Showing papers on "Tilt (optics) published in 2009"

Tilt techniques: investigating the dexterity of wrist-based input

Abstract: Most studies on tilt based interaction can be classified as point-designs that demonstrate the utility of wrist-tilt as an input medium; tilt parameters are tailored to suit the specific interaction at hand. In this paper, we systematically analyze the design space of wrist-based interactions and focus on the level of control possible with the wrist. In a first study, we investigate the various factors that can influence tilt control, separately along the three axes of wrist movement: flexion/extension, pronation/supination, and ulnar/radial deviation. Results show that users can control comfortably at least 16 levels on the pronation/supination axis and that using a quadratic mapping function for discretization of tilt space significantly improves user performance across all tilt axes. We discuss the findings of our results in the context of several interaction techniques and identify several general design recommendations.

A comprehensive study of the phase diagram of KxNa1−xNbO3

Abstract: The phase diagram of lead-free piezoelectric KxNa1−xNbO3 has been studied, with particular focus on the proposed morphotropic phase boundaries, by powder and single crystal x-ray diffraction. The tilt system and cation displacement has been mapped out as a function of temperature and composition, highlighting changes in the oxygen octahedra at x=0.2 and x=0.4 at room temperature. The orthorhombic to monoclinic boundary at x=0.5 has been investigated, with a subtle change in the structure observed. The conclusion is that KxNa1−xNbO3 does not display a morphotropic phase boundary comparable with that in lead zirconate titanate, and that the most significant structural change as a function of composition occurs at x=0.2 because of the change of the tilt system.

Optimization of Tilt Angle for Solar Collector to Receive Maximum Radiation

Abstract: This article examines the theoretical aspects of choosing a tilt angle for the solar flat-plate collectors used at ten different stations in the world and makes recommendations on how the collected energy can be increased by varying the tilt angle. In this paper, the collector surface is assumed to be facing toward equator. For Indian stations, the calculations are based upon the measured values of monthly mean daily global and diffuse solar radiation on a horizontal surface. For other stations, the calculations are based upon the data of monthly mean daily global solar radiation and monthly average clearness index on a horizontal surface. It is shown that nearly optimal energy can be collected if the angle of tilt is varied seasonally, four times a year. Annual optimum tilt angle is found to be approximately equal to latitude of the location. It is found that the loss in the amount of collected energy is around 1 % if the angle of tilt is adjusted seasonally instead of us- ing  opt for each month of the year. The loss of energy when using the yearly average fixed angle is around 15 % com- pared with the monthly optimum tilt.

An Electrothermal Tip–Tilt–Piston Micromirror Based on Folded Dual S-Shaped Bimorphs

Abstract: This paper presents the design, optimization, fabrication, and test results of an electrothermally actuated tip-tilt-piston micromirror with a large optical aperture of 1 mm. The fabrication of the device is a combination of thin-film surface micromachining and bulk silicon micromachining based on silicon-on-insulator wafers. The device has 3-DOF of actuations, including rotations around two axes in the mirror plane, and out-of-plane piston actuation. The micromirror shows an optical scan range of plusmn30deg about both x- and y-axes and displaces 480 mum in the z-axis, all at dc voltages that are less than 8 V. Dynamic testing of the micromirror shows that the thermal response time of each actuator is about 10 ms. Resonant frequencies of the piston and rotation motion are 336 and 488 Hz, respectively. The unique structural design of the device ensures that there is no lateral shift for the piston motion and no rotation-axis shift for the rotation scanning. With the large tip-tilt-piston scan ranges and low driving voltage, this type of device is very suitable for biomedical imaging and laser beam steering applications.

Adaptive Array of Phase-Locked Fiber Collimators: Analysis and Experimental Demonstration

Abstract: We discuss development and integration of a coherent fiber array system composed of densely packed fiber collimators with built-in capabilities for adaptive wavefront phase piston and tilt control at each fiber collimator. In this system, multi-channel fiber-integrated phase shifters are used for phase locking of seven fiber collimators and the precompensation of laboratory-generated turbulence-induced phase aberrations. Controllable x and y displacements of the fiber tips in the fiber collimator array provide additional adaptive compensation of the tip and tilt phase aberration components. An additional control system is utilized for equalization of the intensity of each of the fiber collimator beams. All three control systems are based on the stochastic parallel gradient descent optimization technique. The paper presents the first experimental results of adaptive dynamic phase distortion compensation with an adaptive phase-locked fiber collimator array system.

Tilt and decentration of spherical and aspheric intraocular lenses: Effect on higher-order aberrations

Abstract: Purpose To determine the impact of spherical and aspheric foldable intraocular lens (IOL) tilt and decentration on optical quality after cataract surgery in an intraindividual comparative study. Setting Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany. Methods Randomized implantation of a spherical IOL (Sensar AR40e) was performed in 1 eye and of an aspheric IOL with negative spherical aberration (Tecnis Z9000) in the contralateral eye. Three to 4 months postoperatively, the wavefront was measured and higher-order aberrations (HOAs) were calculated for virtual pupil diameters of 3.5 mm and 6.0 mm. Tilt and decentration of the IOLs were measured using Scheimpflug photography. The tilt and decentration, HOAs, and best corrected visual Strehl ratio of the optical transfer function (BCVSOTF) calculated from the wavefront aberration were compared. The effect of tilt and decentration on HOAs and optical quality was assessed using multiple regression analysis. Results The mean optic tilt was 2.89 degrees ± 1.46 (SD) for the spherical IOL and 2.85 ± 1.36 degrees for the aspheric IOL. The mean optic decentration was 0.19 ± 0.12 mm and 0.27 ± 0.16 mm, respectively. No significant intergroup differences in IOL tilt or decentration were found. Tilt and decentration did not significantly affect the BCVSOTF with either IOL. Conclusions The amounts of tilt and decentration of both IOLs were not large enough to cause deterioration of optical quality. Thus, when IOL tilt and decentration are within normal limits, they do not compromise the correction of spherical aberration by the aspheric IOL.

The Tilt of the Halo Velocity Ellipsoid and the Shape of the Milky Way Halo

Abstract: A sample of roughly 1,800 halo subdwarf stars with radial velocities and proper motions is assembled, using the repeated multi-band Sloan Digital Sky Survey photometric measurements in Stripe 82. Our sample of halo subdwarfs is extracted via a reduced proper motion diagram and distances are obtained using photometric parallaxes, thus giving full phase space information. The tilt of the velocity ellipsoid with respect to the spherical polar coordinate system is computed and found to be consistent with zero for two of the three tilt angles, and very small for the third. We prove that if the inner halo is in a steady-state and the triaxial velocity ellipsoid is everywhere aligned in spherical polar coordinates, then the potential must be spherically symmetric. The detectable, but very mild, misalignment with spherical polars is consistent with the perturbative effects of the Galactic disk on a spherical dark halo. Banana orbits are generated at the 1:1 resonance (in horizontal and vertical frequency) by the disk. They populate Galactic potentials at the typical radii of our subdwarf sample, along with the much more dominant short-axis tubes. However, on geometric grounds alone, the tilt cannot vanish for the banana orbits and this leads to a slight, but detectable, misalignment. We argue that the tilt of the stellar halo velocity ellipsoid therefore provides a hitherto largely neglected but important line of argument that the Milky Way's dark halo, which dominates the potential, must be nearly spherical.

Mobile device with wide-angle optics and a radiation sensor

Abstract: A method and device for displaying content using an integral or remote controller for navigating the content based on dynamic image analysis of the motion of the controller, for example, by tilting. The controller is equipped with wide-angle optics and with a radiation sensor detecting either visible light or infrared radiation. The wide-angle optics may be directed towards the user, whereupon the radiation sensor receives useful images through the wide-angle optics. The images include contrast or thermal differences which it make possible to determine in which way the user has moved the controller. In more detail, a tilt angle or a corresponding change can be calculated and then, on the basis of the change, the content shown on a display is altered. The content is, for example, a menu, game scene or a web page.

Real-ray-based method for locating individual surface aberration field centers in imaging optical systems without rotational symmetry.

Abstract: It has been found that the field dependence of the aberrations of misaligned optical systems made of otherwise rotationally symmetric optical surfaces are often multinodal, including low-order astigmatism and distortion and higher-order coma, astigmatism, oblique spherical, elliptical coma (trifoil), and distortion. The exact location of the nodes in the image is a weighted sum of individual surface contributions. The location of the center of rotational symmetry for the field dependence for all aberrations contributed by a particular rotationally symmetric surface is along the line that connects the center of curvature of the surface with the center of the pupil. Previously, a paraxial ray-trace method was developed to locate the aberration field center for a series of rotationally symmetric surfaces with small tilt and decenter perturbations. The method is based on rotating the coordinate system into the local coordinate system of the surface and then advancing using the conventional paraxial ray-trace equations. This method, developed by Buchroeder [Ph.D. dissertation (University of Arizona, 1976)], heavily constrains how tilts and decenters were implemented in the optical system model, which prevented integration of these equations into an optical design environment. In this paper, a method for locating the aberration field centers using real-ray-trace data that is entirely model independent and, significantly, that is not restricted to small tilts and decenters, is presented. With this new insight, it is now possible to extend any optical design and analysis environment to include multinodal aberration analysis.

The tilt of the halo velocity ellipsoid and the shape of the milky way halo

Abstract: A sample of ~1800 halo subdwarf stars with radial velocities and proper motions is assembled from Bramich et al.'s light-motion catalog of 2008. This is based on the repeated multiband Sloan Digital Sky Survey photometric measurements in Stripe 82. Our sample of halo subdwarfs is extracted via a reduced proper motion diagram and distances are obtained using photometric parallaxes, thus giving full phase-space information. The tilt of the velocity ellipsoid with respect to the spherical polar coordinate system is computed and found to be consistent with zero for two of the three tilt angles, and very small for the third. We prove that if the inner halo is in a steady state and the triaxial velocity ellipsoid is everywhere aligned in spherical polar coordinates, then the potential must be spherically symmetric. The detectable, but very mild, misalignment with spherical polars is consistent with the perturbative effects of the Galactic disk on a spherical dark halo. Banana orbits are generated at the 1:1 resonance (in horizontal and vertical frequencies) by the disk. They populate Galactic potentials at the typical radii of our subdwarf sample, along with the much more dominant short-axis tubes. However, on geometric grounds alone, the tilt cannot vanish for the banana orbits and this leads to a slight, but detectable, misalignment. We argue that the tilt of the stellar halo velocity ellipsoid therefore provides a hitherto largely neglected but important line of argument that the Milky Way's dark halo, which dominates the potential, must be nearly spherical.

Tilt aftereffects and tilt illusions induced by fast translational motion: evidence for motion streaks.

Abstract: Fast-moving visual features are thought to leave neural 'streaks' that can be detected by orientation-selective cells. Here, we tested whether 'motion streaks' can induce classic tilt aftereffects (TAEs) and tilt illusions (TIs). For TAEs, participants adapted to random arrays of small Gaussian blobs drifting at 9.5 deg/s. Following adaptation to directions of 15, 30, 45, 60, 75, and 90 degrees (clockwise from vertical) subjective vertical was measured for a briefly presented test grating. For TIs, the same motions were presented in an annular surround and subjective vertical was measured for a simultaneously presented central grating. All motions were 50% coherent, with half the blobs following random-walk paths and half following a fixed direction. Strong and weak streaks were compared by varying streak length (the number of fixed-walk frames), rather than by manipulating speed, so that speed and coherence were matched in all conditions. Strong motion streaks produced robust TAEs and TIs, similar in magnitude and orientation tuning to those induced by tilted lines. These effects were weak or absent in weak streak conditions, and when motion was too slow to form streaks. Together, these results indicate that motion streaks produced by temporal integration of fast translating features do effectively adapt orientation-selective cells and may therefore be exploited to improve perception of motion direction as described in the 'motion streaks' model.

Effect of tool tilt angle on machining strip width in five-axis flat-end milling of free-form surfaces

Abstract: This paper examines the effect of tool tilt angle on machining strip width in the determination of optimal tool orientation and feed direction in five-axis flat-end milling. The machining strip width is evaluated using the swept profile of the flat-end mill, avoiding both local and global gouging of the tool. An optimization problem is formulated to maximize the machining strip width over feasible gouge-free tool orientations for a constant-feed direction. By solving the optimization problem and analyzing the geometry of the machining strip width, it is shown that identifying the optimal tool tilt angle, instead of following the common practice of setting the tool tilt angle as zero, can significantly increase the machining strip width, especially for 3D free-form surface machining. The optimization has also been extended to identify the optimal feed direction that maximizes the machining strip width at a given cutter contact (CC) point. The minimum curvature direction has been considered as the optimal feed direction at a CC point by researchers. Our results indicate that although the minimum curvature direction is mostly not the optimal feed direction in free-form surface machining, the minimum curvature direction does represent a good approximation of the optimal feed direction at a CC point, in particular for a free-form surface with low-curvature relative to the tool size.

Microwave generation of tilted-polarizer spin torque oscillator

Abstract: Microwave frequency generation in a spin torque oscillator (STO) with a tilted fixed layer magnetization is studied using numerical simulation of the Landau–Lifshitz–Gilbert–Slonczewski equation. The dependence of the STO free layer precession frequency on drive current is determined as a function of fixed layer tilt angle. We find that zero-field STO operation is possible for almost all tilt angles, which allow for great freedom in choosing the detailed layer structure of the STO.

Remote electrical tilt antenna with motor and clutch assembly

Abstract: RET antenna with motor and clutch assembly that is operative to mechanically disengage the DC motor and drive unit (also called the gear-motor unit) from the phase shifter adjustment shaft during a manual tilt operation. Disengaging the gear- motor unit removes the drag of the motor and the high gear ratio gear box from the phase shifter control rod making it easier to manually turn the phase shifter control knob. In addition, the clutch disengages the gear-motor without disengaging the position detector from the phase shifter control rod so that position calibration is not lost during manual tilt adjustment. When the manual tilt operation is completed, the mechanical tilt clutch enables the gear-motor unit to be reliably re-engaged with the phase shifter control rod for motorized electrical tilt operation without having to re¬ calibrate the position detector.

Use of power tilt systems in everyday life.

Abstract: Purpose. The goal of this study was to monitor and describe the use of power tilt systems in everyday life. Additionally, tilt measurements were used to determine if participants performed regular pressure reliefs.Methods. Wheelchair occupancy and seat position of 16 fulltime power wheelchair users were monitored regularly for 1–2 weeks. Daily wheelchair occupancy, typical position, time spent at different tilt angles, tilt frequency and pressure relieving tilt (PRT) frequency were described.Results. Participants used their tilt systems in many different ways, including subjects who typically sat at small (0–14°) tilt angles and subjects who typically sat at medium (15–29°) tilt angles. Few subjects tilted past 45°. Almost all subjects tilted throughout the day, with the median subject performing >3 tilts per hour of wheelchair occupancy. Despite the regular use, few subjects performed regular PRTs (median = 0.13/h)Conclusion. Differences in tilt-use illustrated the variability in function and activity am...

Keystone correction derived from the parameters of projectors

Abstract: A projector determines horizontal and vertical tilt angles. Using the tilt angles and the inherent properties of the projector, keystone correction corner points for the image can be computed. The keystone correction corner points can be used to perform keystone correction on the image.

Optimal design of discrete-value tilt angle of PV using sequential neural-network approximation and orthogonal array

Abstract: This report presents a method for combining sequential neural-network approximation and orthogonal arrays (SNAOA) to determine the tilt angle for photovoltaic (PV) modules. An orthogonal array is first conducted to obtain the initial solution set. The set is then treated as the initial training sample. Next, a back-propagation sequential neural network is trained to simulate the feasible domain for seeking the optimal tilt angle of PV modules. The size of the training sample is greatly reduced due to the use of the orthogonal array. In addition, a restart strategy is also incorporated into the SNAOA so that the searching process may have a better opportunity to reach a near global optimum. The objective is to maximize the output power energy of the modules. In this study, seven Taiwanese areas were selected for analysis. The sun's position at any time and location was predicted by the mathematical procedure of Julian dating; then, the solar irradiation was obtained at each site under a clear sky. To confirm the computer simulation results, an experimental system is conducted for determining the optimal tilt angle of the PV modules. The results show that the annual optimal angle for the Taipei area is 23.25^o; for Taichung, 22.25^o; for Tainan, 21.25^o; for Kaosiung, 20.75^o; for Hengchung, 20.25^o; for Hualian, 22.25^o; and for Taitung, 21^o in Taiwan, and the actual best annual tilt angles are close to the computer simulation results. Additional results related to SNAOA are also reported and discussed as well.

Dipole tilt effects in plasma sheet B y : statistical model and extreme values

Abstract: . With 11 years of Geotail measurements we construct a model of plasma sheet By, depending on IMF By, coordinates X,Y and geodipole tilt angle. At midnight and pre-midnight local times By is positively correlated with tilt (positive in summer). Thus in summer By is shifted towards positive values and in winter towards negative values, so that up to several nT could be added to the IMF influence. The dawn side plasma sheet By generally does not exhibit any tilt dependence, but within 15 RE the weaker negative correlation with tilt was revealed. The tilt dependence is just a useful parametrization and several mechanisms actually affecting plasma sheet By were previously suggested. In particular, similar coupling between tilt and IMF By was earlier found in the ionospheric convection patterns. Besides this average response, extreme By (|By|>5 nT, By>IMF By) were often observed (up to 20–25% of cases during solar maximum and in the pre-midnight sector within 20 RE). They can not be explained by our statistical model and are preliminary interpreted as an "over-reaction" of the magnetosphere in some individual events. Large By field radically changes dynamics of the current sheet and has to be taken into account during substorm-related studies.

Temperature-insensitive FBG tilt sensor with a large measurement range

Abstract: A novel two-dimensional tilt sensor with a large measurement range is demonstrated by using four fiber Bragg gratings (FBGs) attached on a cylindrical cantilever-based pendulum. Experimental results show that tilt accuracy of ±0.2° and resolution of 0.013° have been achieved in the range of −40° to 40°. The temperature effect is automatically eliminated without additional temperature compensation elements.

Off-vertical axis rotation of the visual field and nauseogenicity

Abstract: BACKGROUND: Off-vertical axis rotation (OVAR) causes motion sickness which increases with angle of tilt and is most provocative around 0.2 Hz. The aim was to determine the tilt angle and frequency characteristics for visual OVAR, which is also known to be nauseogenic. METHODS: A computerized scene, as seen by a pilot at moderate altitude, rotated at different frequencies about an axis which could tilt as during OVAR. A concurrent visual detection task controlled attention. Exposures were for 10 min or until nausea developed. There were four experiments: Frequency tuning-visual motion at 0.05, 0.2, and 0.8 Hz, all at 18 degrees tilt of the axis of rotation (N = 14); gross visual tilt tuning-visual motion at 0, 45, and 90 degrees of tilt at 0.2 Hz (N = 12); fine visual tilt tuning -- 18, 36, 54, and 72 degrees tilts at 0.2 Hz (N = 24); and whole-body tilt of the participant at 0, 45, and 90 degrees, viewing rotation about a vertical axis at 0.2 Hz (N = 12). RESULTS: Nauseogenicity was significantly greater at 0.2 Hz than at lower or higher frequencies. Visual tilts 18 degrees to circa 45 degrees were significantly more nauseogenic. No differences were found between whole-body tilts. CONCLUSIONS: Nauseogenicity of visual OVAR peaks around 0.2 Hz, and increases with stimulus strength up to circa 45 degrees tilt, similar to real motion. With higher tilt angles, decreasing nauseogenicity suggests that the visual impact is partially quarantined because the motion would appear patently absurd and not a sensory conflict. Whole-body tilt may have failed to modulate nauseogenicity because of overriding somatosensory cues to Earth vertical.

Vehicular tilt-sensing method and automatic headlight leveling system using the same

Abstract: The present invention discloses a vehicular tilt-sensing method and an automatic headlight leveling system using the same. The method of the present invention comprises steps: using an image capture device to capture an image of the road and obtain at least one instantaneous lane marking line from the image; extending the instantaneous lane marking lines afar to obtain an instantaneous vanishing point; establishing an instantaneous horizontal line passing through the instantaneous vanishing point; calculating from the image the displacement between a datum horizontal line and the instantaneous horizontal line; and calculating the tilt angle with the displacement and the focal length of the image; using the tilt angle to generate a control signal to control level adjusting controllers to adjust headlights, whereby the headlights can provide optimized illumination to enhance night driving safety on a rugged road or in the case that the vehicle is unevenly loaded.

Image display apparatus and control method thereof, and computer program

Abstract: This invention provides a display apparatus which mounts a tilt sensor, and can control whether or not the user makes an image feed operation based on the tilt. An image display apparatus includes a display unit which displays image data recorded in a recording medium, an instruction accepting unit which accepts an instruction to make the image feed operation according to the tilt of the image display apparatus from the user, a tilt detection unit which detects the tilt of the image display apparatus with respect to a predetermined direction, and a display control unit which controls the display unit to display and switch the image data in accordance with a change in tilt detected by the tilt detection unit, when the instruction accepting unit accepts the instruction and the tilt detection unit detects the change in tilt.

Walking robot and method of controlling the same

Abstract: Disclosed are a walking robot and a method of controlling the same, in which impedance control and torso tilt control are achieved complementarily such that impedance can be adjusted according to the tilt of a torso or the tilt of the torso can be adjusted according to the impedance. The method includes measuring a moment of a foot; measuring a tilt of a torso; adjusting the scale of the measured moment based on the tilt of the torso, and controlling the foot based on the scale-adjusted moment; and adjusting the scale of the measured tilt based on a ZMP variation amount of the foot, and controlling the tilt of the torso based on the scale-adjusted ZMP variation amount.

A new method for correcting vehicle license plate tilt

Abstract: In the course of vehicle license plate (VLP) automatic recognition, tilt correction is a very crucial process. According to Karhunen-Loeve (K-L) transformation, the coordinates of characters in the image are arranged into a two-dimensional covariance matrix, on the basis of which the centered process is carried out. Then, the eigenvector and the rotation angle α are computed in turn. The whole image is rotated by −α. Thus, image horizontal tilt correction is performed. In the vertical tilt correction process, three correction methods, which are K-L transformation method, the line fitting method based on K-means clustering (LFMBKC), and the line fitting based on least squares (LFMBLS), are put forward to compute the vertical tilt angle σ. After shear transformation (ST) is imposed on the rotated image, the final correction image is obtained. The experimental results verify that this proposed method can be easily implemented, and can quickly and accurately get the tilt angle. It provides a new effective way for the VLP image tilt correction as well.

Tilt measurements at Vulcano Island

Abstract: A network of tiltmeters has been operational on Vulcano Island for numerous years. At present, the network comprises five functioning borehole stations, four of which are installed at 8-10 m and allow recording very stable, high precision signals with very low noise. We report observations over the last 12 years that illustrate impulsive variations linked to seismicity and long-term (several years) trends in the signals. We suggest a relationship between tilt changes correlated to the strongest regional seismic events and site acceleration; long-term tilt variations analyzed in combination with other ground deformation data seem to represent evidence of a contraction of the La Fossa cone. We also analyzed how the tilt device has the capability to detect possible magma migrations; we considered previous studies that have imaged spatially well-defined levels of magma accumulation beneath La Fossa, and Vulcanello; we concluded that the Vulcano tilt network should be capable of detecting the upward migration of small magma volumes. Finally, we show that no evidence of changes are visible on tilt signals during anomalous degassing episodes (linked to a building up input of magmatic fluids) at the La Fossa thereby evidencing that no magma migration occurred during such events.

Scanning microscopy using a short-focal-length Fresnel zone plate.

Abstract: We demonstrate a form of scanning microscopy using a short-focal-length Fresnel zone plate and a low-NA relay telescope. Owing to a focal length of only 5 microm, the zone plate produces large wavefront tilt and consequently severe vignetting for off-axis illumination. By scanning an optically trapped fluorescent sphere, we measure the vignetted collection region of the zone-plate imaging system. The fluorescence collection efficiency is sharply peaked and has a lateral width of 550 nm, which agrees with numerical simulations.

Focus detection apparatus and control method therefor

Abstract: A focus detection apparatus includes an image sensor including pixels for focus detection for receiving a pair of respective light beams transmitted through different pupil areas of a photographing lens to output a pair of signals; an acquisition unit for acquiring exit window information on the photographing lens; an arithmetic circuit for calculating a tilt for detection area in the detecting position, depending on an image height for a detecting position in which a focus state is detected and on the exit window information; and a calculation unit for calculating the shape of the detection area depending on the calculated tilt, in which the defocus amount is detected on the basis of a phase difference between the pair of signals obtained from pixels for focus detection included in the calculated detection area.