Showing papers on "Interference (wave propagation) published in 1976"

The interpretation of diffraction and interference in terms of energy flow

Abstract: Solutions to Maxwell's equations at a semi-infinite plane and a double slit are used to construct lines of constant amplitude, constant phase and energy flow. The lines of energy flow show how the electromagnetic boundary conditions necessitate a particular undulation in the path of the light energy and that the consequent redistribution of energy corresponds with a diffraction or interference pattern. This interpretation complements the interpretation in terms of the interaction of secondary wavelets due to Huygens.

Optical interference coatings.

Abstract: The OSA topical meeting on Optical Interference Coatings held in February 1976 at Asilomar is briefly reported on, the state of the art surveyed, and future directions recognized.

Excitation of Surface Electromagnetic Waves in Attenuated Total-Reflection Prism Configurations

Abstract: We have carried out theoretical and experimental studies of the excitation of surface electromagnetic waves by volume electromagnetic radiation of finite beam width. The excited leaky surface electromagnetic waves are found to build up along the excitation region and to propagate as free damped waves beyond. Correspondingly, the spatial dependence of the reflected intensity is found to exhibit a two-peak interference structure at the leading edge of the excitation region followed by an exponential decay beyond.

Interference effects in NMR correlation spectroscopy of coupled spin systems

Abstract: The nonlinear behavior of coupled spin systems in NMR correlation spectroscopy is studied theoretically and experimentally. The two principal types of effects result from passage with transverse interference and from passage with longitudinal interference. The phase and relative amplitude of the signals strongly depend upon the applied sweep rate and the effective flip angle utilized in these experiments. Specific examples are cited for the case of coupled two‐spin systems. Guidance for avoiding nonlinear interference effects in NMR correlation experiments is indicated.

Quantum Theory and the Nature of Interference

Abstract: It is shown that many of the difficulties associated with the Copenhagen interpretation of quantum theory are resolved by a new interpretation of interference derived from solutions to Maxwell's equations. An infinite wave model of the photon based on these solutions is described and used to explain the interference of single photons as well as the corpuscular behavior evident in the Compton and photoelectric effects. The wave-particle duality and the uncertainty relations are also discussed. According to the new interpretation of interference in a Young's double-slit experiment, photons which pass through the left-hand slit always arrive in the left-hand part of the screen and no photons pass into this area via the right-hand slit. This conclusion is compared with the viewpoint of the Copenhagen school and an experiment to distinguish between them is suggested.

Interference (holographic) diffraction gratings

Abstract: Diffraction gratings in which the grooves are formed by recording optical interference fringes are rapidly becoming established as alternatives to ruled gratings. In many respects they compare favourably with ruled gratings, but because of both the limitations and the novel features of the interference method of manufacture, a straightforward comparison is not always possible. Whether a ruled or interference grating is to be preferred will strongly depend upon the use to which it is to be put.

Fabry-Perot interference spectrometer

Abstract: A reflecting mirror is disposed behind a single Fabry-Perot interferometer non-perpendicularly relative to the optical axis of the interferometer. The light transmitted through the interferometer parallelly to the optical axis is reflected by the reflecting mirror and, therefore, caused to pass reversely through the interferometer at an angle relative to the optical axis. In this way, a single interferometer offers two different mirror gaps, one for the light path in the forward transmission and the other for the light path in the reverse transmission through the interferometer. The forward and reverse transmission of the light through the interferometer at different mirror gaps serves to enlarge the free spectral range to a notable extent.

Constant amplitude interference squelch system

Abstract: A squelch circuit for muting constant amplitude interference when the signal is absent. The input wave's envelope characteristic is examined so as to determine if the envelope is constant and, if it is, a gate is controlled so that the input wave is muted. Time delay circuitry is provided in one embodiment in order to provide sufficient time to make a determination that constant amplitude interference is present rather than variable amplitude speech before muting the input wave.

Seeing effects removal in a Michelson stellar interferometer

Abstract: There is no unique definition of the fringe contrast in a random structure such as the image given by a Michelson stellar interferometer. A new definition is given here which leads to a contrast value independent of the seeing conditions provided the wave-front perturbations on the two apertures are uncorrelated. Moreover, if simultaneous observations through a single aperture are available, the seeing effects can be completely removed.

5.1. Theory of Two-Element Interferometers

Abstract: Publisher Summary This chapter discusses interferometers and arrays, with a special focus on theory of two-element interferometers. The basic observables in radio interferometry are the correlated amplitude and relative phase of waves from a common source at two points on the wavefront. The vector between the two points on the wavefront is known as the interferometer baseline. Optical interferometers bring the two “signals ” together using mirrors and superpose them onto a detector so that they either reinforce or cancel, depending on their relative phases. The interference of the signals in this manner produces interferometer “fringes.” In radio interferometry, the “signals” at the ends of the baseline can be translated to a lower frequency, transmitted through cables, added and detected or cross correlated and Fourier transformed, or even recorded on magnetic tape for post real-time detection. The chapter illustrates that the effective interferometer aperture is the geometric mean of the two apertures, and the effective system temperature is the geometric mean of the system temperatures. The signal analysis is performed for a point radio source and a two-dimensional Fourier transform relation between brightness and visibility is analyzed.

Interferometric technique for determining ultrasonic wave intensity

Abstract: An interferometer, that simultaneously employs two phase-quadrature reference beams of coherent light which interfere with a signal beam of coherent light reflected from a spot of a displaceable signal mirror insonified by an ultrasonic wave, permits an output signal to be derived which is proportional to the sum of the squares of the ultrasonic frequency component of the interference between the signal beam and each respective one of the reference beams. This output signal is inherently substantially proportional to the intensity of the ultrasonic wave then insonifying the spot of the signal mirror and independent of random phase drift and environmental vibrations in the interferometer. The interferometric technique of the present invention, which permits the ultrasonic wave to be in the form of pulse bursts of only a few cycles so that the output signal can be range-gated, is suitable for use in an ultrasonic-wave measurement and image display system.

Light interference device with low degree of spacial coherence

Abstract: A light interference device comprising a light source having a low degree of spacial coherence, an optical element having a reference surface for interference, an optical system for providing a parallel light bundle, and an optical projection system for projecting interference fringes localized near the interference surface. Said parallel light bundle comes out of the reference surface at an angle θ within the range of 0° < θ ≦ 30°.

Surface profile scanning device - tested object is moved at right angles to direction of movement of scanning sensor

Abstract: The sensor determines the deviation of the object's surface from a surface assigned as a datum surface. The sensor is in the form of a white light two-beam interferometer, whose optical parth's length difference between object and reference beam is wobbled by more than the coherence length of the light used, so that interference phenomena appear periodically when the path length of the reference beam coincides with that of the object beam. Interference phenomena are converted by a photodetector into an electric signal, from which a processing device derives the deviation of the tested surface, including the deviation sense.

Theory of intercollisional interference effects: V. Pressure shift of the interference minimum in the Q branch of H2-rare gas mixtures

Abstract: We extend our previous kinetic theory of intercollisional interference effects to include vibrational perturbations in collisions, and so obtain expressions for the pressure shifts of the interference minima in H2-rare gas mixtures. These shifts are found to be different from those of the isotropic Raman Q lines in the same systems. The use of phase space averages for the analysis of Raman line shifting is discussed.

High speed phase follow up control system - for laser interferometers with continuous recording of displacements in wide amplitude range generates difference current

Abstract: A high-speed phase follow-up control system for laser interferometers, e.g. for user in dilatometers, refractometers, etc. has a recording unit with two photodetectors. The difference in current between the two detectors varies the change in a capacitor, and the capacitor voltage is fed back to the interferometer through a compensator. Pref. when the control system interference signals are produced using a polarised optical system. The control system enables for the first time optical displacements to be continuously recorded in an amplitude range from an Angstrom to several um at very high frequencies which can reach MHz in extreme cases.

Computation of Interference into Angle-Modulated Systems Carrying Multichannel Telephone Signals

Abstract: It is commonly known that, in order to calculate the demodulated noise power of the wanted frequency division multiplexedfrequency modulated (FDM-FM) signal due to interference, the convolution between the power spectra of the wanted FM signal and interference is required to be obtained. This concise paper shows a simple approach to calculate this convolution without direct calculation of the power spectrum of the FDMFM signal when the power spectrum of the interference is given (by measurements or calculation) and the highest and lowest channel frequencies of the baseband signal and rms frequency deviation of the wanted FDM-FM signal are known. Since the calculation of the FDM-FM signal power spectrum is not an easy problem in some cases, this approach makes much simpler an accurate evaluation of the output noise power due to interference.

One-Arm Phase Optical Bridge for Measuring Small Amplitude High Frequency Vibrations

Abstract: In this paper a one-arm phase optical bridge with axial symmetry which utilizes Newton's interference fringes is described and its application for measuring small amplitude high frequency vibrations (1-100 MHz) is also given. With a preliminary modulation of the laser beam and making use of the heterodyne method, a simple lowfrequency lock-in amplifier can be used for lowering the noise. A high sensitivity of about 10-12 m is obtained. An additional lowfrequency modulation of the length of the arm of the bridge, makes it possible to avoid the very difficult problem of maintaining the constant length of the arm, without lowering the sensitivity and the precision of the measurements. In this way the scanning, measuring and registration of the distribution of the vibrations having a component in the direction of the axis of the phase bridge are proved to be very simple.

Application of interferometry to simultaneous multielement atomic emission spectrometry. [Oxygen-hydrogen flame]

Abstract: A technique for simultaneous multielement analysis based on a scanning Fabry-Perot interferometer and atomic emission is described. Detection limits are determined for various common elements using the oxygen-hydrogen flame as a test case. The results show that semitrace to trace levels in solution can be analyzed. This technique is limited to groups of elements which contain relatively few total emission lines in a certain wavelength region. Spectral interference can, in general, be eliminated by the proper choice of the interferometer spacing. Analysis of tap water and parameters essential to this optical scheme are discussed. The main advantages of this technique are the high luminosity and the ability to perform analysis in the millisecond time scale. (auth)

Identification of random auditory waveforms. III. Effect of interference.

Abstract: The identification of specific random waveforms, imbedded within random interference, was examined. Backward interference (interference after the specific waveform) was more effective than forward interference (interference before the specific waveforms). The accuracy of identification with combined interference (interference before and after the specific waveforms) is approximated by an independence model of interference. Under the present test conditions, interference with the identification of specific random waveforms is interpreted to be more nearly related to the interruption of auditory processing than to the masking of signal audibility.Subject Classification: [43]65.58, [43]65.75, [43]65.52.

Interference position monitoring system employing Ronchi gratings

Abstract: A technique for obtaining positional information using a Ronchi grating is described. By employing the grating as a diffraction element, modulation of the phase of a coherent light beam is accomplished. The phase contains information as to the position of the beam on the grating surface. The use of an interference technique allows one to monitor the light phase, and therefore the beam’s position. Using a single grating, directional as well as positional information is obtained in two dimensions. Advantages and other system characteristics are described.

A Field Compensated Interferometer for Wavelength Comparison

Abstract: We have built at the Institut National de Metrologie (INM) a two beam interferometer, of Michelson type, for optical wave-length comparison. It is in vacuum and the separating plate works at Brewster’s angle. Its main quality is to give a flat field of interference at a path difference chosen for measurements (temporarily 250 mm), hence providing a large flux. The standard line of krypton provides a signal-to-noise ratio which allows us to work with a continuous scanning of path difference and a time constant less than 10−1 second.

Optical system for multiplication of two beam interference path difference

Abstract: PURPOSE:To improve interference fringe by moving beam back and forth within many planes parallel to the ray of light incident and shortening the average optical path distance per reciprocating motion.