Showing papers on "Tilt (optics) published in 1977"

Accurate determination of liquid‐crystal tilt bias angles

Abstract: A detailed analysis is given for three techniques used to determine the tilt bias angle of a nematic liquid crystal in contact with a boundary surface. Two of these methods, the crystal rotation and capacitive methods, have severe disadvantages, such as a restricted range of application, an insufficient accuracy, and sometimes require knowledge of nematic material constants which have to be determined by separate experiments. A third and more useful method, a magnetic null method, makes it possible to determine the tilt bias angle directly with only one measurement to an accuracy of 0.1°, regardless of the size of the angle or the nature of the nematic liquid crystal. Using the magnetic null method we have investigated the tilt bias angles of nematics in contact with glass substrates onto which a coating of SiO had been obliquely evaporated. We find that the tilt bias angle decreases with increasing evaporation angle (both angles measured from sample plane) until a critical evaporation angle of ?14° is reached, whereupon the director reorients out of the plane of incidence of the evaporation beam and assumes a direction normal to this plane with a 0° tilt bias. We also find that the tilt bias angle varies from compound to compound for the same evaporation parameters and is influenced by temperature and trace impurities.

Component Analysis of Orientation Illusions

Abstract: Orientation illusions occur when the inducing figure is a line or grating (the tilt illusion) or a square outline frame (the rod-and-frame illusion). In the range of inducing figure tilts between vertical and horizontal, the tilt illusion describes one cycle of positive (direct) and negative (indirect) effects but the rod-and-frame illusion describes two such cycles. In two experiments, angular functions of illusions were measured with the six possible inducing figures which result when two of the four sides of a square inducing frame are deleted. As expected, the parallel-sided frame amputations induced angular functions similar to the tilt illusion and these functions differed from those induced by the orthogonal-sided amputations. In agreement with previous findings on the nonadditivity of tilt illusions, the sum of angular functions induced by frame amputations, which together form a complete frame, were not always equivalent to the angular function induced by a complete frame, and there were asymmetr...

An analysis of coseismic tilt changes from an array in central California

Abstract: location models and are easily identified by coincidence with the earthquake occurrence time. Press [ 1965] reported a strain step of 10 -8 recorded at Kipapa, Oahu, Hawaii, after the magnitude 8.4, 1964 Alaskan earthquake. This particular strain step was of the amplitude expected from the model presented. There were tilt and strain steps associated with other large teleseisms that were orders of magnitude greater than were expected and were suggested to be caused by geologic complexities or instrumental and/or site effects. Wideman and Major [1967] summarize strain step observations for step amplitudes in the range 10-4-10 -o recorded at distances up to 104 km from the source (nuclear as well as seismic) and event magnitudes from 3.0 to 8.5. They determined a strain step amplitude dependence of R-", a = { (R is the epicentral distance). The theoretical analysis by Ben-Menahem et al. [1969] suggests that because the predicted amplitude dependence is quadrupole, not radial, a is in the range I > a > 6, depending upon the source-to-station geometry. McGinley [1968] analyzed anomalously large strain and tilt step data from four earthquakes and suggested that a model of a weak layer in the lower crust or upper mantle could be used to reproduce some features of the observations if the degree of weakening is quite severe. Berg and Lutschak [1973] report tilt steps following local and teleseismic events recorded by the University of Alaska Tripartite Tilt Network that are more than an order of magnitude larger than those expected from Press's [1965] model and tilt step propagation velocities compatible with Rayleigh wave velocities. Although strain steps for the San Fernando earthquake can be fit by a simple half

Effect of age on circulatory response to postural and valsalva tests (39884).

Abstract: SummaryIn order to analyze the effect of age, a study was made of the hemody-namic responses of three groups of normal male subjects (19 to 26, 40 to 49, and 47 to 56 years) to 70° head-up tilt and...

Relation Between Earthquakes, Weather, and Soil Tilt

Abstract: Two years of local earthquake, temperature, and rainfall data taken near a tiltmeter site were used in a study of the numerical relation between these phenomena and the recorded tilt response. A least-squares shaping and predictive error filter approach was used. The relations were ranked in part according to the root mean square (r.m.s.) error of fit across the entire sample space. The tilt data with an annual range of tilt of approximately 10 microradians were fitted to the combined weather data of temperature and rainfall with a 0.75-microradian r.m.s. error. The best fit of earthquakes to these same tilt data is the subclass of events with magnitude (M) > 2.5 within 30 kilometers of the tilt site. The filter that mapped earthquakes to tilt yielded a 1.03-microradian r.m.s. error. The most unusual tilt anomaly over the entire 2-year period has the best fit of rainfall to the data for any single month of the entire data set. This unusual anomaly was the basis of an erroneously predicted earthquake (M ∼ 5). These data indicate that if there are premonitory earthquake signals, they are buried in local meteorlogical noise. Separating an earthquake anomaly from the response to surface phenomena becomes more difficult as the earthquake anomaly lead time approaches the rise time of the soil to weather and seasonal variations.

Pulsed sandwich holography.

Abstract: A new method is introduced which utilizes sandwich holography combined with a pulsed laser. In a special rotating hologram holder two plates sandwiched together are exposed through a slit during the double pulse operation of a laser. The two pulses are separated by less than 1 msec. Afterward, in an evaluating holder, one plate is rotated in relation to the other so that the images from the two pulses are overlapped. Then the two plates are glued together. If the emulsions are separated, fringes caused by object tilt between the two pulses can be eliminated by an analogous, but much larger, tilt of the sandwich hologram during reconstruction. Even the direction of tilt, forward or backward, is found this way.

Influence of the dipole tilt angle on the development of auroral electrojets.

Abstract: Influence of the tilt' angle of the geomagnetic dipole, x, on the development of auroral electrojets was investigated paying attention to the relation with solar wind parameters. Indices AU and AL were used as the measures of the intensities of the eastward and the westward electrojets, and were found to have evident x dependences under the normalized condition of the solar wind velocity, V, and of the GSM southward component, BS, of the interplanetary magnetic field (IMF). The main characteristics of the influence of x are as follows. (1) AL shows very different x dependences for different signs of the By component of the IMF. The x dependences of AL are not independent of its dependence on B3 and V, and hence they have a close relationship with the substorm process initiated from the reconnection of the IMF and geomagnetic field lines at the dayside magnetopause. (2) AU shows very similar x dependences regardless of the sign of B5. The enhancement of AU in the positive range of x can be interpreted as indicating the important role of solar radiation in determining the magnitude of eastward electrojets.

Venetian blind tilter clutch

Abstract: A venetian blind including a rotary tilt rod and tilt rod operator, wherein a yieldable or slip coupling is interposed in motion transmitting relation between the operator and tilt rod to disengage the same upon excessive torque, the coupling including driving and driven elements respectively connected to the operator and tilt rod and having separable interfitting formations configured to effect driving engagement and urge the elements and formations apart, and a resilient device yieldably urging the elements and formations toward each other.

Liquid crystal memory device and method of utilizing same

Abstract: A liquid crystal memory device comprising a liquid crystal layer, means for preconditioning the layer so that at least some of its molecules will be slanted towards one of two possible tilt directions, means for causing at least some of the molecules of said liquid crystal layer to assume their preconditioned tilt direction, and means for determining which of said possible tilt directions has been assumed by the molecules of said liquid crystal layer is disclosed. The method of writing into this device comprises causing the molecules of selected portions of said liquid crystal layer to be preconditioned to slant towards one of two possible tilt directions, causing at least some of said preconditioned molcules to assume their preconditioned tilt direction, causing at least some of the molecules of other portions of said liquid crystal layer to be preconditioned to slant towards the other one of said two possible tilt directions, and causing at least some of said preconditioned molecules to assume their other preconditioned tilt direction.

Evidence of Tilt of the Methyl Top Axis in the r s -structure of Dimethyl Selenide

Abstract: Abstract The complete rs-structure of dimethyl selenide has been determined by using suitably chosen changes in principal moments of inertia of a number of isotopic species. The tilt of the methyl top axis with respect to the C -Se bond, as determined by the analysis of the internal rotation fine structure of the rotational transitions is also evidenced in the rs-structure. The center of mass condition has been used.

Venetian blind tilt limiter

Abstract: A tilt limiting mechanism for a venetian blind including a mounting member non-rotatably positioned in the blind head rail and providing a guideway partially about the tilt rod, a radial extension on the tilt rod extending into the guideway for swinging movement therealong upon tilt rod rotation, and stop members positioned in the guideway to engage the radial extension and limit rotative movement of the tilt rod.

Orientation of slit pupil and visual streak in the eye of the cat

Abstract: The orientation of the visual streak of the cat's retina was compared to that of the long axis of the slit pupil in the same eye. In five paralyzed, anesthetized cats, the retinal projection to the superior colliculus was mapped with electrophysiological techniques. The orientation of the visual streak was estimated from the projection in visual space of the collicular region of high magnification which corresponds to the central projection of the streak. The angle by which the streak was tilted from absolute horizontal was always within one or two degree of the angle by which the pupil axis was tilted from absolute vertical. This relationship was confirmed in three of the animals in which small retinal lesions were placed a known distance from the histologically determined axis of the streak. From the visual coordinates of these lesions, an independent estimate of the streak's orientation was obtained. In each case, the tilt of streak axis from horizontal differed by no more than 0.5 degrees from the tilt of the pupil axis from vertical. The results support the hypothesis that planes containing the long axis of the cat's slit pupil are perpendicular to planes containing the long axis of the visual streak of the same eye.

Motorcycle headlight tilt control

Abstract: A motorcycle headlight tilt control cooperates with wind deflecting fairing. It includes: (a) support means supporting the headlight structure to the fairing so that the headlight is tiltable to tilt the headlight forward beam up and down, (b) a manual control on the fairing, and (c) other means connected with the headlight structure and the manual control to controllably tilt the headlight in response to manual operation of said control, (d) there being a spring acting to transmit force biasing said headlight structure in a tilt direction.

Stabilized-transducer driving device for underwater ultrasonic detection system

Abstract: A gravity stabilized drive mechanism varies the orientation of an underwater ultrasonic transducer in both azimuth and elevation while stabilizing the transducer against the pitching and rolling of a ship. The transducer is freely suspended by a universal joint from a vertical tilt control shaft. The tilt control shaft passes through a hollow azimuth control shaft which, in turn, is rotatably mounted on a platform attached to the ship. Elevation of the transducer is adjusted by rotating the tilt control shaft, and azimuth of the transducer is adjusted by rotating the azimuth control shaft.

Monocularity of color-contingent tilt aftereffects

Abstract: The interaction between monocular channels involved in the color-contingent tilt aftereffect (AE) was investigated by inducing opposite AEs in subjects’ eyes and comparing their magnitudes with those recorded after inducing identical AEs in the two eyes. Measurements obtained under the above two conditions did not differ significantly. No evidence was found for interaction between monocular channels.

Electromagnetic proportional control valve

Abstract: PURPOSE:In a control valve that performs proportioanlcontrol in response to an input signal, 1st and 2nd tilt part materials are connected with a main plunger and a solenoid to work a spool type pilot valve by each tilt part material, ensuring accurate control without stick.

Vibrator tilt control system for vehicle mounted seismic vibrators

Abstract: A system for controlling the tilt of the vehicle and vibrator when the vibrator is being operated on irregular surfaces. Tilt switches detect excessive vehicle tilt. A bleeder network activated by the tilt switches reduces the pressure in the air bag on the side of the vibrator opposite from the direction of the vehicle tilt. A supply network repressurizes the air bag on the side of the vibrator opposite from the direction of the tilt.

Parallel safety coupling for X-ray table tilt drive

Abstract: A safety coupling for an X-ray table tilt drive. An auxiliary coupling means in parallel with the main mechanical drive coupling has a substantially constant amount of free play over the entire operational tilt range of the table so that it ordinarily carries none of the drive force. In the event of mechanical failure of the main drive coupling the free play is taken up and the auxiliary coupling prevents the table from abruptly falling to the rest position.

Electronic control and regulation system

Abstract: A reflector of an optical system has its position controlled by piezoelecc devices operating at three points of the reflector disposed at the apices of an equilateral triangle. These are driven by summing amplifiers each of which has an input to which a signal for producing displacement of the reflector without change of tilt is provided and one or more inputs connected to the output of a matrix circuit responsive to signals for producing tilt of the reflector about two mutually perpendicular axes both perpendicular to the direction of displacement produced by the previously mentioned inputs. The tilt is regulated with reference to a fixed mirror of the system or the like by means of a signal derived from radiation passing through the optical system, by causing a slight rocking back and forth of the mirror first about one axis and then about the other and determining the magnitude and sign of the difference signal for each direction of tilt about the same axis and then adding the resulting correction to a bias voltage representing the desired tilt angle.

Tilt angle measurements of nematic phases of cyano-biphenyl eutectic mixtures

Abstract: The tilt angles of eutectic mixtures of cyano-biphenyl nematics on 5 degrees SiO films have been measured using a conoscopic optical technique. The results show that the tilt angle of a mixture may be calculated from the known tilt angle of the constituents and the composition. It is also shown that the nematic layers adjacent to the aligning surface retain the bulk composition.

Xxray detecting unit for electronic microscope

Abstract: PURPOSE:To reduce the change in X ray strength, by nearly keeping X ray picking up angle even if test piece is leaned, by arranging X ray detecting unit so that a plane containing the axis of electron beam and the tilt axis of test piece is opposed to the test piece.

On the optimum orientation of solar collectors

Abstract: A simple model of atmospheric absorption and scattering, incorporating only three parameters, has been used to fit meteorological data for direct and diffuse radiation and hours of sunshine at latitude 55°N, longitude 6°W. Using this fit for insolation on a horizontal plane, annual and monthly figures for insolation on an inclined plane have been computed. It is found that the annual insolation is relatively insensitive to orientation for angles of tilt between zero and 60°, but that the optimum tilt is 30.5°. When ground reflection is included, the optimum tilt angle rises steadily to 65' as the ground albedo increases from zero to unity. Optimization for summer and winter operation is also considered, as is the effect of various characteristics of practical collectors.

Device for setting and retaining a fixed direction

Abstract: An apparatus for sensing and indicating the orientation of an object, such as a machine part, in a generally horizontal plane comprises two interconnected tilt sensing devices whose resistances vary responsive to the tilt of the devices. At least one of said sensing devices is mounted rotatably and via a bevel gear connected to the object.

Rearrview mirror for car

Abstract: PURPOSE:A rear-view mirror device for a car enabling to tilt the mirror in an optional direction at an optional angle by remote control or manual operation, and having an extremely high reliability.