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

Anomalous refraction and diffraction in discrete optical systems.

Abstract: We experimentally prove that light propagation in a discrete system, i.e., an array of coupled waveguides, exhibits striking anomalies. We show that refraction is restricted to a cone, irrespective of the initial tilt of the beam. Diffraction can be controlled in size and sign by the input conditions. Diffractive beam spreading can even be arrested and diverging light can be focused. The results can be thoroughly theoretically explained.

Neural processing of gravitoinertial cues in humans. III. Modeling tilt and translation responses.

Abstract: All linear accelerometers measure gravitoinertial force, which is the sum of gravitational force (tilt) and inertial force due to linear acceleration (translation). Neural strategies must exist to ...

Large-displacement vertical microlens scanner with low driving voltage

Abstract: We have designed, fabricated, and demonstrated large vertical displacement vertical microlens scanners with low (<10 V) driving voltage using silicon-on-insulator technology. The unique isolated and pre-engaged vertical comb-drive sets and the coupled-torsion flexure design provide both upward and downward piston motions, as well as low driving voltages. Single-directional devices demonstrate maximum static downward displacement of 8 /spl mu/m at 10 V/sub dc/. Bidirectional devices demonstrate vertical actuation from -6.5 to +9 /spl mu/m at max 12 V/sub dc/, and a vertical displacement of up to 55 /spl mu/m peak-to-peak is achieved at the resonance near 400 Hz. The lens motion shows piston motion with a small tilt angle of less than 0.034/spl deg/ and the compensation of the tilt using an isolated comb bank is demonstrated.

Optical system and device using the same

Abstract: A viewing optical system for display devices or an image pickup optical system, which can be used with high efficiency at a plurality of wavelengths and enables bright images to be viewed with satisfactory color reproducibility and well-corrected aberrations. The optical system comprises a first prism, a second prism and a volume hologram element disposed between them and cemented to them. The hologram element comprises a first volume hologram optimized in such a way as to effect diffraction at least at a first wavelength and a second hologram optimized in such a way as to effect diffraction at a second wavelength different from the first wavelength. The first and second holograms are identical with each other in terms of the shape and spacing of interference fringes on their surfaces but different from each other in terms of the spacing and tilt of interference fringes in their hologram media.

Automated high-throughput electron tomography by pre-calibration of image shifts.

Abstract: Electron tomography is a versatile method for obtaining three-dimensional (3D) images with transmission electron microscopy. The technique is suitable to investigate cell organelles and tissue sections (100-500 nm thick) with 4-20 nm resolution. 3D reconstructions are obtained by processing a series of images acquired with the samples tilted over different angles. While tilting the sample, image shifts and defocus changes of several microm can occur. The current generation of automated acquisition software detects and corrects for these changes with a procedure that incorporates switching the electron optical magnification. We developed a novel method for data collection based on the measurement of shifts prior to data acquisition, which results in a five-fold increase in speed, enabling the acquisition of 151 images in less than 20 min. The method will enhance the quality of a tilt series by minimizing the amount of required focus-change compensation by aligning the optical axis to the tilt axis of the specimen stage. The alignment is achieved by invoking an amount of image shift as deduced from the mathematical model describing the effect of specimen tilt. As examples for application in biological and materials sciences 3D reconstructions of a mitochondrion and a zeolite crystal are presented.

Method and arrangement for determining movement

Abstract: To determine the movement of a device, a three-dimensional measurement of the device's acceleration is provided in known directions with regard to the device, and average signals of acceleration signals parallel to different axes are formed to allow tilt angles of the device with respect to gravity to be defined. Acceleration change signals are formed by removing the average signals from their respective acceleration signals parallel to the different axes. The acceleration change signals and the tilt angles of the device are used for forming a component of the acceleration change of the device, which component is parallel to gravity and independent of the position of the device.

Manipulating the column tilt angles of nanocolumnar films by glancing-angle deposition

Abstract: Nanometre-size cobalt columns with tilt angle ranging from ~0? to ~40? and fixed density on Si(100) were fabricated by combining oblique-angle physical evaporation with controlled substrate motion. The column tilt angle can be controlled by the speed and phase of substrate rotation in addition to the angle of the incident vapour beam. A simple geometrical model is proposed to describe the relationship between the tilt angle of the cobalt columns and the rotational parameters (speed and phase), and is consistent with our experimental results.

Integrated waveguide turning mirror in silicon-on-insulator

Abstract: Planar lightwave circuits based on silicon are playing an important role in integrated optical systems. The integrated waveguide turning mirror (IWTM) is an essential component for the compactness of optical devices. We have designed such a mirror with a 90/spl deg/ directional change in silicon-on-insulator (SOI). The fabricated mirror has very small surface roughness. The loss caused by transverse tilt /spl delta//sub t/ and lateral tilt /spl delta//sub l/ is negligible in theory. A 1 /spl times/ 2 beam splitter using the structure is fabricated to test the performance, and turning mirrors of excess loss less than 0.5 dB/mirror are obtained.

Methods and systems for improvement of measurement efficiency in surveying

Abstract: Methods and systems for measuring coordinates of a target, particularly under strong multipath conditions, are described. A satellite navigation system antenna (105) and a tilt sensor (130) are mounted on a range pole (120), with the sensor at the pole's bottom tip. Signals from the antenna and tilt sensor are provided to a receiver (107), which computes the antenna's coordinates from the antenna signals, and the pole tips position from the computed coordinates and the tilt data. The operator places the pole tip on the target and swings the pole by hand over an angle sector of 15 degrees while keeping the tip on the target. Height of the target can be computed with a single measurement set, and X-Y coordinates with just three measurement sets. The use of additional measurements reduces errors in the target's coordinates since multipath errors are uncorrelated during movement of the antenna. Vertical alignment of the pole is unnecessary.

Tilt correction of electronic images

Abstract: A method of correcting the tilt, or rotation, of a casually captured image is described. Having corrected the rotation of the original image, the image is cropped by determining a crop boundary by applying one or more rules of composition to the image. The resulting image is more satisfactorily composed compared with prior art methods.

Dual spot confocal displacement sensor

Abstract: A confocal displacement sensor uses one or two light sources and produces two spots on a sample surface. The reflected intensities from the two spots are detected and measured by one or two detectors. A vertical resolution enhancement can be implemented by modifying the properties of the objective and/or detector lenses. The resultant height profile does not need to be corrected for tilt as is common with all single point surface measurement techniques. A differential scan can be performed with the two spots relatively close together to generate the slope of the height profile. Integrating this profile yields the height profile of the scan. A referential scan can be performed by scanning the reference point across an area of constant height and the measurement point scanned across the feature to be measured to directly generate the height profile.

Guiding vehicle in adjacent swaths across terrain via satellite navigation and tilt measurement

Abstract: A method of guiding a vehicle in adjacent swaths across terrain that may slope comprising the steps of: (1) determining the tilt of the vehicle with respect to Earth due to a slope of the terrain; (2) determining the position with respect to Earth of a predetermined location that is fixed relative to the vehicle; and (3) using the tilt and position determinations to provide information for guiding the vehicle to prevent gaps and overlaps between adjacent swaths as the slope changes.

Gender influence on vasoactive hormones at rest and during a 70° head-up tilt in healthy humans

Abstract: To evaluate the influence of age and gender on the neuroendocrine control of blood pressure in normal subjects, a 13-min 70° head-up tilt (HUT) was applied after 3 h of recumbency to 109 healthy me

Model of tilt sensor system

Abstract: This paper describes the structural concept of an intelligent sensor system for tilt measurement. The accelerometer principle is used for the measurement. The system enables measurement in both axes of the plane. Measurement is controlled by a microprocessor. Measured data are sent via a bus to a PC. The PC is used for data storage and further calculations. The program controls the performance of defined functions, including calibration, by communication between the sensor system and the PC. It is possible to switch between manual (more precise) and automatic calibration of the position setup of the system. The system has measurement precision of 0.5/spl deg/ for each axis in a /spl plusmn/80/spl deg/ range, with no measurable hysteresis, and an immediate response to tilt change. The sensor system is temperature compensated. The LabView development tool is utilized as a service program.

Tilt plane orientation in antiferroelectric liquid crystal cells and the origin of the pretransitional effect.

Abstract: The optic, electro-optic, and dielectric properties of antiferroelectric liquid crystals (AFLCs) are analyzed and discussed in terms of the local tilt plane orientation. We show that the so-called pretransitional effect is a combination of two different electro-optic modes: the field-induced antiphase distortion of the antiferroelectric structure and the field-induced reorientation of the tilt plane. In the presence of a helix, the latter corresponds to a field-induced distortion of the helix. Both electro-optic modes are active only when the electric field has a component along the tilt plane. Thus, by assuring a horizontal surface-stabilized condition, where the helix is unwound by surface action and the tilt plane is everywhere parallel to the cell plates, the pretransitional effect should be suppressed. We also discuss the dielectrically active modes in AFLCs and under which circumstances they contribute to the measured dielectric permittivity.

Running control device

Abstract: A running control device for a watercraft controls propulsion force and tilt angle of a propulsion device relative to the hull of the watercraft. The running control device also sets an optimum trim angle automatically. The running control device includes a propulsion force control section that controls the propulsion force of the propulsion device. The running control device also includes a tilt angle control section that controls the tilt angle of the propulsion device. A target propulsion force calculation module responds to first input information (e.g., watercraft velocity) to calculate a target propulsion force. An amount-of-operation calculation module responds to second input information to calculate an amount of operation of the propulsion device to produce the target propulsion force. The tilt angle control section includes a tilt angle calculation module that determines the tilt angle based on the propulsion force.

Method and system for determining the alignment of a surface of a material in relation to a laser beam

Abstract: The present invention generally relates to a method and system for determining the position and alignment of a plane in relation to an intersecting axis and using that known position and alignment to allow for corrections to be made when using the plane as a reference plane. More particularly, the invention relates to a method and system for determining the angle of tilt of a planar surface in relation to a laser beam, and using the determined angle of tilt to calculate a correction factor to be applied to the laser beam. Briefly stated, the method and system ultimately calculates a correction factor, z-offset, that is applied when using the laser beam in a procedure.

Laser sighting device

Abstract: The present invention provides a laser sighting device, which comprises a tilt detecting device having a liquid member for forming a free liquid surface and a fixed reflection member fixedly mounted, the tilt detecting device being used for detecting angular deviation between the free liquid surface and the fixed reflection member, a main unit for accommodating the tilt detecting device, and a laser beam irradiation unit removably mounted on the main unit.

Optical head apparatus and optical information recording and reproducing apparatus

Abstract: Light emitted from a laser is separated into a main beam, first sub beams, and second sub beams. The distribution intensity of each first sub beams is the same as that of the main beam. The distribution intensity of each second sub beam is different from that of the main beam. The sum of the focusing error signals relating to the main beam and first sub beams is a final focusing error signal. The difference between the tracking error signal relating to the main beam and the tracking error signal of each first sub beam is a final tracking error signal. The deviation of the thickness of the substrate of the disk and the radial tilt thereof are detected on the basis of the deviation of the zero crossing points of the focusing error signal and the tracking error signal relating to the main beam and each second sub beam.

Method and apparatus for controlling cutting tool edge cut taper

Abstract: A tilt control assembly for controlling the tilt of a cutting tool head has a first eccentric support and a second support, with both of the first and second supports connected to the head along an axis of the head. To adjust the position of the head, the first eccentric support may be rotated.

Analysis of modes and behavior of a multiconjugate adaptive optics system

Abstract: We study the so-called three-dimensional mapping of turbulence, a method solving the cone effect (or focus anisoplanatism) by using multiple laser guide stars (LGSs). This method also permits a widening of the corrected field of view much beyond the isoplanatic field. Multiple deformable mirrors, conjugated to planes at chosen altitudes among the turbulent layers, are used to correct in real time the wave fronts measured from the LGSs. We construct an interaction matrix describing the multiconjugate adaptive optics system and analyze the eigenmodes of the system. We show that the global tilt mode is singular because it cannot be localized in altitude, so that it must be corrected only once at any altitude. Furthermore, when the tilt from the LGS cannot be measured, the singularity of the global tilt yields the delocalization of particular forms of defocus and astigmatism. This imposes the use of a single natural guide star located anywhere in the corrected field to measure these modes. We show as an example that the cone effect can be corrected with a Strehl of 0.8 with four LGSs (tilt ignored) on an 8-m telescope in the visible when a single laser star provides a Strehl of 0.1. The maximum field of view of 100 arc sec in diameter can be reconstructed with an on-axis Strehl ratio of 30%. We also show that the measurement of the height of the layers can be done with current techniques and that additional layers, not accounted for, do not significantly degrade the performance in the configuration that we model.

Interferometric, modulation-free laser stabilization

Abstract: We demonstrate novel modulation-free frequency locking of a diode laser, utilizing a simple Sagnac interferometer to create an error signal from saturated-absorption spectroscopy. The interference condition at the output of the Sagnac is strongly affected by the sharp dispersion feature near an atomic resonance. Slight misalignment of the interferometer and subsequent spatially selective, or tilt, detection allows this phase change to be converted into an error signal. Tilt locking has significant advantages over previously described methods, as it requires only a small number of low-cost optical components and a detector. In addition, the system has the potential to be constructed as a plug-and-play fiber-coupled monolithic device to provide submegahertz stability for lasers in the commercial market.

Tilt-compensated interferometers

Abstract: The tilt-compensated interferometers of the present invention are novel variations of Michelson's interferometer that use tilt- and shear-compensation to provide excellent photometric accuracy even when there are imperfections in the scanning motion used to produce variation of path difference. The tilt-compensation mechanism of the present invention consists of antiparallel reflections from a beamsplitter element and a roof reflector element, which elements are held rigidly in alignment. Several particularly useful embodiments of the invention are described. Other advantages of the present invention include photometric stability and reduced cost because manual alignment is not required. This interferometer has applications in spectrometry, spectral imaging and metrology.

Vertical microlens scanner for 3d imaging

Abstract: We have designed, fabricated, and demonstrated a static vertical microlens scanner with large static displacement and low (<10V) driving voltage, using silicon-on-insulator (SOI) technology. The unique isolated vertical combdrive sets and the coupled-torsion flexure design provides for both upward and downward piston motions and the low driving voltage. Single- directional devices demonstrate maximum static downward displacement of 8 µm at 10 Vdc actuation voltage. Bi-directional devices demonstrate vertical actuation from -6.5 µm to +9 µm also at sub-10 V. The devices have mechanical resonant frequencies near 400 Hz, and when operated at resonance, a vertical displacement of up to 55 µm peak-to-peak is achieved at up to 7 Vrms. The lens motion shows near pure piston motion with very small tilt angle of less than 0.034° and the compensation of the tilt using an isolated comb bank is demonstrated.

Multi-Conjugate Adaptive Optics with laser guide stars: performance in the infrared and visible

Abstract: In this paper, the performance of a Multi-Conjugate Adaptive Optics (MCAO) system is evaluated, in the case where several (five) laser guide stars (LGSs) are used. The low-order modes are measured from either a single natural guide star (1NGS) with a 3 × 3 ShackHartmann sensor, or three tip‐tilt stars (3NGS), each measuring only tip and tilt. To widen the corrected field of view, three deformable mirrors are used. These simulations are performed in closed loop, using a Maximum A Posteriori (MAP) control algorithm. It is shown that both systems significantly increase the corrected field of view (FOV). Residual anisoplanatism is seen over the 30-arcsec (diameter) corrected FOV, and it is due to errors in measuring loworder modes. In the visible part of the spectrum, the modelled infrared-optimized system still provides high angular resolution (22 mas ‐ not strictly diffraction limited) over a field of view 10 times larger than the isoplanatic angle. This has a significant impact on the astrophysical instrumentation to be used. Both 1NGS and 3NGS methods provide good correction quality, the second one providing better stability of correction quality within the FOV. The 3NGS system allows the use of guide stars ∼2 mag fainter than the 1NGS approach.

Speed change control method and speed change controller

Abstract: A speed change control method of controlling a speed change ratio of a continuously variable transmission mechanism including a traction continuously variable transmission, includes: estimating a tilt angle of a power roller included in the continuously variable transmission based on an input rotating speed and an output rotating speed of the continuously-variable transmission mechanism; estimating a position of the power roller based on an estimated tilt angle obtained by the tilt angle estimating step and a command signal given to a driving device of adjusting the tilt angle of the power roller; and executing a feedback control operation based on an estimated position of the power roller obtained by the position estimating step.

Theory of T junctions and symmetric tilt grain boundaries in pure and mixed polymer systems

Abstract: We apply self-consistent-field theory to T junctions and symmetric tilt grain boundaries in block copolymer systems with and without the addition of homopolymer. We find that, in the absence of homopolymer, T junctions have a larger free energy per unit area than that of the symmetric tilt junctions with which they compete except for a range of angles between about 100° and 130°. With the addition of homopolymer, this range increases. These results are quite consistent with experiment. As the angle between grains increases towards 180°, the T junction undergoes a morphological change somewhat similar to that which occurs in symmetric tilt grain boundaries. At the onset of this change, the free energy per unit area decreases markedly.

Phase-stepping interferometry: methods for reducing errors caused by camera nonlinearities

Abstract: Phase errors that arise in phase-stepping interferometry are discussed. Investigations were performed by use of a Twyman–Green interferometer equipped with a compensation plate with a variable and servo-controlled tilt angle. With this instrument, phase-stepping errors can be reduced to a negligible level. There are, however, phase errors that are caused by camera nonlinearities. Two methods for minimizing these errors are presented. The first method is based on the simple idea that the interference intensity at the output of a two-beam interferometer has an exact cosine shape. The camera signals were monitored as a function of the tilt angle of the compensation plate, and the deviation from the cosine form was used to produce a correction. The second method is based on the idea that, under specific conditions, errors of an average of two phase measurements may compensate for each other. Numerical calculations were performed and give evidence of this hypothesis. Each method, the signal-correction and the averaging method, drastically reduces errors in evaluation of phases. The combination of both methods is a powerful tool that allows precise phase data to be obtained with an uncertainty, in the range λ/2000 ≈ 0.3 nm, that is caused mainly by signal noise.

Dynamic holography for high-dynamic-range two-dimensional laser wavefront control

Abstract: 'Dynamic holography is demonstrated as a technique for high- dynamic-range, multi-function laser wavefront control. In this paper, we describe three variations for hologram generation and display. These include all-optical holography for severe aberration compensation, computer-processed holography for high-optical-efficiency severe aberration compensation and computer-generated holography for multi- function laser wavefront control including dynamic tip, tilt, focus and aberration control. A prototype hologram display system operates with total optical efficiencies up to 93% and with refresh rates on the order of 10 Hz. The prototype system has resolution sufficient to introduce about 200 waves of diffractive wavefront control at 532 nm optical wavelength.'© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.