Lens Structures Research Articles

Near Field Imaging from Multilayer Lens

Multilayer superlens has been reported that it had advantages over the single metal layer superlens. In this work, single silver layer and Ag-SiO2 multilayer superlens devices working at wavelength of 365 nm were fabricated using standard photolithography method. Grating objects with line/space (190 nm/190 nm) resolution could be resolved through both kinds of lens structures with working distance up to 128 nm. However, Ag-SiO2 multilayer lens shows higher transmittance and image contrast than the single silver layer device, the experimental result proves the theoretical calculation.

Structural design of four-component optically compensated zoom lenses: Use of evolutionary programming

A new approach for ‘ab initio’ synthesis of thin lens structure of optically compensated zoom lenses is reported. This is accomplished by an implementation of evolutionary programming that explores the available configuration space formed by powers of individual components and inter-component separations to obtain globally or quasiglobally optimum solutions for the problem. Normalization of the variables is carried out to get an insight on the optimum structures. The method has been successfully used to get thin lens structures of optically compensated zoom lens systems by suitable formulation of merit function of optimization. Investigations have been carried out on four-component zoom lens structures. Illustrative numerical results are presented.

Phototransduction and clock gene expression in the troglobiont beetlePtomaphagus hirtusof Mammoth cave

Obligatory cave species exhibit dramatic trait modifications such as eye reduction, loss of pigmentation and an increase in touch receptors. As molecular studies of cave adaptation have largely concentrated on vertebrate models, it is not yet possible to probe for genetic universalities underlying cave adaptation. We have therefore begun to study the strongly cave-adapted small carrion beetle Ptomaphagus hirtus. For over 100 years, this flightless signature inhabitant of Mammoth Cave, the world's largest known cave system, has been considered blind despite the presence of residual lens structures. By deep sequencing of the adult head transcriptome, we discovered the transcripts of all core members of the phototransduction protein machinery. Combined with the absence of transcripts of select structural photoreceptor and eye pigmentation genes, these data suggest a reduced but functional visual system in P. hirtus. This conclusion was corroborated by a negative phototactic response of P. hirtus in light/dark choice tests. We further detected the expression of the complete circadian clock gene network in P. hirtus, raising the possibility of a role of light sensation in the regulation of oscillating processes. We speculate that P. hirtus is representative of a large number of animal species with highly reduced but persisting visual capacities in the twilight zone of the subterranean realm. These can now be studied on a broad comparative scale given the efficiency of transcript discovery by next-generation sequencing.

Nanoscale super-resolution imaging via a metal–dielectric metamaterial lens system

We have proposed a method for super-resolution imaging using an interlayer cascaded structure comprising two metamaterial lenses. The metamaterial lenses are designed using the effective medium theory. The lens structures consist of two different planar dielectric films alternated with similar thin metallic films, making a diverging and converging lens. With this two-lens system, an image is formed at the output surface of the lens with subwavelength resolution. We have shown, through numerical simulations and an analytical approach, that an image with resolution nine times smaller than the light wavelength (365 nm) is achievable with this metamaterial lens system. The loss during transmission through the lens system is smaller compared with the hyperlens configuration with a similar design.

Selective Inkjet Printing of Conductors for Displays and Flexible Printed Electronics

A mask-less and selective printing of conductor patterns is of significant importance for all display applications. Printing on structured surfaces such as microlenses or gratings is a challenge. Typically used processes require thermal curing to achieve the conductivity. This limits the applicability to flexible display applications where low temperature processes are preferred, especially for roll to roll (R2R) scale up. We have used an approach of printing a catalyst containing ink, followed by an electroless plating of copper. This paper details the processes, microstructures and properties of highly conductive and printed copper on patterned flat surfaces as well as structures with micro-optic lens structures. A process has been developed on surfaces with lens structures where the conductor is required to be in the valley between the lenses and between structures with narrow lines and narrow pitch. This is a low temperature process, requiring a plating bath temperature of <;45°C and thus very compatible with flexible substrates and R2R processing.

Ab initio synthesis of linearly compensated zoom lenses by evolutionary programming

An approach for ab initio synthesis of the thin lens structure of linearly compensated zoom lenses is reported. This method uses evolutionary programming that explores the available configuration space formed by powers of the individual components, the intercomponent separations, and the relative movement parameters of the moving components. Useful thin lens structures of optically and linearly compensated zoom lens systems are obtained by suitable formulation of the merit function of optimization. This paper reports our investigations on three-component zoom lens structures. Illustrative numerical results are presented.

A pressure core based characterization of hydrate-bearing sediments in the Ulleung Basin, Sea of Japan (East Sea)

[1] The physical characteristics of hydrate-bearing sediments sampled by pressure coring from the Ulleung Basin in the Sea of Japan (East Sea) were investigated using an instrumented chamber capable of testing recovered natural sediments that have never left the methane hydrate stability field. The heterogeneous distribution of segregated hydrate veins and lens structures in sediments results in highly variable geophysical and geomechanical properties. The scaled production test was conducted by controlled depressurization of pressure cores while dissociation and gas production were concurrently monitored using various sensors in the instrumented chamber. The hydrate saturation was estimated to be ∼19.5% in the pore space. Data show a sharp reduction in sediment shear and bulk stiffnesses during hydrate dissociation. Relatively fast gas migration was observed, probably along high-conduction planes left behind as hydrate veins dissociated. The spatial distribution of hydrates in sediment was analyzed based on 3-D image processing. The phenomena relevant to the production test and sampling effects during pressure coring are discussed.

Diamond turning and soft lithography processes for liquid tunable lenses

Making use of the capability of high precision diamond turning in producing 3-dimensional free form optical surfaces with excellent surface finish, molds for various types of liquid tunable microlenses are fabricated. Subsequently, a rapid prototyping process known as soft lithography is applied to the fabricated mold to replicate multiple lens structures. This method provides an efficient and reliable way of generating rotationally symmetric free form optical surfaces that are otherwise difficult to produce with conventional methods such as lithography and etching methods. Using atomic force microscopy, white light interferometry and a mechanical profiler, it is verified that the surface quality and dimensional accuracy of the replicas are preserved. We demonstrate the practical usefulness of the proposed fabrication methods by developing and experimentally testing three different liquid tunable lenses, namely (1) a diffractive/refractive hybrid lens that reduces chromatic aberration within the visible spectrum, (2) a double focusing lens and (3) an aspherical lens that minimizes spherical aberration.

Metrology of multilayer Laue lens structures by means of scanning electron microscope imaging

Scanning electron microscope images obtained on a cross-section of a sputtered multilayer structure have proven to be crucial for qualifying these films for their intended use as a multilayer Laue lens. The quality of the linear Fresnel zone structure is assessed by means of image processing and analyses, and these analyses are then used to qualify the structure for further lens processing. The image analysis as well as problematic SEM artifacts are discussed.

Three-Dimensional Wave Optical Simulation for Image Sensors by Localized Boundary Element Method

A novel wave optical simulation method [a localized boundary element method (BEM)] has been developed. This method enables us to execute 3-D wave optical simulation with much smaller memory space and much shorter calculation time than conventional BEMs or finite-difference time domain methods. The light gathering power dependence on cell size and microlens height and distance, the color shading characteristics of inner lens structures, and the light gathering power and cross talk of light waveguide were analyzed by this method. A smaller cell needs a shorter focal length microlens, which can be realized by inner lens structures in CCD or the waveguide structures in CMOS image sensors. It is shown that this method can optimize these structures by calculating the color shading dependence on the microlens shape and the cross talk dependence on the waveguide materials. This method was found to be powerful and useful for the 3-D wave optical analysis of image sensors.

Microcapillary Electrophoresis Chip Device Integrated with Micro Focusing Lens Structures and Its Biomedical Applications

In this paper, we present a micro-electro-mechanical-system based on a microcapillary electrophoresis chip device integrated with optical detection components, including a micro-focusing lens structure and buried optic fibers. This is a promising approach to enhance the optical signal of the laser-induced fluorescence system for biomedical detection applications. This study utilized microcapillary electrophoresis (micro-CE) chips with two specific polymer materials, polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS). Both are capable of performing multiple-wavelength fluorescence detection by using integrated optic components. These include multimode optic fiber pairs and a micro-focusing-lens structure, embedded downstream of the separation channel. For detection purposes, the fluorescence signals are enhanced by positioning micro-focusing-lens structures at the outlets of the excitation fibers and the inlets of the detection fibers. In this study, two types of micro-focusing-lens are proposed—fixed-focal-length and controllable micro-lenses. They are made from different materials—PMMA and PDMS, respectively. With regard to the fixed-focal-length micro-lenses, the profile of the micro-lens curve can be formed by the defined master mold with specific temperatures and pressures. With regard to the controllable micro-lens design, deformations of the two flexible surfaces can be generated after pressurized index-matching fluid is injected into the pneumatic side-chambers. The side-chambers can be deflected as a double convex lens to focus both the excitation light source and the fluorescent emission signal. Experimental results revealed that the power amplitude of the excitation laser light can be enhanced by up to 5.4 fold. Fluorescein isothiocyanate, dye labeled protein samples and DNA markers are then utilized for micro-CE chip testing. The results indicated that signal amplitude can be enhanced from 1.7 to 2.6 fold when compared with cases without the micro-lens. According to the experimental results, the developed device has a great potential to be integrated with other microfluidic devices for further biomedical applications.

Very Broadband Extended Hemispherical Lenses: Role of Matching Layers for Bandwidth Enlargement

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The design and optimization of very broadband integrated lens antennas (ILAs) constitutes one of the future trends in lens antenna field. To this end we investigate numerically the radiation performance of millimeter wave ILAs coated with multiple anti reflection layers. We propose lens structures of moderate size (four wavelengths in diameter at the center frequency) and made from a dense dielectric material (ceramic). They are illuminated by two kinds of on-axis primary sources, namely a dielectric-loaded metallic waveguide and a patch antenna. This enables to assess the role of the lens illumination law on the performance of broadband ILAs. In particular, we demonstrate that ILAs coated with three stacked quarter wavelength matching layers exhibit a very broadband promising features. First their radiation characteristics remain very stable over a large frequency band: a 36% relative bandwidth is achieved using dielectric-loaded waveguide feeds. Secondly very high values of aperture efficiencies (beyond 91% over a 21% bandwidth) are obtained using printed feeds. The truncation effects of the ground plane and substrate of planar feeds upon the beam characteristics are also studied. We conclude that they must be taken into account at the very first stages of the design process of ILAs. </para>

25.1 Invited Paper: High Resolution Autostereoscopic 3D Display with Scanning Multi‐Electrode Driving Liquid Crystal (MeD‐LC) Lens

AbstractAn autostereoscopic display with full resolution of2D and 3D images with wide viewing angle potential was proposed by combining an “active scanning film” and fast response OLED. In order to realize the active scanning film to project the images to different directions sequentially, Multi‐Electrode Driving Liquid Crystal (MeD‐LC) Lens was utilized. Comparing with traditional LC lens structures, MeD‐LC lens could not only be switched on/off, but also horizontally moved to “scan” and project images. Additionally, MeD‐LC lens was more competitive in respect of structure simplicity and various curvature generations.

Planar Lenses Based on Nanoscale Slit Arrays in a Metallic Film

We experimentally demonstrate planar lenses based on nanoscale slit arrays in a metallic film. Our lens structures consist of optically thick gold films with micron-size arrays of closely spaced, nanoscale slits of varying widths milled using a focused ion beam. We find excellent agreement between electromagnetic simulations of the design and confocal measurements on manufactured structures. We provide guidelines for lens design and show how actual lens behavior deviates from simple theory.

Alignment-tolerant lens structures for acoustic force actuation of cantilevers

In accordance with one aspect of the present invention, a cantilever of a probe-based instrument is deflected by directing a beam of ultrasonic acoustic energy at the cantilever to apply acoustic radiation pressure to the cantilever. The energy is generated by an acoustic actuator. The transmitted beam preferably is focused using a cylindrical lens, providing a beam tightly focused in one dimension and unfocused in a second dimension. In accordance with another aspect of the present invention, a power source such as an RF signal generator is operated so as to spread the spectrum of acoustic radiation on a time scale that is short or comparable to the acoustic roundtrip time. Such a design diminishing the resonance effects and sensitivity to spacing between the cantilever and the acoustic source.

Pigment dispersion syndrome and pigmentary glaucoma – a major review

Pigment dispersion syndrome (PDS) is an interesting condition that can lead to secondary open angle glaucoma. Pigmentary glaucoma is primarily a disease of young people, myopes and men. PDS is characterized by the presence of Krukenberg spindles, iris trans-illumination defects, trabecular meshwork pigmentation and backward bowing of the iris. Posterior bowing of the iris causes rubbing of the pigmented iris epithelium against lens structures, liberation of pigment and trabecular meshwork changes that result in reduced aqueous outflow with the risk of glaucoma. Peripheral laser iridotomy can reverse backward bowing of the iris and may prevent progression of pigmentary glaucoma.

Stereotactic Radiotherapy for Unilateral Orbital Lymphoma and Orbital Pseudo-Tumors: A Planning Study

Orbital lymphoma and Grave's ophthalmopathy (GO) are successfully treated with radiation therapy. The lenses are blocked to prevent cataract formation. However, blocking of the lens by traditional methods can be difficult for tumors located anteriorly and extending into the retrobulbar space. We present a series of 3 patients with orbital lymphoma and 1 with GO treated with stereotactic intensity modulated radiation therapy (IMRT) to spare normal structures, including the lens. Three patients with orbital lymphomas and 1 with unilateral GO were treated with IMRT using a linac with stereotactic capabilities. Avoidance structures included the ipsilateral lens and globe, the contralateral lens and globe, the chiasm, and the brainstem. Two patients with orbital lymphoma were treated with 24 Gy in 12 fractions, and 1 patient was treated with 30.6 Gy in 17 fractions. The patient with GO was treated with 20 Gy in 10 fractions. The dosimetry was analyzed to determine the dose to normal tissues. Patient follow-up varies between 8 and 24 months. The mean minimal dose to the ipsilateral lens was 13.6% of the total dose, the mean maximal dose was 33.5%, and the mean median dose was 19.3%. The mean median dose to the contralateral eye was 1.1% of the total dose. The mean median dose to the chiasm was 14.9% of the total dose. The mean median dose to the brainstem was 1.9% of the total dose. No cataracts or other complications were noted in the 4 patients treated with this technique so far. IMRT gives a more conformal treatment to the orbital contents while sparing normal tissues such as the ipsilateral lens and adjacent critical structures. This should result in fewer complications such as cataracts.

局所境界要素法によるイメージセンサの３次元波動光学シミュレーション

A novel wave optical simulation method (a localized boundary element method) has been developed. This method enables us to execute 3-D wave optical simulation with much smaller memory space and much shorter calculation time than conventional boundary element methods or FDTD (Finite Difference Time Domain) methods. The color shading characteristics of inner lens structures in CCD image sensors and the light-gathering power and crosstalk of light waveguide structures in CMOS image sensors can be analyzed by this method. This method was found to be powerful and useful for wave optical analysis of image sensors.

In Vivo Laser Confocal Microscopic Analysis of Murine Cornea and Lens Microstructures

The purpose of the current study is to investigate in vivo microstructures of anterior segments of normal murine eyes by new-generation in vivo laser confocal microscopy. Twenty-six corneas and lenses from 13 mice were analyzed by in vivo laser confocal microscopy. Murine corneal superficial cells formed a polygonal cell pattern, with a mean cell density of 577 +/- 115 cells/mm2 (mean +/- standard deviation). Corneal basal epithelial cells had dark cytoplasm and were closely organized (9,312 +/- 1,777 cells/mm2). Sub-basal nerve fiber bundles were arranged in a whorl pattern, with both clockwise and counter-clockwise patterns. In the stroma, keratocytes were observed as numerous reflective stellate structures. The endothelial cells were organized in a honeycomb pattern (2,463 +/- 292 cells/mm2). Deeper inside the eye, murine lens epithelial cells were organized in a regular pattern (4,168 +/- 636 cells/mm2) and numerous lens fibers were observed. In vivo laser confocal microscopy can provide high-resolution images of all corneal layers and lens structures of mice without sacrificing animals or tissue preparation.

Integration of a UV curable polymer lens and MUMPs structures on a SOI optical bench

This work presents the design concept of integrating a polymer lens, poly-Si MUMPs and single-crystal-silicon HARM structures on a SOI wafer to form a silicon optical bench. This approach enables the monolithic integration of various optical components on the wafer so as to improve the design flexibility of the silicon optical bench. Fabrication processes, including surface and bulk micromachining on the SOI wafer, have been established to realize bi-convex spherical polymer lenses with in-plane as well as out-of-plane optical axes. In addition, a micro device consisting of an in-plane polymer lens, a thick fiber holder and a mechanical shutter driven by an electrothermal actuator is also demonstrated using the present approach. In summary, this study significantly improves the design flexibility as well as the functions of SiOBs.