scispace - formally typeset
Search or ask a question

Showing papers on "Tilt (optics) published in 1994"


Journal ArticleDOI
TL;DR: In this article, the potential field tilt is defined in terms of the ratio of the first vertical derivative of a potential field to the horizontal gradient of the field, which has the property of being positive over a source and negative elsewhere.

968 citations


Patent
23 Aug 1994
TL;DR: In this article, a small-sized information processor which is used while being held in one hand, and which can scroll a display screen in accordance with a tilt sensor is described, and the processing unit scrolls the display screen of the display unit on the basis of the calculated relative tilt angle.
Abstract: A small-sized information processor which is used while being held in one hand, and which can scroll a display screen in accordance with a tilt. When a scroll start switch is depressed, the tilt angle of a display unit at this time is detected as an initial tilt angle by a tilt sensor. When a predetermined time period has lapsed since the depression of the switch, the tilt angle of the display unit is detected as a second tilt angle by the tilt sensor. The initial tilt angle is subtracted from the second tilt angle by a processing unit, thereby calculating the relative tilt angle of the display unit. The processing unit scrolls the display screen of the display unit on the basis of the calculated relative tilt angle. The scrolling speed of the display unit may well be changed in accordance with the width of the relative tilt angle.

239 citations


Journal ArticleDOI
TL;DR: In this article, the shape of a large plane surface is obtained by connecting phase distributions measured by a small-aperture interferometer, and the accuracy of connection increases in proportion to an exponent of 1.5 of the width of the common area.
Abstract: We propose a method to obtain the shape of a large plane surface by connecting phase distributions measured by a small-aperture interferometer. These separately measured phase distributions cannot be connected directly because the object will tilt or have vertical displacement during the measurements. To correct these errors, the measurements are made so that the adjacent interferograms have common areas, and these interferograms are connected to minimize the difference of the phase distributions in the common areas. A matrix equation is derived to obtain coefficients to correct tilt and vertical displacement, and the accuracy of connection increases in proportion to an exponent of 1.5 of the width of the common area.

184 citations


Journal ArticleDOI
TL;DR: In this paper, a laser-guide-star adaptive-optics system that is capable of continuous compensation at 65-Hz and 130-Hz closed-loop bandwidths on a 1.5m telescope is presented.
Abstract: We report results that were obtained with two generations (Generation I and Generation II) of a laser-guide-star adaptive-optics system that is capable of continuous compensation at 65-Hz (Generation I) and 130-Hz (Generation II) closed-loop bandwidths on a 1.5-m telescope. We used a copper-vapor laser that was focused at a 10-km range as the laser guide star and a range-gated Shack–Hartmann sensor to operate a continuous-facesheet deformable mirror that controlled either 149 or 241 actuators. We used a separate full-aperture sensor and a steering mirror to remove overall tilt. System performance was measured by imaging stars with a high-resolution CCD camera in a narrow spectral band that was centered at 0.88 μm, from which we computed point-spread functions, optical transfer functions, and Strehl ratios. Using the laser guide star, we achieved a FWHM image resolution of 0.13 arcsec and a Strehl ratio of 0.48. Using a natural guide star, we achieved a Strehl ratio of 0.64 at 0.13 arcsec FWHM resolution. We also obtained compensated images of the Trapezium region in Orion in H-α light, using only the laser guide star.

149 citations


Journal ArticleDOI
TL;DR: A method for widening the compensated field of view of an adaptive-optical telescope with multiple deformable mirrors and an array of artificial guide stars is investigated, and an ensemble of wavefront sensor measurements are used to estimate the contribution of a region of the atmosphere to the cumulative phase distortion.
Abstract: We investigate a method for widening the compensated field of view of an adaptive-optical telescope with multiple deformable mirrors and an array of artificial guide stars. An ensemble of wavefront sensor measurements, made with the individual guide stars in the array, is used to estimate the contribution of a region of the atmosphere to the cumulative phase distortion. Our analysis includes the effects of measurement noise, wavefront-sensor sampling, and reconstruction of the wave front from slope measurements. We performed numerical computations for an atmosphere consisting of two turbulent layers: one at 1% of the guide-star altitude with 90% of the total turbulence strength and one at 10% of the guide-star altitude with the remaining 10% of the total turbulence strength. If we assume that r0 = 0.15 m and that a photon-limited wave-front sensor detecting 50 photons/r0-sized subaperture is used, the results indicate that a 0.9-m-square telescope with a diagonal field of view of ~92 μrad ≈ 19 arcsec can use two deformable mirrors, four laser guide stars, and a natural tilt reference star to achieve an rms residual phase error that is <λ/7 over its entire field of view.

129 citations


Journal ArticleDOI
TL;DR: In this article, three distinct tilt grain boundary morphologies were observed: the chevron, the omega boundary, and the T-junction, and a transition from either the cheveron or the Omega boundary to the T junction occurs as the boundary becomes more asymmetric.
Abstract: Tilt grain boundaries in poly(styrene-b-butadiene) lamellar diblock copolymers were characterized using transmission electron microscopy (TEM). Three distinct tilt grain boundary morphologies were observed: the chevron, the omega boundary, and the T-junction. All three boundary types are found to have intermaterial dividing surfaces, separating the polystyrene and polybutadiene microphases, that approximate surfaces of constant mean curvature. The chevron and omega morphologies are observed for symmetric tilt boundaries, and a transition occurs from the chevron to the omega as tilt is increased at constant boundary width. A transition from either the chevron or the omega boundary to the T-junction occurs as the boundary becomes more asymmetric

105 citations


Journal ArticleDOI
V.H. Morcos1
TL;DR: In this article, a mathematical model was developed for calculating the total radiation on a sloped surface and the model was then used to determine the optimum tilt angles for a flat plate collector and the optimal tilt and surface azimuth angles (orientation) for concentrating solar collectors in Assiut, Egypt on a daily basis, as well as for a specified period.

91 citations


Patent
29 Jun 1994
TL;DR: A joystick transducer utilizing a rotating magnetic field within a hollow toroid core, this rotating field drives a polar sensor element to which a 360 degree variable flux coupling element is operated by a joysyick to generate an output signal the phase angle of which corresponds to the azimuth direction of joystick tilt and the amplitude of this same signal correspond to the magnitude of the joystick tilt as discussed by the authors.
Abstract: A joystick transducer utilizing a rotating magnetic field within a hollow toroid core, this rotating field drives a polar sensor element to which a 360 degree variable flux coupling element is operated by a joysyick to generate an output signal the phase angle of which corresponds to the azimuth direction of joystick tilt and the amplitude of this same signal corresponds to the magnitude of joystick tilt. A plurality of independent joysticks are also provide on one hollow driving core.

89 citations


Journal ArticleDOI
TL;DR: The optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope is compared and the adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated.
Abstract: Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope.

80 citations


Patent
26 Jul 1994
TL;DR: In this article, an auto-leveling system is used to detect a deviation between the focus plane of the projection optical system and the surface of the shot area at each of multi-points.
Abstract: In an apparatus which positions an average plane thereof parallel to a best focus plane of a projection optical system even if there is unevenness on a wafer, a leveling stage is tilted on the basis of detection signal from an auto-leveling system and a surface of a shot area on a wafer is positioned in a predetermined tilt position relative to a focus plane of the projection optical system. While such a position being kept unchanged, a deviation between the focus plane of the projection optical system and the surface of the shot area is detected at each of multi-points. Within the shot area, by the use of auto-focus system, an amount of relative tilt between an average plane of the shot area obtained from plural deviations and the focus plane of the projection optical system is calculated, and by the use of thus calculated amount of tilt and the detection signal of auto-leveling system, the focus plane of the projection optical system is positioned in parallel with the average plane of the shot area.

62 citations


Journal ArticleDOI
TL;DR: The linear electro-optic effect in short pitch cholesterics is based on the linear coupling of the medium with an applied electric field as mentioned in this paper, which has a number of remarkable properties.
Abstract: The linear electro‐optic effect in short‐pitch cholesterics is based on the linear coupling of the medium with an applied electric field. It has a number of remarkable properties. The electric field causes the optic axis to tilt in a plane parallel to the surfaces of the cell glass plates, giving the same symmetry as the electro‐optic effects in the smectic C* phase (surface stabilized ferroelectric liquid crystals and deformed helix mode) and the smectic A* phase (soft mode/electroclinic effect). For shutters and displays this guarantees a very wide viewing angle. The induced tilt is a linear function of the applied field, at least for small fields, which gives a well‐controlled continuous grey scale. Furthermore, it is practically independent of temperature. Response times of the order of 100 μs are easily achievable. The most interesting development in this effect would be to extend the linear regime to much larger tilt angles, in particular to 22.5°, where light could be modulated from 100% to zero transmission. In order to do this the perturbation from the quadratic dielectric coupling has to be ruled out or minimized, which requires materials with essentially zero dielectric anisotropy. This has been done, and it has been found that the bare flexoelectric‐induced tilt has a surprising range of linearity: The linear response in tilt could be followed up to about 30° after which the high electric field caused breakdown. The response time is typically about 100 μs and below.

Patent
03 Oct 1994
TL;DR: In this article, a power tilt, telescoping and internally collapsible steering column assembly is provided, which consists of a main housing, a telescope housing, and a tilt head driven by a pair of torsionally rigid axially flexible cables extending generally along the steering column.
Abstract: A power tilt, telescoping and internally collapsible steering column assembly is provided. The assembly comprises a main housing, a telescope housing, and a tilt head. The telescope housing and tilt head are driven by a pair of torsionally rigid axially flexible cables extending generally along the steering column. The cable is adapted by its axial flexibility to axially flex to accommodate the collapse of the telescope housing with respect to the main housing.

Patent
18 Apr 1994
TL;DR: In this paper, a tilt switch attached to a garage door, an RF transmitter coupled to the tilt switch, an RCA receiver, and an indicator controlled by the RF receiver is used to indicate the position of the garage door.
Abstract: A garage door position indicating system includes a tilt switch attached to a garage door, an RF transmitter coupled to the tilt switch, an RF receiver, and an indicator controlled by the RF receiver. The tilt switch supplies an enable signal to the RF transmitter at selected first tilt positions and blocks the enable signal at selected second tilt positions. The RF transmitter generates an RF signal in response to the enable signal. The RF receiver is responsive to the RF signal and controls an indicator to indicate the position of the garage door.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the 5/3-law dependence that characterizes the angular dependence and also appears in connection with the standard Greenwood frequency is an artifact of infinite outer scale that is entirely removable by exclusion of the piston.
Abstract: Modal decomposition of the phase variance between the wave front that is sampled to make a correction and the desired wave front allows inappropriate piston and tilt terms to be excluded from statistical estimates. Mathematical techniques that were developed for calculating Zernike-mode covariances for multiaperture optical systems lead to statistical expressions for angular and focal anisoplanatism and combinations thereof. The 5/3-law dependence that characterizes the angular dependence and also appears in connection with the standard Greenwood frequency is shown to be an artifact of infinite outer scale that is entirely removable by exclusion of the piston. Large piston and/or tilt components significantly affect critical angle and frequency estimates under conditions of practical interest. A finite inner scale or the removal of high-frequency components also produces a characteristic deviation from the 5/3 power law, including a substantial quadratic region for small angles.

Journal ArticleDOI
TL;DR: IOL decentration and/or tilt increase myopia and astigmatism, but could be sources of substantial postoperative refractive errors if the decentration or tile is large.
Abstract: Background Intraocular lens (IOL) decentration and tilt may affect postoperative refractive errors through spherical aberration of the IOL. Methods Through a use of a ray-tracing program and by minimizing algorithm, we calculated theoretical refractive errors for various degrees of IOL decentration and tilt. We compared our results with those obtained by paraxial vergence calculations. Results IOL decentration and/or tilt shifted postoperative refractive errors toward myopia and astigmatism of oblique origin. For example, a 3-millimeter decentration of an IOL resulted in induction of approximately -2.00 diopters (D) sphere and +0.70 D cylinder. IOL tilt affected refractive errors to a lesser degree. The change in refractive error caused by a combination of IOL decentration and tilt depended on the relationship between the geometrical axes of decentration and tilt. In the case of the least favorable combination of 12 degrees of tilt and 3 mm of decentration, it can reach -7.00 D sphere and +4.00 D cylinder. Conclusions IOL decentration and/or tilt increase myopia and astigmatism. They are negligible for small decentrations, but could be sources of substantial postoperative refractive errors if the decentration or tile is large.

Patent
07 Jun 1994
TL;DR: In this paper, a system and method are disclosed for locating an acquisition target consisting of a plurality of concentric rings of alternating levels of reflectivity (bull's-eye pattern) in two-dimensional images such as optically encoded symbologies.
Abstract: A system and method are disclosed for locating an acquisition target consisting of a plurality of concentric rings of alternating levels of reflectivity (bull's-eye pattern) in two-dimensional images such as optically encoded symbologies. Such targets may be found even if they vary in size and tilt angle with respect to an imaging camera. Symmetry characteristics of the targets are used to locate the targets independent of the threshold level selected for determining transitions between rings of different reflectivity.

Patent
08 Jul 1994
TL;DR: In this paper, the authors proposed to obtain a steep shoulder characteristic and to design freely a desired group delay characteristic by providing a weighted apodized electrode formed to an input side and a tilt electrode finger forming to an output side to the device.
Abstract: PURPOSE:To obtain a steep shoulder characteristic and to design freely a desired group delay characteristic by providing a weighted apodized electrode formed to an input side and a tilt electrode finger formed to an output side to the device. CONSTITUTION:A surface acoustic wave stimulated by an input side weighted apodized electrode 2 is propagate from a position A to a position B and the surface acoustic wave propagated in the direction B is transduced again into an electric signal at the output side tilt electrode finger 8 through a shield electrode 4. The surface acoustic wave passing through the tilt electrode finger 8 is attenuated by a sound absorbing agent 6 coated to an end face. Then the propagated surface acoustic wave depends on number of electrode fingers and in the case of the tilt electrode finger at the output side, the characteristic results from multiplication of frequencies equivalent to pitches of each split electrode thereby realizing the broad band characteristic, resulting that a steep shoulder characteristic is realized by the characteristic of the weighted apodized electrode 2.

Patent
Hiromichi Ishibashi1
15 Nov 1994
TL;DR: In this article, an optical disk drive with a light source, a light receiving element and a signal processing circuit for detecting an optical reproduced signal representing information stored in the desired track and control signals for accurately radiating the light beam onto a desired track is presented.
Abstract: An optical disk drive of the present invention includes: a light source for emitting a light beam; an optical system for radiating the light beam onto a desired track formed on an optical disk; a light receiving element for receiving the light beam reflected by the optical disk; and a signal processing circuit for detecting an optical reproduced signal representing information stored in the desired track and control signals for accurately radiating the light beam onto the desired track, in accordance with a light amount of the received light beam, wherein the light receiving element includes first and second light receiving portions, the first light receiving portion receives a part of interference light beams resulting from an interference between a zero-order diffracted light beam and ± first-order diffracted light beams diffracted by the track among the light beam reflected by the optical disk, and the second light receiving portion receives a remaining part of the interference light beams; and wherein the signal processing circuit detects a tilt amount of the optical disk in a radial direction based on a light amount of a light beam received by the first light receiving portion and that received by the second light receiving portion.

Journal ArticleDOI
TL;DR: In this article, the shape of the neutral sheet and magnetopause boundaries can be observed directly from the images and a fitting function that qualitatively matches the observed boundary shape can then be chosen.
Abstract: Eight years of Interplanetary Monitoring Platform (IMP) 8, four years of International Sun Earth Explorer (ISEE) 2, and one year of IMP 7 magnetometer data have been combined to produce an 'image' of the average magnetic field for a YZ cross section (aberrated GSM) of the magnetotail at a downtail distance of 25 R(sub E). The shape of the neutral sheet and magnetopause boundaries can be observed directly from the images. A fitting function that qualitatively matches the observed boundary shape can then be chosen. This approach improves on previous fits to possible unsuitable functional forms specified independently of the data. In addition, as a refinement of previous studies, we have corrected for varying solar wind dynamic pressure and the effects of tail flaring. We find the magnetopause is displaced above the XY plane with increasing dipole tilt. The neutral sheet is found to curve slightly more than the model of Fairlfield (1980) during times of large dipole tilt and near the flanks appears to differ substantially from the neutral sheet shape given by the analytic model of Voigt (1984), the more recent neutral sheet model of Dandouras (1988) based on the Voigt model, and the semi-empirical model of Tsyganenko (1989).

Journal ArticleDOI
TL;DR: In this article, a performance analysis of tip-to-tilt-compensation systems that use natural stars as tilt references is presented, where the authors optimize the system operating parameters to determine performance limits.
Abstract: We present a performance analysis of tip–tilt-compensation systems that use natural stars as tilt references. Taking into account properties of the atmosphere and of the galactic stellar populations, we optimize the system operating parameters to determine performance limits for several varieties of tip–tilt-compensation system operating on a 10-m telescope on Mauna Kea, Hawaii. We find that, for systems that use a single tilt reference star, if the image of the star is uncorrected, a one-axis root-mean-square tilt residual of less than 190 nrad can be obtained for at least 99% of all astronomical objects, whereas if the image of the tilt reference star is fully corrected this limit drops to 90 nrad. For systems that use two tilt reference stars the limits drop to 160 nrad if the images of the stars are uncorrected and to 60 nrad if the images of the stars are fully corrected. These residual tilt levels would permit V-band images with long-exposure resolution of 8.5, 4.2, 7.3, and 2.9 times the diffraction limit, respectively, where the diffraction-limited resolution in the V band is 0.011 arcsec. These results may be compared with the typical seeing of 0.75 arcsec.

Patent
02 Sep 1994
TL;DR: In this paper, a tilt angle adjuster was used to control the distance of the print head from the image receiving drum by rotating a tilt arm and a biasing spring, which rotated the tilt arm together between printing, maintenance and shipping tilt angle positions.
Abstract: A print head (216) tilt angle positioner (258) includes a scroll cam (344), a tilt arm (332), a flexure (334), a tilt angle adjuster (336), and a biasing spring (338). The tilt arm and the print head are attached to a shaft (220) that rotates the tilt arm and the print head together between printing, maintenance, and shipping tilt angle positions to control the distance of the print head from the image receiving drum.

Patent
09 Aug 1994
TL;DR: In this article, a control device is used to calculate the tilt angle of a wire by reading a finish machining shape commanded by a machining program from an NC tape in an NC program anlytic part.
Abstract: PURPOSE:To attain accurately machining tilt surfaces of a workpiece with its upper/lower surfaces not in a similar figure and a workpiece with the axis of the upper/lower surfaces not vertical even with the upper/lower surfaces in a similar figure by correspondingly providing upper/lower guide positions from a commanded finish machining shape, and providing a control device for correcting a wire tilt angle between both the positions. CONSTITUTION:A control device 6 reads a finish machining shape commanded by a machining program from an NC tape 11 in an NC program anlytic part 12, to obtain a machining route for actually moving a wire 1. Next in a moving position arithmetic part 13, positions of upper/lower guides 2, 3 are correspondingly obtained. In an interpolation processing part 14 from positions of these upper/lower guides 2, 3, a tilt angle of the wire 1 is calculated. Thereafter based on the predetermined correction amount, the tilt angle of this wire 1 is corrected in a tapered angle correcting part 15.

Journal ArticleDOI
TL;DR: In this article, surface charging effects on etching profiles during silicon etching in a nonuniform plasma were investigated by scanning electron micrographs and plasma potential measurements, and the distortion in ion trajectories caused by the surface charging was calculated by an ion lens simulator.
Abstract: Surface charging effects on etching profiles during silicon etching in a nonuniform plasma were investigated by scanning electron micrographs and plasma potential measurements. The distortion in ion trajectories caused by the surface charging was calculated by an ion lens simulator. A tilt in the etching profile was found in holes and trenches near a large etched area when an insulating mask such as photoresist or silicon dioxide was used. Ion trajectory calculations showed that this profile tilt was caused by the local electric field resulting from the potential difference between the charged mask surface and the electrically grounded silicon substrate. This profile result agrees well with gate oxide damage results which were also successfully explained by surface charging.

Proceedings ArticleDOI
H.-M. Tzeng1
04 May 1994
TL;DR: In this article, an optical apparatus was built to measure the thermal strain which manifests itself in the tilt of the actuator, which is caused by a reversal of the tilt direction.
Abstract: An optical apparatus was built to measure the thermal strain which manifests itself in the tilt of the actuator. Undergoing a heating-cooling, the actuator exhibits a hysterisis in the thermally-induced tilt. There are four regimes in the evolution of the thermal field in either the heating or the cooling phases. Hysteresis in tilt is caused by a reversal of the tilt direction as the actuator changes its thermal regimes. Analyses of a thermal model for actuator find that the first two regimes are dominated by heat transmission from coil to its immediate, contacting components. In contrast, it is the air conduction from coil to its adjacent components that plays a major role in the latter two regimes. >

Journal ArticleDOI
TL;DR: In this paper, the authors used the Kolmogorov theory to illustrate that the mean square wavefront error E2, which results when the wavefront distortion associated with an artificial guide-star reference is used to compensate a telescope aperture of diameter D, for imaging an object at infinity is given by E2 = (D/d0)5/3.
Abstract: The Kolmogorov theory is used to illustrate that the mean-square wave-front error E2, which results when the wave-front distortion associated with an artificial guide-star reference is used to compensate a telescope aperture of diameter D, for imaging an object at infinity is given by E2 = (D/d0)5/3. The quantity d0 is a measure of the effective diameter of the compensated imaging system (i.e., a telescope with a diameter equal to d0 will have 1 rad of rms wave-front error) and is expressed as an integral over the Cn2 profile. The Cn2-weighting function is expressed in terms of hypergeometric functions whose series representation converges very rapidly. (Typically only a few terms are required). As a result d0 can be evaluated quite quickly on a microcomputer or a scientific calculator. In this study the quantity d0 is evaluated for six Cn2 profiles of interest, illustrating the importance of including the altitude weighting in the theoretical formulation of d0. In addition, this study illustrates the importance of removing the piston and the tilt from the wave-front distortion when assessing the performance of an imaging system.

Proceedings ArticleDOI
Guang-Ming Dai1
31 May 1994
TL;DR: In this paper, a modified Hartmann-Shack wavefront sensor and iterative wavefront reconstruction is presented and a comparison is made between conventional and proposed methods, especially for large sub-aperture configurations.
Abstract: Conventional modal compensation using Zernike polynomial expansion by means of Hartmann-Shackwavefront sensors is discussed. Cross-talk problems of Zernike coefficients have been found to beserious, especially for large sub-aperture configurations. A proposal for use of a modified Hartmann-Shack wavefront sensor and iterative wavefront reconstruction is presented and a comparison is madebetween conventional and proposed methods. 1. INTRODUCTION Wavefront sensing and reconstruction is a key procedure in adaptive optics and other fields, such aspost-detection turbulence compensation. In adaptive optics, there are mainly three different kinds ofwavefront sensing methods, namely shearing interferometry, Hartmann-Shack (hear-after H-S) wavefront sensing and curvature sensing. The first two methods measure the local tilt (first derivative) of the unknown wavefront over a sub-aperture, while the last method measures the wavefront curvature (secondderivative). The purpose of wavefront sensing is to obtain necessary information on wavefronts. Whenthe information is obtained, the reconstruction of the wavefront is performed.In general, wavefront reconstruction can be categorised into two approaches, zonal and modal. In thezonal concept, the wavefront in a certain sub-aperture is fitted by means of phase directional derivativemeasurements. In the modal concept, wavefront is decomposed into a series of orthogonal polynomials,and the coefficients of the polynomials are estimated using the phase derivative measurements. Bothmethods use least square estimation.Modal wavefront reconstruction using H-S wavefront sensing is commonly used, since the H-S wave-front sensing method is widely chosen in adaptive optics and modal reconstruction has been shown tobe superior to zonal reconstruction1. In the modal approach, due to the finite summation of the decom-posed polynomials, cross-talk of high order coefficients unavoidably affects those of lower orders2. Thisproblem is severe, especially when the number of sub-apertures is small. In this paper, we propose the

Journal ArticleDOI
TL;DR: In this paper, a quantitative study of the effect of electric field on the stripe domains formed by layer deformation in chiral smectic A liquid crystals is presented, and the relationship between the optical tilt angle and the tilt angle evaluated from x-ray measurements of the layer thickness indicates that the molecules are tilting as rigid rods.
Abstract: A quantitative study of the effect of electric field on the stripe domains formed by layer deformation in chiral smectic A liquid crystals is presented. X‐ray diffraction studies reveal that the angle between the layer normals in adjacent stripe domains increases with increasing electric field. A simple model is presented to derive the true molecular tilt angle from optical transmission measurements. The relationship between the optical tilt angle and the tilt angle evaluated from x‐ray measurements of the smectic layer thickness indicates that the molecules are tilting as rigid rods.

Patent
29 Aug 1994
TL;DR: In this article, a dual-sided reflector is pivoted along orthogonal axes by pan and tilt mechanisms, one or both of which remain stationary with respect to the yoke.
Abstract: A variable light modifier provides rapid beam deflection and flipping with a minimum of noise, power consumption and heat generation. In one embodiment of the invention, a dual-sided reflector is pivotable along orthogonal axes by pan and tilt mechanisms. The pan and tilt mechanisms are driven by pan and tilt motors, one or both of which remain stationary with respect to the yoke. The variable light modifier can be used to deflect light beams generated by one or more light sources and can reflect the light from one or both reflective surfaces of the reflector.

Patent
Akira Matsubara1, Takao Hayashi1, Murakami Yutaka1, Nakamura Toru1, Hideki Aiko1 
23 Feb 1994
TL;DR: In this paper, the relative tilt of an optical disk and a movable objective lens holder is measured as an output of a differential amplifier which subtracts an output from first photodetectors and detects the reflected light from optical disk from output of second photodeter.
Abstract: The relative tilt of an optical disk and a movable objective lens holder is measured as an output of a differential amplifier which subtracts an output of first photodetectors and which detect the reflected light from optical disk from an output of second photodetectors and which detect the reflected light from a reflector mounted on movable objective lens holder. The signal from differential amplifier is used to tilt movable objective lens holder so that the movable objective lens holder compensates the tilt of optical disk.

Journal ArticleDOI
TL;DR: In this article, an adaptive secondary mirror was developed on a 2.3m telescope to stabilize rapid motion caused by atmospheric turbulence, and the instantaneous position of an image's centroid, or brightest speckle, was measured by a near-infrared camera system which enables the tip-tilt mirror to recenter the image.
Abstract: A prototype adaptive secondary mirror has been developed on a 2.3-m telescope to stabilize rapid motion caused by atmospheric turbulence. The instantaneous position of an image's centroid, or brightest speckle, is measured by a near-infrared camera system which enables the tip-tilt mirror to recenter the image. Correction is accomplished at closed-loop frequencies of less than or = 100 Hz on guide stars with K (2.2 micrometers) magnitudes less than or = 8. Image motion is reduced to less than 0.1 sec rms, removing over 90% of low-frequency (f less than or = 5 Hz) tilt power, leaving less than or = 1 rad exp 2 mean square wave front tilt phase error. In seeing conditions where D/r sub o approximately = 4, long exposures in the H band (1.6 micrometers) exhibit a nearly diffraction-limited resolution of 0.19 sec full width at half maximum (FWHM) (Strehl ratio aprroximately = 0.14)-a factor of 4 improvement over uncorrected images. Reduction of the present static optical errors will improve the Strehl ratio another factor of 2, leading to approximately 70% of the maximum possible Strehl ratio.