional microscope showing resolution better than λ/6.

Single lens 3D-camera with extended depth-of-field

Abstract: Placing a micro lens array in front of an image sensor transforms a normal camera into a single lens 3D camera, which also allows the user to change the focus and the point of view after a picture has been taken. While the concept of such plenoptic cameras is known since 1908, only recently the increased computing power of low-cost hardware and the advances in micro lens array production, have made the application of plenoptic cameras feasible. This text presents a detailed analysis of plenoptic cameras as well as introducing a new type of plenoptic camera with an extended depth of field and a maximal effective resolution of up to a quarter of the sensor resolution.

Optical reading apparatus having variable settings

Abstract: A laser scanning indicia reading apparatus (1000) comprises one or more adjustable aperture assemblies (2024) for adjusting the diameter of a laser beam and adjustable lens assemblies (2026) for adjusting the distance of a laser beam waist (W).

Acoustic focusing by coiling up space

Abstract: We report the design of a gradient index acoustic lens by coiling up space, an entirely different, yet more direct approach compared with previous designs. The proposed model comprises a series of acoustic metamaterial units with curled channels. Acoustic waves propagate freely within the channels but their propagating phases can be delayed at will by adjusting the size of the units. The numerical results show that the designed acoustic metamaterial can mimic an acoustic gradient index lens with arbitrarily large refractive index and considerably high transmission efficiency. This may provide possibilities for the design and application of acoustic lenses.

Non-Uniform Metasurface Luneburg Lens Antenna Design

Abstract: A metasurfing concept is demonstrated and applied in the design of Luneburg lens antennas. Using an array of size-varying circular patches on a dielectric substrate inside a parallel-plate waveguide (PPW) structure variable surface impedance is obtained, which realizes an equivalent refraction index as that of a Luneburg lens. The obtained lens has good bandwidth characteristics and significant fabrication advantages with respect to conventional dielectric lenses. Based on this PPW lens, an H-plane antenna has been designed and simulated.

Wireless powered contact lens with glucose sensor

Abstract: A contact lens having an integrated glucose sensor is provided. The contact lens includes an electrochemical sensor configured to measure the level of glucose in the tear fluid of the eye of the user wearing the contact lens. The electrochemical sensor is powered by radiation off-lens, through an RF antenna or a photovoltaic device mounted on the periphery of the contact lens. The power provided to the contact lens also enables transmission of data from the electrochemical sensor, for example by backscatter communications or optically by an LED mounted to the lens.

Carbon-Nanotube Optoacoustic Lens for Focused Ultrasound Generation and High-Precision Targeted Therapy

Abstract: We demonstrate a new optical approach to generate high-frequency (.15 MHz) and high-amplitude focused ultrasound, which can be used for non-invasive ultrasound therapy. A nano-composite film of carbon nanotubes (CNTs) and elastomeric polymer is formed on concave lenses, and used as an efficient optoacoustic source due to the high optical absorption of the CNTs and rapid heat transfer to the polymer upon excitation by pulsed laser irradiation. The CNT-coated lenses can generate unprecedented optoacoustic pressures of .50 MPa in peak positive on a tight focal spot of 75 mm in lateral and 400 m mi n axial widths. This pressure amplitude is remarkably high in this frequency regime, producing pronounced shock effects and non-thermal pulsed cavitation at the focal zone. We demonstrate that the optoacoustic lens can be used for micro-scale ultrasonic fragmentation of solid materials and a single-cell surgery in terms of removing the cells from substrates and neighboring cells.

Computational adaptive optics for broadband optical interferometric tomography of biological tissue

Abstract: Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard Gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.

Imaging lens and imaging device

Abstract: [Problem] To enable a reduction in size, a reduction in costs, the widening of the angle of view and an increase in performance of an imaging lens, and also to eliminate restrictions on the imaging element used. [Solution] An imaging lens (1) is formed substantially from six lenses in the following order from the object side: a negative first lens (L1); a negative second lens (L2); a positive third lens (L3); a positive fourth lens (L4); a negative fifth lens (L5); and a positive sixth lens (L6). The surface on the object side of the second lens (L2) is a concave surface, and the surface on the object side of the third lens (L3) is a concave surface.

In vivo Brillouin optical microscopy of the human eye

Abstract: We report the first Brillouin measurement of the human eye in vivo. We constructed a Brillouin optical scanner safe for human use by employing continuous-wave laser light at 780 nm at a low power of 0.7 mW. With a single scan along the optic axis of the eye, the axial profile of Brillouin frequency shift was obtained with a pixel acquisition time of 0.4 s and axial resolution of about 60 μm, showing the depth-dependent biomechanical properties in the cornea and lens.

Nonimaging Fresnel Lenses: Design and Performance of Solar Concentrators

Abstract: Executive Summary.- 1 Lenses and Mirrors for Solar Energy.- 1.1 Photovoltaic or Thermal Concentration?.- 1.2 Classification of Solar Concentrators.- 2 Nonimaging Optics.- 2.1 Nonimaging Concentration.- 2.2 Generalized Ideal Concentration.- 2.3 Lagrange Invariant.- 2.4 Nonimaging Mirrors.- 3 Fresnel Lens Optics.- 3.1 Reflection and Refraction.- 3.2 Total Internal Reflection.- 3.3 Deviation.- 3.4 Refractive Indices.- 3.5 Minimum Dispersion.- 4 Earlier Fresnel Lenses.- 4.1 History of Fresnel Lenses.- 4.2 Recent Developments.- 4.3 Simple Fresnel Lenses.- 4.4 Domed or Arched Fresnel Lenses.- 5 Nonimaging Fresnel Lens Design.- 5.1 Applied Nonimaging Lens Design.- 5.2 The Optimum Linear Lens.- 5.3 Rotational Symmetry.- 5.4 Arbitrary Shapes.- 5.5 Diverger Lens for Lighting.- 6 Lens Evaluation.- 6.1 Losses.- 6.2 Transmittance.- 6.3 Geometrical Losses.- 6.4 Concentration Ratios.- 6.5 Nonideal Concentration.- 7 Optimization of Stationary Concentrators.- 7.1 Choice of Stationary Collector.- 7.2 Solar Radiation Model.- 7.3 Radiation on a Tilted Plane.- 7.4 Acceptance by a Solar Concentrator.- 7.5 Compound Parabolic Concentrators.- 7.6 Quasi-3D Concentrators.- 8 Prototype Design, Manufacturing, and Testing.- 8.1 Prototypes of Choice.- 8.2 Prism Size.- 8.3 Lens Redesign.- 8.4 Lens Manufacturing.- 8.5 Sample.- 8.6 Preliminary Tests.- 8.7 Partial Absorber Illumination.- 8.8 Tracking.- 9 Concentrated Sunlight and Photovoltaic Conversion.- 9.1 Flux Density.- 9.2 Solar Disk Size and Brightness.- 9.3 Spectral Color Dispersion.- 9.4 Concentrator Cells.- 9.5 Multijunction Devices.- 9.6 Photovoltaic System Performance.- 9.7 Concentration and Cost.- 10 Solar Thermal Concentrator Systems.- 10.1 Solar Resources.- 10.2 Solar Sorption Air Conditioning.- 10.3 Energy and Exergy.- 10.4 Exergy of a Concentrating Collector.- 11 Solar Concentration in Space.- 11.1 Space Concentrator Arrays.- 11.2 Design Challenges in Space.- 11.3 Lenses and Mirrors!.- References.

Omnidirectional broadband acoustic absorber based on metamaterials

Abstract: We present the design, construction, and experimental characterization of the acoustic analogue of the so called photonic black-hole. The fabricated sample has cylindrical symmetry and consists of two parts, a shell that bends the sound towards the center and a core that dissipates its energy. The shell is made of a metamaterial that perfectly matches the acoustic impedance of air and behaves like a gradient index lens. The experimental data obtained in a multi-modal impedance chamber demonstrate that the proposed acoustic black-hole acts like an onmidirectional broadband absorber with strong absorbing efficiency.

Silicone hydrogel contact lenses

Abstract: Ophthalmically compatible contact lenses include lens bodies configured for placement on a cornea of an animal or human eye. The lens bodies are made of a hydrophilic silicon-containing polymeric material. The lens bodies have oxygen permeabilities, water content, surface wettabilities, flexibilities, and/or designs to be worn by a lens wearer even during sleep. The present lenses can be worn on a daily basis, including overnight, or can be worn for several days, such as about thirty days, without requiring removal or cleaning.

The boss emission-line lens survey (Bells). I. A large spectroscopically selected sample of lens galaxies at redshift 0.5

Abstract: We present a catalog of 25 definite and 11 probable strong galaxy–galaxy gravitational lens systems with lens redshifts 0.4 <~ z <~ 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift.We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy–galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulgedominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution.

Dielectric antenna and fill level sensor using the radar principle

Abstract: A dielectric antenna (1) having at least one supply element (2) and at least one lens (3) formed of a dielectric material. The dielectric antenna makes it possible to measure the surface of a medium with an essentially consistent measuring accuracy in that the lens (3) has an outer component (4) and an inner component (5). The outer component (4) has a radiating surface (6) that is spherical and an inner surface (7) that is spherical, and the inner component (5) has a contact surface (8) that spherical. Furthermore, the antenna is usable as part of a fill level sensor operating on the radar principle.

The CFHTLS-Strong Lensing Legacy Survey (SL2S): Investigating the group-scale lenses with the SARCS sample

Abstract: We present the Strong Lensing Legacy Survey-ARCS (SARCS) sample compiled from the final T0006 data release of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) covering a total non-overlapping area of 159 deg2. We adopt a semi-automatic method to find gravitational arcs in the survey that makes use of an arc-finding algorithm. The candidate list is pruned by visual inspection and ranking to form the final SARCS sample. This list also includes some serendipitously discovered lens candidates which the automated algorithm did not detect. The SARCS sample consists of 127 lens candidates which span arc radii ~2''-18'' within the unmasked area of ~150 deg2. Within the sample, 54 systems are promising lenses among which, we find 12 giant arcs (length-to-width ratio ≥8). We also find two radial arc candidates in SL2SJ141447+544704. From our sample, we detect a systematic alignment of the giant arcs with the major axis of the baryonic component of the putative lens in concordance with previous studies. This alignment is also observed for all arcs in the sample and does not vary significantly with increasing arc radius. The mean values of the photometric redshift distributions of lenses corresponding to the giant arcs and all arcs sample are at z ~ 0.6. Owing to the large area and depth of the CFHTLS, we find the largest sample of lenses probing mass scales that are intermediate to cluster and galaxy lenses for the first time. We compare the observed image separation distribution (ISD) of our arcs with theoretical models. A two-component density profile for the lenses which accounts for both the central galaxy and the dark matter component is required by the data to explain the observed ISD. Unfortunately, current levels of uncertainties and degeneracies accommodate models both with and without adiabatic contraction. We also show the effects of changing parameters of the model that predict the ISD and that a larger lens sample might constrain relations such as the concentration-mass relation, mass-luminosity relation, and the faint-end slope of the luminosity function.

Image capturing optical lens assembly

Abstract: An image capturing optical lens assembly includes, in order from an object side to an image side, a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, a second lens element with negative refractive power, a third lens element with negative refractive power having a concave object-side surface and a convex image-side surface, and a fourth lens element with refractive power having a concave image-side surface. The object-side surface and the image-side surface of the fourth lens element are aspheric. Either or both of the object-side surface and the image-side surface have at least one inflection point formed thereon.

Apparatus and method for creating a stable optical interface

Abstract: A system and a method for creating a stable and reproducible interface of an optical sensor system for measuring blood glucose levels in biological tissue include a dual wedge prism sensor attached to a disposable optic that comprises a focusing lens and an optical window The disposable optic adheres to the skin to allow a patient to take multiple readings or scans at the same location The disposable optic includes a Petzval surface placed flush against the skin to maintain the focal point of the optical beam on the surface of the skin Additionally, the integrity of the sensor signal is maximized by varying the rotation rates of the dual wedge prisms over time in relation to the depth scan rate of the sensor Optimally, a medium may be injected between the disposable and the skin to match the respective refractive indices and optimize the signal collection of the sensor

Multi-lens camera

Abstract: A camera with multiple lenses and multiple sensors wherein each lens/sensor pair generates a sub-image of a final photograph or video. Different embodiments include: manufacturing all lenses as a single component; manufacturing all sensors as one piece of silicon; different lenses incorporate filters for different wavelengths, including IR and UV; non-circular lenses; different lenses are different focal lengths; different lenses focus at different distances; selection of sharpest sub-image; blurring of selected sub-images; different lens/sensor pairs have different exposures; selection of optimum exposure sub-images; identification of distinct objects based on distance; stereo imaging in more than one axis; and dynamic optical center-line calibration.

A metamaterial waveguide lens

Abstract: A metamaterial waveguide structure is disclosed. In some approaches the metamaterial waveguide structure is compressed along an optical axis using transformation optics techniques. An example is a Rotman lens that is compressed by 27 percent along the optical axis while maintaining the beam steering range, gain and side lobe amplitudes over a broad frequency range. In some approaches the metamaterial waveguide structure includes a plurality of complementary metamaterial elements patterned on a conducting surface of the waveguide.

Design of Novel Compound Fresnel Lens for High-Performance Photovoltaic Concentrator

Abstract: We present a new design of compound Fresnel-R concentrator which is composed of two lenses: a primary lens (Fresnel lens) that works by total internal reflection at outer sawteeth but refraction at inner sawteeth, and a ringed secondary lens that works by refraction. In contrast to previous Fresnel lens concentrators, this design increases the acceptance angle, improves the irradiance uniformity on the solar cell, and reduces the aspect ratio significantly. Meanwhile several sawteeth of the primary Fresnel lens can correspond to a same ring of secondary lens, which will efficiently lower the complexity of designing and manufacturing. Moreover, in order to reduce the influence of manufacturing tolerances and to increase the optical efficiency further, the central part of the bottom of the secondary lens which directly adhered to the solar cell is designed as a cone-shaped prism to collect the sunlight that does not reach the solar cell. Finally, we provide simulations and analyses of the design method an optical efficiency more than 80% and an aspect ratio smaller than 0.5 can be achieved.

Spherical media and geodesic lenses in geometrical optics

Abstract: This paper presents a general approach to solving the problems of inverse scattering in three-dimensional isotropic media with a spherically symmetric refractive index distribution. It is based on equivalence of the central section of an inhomogeneous medium and corresponding geodesic lens, which is a non-Euclidean surface with constant refractive index. We use this approach for solving the Luneburg inverse problem and also for the derivation and design of absolute instruments that provide perfect imaging within the frame of geometrical optics. In addition, we solve the generalized Luneburg inverse problem, which leads to the discovery of a new class of magnifying lenses.

Vehicular camera system

Abstract: A vehicular camera system includes an imager assembly that can include an imager disposed on an imager circuit board and a lens positioned to direct light to the imager. A main circuit board is operatively connected to the imager circuit board. The main circuit board can include at least one processor for processing images captured by the imager. The main circuit board has an opening, and at least a portion of the imager assembly extends through the opening.

Lens stack arrays including adaptive optical elements

Abstract: Systems and methods in accordance with embodiments of the invention incorporate adaptive optical elements into optical channels in a lens stack array In one embodiment, an array camera module includes a lens stack array, that includes at least two lens stacks, where at least one lens stack includes an adaptive optical element that can adjust the characteristics of the transmission of light in the optical channel defined by the corresponding lens stack in response to at least one electrical signal, a sensor including a focal plane for each lens stack within the lens stack array, and circuitry configured to control at least one adaptive optical element, where the lens stack array and the sensor are configured so that each lens stack can form an image on a corresponding focal plane

Spectral transmission of the human crystalline lens in adult and elderly persons: color and total transmission of visible light.

Abstract: Purpose To experimentally measure the spectral transmission of human crystalline lenses belonging to adult and elderly persons, and to determine the color and total transmission of visible light of such crystalline lenses. Methods The spectral transmission curve of 32 human crystalline lenses was measured using a PerkinElmer 800UV/VIS spectrometer. Total transmission of visible light and the chromatic coordinates of these crystalline lenses were determined from these curves for solar illumination. Results The crystalline lens that filters UV and its transmission in the visible spectrum decreases with age; such a decrease is greater for short wavelengths. The total transmission of visible light decreases, especially after the age of 70 years, and the crystalline color becomes yellower and saturated. Conclusions The great variability existing in the spectral transmission of the human crystalline lens is lesser between the ages of 40 and 59 years, but greater from the age of 60 and older. The decrement in transmittance between these two age groups varies from 40% for 420 nm to 18% for 580 nm. Nevertheless, it is proven that age is not the only parameter affecting crystalline transmission. In the range of 40 to 59 years, age does not bear an influence on total transmission of light, but from 60 years and older it does. Moreover, the light transmitted decreases with age. This total transmission of light is similar to or lower than the amount that the different intraocular lenses transmit, even with a yellow or orange filter. The color of the human lens becomes yellowish and saturated with age.