Showing papers on "Phase (waves) published in 1973"

Monochromatic Phase Curves and Albedos for the Lunar Disk

Abstract: Photoelectric observations of the entire lunar disk made in 1964-1965 over phase angles from 6 to 12 deg in nine narrow bands from 0.35 to 1.0 microns and in UBV are reviewed. Phase curves are presented as a function of wavelength. The results confirm a reddening with increasing phase angle found by previous investigators for particular areas.

An examination of an iterative method for the solution of the phase problem in optics and electron optics: I. Test calculations

Abstract: An evaluation is made of an iterative method for determining the amplitude and phase from the image intensity recorded in optical systems. The method, which requires two images recorded at different lens defocus values, is tested with simulated data subject to error arising from the photographic recording of the image. In the case of error-free data, the solution for the phase distribution appears to be indeterminate to within a constant. The results for photographic noise levels of up to 20% of the maximum image intensity reflect the small effect of error on the calculated phase distribution. The calculation of phase distributions for both symmetric and asymmetric amplitude-phase distributions shows that the use of two images, taken at defocus values differing by about 100 nm in electron optics and about 1 mm in optics (depending on the numerical aperture of the objective lens), may be used to determine the complex object wave-function in both dark-field and bright-field optics.

Phase‐matched far‐infrared generation by optical mixing of dye laser beams

Abstract: We report the use of a dual‐frequency dye laser system to generate continuously tunable far‐infrared radiation over the frequency range from 20 to 190 cm−1. We have investigated both collinear (forward and backward) and noncollinear phase matching in LiNbO3 over most of this frequency range and forward collinear phase matching in ZnO, ZnS, CdS, and CdSe at selected frequencies.

Design and synthesis of random phase diffusers

Abstract: This paper considers diffusers characterized by random variations of optical path, such as ground-glass-surface diffusers. The theoretical limits on the light distributions realizable with random phase diffusers are derived, and the important parameters controlling these light distributions are identified. Methods for generating controlled random signals that, when converted to optical-path variations, have the correct parameters to synthesize diffusers with any desired, realizable light distribution are described. Some goniophotometric data taken from diffusers synthesized by this method are given in support of the theory. These results represent a basic solution of the random-phase-diffuser synthesis problem.

Quantum Theory of Nonlinear Optical Processes with Time-Dependent Pump Amplitude and Phase: Frequency Conversion

Abstract: The behavior of a simple theoretical model of a quantum-frequency converter with a time-dependent pump amplitude and phase is analyzed quantum mechanically. A sufficient condition ensuring periodic frequency conversion between the modes is found and exact solutions are given in these cases. The complete time-dependent density matrices which give the most complete statistical description of the system are presented for a variety of initial states of the system. In the general case where the sufficient condition is not satisfied, time-dependent-perturbation-theory results give corrections to the amplitude and the period of the energy exchange between the modes. Comparisons are made between these results and those of other authors.

Ideal laser amplifier as a phase measuring system of a microscopic radiation field

Abstract: A measuring system is described for the phase determination of a microscopic radiation field. The essential element of this system is a Q-switched Nd:YAG laser which serves as an ideal laser amplifier with a high amplification of approximately 1010, having insignificant quantum noise. The result for a phase measurement of several photons (about five) is presented.

System for phase aligning parallel signal processing channels

Abstract: A system for automatically phase aligning parallel signal processing channels such as those used in the receiving system of monopulse radars, for example. Test signals having a predetermined phase relationship are applied at the inputs of each of two signal processing channels and a phase detector measures the phase of the resulting output signals. The phase detector''s output signal is processed to control a variable phase shifter, series coupled with the local oscillator signal applied to a mixer in one of these channels, so as to cause the test signals at the output of the two processing channels to have a predetermined phase relationship.

Method and apparatus for treating multi-phase systems

Abstract: THE METHOD OF TREATING A MULTI-PHASE SYSTEM TO ENHANCE THE SEPARABILITY OF AT LEAST ONE DISCONTINUOUS PHASE CONTAINED THEREIN COMPRISING SUBJECTING THE SYSTEM TO AT LEAST TWO DITURBANCES PROPAGATED WITHIN THE SYSTEM TO FORM AT LEAST TWO WAVE TRAINS AT TWO DIFFERENT FREQIENCIES WITHIN THE AUDIO FREQUENCY RANGE, WHILE AVOIDING CAVITATION WITHIN THE SYSTEM. THE PRESENT INVENTION ALSO DISCLOSES AN APPARATUS FOR TREATING A MULTI-PHASE SYSTEM HAVING A LIQUID CONTINUOUS PHASE TO ENHANCE THE SEPARABILITY OF A DISPERSED PHASE CONTAINED WITHIN THE SYSTEM, COMPRISING MEANS FOR CONFIRNING A VOLUME OF THE SYSTEM TO BE TREATED, AND FIRST AND SECOND MEANS FOR GENERATING VIBRATORY DISTURBANCES WITHIN THE VOLUME TO FORM RESPECTIVE TRAINS OF WAVES THEREWITHIN, THE FIRST AND SECOND GENERATING MEANS BEING POSITIONED WITH RESPECT TO EACH OTHER SO THAT THE RESPECTIVE WAVE TRAINS FORMED WITHIN THE VOLUME MIX.

Determination of Horn Antenna Phase Centers by Edge Diffraction Theory

Abstract: The edge diffraction method of analysis utilized in the past to determine amplitude patterns is extended in this paper to predict the radiation phase center of pyramidal horn antennas. A series of extensive phase and amplitude measurements were performed on these antennas to determine the validity of the theoretical results. The measurements were performed over a frequency range of 7.5 to 10.5 GHz in the E plane of the antennas. The phase measurements were accurate to ±0.2 electrical degrees, so that the phase center locations relative to the horn apertures were repeatably determined to better than 0.010 inch for horn apertures as large as 7 inches. The results of the measurements indicate that excellent agreement is obtained with the theory in predicting the phase center location of the larger horns (kRE > 50). For the smaller horns, however, there is a large discrepancy between the theory and measurements. The measured phase centers of the smaller horns exhibit a large variation with frequency which cannot be explained with the existing theory. Several reasons for the discrepancy are presented, and it is concluded that a more rigorous approach involving higher order modes has to be developed for the smaller horns.

Method of hologram recording with reduced speckle noise

Abstract: A sampling mask having a regular array of light transmitting areas is superimposed by a phase mask having a random array of phase shifting areas. The superimposed sampling and phase masks are holographically recorded for producing a hologram which later acts as a beam splitter to provide object and reference beams. The hologram so prepared is illuminated with a spatially incoherent broad source of light and imaged through an optical system. The zero order diffracted wave serves as the reference beam and the first order diffracted wave is used to illuminate an object transparency which is placed in the focused beam of the first order wave. Each point source of light from the spatially incoherent broad light source produces a corresponding interference fringe pattern, and it is shown that the interference pattersn exactly overlaps one upon another so that sharply defined fringe contrast results. The size of the light source is determined only by the required degree of resolution which in turn is dependent on the sampling spacing. The use of the incoherent broad light source enables uniform illumination of the object transparency, resulting in high-quality holograms with reduced speckle noise.

Optical noncontacting surface sensor for measuring distance and angle of a test surface

Abstract: An optical sensor is described for providing an output responsive to the position and normality of a test surface with respect to a predetermined plane. A beam of radiant energy is focused by a lens onto the test surface, while being modulated along its optical axis by a first mirror oscillating at one frequency and being modulated transverse to its optical axis by a second mirror at a second frequency. The first harmonic of the frequency of the modulation of the first mirror is then monitored as to phase and amplitude by a single photodetector to provide a measure of the direction and distance of the test surface from the determined plane. The sum or difference harmonic of the radiant energy reflected from the test surface is also monitored as to phase and amplitude by the same photodetector to provide a measurement of the normality of the test surface with respect to the determined plane.

Surface acoustic wave phase control device

Abstract: A surface acoustic wave device in which a phase or velocity shifting electrically conductive layer is located between the receiving and transmitting transducers. In one embodiment as a filter, the phase shift may be varied as a function of frequency over a broad range of frequencies by varying the shape of the conductive layer thereby permitting a desired phase response to be achieved.

Thin film waveguide with a periodically modulated nonlinear optical coefficient

Abstract: A phase matched thin film waveguide supportive of electromagnetic wave energy having angular frequencies is disclosed. In one embodiment, the waveguide includes a sequence of strips each of length A/2 in the direction of wave energy propagation and spaced apart from one another a distance A/2, A = 2 pi / DELTA beta , where DELTA beta is the phase constant difference required to satisfy the relationship beta 1 + beta 2 = beta 3 + DELTA beta , beta 1, beta 2 and beta 3 being, to a first order of approximation, the phase constants respectively of the wave energy. In other embodiments, the spaces between the strips are filled with materials whose nonlinear optical coefficient is either zero or different from the nonlinear optical coefficient of the spaced apart strips. The filling material's index of refraction is substantially equal to that of the spaced apart strips.

Direction locating system

Abstract: An instantaneous, omnidirectional direction finding system for locating an incoming wave over a complete 360° arc in space employing a circular antenna array and a fixed phase shifting network for deriving from said array a differently time phase shifted signal for each different spatial direction. The array observes all spatial directions continuously, as opposed to a sequential angular scanning technique. In a preferred system, the phase shifting network provides a plurality of output modes wherein the incoming wave is defined by different phase displaced signals that are compared and quantized to obtain a digital code representing direction.

Method and means for investigating the distribution of electrical conductivity in the ground

Abstract: The invention relates to the obtaining of highly diagnostic information concerning the distribution of electrical conductivity (resistivity) in the ground between two points by creating an electromagnetic field whose frequency can be varied over a desired range at one of the points and detecting and comparing at the other of the points, at a plurality of transmitted frequencies, components of the magnetic and/or electric field which are in phase and out of phase with a reference signal derived electromagnetically at the second point from the transmitted field whereby no cable or other physical connection between the two points are required. The invention also relates to apparatus by means of which the electromagnetic field is created, the reference signal electromagnetically derived and the in phase and out of phase magnetic and/or electric field components detected.

Elastic scattering of slow electrons by helium.

Abstract: The optical potential model of Pu and Chang (1966) is extended to include EPV diagrams. Calculations are carried out for the s, p and d wave phase shifts at energies up to 17 eV. The results for s and p waves are in close agreement with those of other recent calculations and, with a phase shift analysis of experimental data. The d wave results lie between the full polarized orbital and the Green function expansion results. It is shown that third order diagrams are required for an accurate evaluation of the static polarizability, yielding alpha =1.372 a03, and estimates are made of the third order corrections to the d-wave phase shift, which brings the optical potential values into good agreement with the full polarized orbital results.

Wood slope of grain indicator

Abstract: A method and apparatus for detecting wood grain slope by measuring the direction of the maximum and minimum electrical capacitance with respect to the axis of a piece of lumber The method comprises rotating a pair of electrically energized capacitor plates closely adjacent a surface of the piece of lumber under test, measuring the sinusoidal variations in the capacitance value obtained as an analogue signal, comparing this signal as to phase with a reference signal related in frequency to the rotation of the capacitor plates, said phase relation being indicative of the direction of grain The apparatus comprises a pair of spaced flat capacitor plates formed in the surface of a circular disc over which the wood workpiece would travel, means for rotating the disc at a precise rotation speed, means for measuring the sinusoidally varying capacitance in the form of a voltage, means for comparing the phase of this voltage with the phase of a reference AC voltage whose frequency is directly related to the rotation speed of the disc, and whose phase corresponds to zero slope-of-grain, means for measuring variations in phase displacement, said variations being directly related to variations of the grain slope of the wood from parallel to the wood piece axis For three dimensional indicators two similar devices are placed at right angles such that two surfaces of the lumber are scanned at the same time

Microwave phase shifting apparatus

Abstract: Apparatus for phase shifting between radiating elements of an antenna array by utilizing the inherent phase difference existing between frequency locked oscillators. Power from a master oscillator is injected into a plurality of slave oscillators, each of which feeds a different radiating element. The slave output is also fed through a directional coupler into a phase comparator which receives a comparison output signal from the master oscillator. The comparator output and a DC phase reference voltage are applied to a differential amplifier whose output forces the free-running frequency of the slave oscillator to change until the comparator output equals phase reference voltage.

Parallel optical stage laser systems

Abstract: Disclosed are laser amplifier systems for producing unlimited amounts of laser power having controllable frequencies and good optical qualities A source of controllable frequency coherent energy is directed through a plurality of parallel optical channels, each of which contains laser power amplification means The outputs from the parallel channels are combined spatially parallel to form a system component laser output having an aligned phase front A sample beam is taken from each amplification channel and is processed with a phase sensitive optical detector to produce suitable error signals which are used to vary the optical pathlengths of the system necessary to align the phase fronts In addition, an autoalignment or a phase measurement technique maintains the spatial parallelism in the output

Linear phase microscopy.

Abstract: A technique is described for measuring the phase of complex transmitting objects. It consists of two basic parts. The first is an optical system that imposes the phase of an object onto a sinusoidal carrier in the form of a phase modulation. This is accomplished using interferometric and optical heterodyning techniques. The second is a phase detection system that converts this phase modulation into a signal that is directly proportional to the phase of the object. This technique measures phase variations from zero to 16π, (2π ambiguities are avoided) with a spatial resolution of 600 cycles/mm and a phase resolution of 2π/100. Analysis of this technique and experimental results are given.

Logging while drilling encoder

Abstract: In a logging-while-drilling system motor speed is changed in order to change the phase of an acoustic signal between two phase states. In carrying out a change in phase state, a step voltage is initially applied to a motor control circuit. Added to the step voltage is a linearly increasing voltage. The amount of phase shift in the acoustic signal is detected, and upon the occurrence of a predetermined phase shift the voltage applied to the motor control circuit is reduced to a lesser value. The application of the voltage of lesser value is continued for a predetermined time at which the acoustic signal will have substantially attained the other phase state. The rotary valve driven by the motor imparts a high degree of phase coherence to the acoustic signal which it generates. Rotation of the motor is phase locked to a highly stable clock in near optimal manner by sampling the phase error between the clock and the motor angular position reference every half period of the acoustic signal.

Method and apparatus for the no-contact measurement of velocities, changes in relative position, or displacement paths

Abstract: Light diffracting or dispersing properties of an object dividing a wave front in angular differently oriented wave fronts are used for no-contact optical velocity-, acceleration-, change in relative position- or displacement path measurements of said object movable relative to a measuring head. No systematic markings affecting light phase or amplitude on the measuring surface are disposed in the depth of field of imaging system. Measurements are made respectively to one coordinate associated to one of the six possible spatial degrees of freedom of motion. The object under test and an optical component yielding sharply defined angular relationship among different but combined wave fronts are conjugatedly disposed in the imaging system. Light modulations produced upon changing the relative position are photoelectrically converted into signals exhibiting a frequency change proportional to linear or angular velocity variation. The measurement is improved by using components having negligible light absorption, and determining angular relationship among the wave fronts. Light fluxes from interaction among partial wave fronts containing information concerning the object movement, derived from solid angle areas of equal modulation phase are converted separately into photoelectrical signals having sinusoidally varying modulation characteristics with the respective measuring coordinate. The modulation period cycles are half as long as the statistical spatial frequency components of the object under test. The light energy proportions are split off from and outside the solid angle area of the illumination aperture. The electric signals produced are evaluated as direct or carrier-frequency signals with respect to the measured qualities desired.

Digital phase-locked loop

Abstract: An all digital phase-locked loop derives a loop output signal from an accumulator output terminal. A phase detecting exclusive OR gate is fed by the loop digital input and output signals. The output of the phase detector is a bi-level digital signal having a duty cycle indicative of the relative phase of the input and output signals. The accumulator is incremented at a first rate in response to a first output level of the phase detector and at a second rate in response to a second output level of the phase detector.

Ferroelectric and Ferroelastic Phase Transformations in Which the Soft Waves Have a Wavelength Equal to a General Rational Number Times the Lattice Constant

Abstract: Ferroelectric phase transformations and ferroelastic ones in which the soft vibration modes have a wavelength equal to a general rational number λ/µ (λ, µ: integers) times the relevant lattice constant are theoretically investigated. As an example it is assumed that the space group of the prototypic phase is Pnam and that the wave normal of the soft vibration modes is perpendicular to the symmetry planes n . It is found out how λ and µ influence the dielectric and elastic properties and the space group of the phase resulting from condensation of the soft waves.

The Properties of Phase Modulated Soliton Trains

Abstract: Using nonlinear LC networks which are equivalent to a one dimensional nonlinear lattice, the solitariness and the recurrence phenomena are experimentally investigated for a pair of soliton trains of which the phases are independently modulated. Using a phase modulation system, up to 30% modulation is obtained. This modulation ratio is about 3 time larger than that for an amplitude modulation system.