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R.F. Humphryes

Bio: R.F. Humphryes is an academic researcher from University College London. The author has contributed to research in topics: Microsound & Phase (waves). The author has an hindex of 3, co-authored 3 publications receiving 146 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the theoretical and experimental progress on topographic guides for the development of surface wave microsound systems is reviewed, and some preliminary results on topographical guides are presented.
Abstract: An important requirement for the development of surface wave microsound systems is the ability to guide the energy. The theoretical and experimental progress towards this aim is reviewed. Some preliminary results on topographic guides are presented. Measurement techniques make use of phase-sensitive laser probes to detect the CW surface waves. The technique permits very accurate determination of dispersion characteristics.

71 citations

Journal ArticleDOI
01 Feb 1972
TL;DR: In this paper, the operation and design of an optical heterodyne probe, capable of high-precision phase and group-velocity measurement, is described and compared on the basis of sensitivity and stability.
Abstract: The investigation of acoustic-field distributions on free surfaces is important in several different classes of application. Measurements of the phase of acoustic surface waves using optical probes allow direct measurement of their velocity. A number of different optical-probe types are compared on the basis of sensitivity and stability. The operation and design of an optical heterodyne probe, capable of high-precision phase and group-velocity measurement, is described.

70 citations

Proceedings ArticleDOI
01 Oct 1969
TL;DR: In this paper, the theoretical and experimental progress on topographic guides for the development of surface wave microsound systems is reviewed, and some preliminary results on topographical guides are presented.
Abstract: An important requirement for the development of surface wave microsound systems is the ability to guide the energy. The theoretical and experimental progress towards this aim is reviewed. Some preliminary results on topographic guides are presented. Measurement techniques make use of phase-sensitive laser probes to detect the CW surface waves. The technique permits very accurate determination of dispersion characteristics.

10 citations


Cited by
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Journal ArticleDOI
TL;DR: A review of the various optical methods to detect ultrasound at the surface of opaque solids is presented, including description of knife-edge techniques, optical heterodyning, differential interferometry, and velocity (time-delay) interferometer methods.
Abstract: A review of the various optical methods to detect ultrasound (bulk and surface waves) at the surface of opaque solids is presented. The most useful techniques are thoroughly analyzed. Their performance when nonideal conditions are encountered, such as vibrations, air turbulence, and rough light scattering surfaces is evaluated. This review includes a description of knife-edge techniques, optical heterodyning, differential interferometry, and velocity (time-delay) interferometry methods, plus a mention of various less-important tech-

625 citations

Journal ArticleDOI
01 Aug 1970
TL;DR: In this article, the propagation of various elastic waves at the surfaces of solids is considered, followed by descriptions of the many ways which have been demonstrated for transduction between surface elastic waves and electromagnetic waves.
Abstract: Many of the recently discovered characteristics and applications to electronics of surface elastic waves are discussed. First the propagation of various elastic waves at the surfaces of solids is considered, followed by descriptions of the many ways which have been demonstrated for transduction between surface elastic waves and electromagnetic waves. Surface-wave amplification, primarily in semiconductors, and wave guiding, focusing, and reflection are examined. The properties of these waves suit them for use in a number of applications, which are discussed, ranging from realization of electronic amplifiers, frequency and analog time-domain filters, and coding devices, to the modulation of light beams and the measurement of surface properties of solids. Many references to the recent surface-wave literature are included.

328 citations

Journal ArticleDOI
TL;DR: A new technique has been developed that employs highly focused laser beams for both generating and detecting thermal waves in the megahertz frequency regime and includes a comprehensive 3-D depth-profiling theoretical model; it has been used to measure the thickness of both transparent and opaque thin films with high spatial resolution.
Abstract: A new technique has been developed that employs highly focused laser beams for both generating and detecting thermal waves in the megahertz frequency regime. This technique includes a comprehensive 3-D depth-profiling theoretical model; it has been used to measure the thickness of both transparent and opaque thin films with high spatial resolution. Thickness sensitivities of ±2% over the 500–25,000-A range have been obtained for Al and SiO2 films on Si substrates.

242 citations

Journal ArticleDOI
20 Feb 2019
TL;DR: In this article, the state of the art in nanoscale electro-and optomechanical systems with a focus on scalable platforms such as silicon is summarized and perspectives on what these new systems may bring and what challenges they face in the coming years.
Abstract: Radio-frequency communication systems have long used bulk- and surface-acoustic-wave devices supporting ultrasonic mechanical waves to manipulate and sense signals. These devices have greatly improved our ability to process microwaves by interfacing them to orders-of-magnitude slower and lower-loss mechanical fields. In parallel, long-distance communications have been dominated by low-loss infrared optical photons. As electrical signal processing and transmission approach physical limits imposed by energy dissipation, optical links are now being actively considered for mobile and cloud technologies. Thus there is a strong driver for wavelength-scale mechanical wave or “phononic” circuitry fabricated by scalable semiconductor processes. With the advent of these circuits, new micro- and nanostructures that combine electrical, optical, and mechanical elements have emerged. In these devices, such as optomechanical waveguides and resonators, optical photons and gigahertz phonons are ideally matched to one another, as both have wavelengths on the order of micrometers. The development of phononic circuits has thus emerged as a vibrant field of research pursued for optical signal processing and sensing applications as well as emerging quantum technologies. In this review, we discuss the key physics and figures of merit underpinning this field. We also summarize the state of the art in nanoscale electro- and optomechanical systems with a focus on scalable platforms such as silicon. Finally, we give perspectives on what these new systems may bring and what challenges they face in the coming years. In particular, we believe hybrid electro- and optomechanical devices incorporating highly coherent and compact mechanical elements on a chip have significant untapped potential for electro-optic modulation, quantum microwave-to-optical photon conversion, sensing, and microwave signal processing.

163 citations

Journal ArticleDOI
TL;DR: Tsai et al. as mentioned in this paper proposed a wideband guided-light beam-deflector using tilting surface acousto-optic Bragg devices, which achieved state-of-the-art performance.
Abstract: [45] C. S. Tsai, Le T. Nguyen. M. A. Alhaider, “Wideband Acoustotwo Tilting Surface Acoustic Waves,” Appl. Phys. Lett. 26, optic Guided-Light Beam Deflector Using Tilting Surface 140-143, February 15,1975. Acoustic Waves,” 1974 Ultrasonics Symposium Proceedings, [47] C. S. Tsai, M. A. Alhaider, Le T. Nguyen and B. Kim, “WideIEEE Cat.. # 74. C H 0 896-1SU. 768-772. band Guided-Wave Acoustooptic Bragg Devices Using Multiple [46] C. S. Tsai, Le T: Nguyen, 8. K.’Yao and M. A. Alhaider, “HighTilting Surface Acoustic Waves,” Talk-36, Conference on Laier performance Acousto-optic Guided-light Beam Device Using Engineering and Applications, Washington, D. C., May 1975

133 citations