Showing papers on "Tilt (optics) published in 1990"

Adaptive optics for array telescopes using neural-network techniques

Abstract: IMAGES formed by ground-based telescopes are marred by atmospheric 'seeing9. The plane wavefront from an unresolved star is distorted by continually changing turbulent fluctuations in the air's refractive index. Diffraction-limited performance can in principle be recovered through the methods of adaptive optics, in which the instantaneous wavefront shape is sensed and corrected in real-time by deformable optics that cancel the distortion1,2. The highest resolution will be achieved when this technique is applied to multiple-telescope arrays. For such arrays, the biggest errors caused by seeing at infrared wavelengths are the variations in pathlength and wavefront tilt between array elements. We show here that these errors can be derived by an artificial neural network, given only a pair of simultaneous in-focus and out-of-focus images of a reference star formed at the combined focus of all the array elements. We have optimized a neural network appropriate for 2.2-μm wavelength imaging at the Multiple Mirror Telescope in Arizona. Corrections made by moving the beam-combining mirrors will largely recover the diffraction-limited profile, with a resolution of 0.06 arcsec.

In vivo measurement of posterior chamber intraocular lens decentration and tilt.

Abstract: • We report what to our knowledge is the first extensive in vivo clinical study of intraocular lens decentration and tilt. Measurements of posterior chamber intraocular lenses, all implanted by the same surgeon in 89 eyes, showed that decentration and tilt consistently differed between right and left eyes. Lenses tended to decenter superotemporally and tilt with their superonasal edges tipped forward. Decentration magnitude relative to the cornea light reflex axis and line of sight averaged 0.64 mm, with decentration increasing slightly with increased axial length. Average tilt was 6.75°, and the average tilt-induced astigmatism was 0.27 diopter. Tilt magnitude decreased with increased axial length, as did tilt-induced astigmatism and plus sphere.

Asymmetric coherent tilt boundaries formed by molecular beam epitaxy

Abstract: The authors describe a novel system in which low-angle, asymmetric tilt boundaries organise spontaneously under conditions of molecular beam epitaxial growth. In the cases studied, the (1012) surfaces of hexagonal rare earths grow coherently but tilted on the (211) surfaces of BCC transition metals. The main driving forces are interfacial coherency and the relief of long-range epitaxial strain.

Mars: Change in Axial Tilt Due to Climate?

Abstract: The average tilt of Mars' equator with respect to its orbital plane may have increased significantly over the age of the solar system. Obliquity oscillations might have induced changes in the climate, which altered the mass distribution and hence the solar torque on the planet. Viscous deformation attributable to loading by the large polar caps expected at low obliquity may have induced secular changes in the axial tilt. Earth-like effective viscosities can account for virtually the entire present obliquity of 24.4 degrees. Thus the present average tilt of Mars may not be primordial.

Tilt correction system

Abstract: The invention concerns a tilt correction system with at least one pair of cylinder and piston assemblies which are hydraulically operated. The extent of tilt correction is limited by grooves internal to the cylinders of the assemblies which short hydraulic potentials once the pistons of the assemblies have moved from a rest position to a position adjacent the grooves. A preferable arrangement includes connecting each assembly between an anti-roll bar and an axle.

The meandering orbit effect on stabilization of the tilting instability in a field‐reversed configuration

Abstract: The ion kinetic effect in the tilt disruption of a field‐reversed configuration is investigated by means of a three‐dimensional particle simulation. It is found that the tilt disruption is completely suppressed when s≊1, where s measures the number of ion gyroradii over the radial distance between the magnetic separatrix line and the field‐null line. A prolate magnetic well is formed around the field‐null line, in which ions do not execute gyration but meander along the field‐null line. For the case of s≊1 a large number of ions exist in the magnetic well and move on stable orbits around the major axis with an average rotation velocity nearly equal to half the thermal velocity. As s becomes larger than 1, the number of ions in the magnetic well decreases and the stabilization effect is reduced. It is also found that an anisotropy is created in the ion thermal pressure profile owing to the anisotropy of the meandering orbits and that the electric field fluctuation always remains at a low level, and thus the electric field plays no essential role in the tilt stabilization.

Window blind slat ladder and tilt drum

Abstract: A venetian blind tilt drum eliminates the separate staples, crimped sleeves and bullet-like members normally used to connect the vertical legs of a cord tilt ladder to the drum. The tilt drum is of one-piece construction and includes a top surface from which preferably three cord impalement integral barbs extend. A first barb of generally pyramidal shape is positioned on an upper top surface of the drum on the drum vertical centerline, parallel to the longitudinal axis of the drum and with a pointed vertex of the barb extending above that axis. A pair of similar second and third barbs also integral with the drum are offset from the drum vertical centerline, with each pointed vertex also parallel to the drum longitudinal axis but extending in an opposite direction than the first barb. Depending on the particular tilt ladder construction the upper distal ends of the tilt ladder both may be impaled on the first barb or one distal end impaled on the second barb and the other distal end impaled on the third barb. Each barb may includes at least one notch adjacent to its base so as to retain portions of a pierced distal end or ends securely on the tilt drum. After the vertical legs of the tilt ladder have been affixed to the drum barbs, the drum is rotatable by rotary action of a blind slat tilt wand, tilt gearing and a tilt rod shaft.

Two-dimensional OCP wavefront sensor employing one-dimensional optical detection

Abstract: An improved two-dimensional optical centroid processor ("OCP") wavefront sensor is described in which a scanning mirror 146 scans the wavefront of input light 130 to provide a scanned beam 148 (i.e. a portion of the wavefront). The scanned beam 148 is focused on an OCP 168 filter comprising four rows of mask cells. The filtered light emanating from the cells impinges on one-dimensional photodetector devices 192, 198, 202, 206 (i.e. photodetector rows). Thus, the scanning of the wavefront by the scanning mirror provides two-dimensional measurement while employing one-dimensional photodetector devices. Each of the photodetector devices provides an output to a ratio calculator 201 which is used to correct the tilt in the wavefront by driving a deformable mirror (not shown).

Backscattered Electron Imaging

Abstract: Experiment 8.1: E-T Detector Collection Efficiency. The solid angle and efficiency of a specific E-T detector for direct collection of BSEs is: (a) Area, A, of scintillator (cm2) = 1.5 cm2. (b) Distance, r, from specimen to scintillator (cm) = 4 cm. (c) Solid angle, Ω = A/r2 = 1.5/16 = 0.094 steradians. (e) For a specimen set normal to the beam (0° tilt), approximate take-off angle = 45°.

Apparatus for maintaining a disk and optical head in orthogonal relation

Abstract: An optical head which optically records and regenerates data by condensing light beams from a light source on the disk surface, wherein a plurality of piezoelectric elements are arranged to correct the tilt of a condensing lens or the tilt of optical system supporting means for making the optical axis of the condensing lens for condensing light beams on the disk surface or the light beams orthogonal to the disk surface. An optical disk drive provided with an optical head, wherein a plurality of piezoelectric elements are arranged to correct the tilt of the disk for making the optical axis of a condensing lens which condenses light beams on the disk surface orthogonal to the disk surface.

Raster scanner including scanning beam tilt correction

Abstract: A raster output scanner in which a movable scanning element scans a high intensity beam across a movable imaging member to record images thereon. The velocity of the imaging member is controlled relative to the beam, and the tilt of the beam is adjusted relative to the imaging member.

Motor for sailing using wave energy

Abstract: The invention relates to a device for sailing using wave energy, by converting the up-down linear movement into a horizontal directional thrust. The element B can tilt and is fitted with two stops K and L. Any thrust generated by the element A is converted into a horizontal thrust by the element B in the direction of the arrow F. The device according to the invention is particularly intended for moving boats by wave energy.

Axial piston machine of the swashplate type with radial motion of tilt axis

Abstract: The invention relates to an axial piston machine of the swashplate type in which the drive shaft passes through the swash plate, the swash plate can be tilted about an effective tilt axis so that its working surface supporting the pistons has a radial component of motion relative to the drive shaft as it is tilted in the direction of which the effective tilt axis is displaced parallel as the swashplate is tilted. In order to adjust the swashplate to a larger tilt angle, according to the invention the effective tilt axis is adjusted radially in a direction opposite to the direction of the radial component of motion (R) of the swashplate working surface.

Twisting Techniques Used in High Bar Dismounts

Abstract: At the 1988 Seoul Olympic Games, eight full twisting somersault dismounts from the high bar were filmed using two cameras during the compulsory exercises of the Men’s High Bar competition. Angles describing body configuration and orientation were determined and were input into a computer simulation model of aerial movement. The deviations between simulation and film were less than 2.5° for tilt angles and less than 0.07 revolutions for twist angles. The twisting techniques employed were quantified using the tilt angle as a measure of twisting potential. Contributions to the maximum tilt angle were determined using simulations based on modifications of the film data. Each of the eight competitors obtained most of the tilt using aerial rather than contact techniques. In general, the majority of the aerial contributions arose from asymmetrical arm and hip movements.

Adaptive coherent optical receiver array

Abstract: A linear four element adaptive heterodyne optical receiver array employing semiconductor lasers is described. The array adaptively adjusts the phase of each subaperture IF signal to correct for wavefront tilt and distortion and non-uniform optical and RF path delays across the array by phase-locking each channel to a reference channel.

Power tilt device

Abstract: A compact self-contained trim and tilt unit for a marine outboard drive that can be nested between the supporting brackets of the outboard drive so that all components are protected and so that external piping is avoided.

Distance and tilt sensing apparatus

Abstract: In the distance and tilt sensing apparatus disclosed herein, an image of a light source is projected by a lens obliquely onto a surface to be sensed. A ring reticle is interposed in the optical path between the light source and the lens at a distance from the lens substantially equal to its focal length. A second lens projects a remote image of the first object image onto a detector. The light projected from the second lens is split into two paths. An aperture reticle is interposed in one of the paths at a distance from the second lens substantially equal to its focal length, an image of the center of the ring reticle being formed on the aperture reticle. A position responsive optical detector aligned with the aperture reticle senses the position of the image of the center of the ring reticle relative to the center of the aperture and that position is indicative of the tilt of the surface around an axis essentially perpendicular to the axis of the incident light.

Optical positioner and connector

Abstract: A positioner for accurately and precisely positioning an optical member such as a lens aligned with the tip of an optical fiber in relation to an optical device such as a beam launcher/splitter; the positioner includes a tilt base mounted in a frame and angularly displaceable about orthagonal X and Y axes defined by three ball bearings all engaging one surface of the tilt base and all biased against the tilt base. Two differential screws mounted on the frame engage two of the ball bearings to effect angular yaw and pitch adjustments. The tilt base is connected to a retainer support in turn connected to a retainer member; two additional differential screws engage the support through further ball bearings to effect linear movements of the retainer member along the X and Y axes. The retainer member includes a lens and an adapter aligned along the Z axis with an optical fiber cable whose tip is releasably connected to the adapter; the adapter has an internal flange that accurately locates the tip of the optical fiber at the focal point of the lens.

Mechanically adjustable balance and sensitive tilt meter

Abstract: A torsion balance has been modified by clamping the fibre, under tension, at both the top and the bottom of the instrument housing. Operating with the centre of mass of the boom displaced from the near vertical fibre, the instrument is influenced by the Earth's gravitational field as well as by the shear modulus of the fibre. This causes the restoring constant of the balance to depend on the angle of tilt between the fibre direction and local vertical. The contribution from the Earth's field either adds to or subtracts from that of the shear modulus, according to the direction of tilt. The result is an instrument of variable sensitivity when used as a force-measuring device. It can also be configured to function as a highly sensitive tilt meter.

Double-sided reproducing disk player

Abstract: A double-sided reproducing disk player wherein reduction in size and simplification in structure of a carriage can be attained and reduction in number of parts and simplification in construction of the entire arrangement can be attained to attain reduction in overall size and also in production cost. The player comprises upper and lower face guide mechanisms for guiding a carriage, on which an optical pickup is carried, along upper and lower surfaces of a disk, respectively. The upper and lower face guide mechanisms are carried on a carrying device which is supported for tilting motion on a stationary frame of the player, and the tilt angle of the carrying device with respect to the stationary frame is adjusted by a tilt angle adjusting device. The tilt angle adjusting device includes an eccentric member on the stationary frame and a spring for biasing the carrying device into cooperation with the eccentric member. The eccentric member is rotated by a motor in response to a tilt angle of the carrying device detected by a tile angle detecting sensor.

Optical centroid processor wavefront sensor

Abstract: An improved optical centroid processor wavefront sensor is described in which an image is optically impinged on a plurality of mask arrays. A group of mask arrays, having a coarse dependant function, filters light onto corresponding photodetector arrays. The output of the photodetectors provide a coarse signal indicative of spot displacement over an increased tilt dynamic range. Another group of mask arrays, having a fine dependant function, filters light onto corresponding photodetector arrays. The output of the photodetectors provide a fine signal indicative of spot displacement with an increased accuracy. The coarse and fine signals may be employed by a deformable mirror to correct aberrations in a light beam wavefront.

Steering system for vehicle

Abstract: A steering system for a vehicle has a tilt mechanism for adjusting the height of a steering wheel. The steering wheel can be tilted through a larger angular range while the vehicle is parking but is inhibited from being tilted out of a smaller angular range included in the larger angular range while the vehicle is running.