Showing papers on "Tilt (optics) published in 1997"

Octahedral Tilting in Perovskites. II. Structure Stabilizing Forces

Abstract: The 23 Glazer tilt systems describing octahedral tilting in perovskites have been investigated. The various tilt systems have been compared in terms of their A-cation coordination and it is shown that those tilt systems in which all the A-cation sites remain crystallographically equivalent are strongly favored, when all the A sites are occupied by the same ion. Calculations based on both ionic and covalent models have been performed to compare the seven equivalent A-site tilt systems. Both methods predict that when the tilt angles become large, the orthorhombic a+b−b− tilt system will result in the lowest energy structure. This tilt system gives the lowest energy structure because it maximizes the number of short A—O interactions. The rhombohedral a−a−a− tilt system gives a structure with a slightly lower Madelung energy, but increased ion–ion repulsions destabilize this structure as the tilt angles increase. Consequently, it is stabilized by highly charged A cations and small to moderate tilt angles. The ideal cubic a0a0a0 tilt system is only observed when stabilized by oversized A cations and/or M—O π-bonding. Tilt systems with nonequivalent A-site environments are observed when at least two A cations with different sizes and/or bonding preferences are present. In these compounds the ratio of large-to-small cations dictates the most stable tilt system.

Scanning optical device

Abstract: A scanning optical device includes a light source having a plurality of light emitting points, a deflector for deflecting a plurality of light beams emitted from the light source, and an optical system for guiding the plurality of light beams emitted from the light source onto a surface to be scanned. In the scanning optical device, a predetermined condition is satisfied among a light emitting interval between the plurality of light emitting points, a tilt angle of the plurality of light emitting points, juxtaposed in the main scanning direction, and inclined in the sub scanning direction about the optical axis as the center, the beam interval of the plurality of light beams on the surface to be scanned, and imaging magnifications of the optical system in the main and sub scanning directions.

Hand-held image display device

Abstract: A hand-held image display device (10) has a display (12) and at least one sensor (14, 16) responsive to an angle of tilt of the device (10). The tilt of the device is used to effect a scrolling function of the display (12).

Effect of Pco2 Changes Induced by Head-Upright Tilt on Transcranial Doppler Recordings

Abstract: Background and Purpose Transcranial Doppler (TCD) monitoring of mean blood flow velocity (mV) during head-upright tilt can allow testing of cerebral autoregulation. Nonetheless, head-upright tilt can induce changes in the ventilation-perfusion relationship and/or respiratory activity that might influence TCD data. Methods Forty-eight healthy volunteers underwent monitoring of mV and end-tidal CO2 in the horizontal position and during head-upright tilt. Results Both mV and end-tidal CO2 significantly decreased in orthostasis ( P <.01). Linear regression analysis showed a significant linkage between end-tidal CO2 and mV changes ( r =.83, P <.01). Conclusions Changes in ventilation-perfusion ratio and in the respiratory pattern induced by head-upright tilt can significantly influence TCD data by determining a Pco2 decrease.

Tilt-scrolling on the sunpad

Abstract: Scrolling techniques for computing devices are disclosed which respond to the amount of tilt, measured against a reference, experienced by a control unit. The user set the reference by activating a switch while the control unit is in an orientation selected by the user. Once the reference is set, the direction and rate of scrolling is determined by the direction and amount of tilt. The control unit may be built into a hand held computing device such as the Sun Pad.

Experimental study of the effect of non-Kolmogorov stratospheric turbulence on star image motion

Abstract: The effect of non-Kolmogorov stratospheric turbulence on star image motion is for the first time experimentally investigated with a ground-based telescope. A new approach permitting isolation of star image motion induced solely by atmospheric turbulence is employed. In this technique Polaris image wander is recorded with the telescope bolted in place to minimize uncontrolled telescope motion. High resolution temporal and spatial statistics of wave-front tilt are obtained. The dependencies of tilt variance, tilt power spectra, and tilt temporal correlation on telescope diameter are investigated for five apertures in the range 0.1-1.5 m. The experimental data show the dependence of tilt variance on telescope diameter does not follow the predictions of the Kolmogorov and von Karman models. The graph of the measured dependence has a “knee” which can be explained only by assuming a non-Kolmogorov stratospheric turbulence effect. The difference between tilt components in different axes indicates anisotropy in stratospheric turbulent inhomogeneities. The slopes of the measured tilt power spectra, approximately -1 in the low frequency range and -8/3 in the high frequency range, do not agree with theoretical predictions. The measured tilt temporal correlation scale is in the range 0.1-1.0 s, and the behavior of the correlation coefficients indicates the effect of large scale inhomogeneities not predicted by the conventional model. Uncontrolled telescope motion is manifested as a “bump” in the tilt power spectra in the range 70-90 Hz, but this makes an insignificant contribution to Polaris jitter variance.

Measurement of astigmatism by automated infrared photoretinoscopy

Abstract: :Background.There are basically two possibilities to measure cylindrical refractive errors by eccentric photorefraction. The first is to determine the size and the tilt of the light crescent in the subject's pupil. Sphere, cylinder, and axis can be obtained from two pictures with the knife e

Interfaces of modulated phases

Abstract: Numerically minimizing a continuous free-energy functional which yields several modulated phases, we obtain the order-parameter profiles and interfacial free energies of symmetric and nonsymmetric tilt boundaries within the lamellar phase, and of interfaces between coexisting lamellar, hexagonal, and disordered phases. Our findings agree well with chevron, omega, and T-junction tilt-boundary morphologies observed in diblock copolymers and magnetic garnet films.

Active Dual Mode Tilt Control for Narrow Ground Vehicles

Abstract: SUMMARY Small, narrow commuter vehicles have attracted considerable interest in recent years as a means to increase the utilization of existing freeways and parking facilities. However, conventional narrow track vehicles are likely to have reduced stability against overturning during hard cornering. A possible solution to this problem lies in vehicles which tilt toward the inside of a turn. Two different ways to achieve this tilt will be analyzed. For direct tilt control (DTC) an actuator forces the upper part of the vehicle to tilt. Steering tilt control (STC) uses steering to control the tilt as is done by motorcycle or bicycle riders. At low speeds, only the DTC system is effective while at high speeds the STC offers less lateral acceleration for the passenger during transient cornering and may seem more natural. The two methods of control will be studied separately and it will be shown that even though the same steady state tilt can be achieved with either system, the transient behavior of the systems...

Focus spot detection method and system

Abstract: A method and system for detecting focus spots. Data from a file created during stepper operation is extracted to get field coordinate position, leveling scheme, and tilt with respect to the x- and y-axes, and wafer height with respect to the focal plane for the multiple fields on the multiple wafers in a production batch. A delta value is calculated for the x- and y-axes tilt data which averages the tilt of each field with its surrounding fields. Delta values are placed in a 3-dimensional data structure linking neighboring fields and corresponding fields on subsequent wafers. Focus spots are detected by the repeated presence of data spikes over the sum of the arithmetic mean and some multiple of the standard deviation of the delta values.

Pan/tilt support with concentric drive shafts

Abstract: A pan/tilt device consists of a pan motor and a tilt motor on a motor mount structure, a camera mount structure rotatable by the pan motor about the pan axis, a camera bracket on the camera mount structure rotatable by the tilt motor along the tilt axis. A pair of concentric drive shafts extend from the motor mount structure to the camera mount structure to accomplish the pan and tilt functions. The pan/tilt device is capable of remote operation over a computer network.

High-Order Interior Caustics Produced in Scattering of a Diagonally Incident Plane Wave by a Circular Cylinder

Abstract: We examine scattering of a family of initially parallel diagonally incident rays by a dielectric circular cylinder and show that the interior and exterior caustics that occur are qualitatively identical to those produced at normal incidence. We find, however, that (1) varying the plane-wave tilt angle has the same effect on the caustics as varying the refractive index of the cylinder at normal incidence and (2) high-order interior caustics are visible because of larger internal-reflection Fresnel coefficients at diagonal incidence than at normal incidence. We also observe noncaustic ray trajectories produced by the sharp peaking of internal-reflection Fresnel coefficients at large ray impact parameters, as well as another class of internal caustics produced by scattering from inhomogeneities in our glass cylinder.

Focus and tilt adjusting system for lithography aligner, manufacturing device or inspection device

Abstract: PROBLEM TO BE SOLVED: To realize a focus and tilt adjusting system which enables high- precision focus control and high precision tilt control by a method wherein the position of the principal surface of a substrate in the z-direction is detected in the scanning direction, a direction intersecting the scanning direction, and a direction intersecting the scanning direction from the image forming direction respectively, and a focus of an image projected onto the substrate is adjusted basing on the detection values. SOLUTION: Forcus detecting systems GDL and GDR are each equipped with focus detection points positioned in front and at the rear of an imaging field, respectively, with respect to the direction of a scanning movement of a wafer W in scanning projection aligner. Seeing from above the surface (XY plane) of a wafer W, a focus detecting system GDC is equipped with a detection point located in a non-scanning direction vertical to the scanning direction of the imaging field of a 1/4 reduction projection lens PL. Z actuators 32A, 32B, 32C are driven by an optimal distance by an AF control unit 38 basing on the detection data supplied from the focus detection systems GDL, GDR and GDC.

Generating f0 contours for speech synthesis using the tilt intonation theory.

Abstract: This paper presents a method for generating F 0 contours for a speech synthesis system using the Tilt intonation theory ((10], 9]). The Tilt theory ooers an abstract description of natural F 0 contours which may be derived automatically from natural speech. Given a speech database labelled with Tilt events, this paper shows how that data may be used to train a model which can adequately predict Tilt parameters from features available in a text to speech system and hence produce natural sounding F 0 contours. After a short description of the Tilt theory, the database used and the necessary features used to generate the parameters are presented. For comparison , this work is contrasted with a previous similar experiment on the same database using the ToBI intonation labelling system 2]. The Tilt method not only produces better results (RMSE 32.5 and correlation 0.60) but as it ooers automatic labelling of data, it promises the ability to more easily train from general speech databases. In the task of rendering natural sounding speech from raw text, one of the many tasks is generating natural sounding intonation. A number of intonation theories have been utilised in various systems to try to do this task. As the quality of speech synthesis improves, a greater demand is put on the intonation system to produce more varied intonation tunes. Because of this demand, and the requirement to quickly and easily add new voices and new accents to our systems, intonation systems should be train-able, where appropriate, from natural speech data. ToBI 7] ooers a well-deened intonation phonology for labelled speech. It is probably still the most widely available standard labelling system. The ToBI labelling system itself does not deene a mechanism to go from the labels to an F 0 contour, or the reverse. However there are both hand written rule systems (e.g. 1]) and statistically trained methods (e.g. 2]) which do this task. The Tilt intonation theory has been shown to be a good representational method for natural F 0 contours 10] but prior to the work presented here it has not been shown that Tilt parameters could be predicted reliably from text input. Tilt and ToBI typify two major classes of intonation system. Tilt comes from a data-driven approach attempting to form an abstraction of the natural contour but maintaining mechanism to recreate it. ToBI takes a more linguistic or phonological approach specifying …

Method and apparatus for reducing ghost images with a tilted cholesteric liquid crystal panel

Abstract: A collimating apparatus that reduces ghost images in the field of view of a main image generated. The collimating apparatus includes a meniscus lens having a reflective concave surface; a cholesteric liquid crystal (CLC), aligned on an axis common with the meniscus lens, disposed on the concave side of the meniscus lens, positioned to reflect light onto the concave surface and having a tilt making the normal of the CLC different from the normal of the meniscus lens; and an image source, disposed on the convex side of the meniscus lens and having a tilt corresponding to the tilt of the CLC. The tilted pair of the meniscus and image source direct any ghost images produced by light leaking through the CLC away from the line of sight of an observer of the main image.

Computed tomography scanning apparatus and method for generating parallel projections using non-parallel slice data

Abstract: A nutating slice CT image reconstruction apparatus and method generates a set of projection data using helical cone-beam scanning. The three-dimensional projection data is used to reconstruct a series of planar image slices. The slices are selected such that they define a tilt angle and a rotation angle with respect to the longitudinal axes of the object being scanned. Successive slices have equal tilt angles but changing rotation angles such that normal axes of successive slices define a nutation and precession about the longitudinal axis of the object. Projection data for the tilted slices are formed of selected one-dimensional fan-beam data. As such, the projection data can be applied to conventional two-dimensional reconstruction approaches to generate an image. The projection data can also be used to generate two-dimensional projection images at one or more stationary projection angles through an object being scanned. The nutation or tilt of image volume elements can be compensated for to provide a more accurate image and more accurate target assessment such as accurate total mass determination. A parallel processing architecture can be used to generate and process the nutated slices with improved efficiency.

Ultra-high tilt specimen cryotransfer holder for electron microscope

Abstract: An ultra-high tilt cryotransfer holder is provided which is capable of rotating a specimen through a full 360° tilt angle (180° from horizontal in both clockwise and counterclockwise directions) without spillage of cryogenic liquid, and while maintaining proper protection and cooling of the specimen. The cryotransfer holder includes a holder body having a specimen tip and a source of cooling for the specimen tip. The specimen tip includes a specimen grid of a thermally conductive material which has a plurality of grid openings between crossing grid bars. The grid may be extended from the holder into a forward viewing position or retracted into a protected position within a cryoshield.

Wave-front aberration compensation unit, wave-front aberration compensation device, and optical pickup

Abstract: An LCD panel will rotate based on an external control signal by a prescribed angle such portion of light flux, that enters an objective lens, corresponding to a predetermined incident point and, at the same time, will change by a prescribed length an optical path of this portion of optical flux whose aberrations are in excess of a prescribed standard value. It is thus possible to compensate the wave-front aberrations due to the differences in the effective optical-path length and also to control the effective numerical aperture of the objective lens by utilizing linearly polarized light as the light to be emitted from the laser beam source. It is also possible to compensate the aberrations due the differences in the substrate thickness of the optical recording medium and those due to a tilt of the optical recording medium.

Tilt sensing device and method for its operation

Abstract: A tilt sensing device and method for its operation, the device being of the type comprising (a) a housing, (b) a radiation transmitter and a radiation receiver arranged in or at the housing to form a beam path therebetween, (c) a radiation obstructing or deflecting body movable in relation to the beam path and (d) a rest surface for the body defining at least two possible rest positions for the body relative to the beam path between which rest positions the body can move by gravity at defined tilt angles for the device and which rest positions are selected to give a detectable output difference from the radiation receiver depending on which of the rest positions is occupied by the body. The size of the movable body, expressed as the diameter of a sphere of corresponding volume, is less than 10mm. Operation of the device includes monitoring the output from the receiver to obtain an amplitude versus time function and processing data from the function to obtain a modified signal.

Identification of Cutter Axis Tilt in End Milling

Abstract: The scope of the paper is to discuss the identification of cutter axis tilt in end milling process via cutting force analysis. Cutter axis tilt redistributes the chip load among flutes thereby generating minor frequency components of cutting forces. These minor components can be utilized to infer the tilt geometry during the cutting action. This study involved the mathematical representation of chip thickness variation due to tilt, the modeling of local forces in relation to instantaneous chip thickness, the formulation of total cutting forces through convolution integration in the angle domain, the derivation of dynamic force components in the frequency domain, and the solution for tilt geometry from the dynamic cutting forces. Results show that the tilt magnitude and orientation can be estimated given the dynamic cutting force components along with the tool/work geometry, cutting parameters, and machining configuration. Numerical simulation results confirmed the validity of the angle domain convolution approach, and the end milling experimental data agreed with the analytical model.

Optical apparatus for determining the height and tilt of a sample surface

Abstract: A device is provided for determining the height and/or tilt of local features on the surface of a sample. The device includes a laser projecting a collimated beam at an oblique angle at a reflection point on the sample surface and a converging lens having an optical axis extending at an angle of reflection equal to the angle of incidence from the reflection point. The focusing characteristics of the lens are used to separate the deflection of the reflected collimated beam due to tilt of the surface from such deflection due to linear displacement of the surface.

Dual Focus Optical Head with a Hologram-Integrated Lens

Abstract: A dual focus optical head with a holographic optical element (HOE) that can read both 0.6 mm disks and 1.2 mm disks has been developed. To ensure practicality and mass-producibility of the head, we examined servo-signal characteristics and evaluated allowable ranges for the misalignment of the HOE, the wavelength deviation, the disk tilt angle and the defocus distance. It was found that stable servo operation can be obtained and that except for the issue of coma aberration, the allowable ranges are wide enough for mass-production. When an objective lens having initial coma aberration is used with a plane-type HOE, coma aberration still remains for the 1.2 mm disk after performing skew adjustment for the 0.6 mm disk. We found that the aberration can be reduced by integrating an HOE with the objective lens on its first surface.

Tilt servo apparatus for use in optical disc reproducing apparatus

Abstract: A tilt servo apparatus in an optical disc reproducing apparatus operates promptly and certainly when reading recording information of an optical disc recorded at high density. The tilt servo apparatus is used in an optical disc reproducing apparatus having an optical pickup including a liquid crystal panel for an aberration correction on which a transparent electrode is formed and divided into segments of predetermined shapes, and irradiating a laser beam via the liquid crystal panel for the aberration correction and the objective lens, and receiving an obtained reflection light. The tilt servo apparatus has: tilt detecting for detecting a signal corresponding to a tilting angle in a radial direction between the information recording surface of the optical disc and an optical axis of the objective lens; and a driving circuit for variably driving voltages which are applied to the divided portions of the liquid crystal panel, respectively. The driving circuit drives so that predetermined voltages are applied to the respective divided segments of the liquid crystal panel according to a detection output of the tilt detecting and a phase difference between respective laser beams passing through the divided portions is adjusted, thereby correcting the aberration of the objective lens inclined at the tilting angle relative to the information recording surface of the optical disc.

Investigations on the field-induced switching behaviour in an antiferroelectric liquid crystal

Abstract: The switching currents and field-induced apparent tilt angles in an antiferroelectric liquid crystal, (R)-MHPOBC, were measured. The structural differences among different smectic C* subphases may sensitively reflect the field or temperature dependence of the apparent tilt angle. In a thin cell, the apparent tilt angle was found to change in two steps as a function of field strength in the SmC*alpha and SmC* phases: a steep increase at lower fields and a small linear increase at higher fields. The steep increase in apparent tilt angle is divided into two parts via a plateau in the ferrielectric SmC*gamma phase. Stepwise change with a plateau is also seen in the relation of apparent tilt angle versus temperature under various electric fields. Moreover, the apparent tilt angle in the vicinity of the plateau is almost temperature- and field-independent, implying a preferred orientation of the molecules in the ferrielectric state. The influence of the cell thickness on the structural changes was also investig...

Analysis of integrated optical waveguide mirrors

Abstract: A new method is presented to analyze reflection losses of integrated mirrors, taking into account the exact guided mode profile and assuming that this profile remains unchanged up to the reflecting plane. The fraction of the reflected light coupled to one of the guided modes of the output waveguide is calculated, taking into account the mirror reflection coefficient. The influence of both translation and tilt of the reflecting plane is investigated. The method applies for every guided mode and any reflection angles. Numerical calculations are derived for a 90/spl deg/ optical corner mirror.

Multislice Method for Large Beam Tilt with Application to HOLZ Effects in Triclinic and Monoclinic Crystals

Abstract: Three existing multislice formulations (MS) that are claimed to be applicable for large beam tilt are introduced in a unified form and the validity of these formulations for large beam tilt is evaluated. It is shown that one formula, which is called MSSBT (the MS for small beam tilt), is valid only for tilt angles less than 6°, but the second one, which is called MSLBT (the MS for large beam tilt), can be used for tilt angles as large as 20°, while the third one yields results very close to the MSLBT results for tilt angles up to 12°. Simulations also show that the accuracy of the MSLBT is independent of the scattering power of the atoms. The reasons for the inaccuracy of these multislice formulations for beam tilt (MSBT) and the differences between the three MSBT formulations are discussed based on the complete Schrodinger equation, which includes back-scattering effects. For calculating the higher-order Laue-zone (HOLZ) effects from triclinic and monoclinic crystals, it is pointed out that the slices have to be cut parallel to the ab plane of the crystal and MSBT formulations should be used. The computational formulations for potentials of the crystal slices and the propagator are derived based on the transformations between the crystallographic coordinate system and the working coordinate system. Calculations of the HOLZ reflections for the monoclinic crystal Na2Ti3O7 [001] are carried out. It is shown that for triclinic and monoclinic (when the beam direction is along the c axis) crystals HOLZ effects dynamically influence not only the intensity but also the symmetry of zero-order Laue-zone (ZOLZ) diffraction patterns. Hence, in that case, the projection approximation for simulating the HRTEM images may not be used.