Showing papers on "Tilt (optics) published in 1975"

Stereoscopic Tilt and Size Aftereffects

Abstract: Adaptation to a random-dot stereograting with no monocularly visible contours produces a tilt aftereffect in a briefly-viewed test stereograting. The effect is maximal for adapting orientation at ±20–30° from the test orientation. Similarly, the perceived spatial frequency of a stereograting is altered by adaptation to a stereograting of adjacent spatial frequencies.

Active annular-beam laser autocollimator system.

Abstract: An autocollimator using an axicon and a beam expander telescope to generate a 12.5-cm. o.d. annular beam of helium–neon laser light with high (25:1) diameter-to-width ratio has been developed. It is used with a two-axis, electromagnetically actuated mirror assembly to acquire automatically and maintain dynamically autocollimation from a nearby but separately mounted annular mirror. The servo system controls beam alignment even though angular vibratory motions of the annular mirror make it appear to tilt relative to the autocollimator as much as 7 mrad at frequencies below 300 Hz. This paper describes the optical system and the alignment sensing and control system.

Simultaneous visuomotor adaptation to optical tilt and displacement

Abstract: Change in visuomotor direction and orientation was measured following simultaneous exposure to optical displacement and tilt. Adaptation to both transforms simultaneously was not different from adaptation to each transform separately. These results are consistent with previous work involving purely visual change, and suggest that the two kinds of adaptation involve independent processes for locus-specific and relational analysis.

Precision mirror mount

Abstract: Positioning of a mirror mount plate is achieved by driving four differential screw actuators by geared stepping motors providing tip and tilt as well as translation. The plate on which the mirror is mounted is suspended by four specially designed flexure assemblies.

Interferometer mirror tilt correcting system

Abstract: An interferometer having servo means for automatically adjusting the angular tilt of a reflecting surface in one of two paths to maintain the exit beams from the two paths parallel to each other. Three detectors at the output of the interferometer are disposed on mutually perpendicular axes which define a plane normal to the nominal exit beam axis. One detector at the origin of the axes is used as a reference for separate phase-difference comparison with the outputs of the other two detectors on the X and Y axes to develop servo error signals.

Depth adjacency and the rod-and-frame illusion

Abstract: In Experiment I, the tactile adjustment of a comparison bar was used to measure the change in the rod-and-frame illusion as a function of the stereoscopic position of the rod relative to the frame. A vertical rod was presented at a near, a middle, or a far distance, with a single frame tilted counterclockwise at the near distance, a single frame tilted clockwise at the far distance, or two frames of opposite tilt presented simultaneously at the near and far distances. When only one frame was present, displacement of the rod in front of the far frame but not behind the near frame significantly reduced the illusion. When both frames were present, the illusion was determined mainly by the frame at the apparent distance of the rod. In Experiment II, the tactile method of measuring perceived tilt was validated for the range of perceived tilts encountered in Experiment I. The results of Experiment I are discussed in terms of the perceptual resolution of the conflict between relative and absolute cues of tilt.

Static deformation due to the fault spreading over several layers in a multi-layered medium part ii: strain and tilt

Abstract: Strain and tilt fields due to the fault spreading over several layers in a multi-layered medium are investigated. Using the matrix method, integral representations for the strain and tilt filds caused by a dislocation with an arbitrary orientation, at any depth, in a multi-layered medium are obtained from the analytical expressions of the static displacement fields derived by SATO (1971). Machine program for the static deformations (displacements, strains and tilts) is completed, by which contour or vector map of each component can also be obtained. Some numerical examples by using this program are Presented for the purpose of elucidating the effect of multi-layered structure on the strain and tilt fields at the surface. It is concluded that the effect caused by soft layer at the surface (representing sedimentary cover) is significant on both the magnitudes of the deformation fields and their patterns.

Kinetics of Vapor-Grown Tellurium Whiskers

Abstract: Growth of tellurium whiskers has been observed continuously in the specimen chamber of an electron microscope. In most of needle-like whiskers their axes tilt suddenly or gradually after they reach a certain length. In the growth before the tilt the length increases exponentially with time, but after the tilt the growth rate drops and in more than half of them the growth ceases gradually. The exponential growth can be explained on the basis of the axial dislocation mechanism controlled by the diffusion of adatoms on the side surface of the whisker to the growth tip. The decrease in the growth rate after the tilt is ascribed to the axial dislocation slipping out of the whiskers by thermal agitation. It is also suggested that the length of whiskers at the tilt is nearly equal to the mean displacement of adatoms on the side surface.

Decay of visual adaptation to tilt and displacement

Abstract: Persistence in the dark following 48 min of visual adaptation to tilt and displacement was compared in two experiments to determine if same or different processes are involved in the two kinds of adaptation. Decay of tilt adaptation occurred rapidly, all within about 16 min. However, it was not complete and some residual tilt adaptation persisted for at least as long as 56 min. Decay of displacement adaptation occurred more slowly but was clearly complete after at most 56 min in the dark. Displacement adaptation appears to be entirely subject to decay, while tilt adaptation involves an additional, more long-term component. Results are interpreted in terms of independent systems for the perception of location and orientation.

Effective wave tilt and surface impedance over a laterally inhomogeneous two‐layer Earth

Abstract: Using a perturbation method, the effect of a simple two-dimensional model on the electromagnetic fields at the surface of the Earth is considered for a postulated downcoming plane wave. The calculated change in the surface impedance and wave tilt due to lateral inhomogeneities is examined. It is found that the magnetic wave tilt (Hz/Hx) is most seriously affected by such anomalies. This may have important consequences on electromagnetic probing of nonuniform portions of the Earth's crust. (auth)

Improved stressing apparatus for photoelasticity measurements

Abstract: An improved, direct reading stressing apparatus has been constructed for measuring photoelastic constants. Highly uniform stresses are obtained with minimal specimen tilt.

Interferometer optical system

Abstract: An interferometer optical system for general use to measure optical parallelism or relative rotational or joint translational positions of the two spaced subject mirrors uses coherent light split into two beams which are directed, one normal to one of the two mirrors and the other normal to the other of the two mirrors. The reflections of these two beams are then superimposed on a target which reveals a light interference pattern indicative of the parallelism or relative rotation or joint translation of the two mirrors. In preferred embodiments, in order to compensate for the mutual tilt of the subject mirrors with respect to the plane of the beams incident thereon, the path of one of the beams to and from the subject mirror includes a corner mirror, or retrodirective mirror, and the path of the other beam includes at least one adjustable mirror.

Moveable optical probe for viewing a scale model with image tilting

Abstract: An optical arrangement, particularly for ground-based flight simulating apparatus of the type using an optical probe moving over a terrain model to provide a visual display of terrain overflown. In such apparatus, during simulated flight, variation of tilt of the model surface relatively to the probe optical axis gives rise to a primary image also tilted relatively to the probe optical axis. The invention solves the problem of providing an in-focus image on a television camera tube the target of which is fixed orthogonal to the probe axis. The arrangement comprises first and second optical imaging systems, and optical axis deflecting means therebetween, usually lens, prism or mirror elements, producing a tilt of the in-focus image plane of the overall system, to compensate for the primary image tilt. The optical arrangement may equally be applied to a laser beam scanned terrain model.

Optical alignment techniques

Abstract: The invention comprises an afocal lens system having unitary magnificationhich is either positive or negative and suitable for indicating departures of a reference point or a reference axis respectively from coincidence with a relatively fixed datum axis. The reference point or axis is included by the axis of the lens system, and the datum axis is defined by a line through an object and the zero position of an image of that object produced by the lens system. The lens system indicates the said departures from coincidence by means of shifts of the image from the zero position. The positive magnification afocal lens system is sensitive to tilt but insensitive to displacement, whereas the reverse is true of the negative magnification version. This feature allows tilt and displacement to be monitored separately.

Dipping interior driving mirror - with tilt operation controlled by twisting eccentric cam to retain setting

Abstract: The interior driving mirror is mounted on its fitting stalk by means of a ball joint with friction to hold it in the selected setting. The mirror itself is mounted on a support plate which is pivotted about a horizontal axis at the top of the mirror housing. This enables the mirror to be tilted from a daylight to a nighttime setting. In order that the tilting operation does not disturb the mirror setting the tilt control comprises a knob under the mirror housing, which is twisted to tilt the mirror. The knob is fitted with an eccentric pin which engages a slot in the bottom of the pivotted plate for a simple, low torque adjustment.

Scrap box carrier

Abstract: A mobile carrier for large scrap steel carrying boxes including a main wheeled frame with steerable, powered wheels and a support or tilt frame suspended on the main frame for vertical movement. The tilt frame fits around and locks to the box with the box itself forming a structural member preventing spreading of the frame. Hydraulic actuators suspend the tilt frame allowing it to pick up a box, carry it with the main frame, and tilt the box to dump the scrap contents.

Tone arm for record players and record changers

Abstract: A mounting for supporting a pickup or a tone arm includes an elongated flat plate having a weakened portion to serve as a pivot at one end and a screw threaded tilt adjustment at the other end.

Backhoe bucket tilt

Abstract: A backhoe has a main boom mounting a jib boom rotatably and pivotally. The jib boom journals a yoke about one axis and a bucket is pivotal on the yoke about a transverse axis and a hydraulic cylinder drive having a double-ended piston extending between arms of the yoke is adjustable to tilt the bucket to keep its lower edge level when desired.

Astigmatic beam generation from stigmatic beam - two spherical collecting lenses and transparent plate are combined

Abstract: The focal points of the two collecting lenses are in coincidence between the collecting lenses or are displaced relative to each other A transparent coplanar plate is positioned at a tilt in the beam path between the lenses The angle between the plate normal and the optical axis amounts to THETA The parallel beams, which are incoming from the left, are focussed by the lens in a focal point and pass in the following divergent beam path through the plate The variation of the cross-section of the beams in the X and Y directions differs The beams are aligned in parallel by the lens