Showing papers on "Lens (optics) published in 2010"
TL;DR: It is experimentally demonstrated that the incorporation of gain material in the high-local-field areas of a metamaterial makes it possible to fabricate an extremely low-loss and active optical NIM.
Abstract: Much research activity is being devoted to the design and fabrication of metamaterials, artificially tailored composites with the counter-intuitive optical property of a negative refraction index. There is an exciting and wide range of possible applications that could be developed with such negative-index materials, including invisibility cloaks and 'perfect' lenses, but a major hurdle is that the performance is severely limited by absorption losses. Vladimir Shalaev and colleagues now demonstrate an approach that could lead to a breakthrough in this area; they have incorporated an optical gain medium within the metamaterial as a way to compensate the intrinsic loss, and show that optical pumping leads to a significantly improved negative refraction index and performance-related figure-of-merit at visible wavelengths. The study confirms that it is possible to design an optical metamaterial that is not limited by the intrinsic loss of its metal constituent. Metamaterials have the counterintuitive optical property of negative refraction index. They have a wide range of possible applications, including 'invisibility cloaks' and perfect lenses, but their performance is severely limited by absorption losses. These authors have incorporated an optical gain medium within a metamaterial as a way to compensate the intrinsic loss, and show that optical pumping leads to a significantly improved negative refraction index and figure of merit within the 722–738-nm visible wavelength range. The recently emerged fields of metamaterials and transformation optics promise a family of exciting applications such as invisibility, optical imaging with deeply subwavelength resolution and nanophotonics with the potential for much faster information processing. The possibility of creating optical negative-index metamaterials (NIMs) using nanostructured metal–dielectric composites has triggered intense basic and applied research over the past several years1,2,3,4,5,6,7,8,9,10. However, the performance of all NIM applications is significantly limited by the inherent and strong energy dissipation in metals, especially in the near-infrared and visible wavelength ranges11,12. Generally the losses are orders of magnitude too large for the proposed applications, and the reduction of losses with optimized designs seems to be out of reach. One way of addressing this issue is to incorporate gain media into NIM designs13,14,15,16. However, whether NIMs with low loss can be achieved has been the subject of theoretical debate17,18. Here we experimentally demonstrate that the incorporation of gain material in the high-local-field areas of a metamaterial makes it possible to fabricate an extremely low-loss and active optical NIM. The original loss-limited negative refractive index and the figure of merit (FOM) of the device have been drastically improved with loss compensation in the visible wavelength range between 722 and 738 nm. In this range, the NIM becomes active such that the sum of the light intensities in transmission and reflection exceeds the intensity of the incident beam. At a wavelength of 737 nm, the negative refractive index improves from −0.66 to −1.017 and the FOM increases from 1 to 26. At 738 nm, the FOM is expected to become macroscopically large, of the order of 106. This study demonstrates the possibility of fabricating an optical negative-index metamaterial that is not limited by the inherent loss in its metal constituent.
745 citations
TL;DR: In this article, the authors used spatial wavefront shaping to improve the focusing resolution of a lens by using wave front shaping to compensate for scattering in an inhomogeneous medium between the lens and the focal plane.
Abstract: Optical microscopy and manipulation methods rely on the ability to focus light to a small volume. However, in inhomogeneous media such as biological tissue, light is scattered out of the focusing beam. Disordered scattering is thought to fundamentally limit the resolution and penetration depth of optical methods1,2,3. Here we demonstrate, in an optical experiment, that scattering can be used to improve, rather than deteriorate, the sharpness of the focus. The resulting focus is even sharper than that in a transparent medium. By using scattering in the medium behind a lens, light was focused to a spot ten times smaller than the diffraction limit of that lens. Our method is the optical equivalent of highly successful methods for improving the resolution and communication bandwidth of ultrasound, radio waves and microwaves4,5,6. Our results, obtained using spatial wavefront shaping, apply to all coherent methods for focusing through scattering matter, including phase conjugation7 and time-reversal4. Light is scattered out of a focusing beam when an inhomogeneous medium is placed between the lens and the focal plane. Now, scientists experimentally demonstrate that scattering can be exploited to improve, rather than deteriorate, the focusing resolution of a lens by using wavefront shaping to compensate for scattering.
716 citations
TL;DR: The low cost and very-high spatial resolution associated with the camera-UAV system may provide important information for site-specific agriculture.
Abstract: Payload size and weight are critical factors for small Unmanned Aerial Vehicles (UAVs). Digital color-infrared photographs were acquired from a single 12-megapixel camera that did not have an internal hot-mirror filter and had a red-light-blocking filter in front of the lens, resulting in near-infrared (NIR), green and blue images. We tested the UAV-camera system over two variably-fertilized fields of winter wheat and found a good correlation between leaf area index and the green normalized difference vegetation index (GNDVI). The low cost and very-high spatial resolution associated with the camera-UAV system may provide important information for site-specific agriculture.
419 citations
TL;DR: The design, realization and measurement of a three-dimensional approximate transformation-optics lens in the microwave frequency band is shown, made of non-resonant metamaterials, which are fabricated with multilayered dielectric plates by drilling inhomogeneous holes.
Abstract: Lenses with superior performance with respect to conventional uniform materials are desirable. The authors show a three-dimensional lens, made of multilayered metamaterials and based on approximate transformation optics, which works in different polarizations at broad viewing angles and with wide bandwidth.
417 citations
TL;DR: In this article, a Bayesian analysis of the strong gravitational lens system B1608+656 is presented, incorporating new, deep Hubble Space Telescope (HST) observations, a new velocity-dispersion measurement of 260 ± 15 km s-1 for the primary lens galaxy, and an updated study of the lens' environment.
Abstract: Strong gravitational lens systems with measured time delays between the multiple images provide a method for measuring the "time-delay distance" to the lens, and thus the Hubble constant. We present a Bayesian analysis of the strong gravitational lens system B1608+656, incorporating (1) new, deep Hubble Space Telescope (HST) observations, (2) a new velocity-dispersion measurement of 260 ± 15 km s-1 for the primary lens galaxy, and (3) an updated study of the lens' environment. Our analysis of the HST images takes into account the extended source surface brightness, and the dust extinction and optical emission by the interacting lens galaxies. When modeling the stellar dynamics of the primary lens galaxy, the lensing effect, and the environment of the lens, we explicitly include the total mass distribution profile logarithmic slope γ' and the external convergence κext we marginalize over these parameters, assigning well-motivated priors for them, and so turn the major systematic errors into statistical ones. The HST images provide one such prior, constraining the lens mass density profile logarithmic slope to be γ' = 2.08 ± 0.03; a combination of numerical simulations and photometric observations of the B1608+656 field provides an estimate of the prior for κext: 0.10+0.08 -0.05. This latter distribution dominates the final uncertainty on H 0. Fixing the cosmological parameters at Ωm = 0.3, ΩΛ = 0.7, and w = -1 in order to compare with previous work on this system, we find H 0 = 70.6+3.1 -3.1 km s-1 Mpc-1. The new data provide an increase in precision of more than a factor of 2, even including the marginalization over κext. Relaxing the prior probability density function for the cosmological parameters to that derived from the Wilkinson Microwave Anisotropy Probe (WMAP) five-year data set, we find that the B1608+656 data set breaks the degeneracy between Ωm and ΩΛ at w = -1 and constrains the curvature parameter to be -0.031 <Ωk <0.009 (95% CL), a level of precision comparable to that afforded by the current Type Ia SNe sample. Asserting a flat spatial geometry, we find that, in combination with WMAP, H 0 = 69.7+4.9 -5.0 km s-1 Mpc-1 and w = -0.94+0.17 -0.19 (68% CL), suggesting that the observations of B1608+656 constrain w as tightly as the current Baryon Acoustic Oscillation data do. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program No. GO-10158.
416 citations
TL;DR: In this paper, the authors combine modern silicon microtechnology with advanced deposition methods to fabricate nanocrystalline-diamond lenses for third and fourth-generation synchrotron sources.
Abstract: Diamond has unique properties which make it the ideal material for use in synchrotron instrumentation. X-ray optics made of diamond are almost transparent, they possess strength, and are subject to very low thermal expansion; therefore they will be able to withstand the powerful beams generated by fourth-generation light sources without compromising brilliance. For this reason, several groups are attempting fabrication of refractive lenses and zone plates made of diamond. Lithography and, in general, microfabrication technology, are the ultimate tools for the innovation of synchrotron focusing optics. We propose to combine modern silicon microtechnology with advanced deposition methods to fabricate nanocrystalline-diamond lenses for third- and fourth-generation synchrotron sources. The fabrication method is described here and microfocusing synchrotron tests are illustrated.
400 citations
Patent•
11 Aug 2010
TL;DR: In this article, an optical reading device is described having an image sensor having a sensor array of pixels which are exposed to an image; a printed circuit board (PCB) for carrying the image sensor; a lens assembly for focusing light on the sensor array; a support assembly integral with the lens retainer, the support assembly having a containment section for containing the image sensors; and a thermally and electrically conductive elastomeric gasket disposed between the containment section and the sensor.
Abstract: An optical reading device is described having an image sensor having a sensor array of pixels which are exposed to an image; a printed circuit board (PCB) for carrying the image sensor; a lens assembly for focusing light on the sensor array; a lens retainer for retaining the lens; a support assembly integral with the lens retainer, the support assembly having a containment section for containing the image sensor; and a thermally and electrically conductive elastomeric gasket disposed between the containment section and the image sensor and for contacting the image sensor.
344 citations
Patent•
19 Oct 2010
TL;DR: An optical imager includes an image sensor for capturing images of targets and outputting image signals; a lens for focusing the target on the image sensor as a function of lens position; a memory for storing predetermined lens positions determined from predetermined target sizes; and a controller for determining current target size based on captured images and positioning the lens at a predetermined lens position by correlating current target sizes with predetermined target size as mentioned in this paper.
Abstract: An optical imager includes: an image sensor for capturing images of targets and outputting image signals; a lens for focusing the target on the image sensor as a function of lens position; a memory for storing predetermined lens positions determined from predetermined target sizes; and a controller for determining current target size based on captured images and positioning the lens at a predetermined lens position by correlating current target size with predetermined target sizes.
321 citations
TL;DR: By designing the reflectance and the phase of non-periodic HCGs, both focusing reflectors and lenses can be constructed and HCG optics can simultaneously focus the reflected and transmitted waves, with important technological implications.
Abstract: We propose planar, high numerical aperture (NA), low loss, focusing reflectors and lenses using subwavelength high contrast gratings (HCGs). By designing the reflectance and the phase of non-periodic HCGs, both focusing reflectors and lenses can be constructed. Numerical aperture values as high as 0.81 and 0.96 are achieved for a reflector and lens with very low losses of 0.3 and 0.2 dB, respectively. The design algorithm is also shown to be readily extended to a 2D lens. Furthermore, HCG optics can simultaneously focus the reflected and transmitted waves, with important technological implications. HCG focusing optics are defined by one-step photolithography and thus can be readily integrated with many devices including VCSELs, saturable absorbers, telescopes, CCDs and solar cells.
257 citations
26 Jul 2010
TL;DR: This work presents a novel rendering system for defocus blur and lens effects and introduces an intuitive control over depth-of-field effects, which achieves more precision than competing real-time solutions and is mostly indistinguishable from offline rendering.
Abstract: We present a novel rendering system for defocus blur and lens effects. It supports physically-based rendering and outperforms previous approaches by involving a novel GPU-based tracing method. Our solution achieves more precision than competing real-time solutions and our results are mostly indistinguishable from offline rendering. Our method is also more general and can integrate advanced simulations, such as simple geometric lens models enabling various lens aberration effects. These latter is crucial for realism, but are often employed in artistic contexts, too. We show that available artistic lenses can be simulated by our method. In this spirit, our work introduces an intuitive control over depth-of-field effects. The physical basis is crucial as a starting point to enable new artistic renderings based on a generalized focal surface to emphasize particular elements in the scene while retaining a realistic look. Our real-time solution provides realistic, as well as plausible expressive results.
256 citations
TL;DR: A qualitatively new way of generating high-energy acoustic pulses, which may improve imaging capabilities through increased accuracy and signal-to-noise ratios and may lead to more effective nonintrusive scalpels, for example, for cancer treatment.
Abstract: Acoustic lenses are employed in a variety of applications, from biomedical imaging and surgery to defense systems and damage detection in materials. Focused acoustic signals, for example, enable ultrasonic transducers to image the interior of the human body. Currently however the performance of acoustic devices is limited by their linear operational envelope, which implies relatively inaccurate focusing and low focal power. Here we show a dramatic focusing effect and the generation of compact acoustic pulses (sound bullets) in solid and fluid media, with energies orders of magnitude greater than previously achievable. This focusing is made possible by a tunable, nonlinear acoustic lens, which consists of ordered arrays of granular chains. The amplitude, size, and location of the sound bullets can be controlled by varying the static precompression of the chains. Theory and numerical simulations demonstrate the focusing effect, and photoelasticity experiments corroborate it. Our nonlinear lens permits a qualitatively new way of generating high-energy acoustic pulses, which may improve imaging capabilities through increased accuracy and signal-to-noise ratios and may lead to more effective nonintrusive scalpels, for example, for cancer treatment.
TL;DR: A microoptical approach to ultra-compact optics for real-time vision systems that are inspired by the compound eyes of insects that achieves approx.
Abstract: We propose a microoptical approach to ultra-compact optics for real-time vision systems that are inspired by the compound eyes of insects. The demonstrated module achieves approx. VGA resolution with a total track length of 1.4 mm which is about two times shorter than comparable single-aperture optics on images sensors of the same pixel pitch. The partial images that are separately recorded in different optical channels are stitched together to form a final image of the whole field of view by means of image processing. A software correction is applied to each partial image so that the final image is made free of distortion. The microlens arrays are realized by state of the art microoptical fabrication techniques on wafer-level which are suitable for a potential application in high volume e.g. for consumer electronic products.
TL;DR: In this paper, a new concept of dielectric subwavelength grating leveraging high index contrast to manipulate light to achieve ultra broad band reflector, high-Q resonator, planar high numerical aperture lens and reflector was discussed.
Abstract: We discuss a new concept of dielectric subwavelength grating leveraging high index contrast to manipulate light to achieve ultra broad band reflector, high-Q resonator, planar high numerical aperture lens and reflector, and hollow-core integrated optics.
TL;DR: In this paper, the design of a 2D broadband Luneburg lens antenna implemented using printed circuit board techniques is detailed, and the measured half power beamwidth of the experimental antenna is 4.34°.
Abstract: The design of a 2D broadband, Luneburg lens antenna implemented using printed circuit board techniques is detailed. The refractive index of the lens is controlled through a combination of meandering crossed microstrip lines and varying their widths. The 12.4λ° diameter lens is designed to operate in the transverse electromagnetic (TEM) mode at 13 GHz. The lens antenna was designed, fabricated, and measured. The measured half power beamwidth of the experimental antenna is 4.34°.
TL;DR: In this paper, a planar waveguide is coupled with localized features placed at each lens focus to yield a thin, flat profile for moderate solar concentration systems which may be fabricated by low-cost roll manufacture.
Abstract: We present a new approach to solar concentration where sunlight collected by each lens in a two-dimensional lens array is coupled into a shared, planar waveguide using localized features placed at each lens focus. This geometry yields a thin, flat profile for moderate concentration systems which may be fabricated by low-cost roll manufacture. We provide analyses of tradeoffs and show optimized designs can achieve 90% and 82% optical efficiency at 73x and 300x concentration, respectively. Finally, we present preliminary experimental results of a concentrator using self-aligned reflective coupling features fabricated by exposing molded SU-8 features through the lens array.
TL;DR: A feedback modification method based on variable separation mapping is proposed in the design of free-form optical system with uniform illuminance for LED source, and a smooth optical system is established with single freeform surface regenerated by adding feedback to the lens design for a point light source.
Abstract: A feedback modification method based on variable separation mapping is proposed in the design of free-form optical system with uniform illuminance for LED source. In this method, the non-negligible size of LED source is taken into account, and a smooth optical system is established with single freeform surface regenerated by adding feedback to the lens design for a point light source. More rounds of feedback can improve the lens performance. As an example, a smooth free-form lens with rectangular illuminance distribution is designed, and the illuminance uniformity is improved from 18.75% to 81.08% after eight times feedback.
TL;DR: A systematic perspective on the development of micro-optofluidic lenses and categorizes them according to the concept of tunability, which shows their tunability over solid lens systems without the use of large actuators.
Abstract: This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field.
Patent•
20 Aug 2010TL;DR: In this paper, an optical waveguide having a first end, a second end opposing the first end and a viewing surface extending at least partially between the first and the second end, and a back surface opposing the viewing surface is disclosed.
Abstract: Embodiments of optical collimators are disclosed. For example, one disclosed embodiment comprises an optical waveguide having a first end, a second end opposing the first end, a viewing surface extending at least partially between the first end and the second end, and a back surface opposing the viewing surface. The viewing surface comprises a first critical angle of internal reflection, and the back surface is configured to be reflective at the first critical angle of internal reflection. Further, a collimating end reflector comprising a faceted lens structure having a plurality of facets is disposed at the second end of the optical waveguide.
Patent•
12 Aug 2010
TL;DR: In this paper, a camera-shake correction device (10) is proposed to correct camera shake by moving the entire auto-focusing lens drive device (20) in a first direction (X) and a second direction (Y) which are perpendicular to the optical axis (O) and are parallel to each other.
Abstract: A small size, low profile camera-shake correction device. A camera-shake correction device (10) corrects camera shake by moving the entire auto-focusing lens drive device (20) in a first direction (X) and a second direction (Y) which are perpendicular to the optical axis (O) and are perpendicular to each other, the auto-focusing lens drive device (20) being provided with a focusing coil (26) and a permanent magnet (28) which is disposed on the outside of the focusing coil. The camera-shake correction device (10) includes: a base (14) disposed so as to be spaced from the bottom surface of the auto-focusing lens drive device (20); suspension wires (16) which each have one end affixed to the outer peripheral section of the base, which extend along the optical axis (O), and which support the entire auto-focusing lens drive device (20) in such a manner that the auto-focusing lens drive device (20) is rockable in the first direction (X) and the second direction (Y); and a camera-shake correcting coil (18) disposed so as to face the permanent magnet (28).
Patent•
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19 Mar 2010
TL;DR: In this paper, a dual sensor camera that uses two aligned sensors each having a separate lens of different focal length but the same f-number is used to combine the wide FOV image from one sensor and the narrow FOV images from the other sensor to form a combined image.
Abstract: A dual sensor camera that uses two aligned sensors each having a separate lens of different focal length but the same f-number. The wider FOV image from one sensor is combined with the narrower FOV image from the other sensor to form a combined image. Up-sampling of the wide FOV image and down-sampling of the narrow FOV image is performed. The longer focal length lens may have certain aberrations introduced so that Extended Depth of Field (EDoF) processing can be used to give the narrow FOV image approximately the same depth of field as the wide FOV image so that a noticeable difference in depth of field is not see in the combined image.
TL;DR: This letter experimentally investigated the plasmonic focusing properties of the spiral lens using a collection mode near-field scanning optical microscope using a single Archimedes' spiral slot with a single turn.
Abstract: A spiral plasmonic lens can focus circular polarization of a given handedness while simultaneously defocus the circular polarization of the opposite chirality, which may be used as a miniature circular polarization analyzer. In this letter, we experimentally investigated the plasmonic focusing properties of the spiral lens using a collection mode near-field scanning optical microscope. A single Archimedes' spiral slot with a single turn was etched through gold thin film as a spiral plasmonic lens. The plasmonic field at the focus of a spiral lens strongly depends on the spin of the incident photon. Circular polarization extinction ratio better than 50 is obtainable with a device size as small as only 4 times of surface plasmon wavelength.
01 Oct 2010
TL;DR: In this article, a massive PTFE lens body was used for 25 GHz industrial radar measurements in industrial tanks, achieving a measured aperture efficiency of 104% at a diameter of 74 mm.
Abstract: A dielectric lens antenna for 25 GHz industrial radar measurements in industrial tanks is presented. Due to the limited diameter, the aperture efficiency is an important benchmark for these applications. The presented approach uses a massive PTFE lens body, which results in a measured aperture efficiency of 104% at a diameter of 74 mm. This corresponds to a gain of 25.9 dBi. The main lobe has a tight 3 dB angular width of 8.4°/ 8.6° with a side lobe level of −17.0 dB /−17.6 dB.
Patent•
03 Mar 2010
TL;DR: In this paper, a millimeter-wave quasi-optical integrated dielectric lens antenna and an array thereof was designed for radar applications, where the antenna array is arranged into a linear array or an area array.
Abstract: The invention relates to the technical field of radar, in particular to a millimeter-wave quasi-optical integrated dielectric lens antenna and an array thereof. The array consists of a microstrip integrated antenna, a dielectric lens, an objective lens, an array base, a reflecting mirror, a protective cover and a beam transfer switch; one end face of the dielectric lens is a hemisphere or an ellipsoid, while the other end face is a cylindrical section; the microstrip integrated antenna is generated by an dielectric substrate, the front surface of the dielectric substrate is closely adhered tothe cylindrical section of the dielectric lens and serves as a feed source, and the back surface is grounded; the hemispherical or ellipsoidal end face of the dielectric lens is an antenna radiating surface; the length of the cylindrical part of the dielectric lens can be changed; the antenna array is arranged into a linear array or an area array; the array base and the reflecting mirror have conical quasi-optical reflecting mirror surfaces; the focus of the objective lens of the linear array or the area array aligns with the central line of the dielectric lens; the protective cover is arranged outside; and the antenna array is controlled by the beam transfer switch. The antenna structure has strong shock resistance and dust prevention, and is suitable for millimeter-wave radars for planes, automobiles and ships, and receiving/emitting sensing of communication equipment.
TL;DR: In this article, a two-dimensional model combining the finite element method and the cellular automaton technique was developed to simulate dendritic growth occurring in the molten pool during the laser-engineered net shaping (LENS) process.
TL;DR: In this paper, the index-gradient is achieved in these type of flat lenses by a gradual modification of the sonic crystal filling fraction along the direction perpendicular to the lens axis, and the focusing performance is well described by an analytical model based on ray theory as well as by numerical simulations based on the multiple-scattering theory.
Abstract: Gradient index sonic lenses based on two-dimensional sonic crystals are here designed, fabricated, and characterized. The index-gradient is achieved in these type of flat lenses by a gradual modification of the sonic crystal filling fraction along the direction perpendicular to the lens axis. The focusing performance is well described by an analytical model based on ray theory as well as by numerical simulations based on the multiple-scattering theory.
Patent•
18 Oct 2010
TL;DR: In this paper, a zoom lens includes, in order from an object side to an image side, a first lens group having positive refractive power which is immovable for zooming, a second lens group for variable power having negative refractive powers, a third lens group of variable power, a fourth lens group with negative power, and a fifth group with positive power which corrects variation of an image plane associated with variable power.
Abstract: PROBLEM TO BE SOLVED: To obtain a zoom lens having a wide field angle, a high zoom ratio, and high optical performance over the entire zoom range SOLUTION: The zoom lens includes, in order from an object side to an image side, a first lens group having positive refractive power which is immovable for zooming, a second lens group for variable power having negative refractive power, a third lens group for variable power having negative refractive power, a fourth lens group having positive refractive power which corrects variation of an image plane associated with variable power, and a fifth lens group having positive refractive power which is immovable for zooming The second lens group moves to the image side during zooming from a wide angle end to a telephoto end, while the third lens group moves to draw a convex trajectory toward the object side A focal length fw of the entire system at the wide angle end, a zoom ratio Z, and a focal length fz of the entire system at a zoom position where the third lens group is located closest to the object side are each properly set COPYRIGHT: (C)2011,JPO&INPIT
TL;DR: A new design for an aberration-corrected low energy electron microscope (LEEM) and photo electron emission microscope (PEEM), equipped with an in-line electron energy filter, that makes use of two magnetic prism arrays to guide the electron beam from the sample to the electron mirror, removing chromatic dispersion in front of the mirror by symmetry.
Patent•
30 Jun 2010TL;DR: In this article, an antenna element suitable for integrated arrays at terahertz frequencies is disclosed, which comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g., silicon, antenna fed by a leaky wave waveguide feed.
Abstract: An antenna element suitable for integrated arrays at terahertz frequencies is disclosed. The antenna element comprises an extended spherical (e.g. hemispherical) semiconductor lens, e.g. silicon, antenna fed by a leaky wave waveguide feed. The extended spherical lens comprises a substantially spherical lens adjacent a substantially planar lens extension. A couple of TE/TM leaky wave modes are excited in a resonant cavity formed between a ground plane and the substantially planar lens extension by a waveguide block coupled to the ground plane. Due to these modes, the primary feed radiates inside the lens with a directive pattern that illuminates a small sector of the lens. The antenna structure is compatible with known semiconductor fabrication technology and enables production of large format imaging arrays.
TL;DR: A wirelessly-powered active contact lens comprised of a transparent polymer substrate, loop antenna, power harvesting IC, and micro-LED is presented, demonstrating wireless power transfer at 10 cm distance using the custom IC and on-lens antenna.
Abstract: We present progress toward a wirelessly-powered active contact lens comprised of a transparent polymer substrate, loop antenna, power harvesting IC, and micro-LED. The fully integrated radio power harvesting and power management system was fabricated in a 0.13 μm CMOS process with a total die area of 0.2 mm2. It utilizes a small on-chip capacitor for energy storage to light up a micro-LED pixel. We have demonstrated wireless power transfer at 10 cm distance using the custom IC and on-lens antenna.
TL;DR: In this paper, the optical properties of spectrally broadband metamaterial-based gradient index (GRIN) lenses have been studied for terahertz imaging systems with high spatial resolution.
Abstract: The development of innovative terahertz (THz) imaging systems has recently moved in the focus of scientific efforts due to the ability to screen substances through textiles or plastics. The invention of THz imaging systems with high spatial resolution is of increasing interest for applications in the realms of quality control, spectroscopy in dusty environment and security inspections. To realize compact THz imaging systems with high spatial resolution it is necessary to develop lenses of minimized thickness that still allow one to focus THz radiation to small spot diameters with low optical aberrations. In addition, it would be desirable if the lenses offered adaptive control of their optical properties to optimize the performance of the imaging systems in the context of different applications. Here we present the design, fabrication and the measurement of the optical properties of spectrally broadband metamaterial-based gradient index (GRIN) lenses that allow one to focus THz radiation to a spot diameter of approximately one wavelength. Due to the subwavelength thickness and the high focusing strength the presented GRIN lenses are an important step towards compact THz imaging systems with high spatial resolution. Furthermore, the results open the path to a new class of adaptive THz optics by extension of the concept to tunable metamaterials.