Showing papers on "Lens (optics) published in 2002"

Improved light out-coupling in organic light emitting diodes employing ordered microlens arrays

Abstract: We demonstrate that ordered microlens arrays with 10 μm diam poly-dimethyl-siloxane lenses attached to glass substrates increase the light output of organic light emitting devices (OLED) by a factor of 1.5 over unlensed substrates. The lenses, which are considerably smaller than, and not aligned to the OLEDs, outcouple light that is emitted outside of the escape cone of the substrate. We show that an electrophosphorescent device based on a fac tris(2-phenylpyridine)Iridium (Ir(ppy)3) doped emitting layer has its external quantum efficiency increased from 9.5% using a flat glass substrate, to 14.5% at low current densities using a substrate with microlenses. No change in the emission spectrum is observed for different viewing angles using the lens arrays.

High-resolution optical coherence tomography over a large depth range with an axicon lens.

Abstract: In optical coherence tomography, axial and lateral resolutions are determined by the source coherence length and the numerical aperture of the sampling lens, respectively. Whereas axial resolution can be improved by use of a broadband light source, there is a trade-off between lateral resolution and focusing depth when conventional optical elements are used. We report on the incorporation of an axicon lens into the sample arm of an interferometer to overcome this limitation. Using an axicon lens with a top angle of 160 degrees , we maintained 10-microm or better lateral resolution over a focusing depth of at least 6 mm. In addition to having high lateral resolution, the focusing spot has an intensity that is approximately constant over a greater depth range than when a conventional lens is used.

Optical device for bar-code reading, method for manufacturing an optical device, and light projection/receiving package

Abstract: An optical device for bar-code reading capable of improving the degree of freedom in design of component lenses so as to allow free positional adjustment of the lenses while ensuring downsizing and weight reduction of the device, and a method for manufacturing are disclosed. An optical device for bar-code reading comprises a light emitting element; a light projection lens for focusing light from the light emitting element so as to irradiate a bar code; a light receiving lens for focusing reflected light from the bar code and having formed therein a penetrating hole which penetrates a plane of incidence of light and a plane of outgoing of light, in which the light projection lens is inserted; and a light receiving element for receiving the light focused by the light receiving lens so as to perform photo-electric conversion.

Led light assembly

Abstract: An light source utilizes a parabolic reflector to collimate light emitted from at greater than a predetermined angle relative to the optical axis of an LED arranged at the focus of the reflector. An optional collimating lens is arranged to collimate light emitted at less than the predetermined angle. Both variations provide light in the form of a substantially collimated beam. The parabolic reflector is preferably extended along its focal point to form a linear parabolic section having a linear focal axis. A linear array of LEDs is arranged such that the linear focal axis passes through the area of light emission of each LED. The linear parabolic section may be provided with parabolic dish ends. Alternatively, the ends of the parabolic section may be left open for increased wide angle visibility.

Individualized compensation of anterior segment birefringence during scanning laser polarimetry.

Abstract: Purpose To describe a method for assessment and individualized compensation of anterior segment birefringence with scanning laser polarimetry. Methods A scanning laser polarimeter (GDx Nerve Fiber Analyzer; Laser Diagnostic Technologies, Inc., San Diego, CA) was modified to accommodate a variable compensator. The magnitude and axis of anterior segment birefringence of normal eyes were determined from a polarimetry image of the Henle fiber layer. The variable compensator was then adjusted to minimize anterior segment birefringence. Retinal nerve fiber layer (RNFL) and macular measurements were then obtained. Macular images with individualized compensation served to verify the effectiveness of the compensation. To demonstrate individualized compensation, two sets of three images each were obtained from four eyes of four normal subjects. One set was obtained with individualized compensation and another with fixed compensation, as used in the commercial polarimetry system. Results In the tested eyes, the magnitude of anterior segment birefringence ranged from 21.7 to 86.3 nm, and the slow axis ranged from 5.7 degrees nasally upward to 54.3 degrees nasally downward. The maximum residual retardation resulting from compensation was 70 nm for fixed compensation and 11.5 nm for individualized compensation. The compensation residual directly affected the assessment of the RNFL by scanning laser polarimetry. RNFL images obtained with individualized compensation were more consistent with the expected anatomy of the eye. In the eyes measured, the range of RNFL thicknesses appeared to be narrower with the variable corneal and lens compensator (VCC) compared with the fixed corneal compensator (FCC). Conclusions In eyes with a normal macula, the magnitude and axis of anterior segment birefringence can be determined from a polarimetry image of the Henle fiber layer. Individualized anterior segment compensation can be achieved with the described method so that the measured birefringence largely reflects the RNFL birefringence. Whether and how macular diseases affect this method remain to be investigated.

Electro-optic lens with integrated components

Abstract: A range finder device (2170) and (2160) for use with a controller (2140) in an optical system (2100) is disclosed comprising a transmitter (2160) configured to produce a first beam of non-visible radiation for intersecting a perceived object, and a receiver (2170) configured to detect a second beam of non-visible radiation reflected from the perceived object, the controller (2140) configured to determine a viewing distance of the perceived object based on signals received from the transmitter (2160) and receiver (2170). A method of controlling an optical lens is disclosed comprising utilizing a range finder to determine the viewing distance of an object perceived through an electro-active lens (2120). An optical lens system (2100) is disclosed, comprising an electro-active lens (2120) and a controller (2140) coupled to the lens configured to adjust a focal length of at least a portion of the electro-active lens (2120) based on a signal from a range finder device.

Critical dimension analysis with simultaneous multiple angle of incidence measurements

Abstract: A method and apparatus are disclosed for evaluating relatively small periodic structures formed on semiconductor samples. In this approach, a light source generates a probe beam which is directed to the sample. In one preferred embodiment, an incoherent light source is used. A lens is used to focus the probe beam on the sample in a manner so that rays within the probe beam create a spread of angles of incidence. The size of the probe beam spot on the sample is larger than the spacing between the features of the periodic structure so some of the light is scattered from the structure. A detector is provided for monitoring the reflected and scattered light. The detector includes multiple detector elements arranged so that multiple output signals are generated simultaneously and correspond to multiple angles of incidence. The output signals are supplied to a processor which analyzes the signals according to a scattering model which permits evaluation of the geometry of the periodic structure. In one embodiment, the sample is scanned with respect to the probe beam and output signals are generated as a function of position of the probe beam spot.

Kerr-lens, mode-locked lasers as transfer oscillators for optical frequency measurements

Abstract: We introduce a novel concept for optical frequency measurement and division which employs a Kerr-lens, mode-locked laser as a transfer oscillator whose noise properties do not enter the measurement process. We experimentally demonstrate that this method opens up the route to phase-link signals with arbitrary frequencies in the optical or microwave range while their frequency stability is preserved.

Wide-scan spherical-lens antennas for automotive radars

Abstract: A new approach to wide scan-angle antennas at millimeter-wave frequencies is introduced with special focus on ease of manufacturing and reliability. The system is composed of planar feed antennas (tapered-slot antennas), which are positioned around a homogeneous spherical Teflon lens. Beam scanning can be achieved by switching between the antenna elements. The spherical-lens system is analyzed through a combined ray-optics/diffraction method. It is found that a maximum efficiency of 50%-55% can be achieved using Teflon, Rexolite, or quartz lenses. The efficiency includes taper, spillover, and reflection loss. Calculations also indicate that the maximum lens diameter is 30-40 /spl lambda//sub 0/, which results in a maximum directivity of 39.5-42 dB. Measurements done on a single-element feed and a 5-cm Teflon lens agree very well with theory and result in a 3-dB beamwidth of 5.5/spl deg/ and better than -20-dB sidelobe levels at 77 GHz. Absolute gain measurements show a system efficiency of 46%-48% (including dielectric loss). A 23- and 33-element antenna array with a scan angle of /spl plusmn/90/spl deg/ and a -3.5- and -6-dB crossover, respectively, in the far-field patterns was also demonstrated. The 23-element array resulted in virtually no gain loss over the entire 90/spl deg/ scan angle. This represents, to our knowledge, the first wide scan-angle antenna at millimeter-wave frequencies.

Aspects of basic OCT engine technologies for high speed optical coherence tomography and light source and other improvements in optical coherence tomography

Abstract: An optical coherence tomography (OCT) system including an interferometer provides illuminating light along a first optical path to a sample and an optical delay line and collects light from the sample along a second optical path remitted at several scattering angles to a detector. In one embodiment, illuminating light is directed along a number of incident light paths through a focusing lens to a sample. The light paths and focusing lens are related to the sample and to both the incident light source and the detector. In another embodiment, a focusing system directs light to a location in the sample. A transmission grating or acousto-optic modulator directs light from the sample at an angle representative of the wavelength of the incident light on the transmission grating or acousto-optic modulator.

Image acquisition with depth enhancement

Abstract: A minimally invasive, medical, image acquisitions system outputs a light beam (30, 32) or pulse which illuminates a precise spot size. A plurality of photon detectors (14) detect returning photons (44) from the object, including the spot. Pixel resolution is determined by the area of the illumination spot (and thus the lens configuration), rather than an area sensed by the detector. Depth enhancement is determined by correlating images detected by the respective detectors, or alternatively by a range finding method based on phase difference, time of light, frequency or interferometry.

Contact lens practice

Abstract: Part 1 Introduction Historical perspective. The anterior eye Visual optics Clinical instruments Part 2 Soft contact lenses Soft lens materials Soft lens manufacture Soft lens optics Soft lens measurement Soft lens design and fitting Soft toric lens design and fitting Soft lens care systems Part 3 Rigid contact lenses Rigid lens materials Rigid lens manufacture Rigid lens optics Rigid lens measurement Rigid lens design and fitting Rigid toric lens design and fitting Rigid lens care systems Part 4 Lens replacement modalities Unplanned lens replacement Daily soft lens replacement Planned soft lens replacement Planned rigid lens replacement Part 5 Special lenses and fitting considerations Scleral lenses Tinted lenses Presbyopia Continuous wear Sport Keratoconus High ametropia Paediatric fitting Therapeutic applications Post-refractive Surgery Post-keratoplasty Orthokeratology Diabetes Part 6 Patient examination and management History taking Preliminary examination Patient education Aftercare Complications Digital imaging Compliance Practice management Appendices Index

Image projecting device and method

Abstract: An image projecting device and method are presented. The device comprises a light source system operable to produce a light beam to impinge onto an active surface of a spatial light modulator (SLM) unit formed by an SLM pixel arrangement; and a magnification optics accommodated at the output side of the SLM unit. The light beam impinging onto the SLM pixel arrangement has a predetermined cross section corresponding to the size of said active surface. The SLM unit comprises first and second lens' arrays at opposite sides of the pixel arrangement, such that each lens in the first array and a respective opposite lens in the second array are associated with a corresponding one of the SLM pixels

Lens with refractive and reflective surfaces

Abstract: A lens mounted to a light emitting diode package internally redirects light within the lens so that a majority of light is emitted from the lens approximately perpendicular to a package axis of the light emitting diode package. In one embodiment, the light emitted by the light emitting diode package is refracted by a sawtooth portion of the lens and reflected by a total internal reflection portion of the lens.

Three-dimensional position detection of optically trapped dielectric particles

Abstract: A theory is presented together with simulation results that describe three-dimensional position detection of a sphere located in a highly focused beam by back-focal plane interferometry. This technique exploits the interference of scattered and unscattered light, which is projected on a quadrant photodiode placed in the back-focal plane of a condenser lens. Due to the Gouy-phase shift inherent in focused beams, it is not only possible to determine the lateral but also the axial position of a spherical particle with nanometer accuracy. In this paper we describe the calculation of arbitrary focused electromagnetic fields, the Gouy phase shift, Mie scattering by focused beams and the resulting position signals using the angular momentum representation. The accuracy and the sensitivity of the detection system are investigated theoretically for various sphere parameters. Both accuracy and sensitivity depend on the incident light distribution as well as on the particle’s properties and position. It is further shown that the maximum capture angle of the detection lens influences the detector’s sensitivity in a nonlinear manner. Additionally, for optical trapping applications the influence of the laser power is taken into account and is considered through a noise analysis. For all investigated trapping conditions the reconstructed position deviates on average <1 nm laterally and <5 nm axially from the actual particle position.

A Numerical Characterization of Particle Beam Collimation by an Aerodynamic Lens-Nozzle System: Part I. An Individual Lens or Nozzle

Abstract: Particle beams have traditionally been produced by supersonic expansion of a particle-laden gas through a single nozzle to vacuum However, it has been shown that, by passing the particle-laden gas

Optical Properties of Liquid Crystal Lens of Any Size : Optics and Quantum Electronics

Abstract: A liquid crystal lens with a simple cell structure is prepared using a hole-patterned electrode and an intermediate insulating layer. The focal length is variable and is a function of the applied voltage. With this new structure, it is possible to fabricate liquid crystal lenses of any size.

Multifocal ophthalmic lenses

Abstract: The invention provides a pair of multifocal lenses for the correction of presbyopia. The dominant eye lens has an optic zone with the distance optical power required and additional zones of either or both distance and near optical power. The non-dominant eye lens has an optic zone with the near optical power and additional zones of either or both near and distance optical power.

The asymmetric lossy near-perfect lens

Abstract: We extend the ideas of the perfect lens recently proposed [J.B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] to an alternative structure. We show that a slab of a medium with negative refractive index bounded by media of different positive refractive index also amplifies evanescent waves and can act as a near-perfect lens. We examine the role of the surface states in the amplification of the evanescent waves. The image resolution obtained by this asymmetric lens is more robust against the effects of absorption in the lens. In particular, we study the case of a slab of silver, which has a negative dielectric constant, with air on one side and other media such as glass or GaAs on the other side as an ‘asymmetric’ lossy near-perfect lens for p-polarized waves. It is found that retardation has an adverse effect on the imaging due to the positive magnetic permeability of silver, but we conclude that subwavelength image resolution is possible in spite of it.

Radiation emitter device having an integral micro-groove lens

Abstract: The radiation emitter device of the present invention includes at least two radiation emitters emitting radiation of different wavelengths, first and second electrical leads electrically coupled to at least one of the radiation emitters, and an encapsulant configured to encapsulate the radiation emitters and a portion of the first and second electrical leads. The encapsulant is further configured to have a surface defining an optical lens including a plurality of concentric circular grooves. The optical lens is preferably a divergent lens. Preferably, the lens is a multi-faceted Fresnel lens structure having a plurality of risers and Fresnel facets defining the plurality of concentric circular grooves. The radiation emitter device may further include a secondary reflective cup, preferably a parabolic or elliptical reflective cup, disposed proximate the encapsulant about the periphery of the Fresnel lens structure.

Measuring system with improved method of reading image data of an object

Abstract: When a scanning start position set signal is input in an area image sensor, the content is transferred to a vertical scanning circuit, and the scan start position is set. Image of a desired row is read by horizontal scanning. Then, one shift signal for vertical scanning is input, the position of scanning is shifted by one row, and horizontal scanning is performed. Thus image of the next row is read. By repeating this operation, a desired strip-shaped image is read. The shape of the object is determined and when a portion is determined to have complicated shape, the image data is input by means of a lens having long focal length, and image data of other portions are input by means of a lens having short focal length. By putting together a plurality of input image data, image data as a whole is generated.

Optical Properties of Liquid Crystal Lens of Any Size

Abstract: A liquid crystal lens with a simple cell structure is prepared using a hole-patterned electrode and an intermediate insulating layer. The focal length is variable and is a function of the applied voltage. With this new structure, it is possible to fabricate liquid crystal lenses of any size.

Scanning directional antenna with lens and reflector assembly

Abstract: An antenna comprising a feed (42) for delivering electromagnetic energy to a rotatable combination of a dielectric lens (44) and a reflective surface (46). The combination of the dielectric lens and the reflective surface is placed proximate to and in front of an energy feed, such as a horn (42), to support the scanning of an antenna beam in response to rotation of the lens/reflective surface assembly. The lens typically comprises a dielectric material and the reflective surface can comprise a thin layer of material operable to reflect electromagnetic energy. For example, the lens can comprise a half-cylinder shape of dielectric material and the reflective surface can be applied to the flat portion of the half-cylindrical lens. Alternatively, the antenna can comprise two or more electromagnetic feeds (72a, 72b, 72c, 72d) and a cylindrical lens of dielectric material including a centrally embedded, two-sided reflective surface. A positioning system can be used to rotate the combination of the lens and the reflective material proximate to and in front of the electromagnetic feed(s).

Self-calibrating, digital, large format camera with single or multiple detector arrays and single or multiple optical systems

Abstract: Large format, digital camera systems (10, 100, 150, 250, 310) expose single detector arrays 20 with multiple lens systems (12, 14, 16, 18) or multiple detector arrays (104, 106, 108, 110, 112, 114, 116, 118, 120, 152, 162, 172, 182, 252, 262, 272, 282, 322, 324) with one or more single lens systems (156, 166, 176, 186) to acquire sub-images of overlapping sub-areas of large area objects. The sub-images are stitched together to form a large format, digital, macro-image (80, 230', 236', 238', 240'), which can be colored. Dampened camera carrier (400) and accelerometer (404) signals with double-rate digital signal processing (306, 308) are used.

Planar solar concentrator power module

Abstract: A planar concentrator solar power module has a planar base, an aligned array of linear photovoltaic cell circuits on the base and an array of linear Fresnel lenses or linear mirrors for directing focused solar radiation on the aligned array of linear photovoltaic cell circuits. The cell circuits are mounted on a back panel which may be a metal back plate. The cell circuit area is less than a total area of the module. Each linear lens or linear mirror has a length greater than a length of the adjacent cell circuit. The cell circuit may have cells mounted in shingle fashion to form a shingled-cell circuit. In an alternative module, linear extrusions on the circuit element have faces for mounting the linear mirrors for deflecting sun rays impinging on each mirror onto the shingled-cells. The linear extrusions are side-wall and inner extrusions with triangular cross-sections. The circuit backplate is encapsulated by lamination for weather protection. The planar module is generally rectangular with alternating rows of linear cell circuits and linear lenses or linear mirrors.

Viewing-angle-enhanced integral imaging by lens switching

Abstract: In spite of the many advantages of integral imaging, its narrow viewing angle has been a disadvantage. We propose a method to enhance the viewing angle of integral imaging by opening and shutting each lens in the array (i.e., the elemental lenses) sequentially. We prove our idea by using a mask that has a pattern of an on-off vertical array of apertures. Moving the mask prevents the aliasing of a neighboring lens. Thus image overlap or image flipping is reduced and the viewing angle of the system is increased.

Microscope for operation

Abstract: Light beams for a binocular is formed by an objective lens and a pair of relay lenses, three-dimensional observation for an assistant equivalent to that for the operator can be realized by using a binocular eyepiece optical system for the assistant via a split optical system the position where the assistant faces the operator. A part of at least one of the binocular light beams is incident on a pupil-division optical system to form the pupil-divided binocular light beams. Three-dimensional observation by the pupil division can be realized even when the binocular eyepiece optical system side for an assistant is rotated and set in the direction aside the operator.

Influence of substrate-lens design in terahertz time-domain spectroscopy

Abstract: We describe measurements of the angular radiation patterns from lens-coupled terahertz antennas fabricated on photoconductive substrates. These measurements were performed with a novel terahertz (THz) time-domain spectrometer in which the femtosecond optical pulses used to gate the emitter and receiver antennas were delivered by optical fiber. We used this system to perform a comparison between the two substrate-lens designs commonly used in THz time-domain spectrometers. We measured both E-plane and H-plane emission patterns for a 90° bow-tie antenna. By comparing these experimental results with simulations based on Fresnel–Kirchoff diffraction, we find that the choice of substrate-lens design is important in determining not only the directivity of the emitted beam but also the spectral bandwidth. These results emphasize the significance of this crucial component in the design of broadband THz spectrometers.

Gradient-index optics

Abstract: 1 Light Propagation in GRIN Media.- 1.1 Introduction.- 1.2 Vector Wave Equations.- 1.3 Scalar Wave Equation.- 1.4 Parabolic Wave Equation.- 1.5 Ray Optics: Axial and Field Rays.- 2 Imaging and Transforming Transmission Through GRIN Media.- 2.1 Introduction.- 2.2 The Kernel Function.- 2.3 Imaging and Fourier Transforming Through GRIN Media.- 2.4 Fractional Fourier Transforming in GRIN Media.- 2.5 Modal Representation of the Kernel.- 3 GRIN Lenses for Uniform Illumination.- 3.1 Introduction.- 3.2 Transmittance Function of a GRIN Lens for Uniform Illumination.- 3.3 GRIN Lens Law: Imaging and Fourier Transforming by GRIN Lens.- 3.4 Geometrical Optics of GRIN Lenses.- 3.5 Effective Radius, Numerical Aperture, Aperture Stop, and Pupils.- 3.6 Diffraction-Limited Propagation of Light in a GRIN lens.- 3.7 Effect of the Aperture on Image and Fourier Transform Formation.- 4 GRIN Lenses for Gaussian Illumination.- 4.1 Introduction.- 4.2 Propagation of Gaussian Beams in a GRIN Lens.- 4.3 GRIN Lens Law: Image and Focal Shifts.- 4.4 Effective Aperture.- 5 GRIN Media with Loss or Gain.- 5.1 Introduction.- 5.2 Active GRIN Materials: Complex Refractive Index.- 5.3 The Kernel Function.- 5.4 Focal Distance and Focal Shift for Uniform Illumination.- 5.5 Gaussian Illumination in an Active GRIN Medium: Beam Parameters.- 5.6 Transformation of a Gaussian Beam into a Uniform Beam.- 6 Planar GRIN Media with Hyperbolic Secant Refractive Index Profile.- 6.1 Introduction.- 6.2 Ray Equation and ABCD Law.- 6.3 Focusing and Collimation Properties.- 6.4 Numerical Aperture: On-Axis and Off-Axis Coupling.- 6.5 Mode Propagation.- 6.6 The Kernel Function.- 6.7 Diffraction-Free and Diffraction-Limited Propagation of Light.- 7 The Talbot Effect in GRIN Media.- 7.1 Introduction.- 7.2 Light Propagation and Imaging Condition.- 7.3 The Integer Talbot Effect.- 7.4 Self-Image Distances.- 7.5 Fractional Talbot Effect: Unit Cell.- 7.6 Effect of Off-Axis Source and Finite Object Dimension on Self-Images.- 8 GRIN Crystalline Lens.- 8.1 Introduction.- 8.2 The Optical Structure of the Human Eye.- 8.3 The GRIN Model of the Crystalline Lens.- 8.4 The Gradient Parameter: Axial and Field Rays in the Crystalline Lens.- 8.5 Refractive Power and Cardinal Points of the Crystalline Lens.- 9 Optical Connections by GRIN Lenses.- 9.1 Introduction.- 9.2 GRIN Fiber Lens.- 9.3 Anamorphic Selfoc Lens.- 9.4 Tapered GRIN Lens.- 9.5 Selfoc Lens.- References.

Hybrid electro-active lens

Abstract: An electro-active lens (100, 200, 300) that may include first (110, 115, 120, 122, 125) and second (135, 137, 140, 145, 150) electro-active cells, having controlled birefringence (e.g. a Nematic liquid crystal) the cells being adjacent to and stacked upon each other and, when in a resting state, oriented orthogonal to each other to reduce birefringence.