We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating w... more We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating within a thin silicon plate. A high frequency acoustic point focus lens was used to form a small point source within the plate. A laser interferometric system was used to visualize the acoustic wave propagation. Distinct amplitude patterns at each focal plane were experimentally visualized. The measured amplitude patterns exhibited the cubic symmetry of the material and the effects of focusing of the source outside and inside the material.
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Aug 1, 2004
Acoustic methods are well known and have been used to measure various intrinsic material properti... more Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methods-it is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100's of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper reviews recent applications of laser acoustic methods for determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. Optical acoustic imaging is both quantitative and rapid.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the U.S. Government or the sponsoring agency.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government.
Review of Progress in Quantitative Nondestructive Evaluation, 1988
During fabrication of monolithic ceramic silicon carbide very localized regions of high porosity ... more During fabrication of monolithic ceramic silicon carbide very localized regions of high porosity can be produced. This porosity often consists of a very large density of small pores. Even at ultrasonic wavelengths considerably larger than the pore size, significant effects can be observed in ultrasonic wave propagation through these materials. These effects include attenuation, scattering, and changes in wave velocity. This paper describes the characterization of such a porosity distribution in SiC utilizing these ultrasonic techniques and their correlation with x-ray and optical microscopy measurements. Significant effects were observed due to the nonuniformity of the porosity, which resulted in enhancement of signal amplitudes greatly exceeding attenuation effects due to scattering. This unexpected result proved to be most sensitive to the boundaries of the porosity distribution and provided one of the best techniques for delineating its extent.
The Journal of the Acoustical Society of America, 1996
A new noncontacting optical method of vibration detection has been developed that utilizes the ph... more A new noncontacting optical method of vibration detection has been developed that utilizes the photorefractive effect in select materials to form an optical ‘‘lock‐in’’ amplifier. The method synchronously detects the optical phase shift of an object beam scattered from a vibrating specimen surface. Four‐wave mixing and conventional sychronous detection allow measurement of both the vibration amplitude and phase directly as a function of the excitation frequency. Narrow bandwidth detection can be achieved at frequencies from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The method has been implemented using Bismuth silicon oxide providing a resolution bandwidth of about 130 Hz and flat frequency response up to the MHz region. Both synchronous and random vibration excitation methods can be used providing a minimum detectable displacement amplitude of 0.002 nm, at present, with the possibility of further improvement. Application of the method to resonant...
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2003
A full-field view laser ultrasonic imaging method has been developed that measures acoustic motio... more A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by using dynamic holography with photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed that is capable of operation at Gigahertz frequency and micron length scales. Both acoustic amplitude and phase are recorded, allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies of 800-900 MHz, illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric-to-acoustic coupling of these devices and their performance. Images of 256 x 240 pixels are recorded at 18 fps rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level at each pixel calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.
The first measurements of elastic vibrations of an object in-situ to a high gamma irradiation fie... more The first measurements of elastic vibrations of an object in-situ to a high gamma irradiation field using a laser coupled resonant ultrasound method are described. A vibration mode of an Inconel hollow capped cylinder was measured throughout a period of 170 hours as the gamma radiation field was increased to 104 Gray/hour. The vibration mode frequency was observed to change in a manner consistent with the temperature dependence of the elastic stiffness coefficients of the material. These results illustrate the efficacy of the laser approach for real-time resonant ultrasound measurements in this severely hostile nuclear environment.
-Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowl... more -Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their properties is needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling including both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode exc...
Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowle... more Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their properties is needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling including both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode exci...
We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating w... more We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating within a thin silicon plate. A high frequency acoustic point focus lens was used to form a small point source within the plate. A laser interferometric system was used to visualize the acoustic wave propagation. Distinct amplitude patterns at each focal plane were experimentally visualized. The measured amplitude patterns exhibited the cubic symmetry of the material and the effects of focusing of the source outside and inside the material.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the United States Government or the sponsoring agency.
July 25-30, 2004 31 st Annual Reviews of Progress in Quantitative Nondestructive Evaluation This ... more July 25-30, 2004 31 st Annual Reviews of Progress in Quantitative Nondestructive Evaluation This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government.
The focus of this presentation is to describe our efforts at laser generation of high frequency s... more The focus of this presentation is to describe our efforts at laser generation of high frequency surface acoustic waves and detection of the nonlinear contribution in the acoustic near-field of the source. Narrow band acoustic generation is accomplished by interfering two pulsed laser beams at the surface of the sample. A Michelson interferometer, that incorporates a high power microscope objective, is used to detect the acoustic disturbance. Detection near the source combined with high frequency generation ($0.1 GHz) facilitates investigation of fundamental processes of harmonic generation on length scales comparable to grain size dimensions. Published by Elsevier Science B.V.
Page 1. Observation of Flexural Modes in FBAR Resonators at MHz Frequencies John D. Larson III (S... more Page 1. Observation of Flexural Modes in FBAR Resonators at MHz Frequencies John D. Larson III (SM) Electronic Research Laboratories, Agilent Laboratories, 3500 Deer Creek Road, Palo Alto, CA, 94304 Richard C. Ruby ...
Review of Progress in Quantitative Nondestructive Evaluation, 1988
Localized heating produced by absorption from a pulsed laser provides an efficient noncontacting ... more Localized heating produced by absorption from a pulsed laser provides an efficient noncontacting source of ultrasonic waves in materials. This paper describes the results of experiments conducted to illustrate the feasibility of this type of source for microstructure characterization in metal and ceramic materials. Piezoelectric and capacitive wide bandwidth detection transducers have been used to record attenuation and scattering in these materials for comparison with the conventional pulse echo technique. The laser source was found to be an efficient, versatile, and wide bandwidth noncontacting source.
We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating w... more We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating within a thin silicon plate. A high frequency acoustic point focus lens was used to form a small point source within the plate. A laser interferometric system was used to visualize the acoustic wave propagation. Distinct amplitude patterns at each focal plane were experimentally visualized. The measured amplitude patterns exhibited the cubic symmetry of the material and the effects of focusing of the source outside and inside the material.
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Aug 1, 2004
Acoustic methods are well known and have been used to measure various intrinsic material properti... more Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methods-it is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100's of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper reviews recent applications of laser acoustic methods for determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. Optical acoustic imaging is both quantitative and rapid.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the U.S. Government or the sponsoring agency.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government.
Review of Progress in Quantitative Nondestructive Evaluation, 1988
During fabrication of monolithic ceramic silicon carbide very localized regions of high porosity ... more During fabrication of monolithic ceramic silicon carbide very localized regions of high porosity can be produced. This porosity often consists of a very large density of small pores. Even at ultrasonic wavelengths considerably larger than the pore size, significant effects can be observed in ultrasonic wave propagation through these materials. These effects include attenuation, scattering, and changes in wave velocity. This paper describes the characterization of such a porosity distribution in SiC utilizing these ultrasonic techniques and their correlation with x-ray and optical microscopy measurements. Significant effects were observed due to the nonuniformity of the porosity, which resulted in enhancement of signal amplitudes greatly exceeding attenuation effects due to scattering. This unexpected result proved to be most sensitive to the boundaries of the porosity distribution and provided one of the best techniques for delineating its extent.
The Journal of the Acoustical Society of America, 1996
A new noncontacting optical method of vibration detection has been developed that utilizes the ph... more A new noncontacting optical method of vibration detection has been developed that utilizes the photorefractive effect in select materials to form an optical ‘‘lock‐in’’ amplifier. The method synchronously detects the optical phase shift of an object beam scattered from a vibrating specimen surface. Four‐wave mixing and conventional sychronous detection allow measurement of both the vibration amplitude and phase directly as a function of the excitation frequency. Narrow bandwidth detection can be achieved at frequencies from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The method has been implemented using Bismuth silicon oxide providing a resolution bandwidth of about 130 Hz and flat frequency response up to the MHz region. Both synchronous and random vibration excitation methods can be used providing a minimum detectable displacement amplitude of 0.002 nm, at present, with the possibility of further improvement. Application of the method to resonant...
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2003
A full-field view laser ultrasonic imaging method has been developed that measures acoustic motio... more A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by using dynamic holography with photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed that is capable of operation at Gigahertz frequency and micron length scales. Both acoustic amplitude and phase are recorded, allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies of 800-900 MHz, illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric-to-acoustic coupling of these devices and their performance. Images of 256 x 240 pixels are recorded at 18 fps rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level at each pixel calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.
The first measurements of elastic vibrations of an object in-situ to a high gamma irradiation fie... more The first measurements of elastic vibrations of an object in-situ to a high gamma irradiation field using a laser coupled resonant ultrasound method are described. A vibration mode of an Inconel hollow capped cylinder was measured throughout a period of 170 hours as the gamma radiation field was increased to 104 Gray/hour. The vibration mode frequency was observed to change in a manner consistent with the temperature dependence of the elastic stiffness coefficients of the material. These results illustrate the efficacy of the laser approach for real-time resonant ultrasound measurements in this severely hostile nuclear environment.
-Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowl... more -Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their properties is needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling including both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode exc...
Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowle... more Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their properties is needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling including both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode exci...
We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating w... more We present a hybrid acoustic imaging technique to directly visualize acoustic waves propagating within a thin silicon plate. A high frequency acoustic point focus lens was used to form a small point source within the plate. A laser interferometric system was used to visualize the acoustic wave propagation. Distinct amplitude patterns at each focal plane were experimentally visualized. The measured amplitude patterns exhibited the cubic symmetry of the material and the effects of focusing of the source outside and inside the material.
This is a preprint of a paper intended for publication in a journal or proceedings. Since changes... more This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this paper are not necessarily those of the United States Government or the sponsoring agency.
July 25-30, 2004 31 st Annual Reviews of Progress in Quantitative Nondestructive Evaluation This ... more July 25-30, 2004 31 st Annual Reviews of Progress in Quantitative Nondestructive Evaluation This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint should not be cited or reproduced without permission of the author. This document was prepared as a account of work sponsored by an agency of the United States Government.
The focus of this presentation is to describe our efforts at laser generation of high frequency s... more The focus of this presentation is to describe our efforts at laser generation of high frequency surface acoustic waves and detection of the nonlinear contribution in the acoustic near-field of the source. Narrow band acoustic generation is accomplished by interfering two pulsed laser beams at the surface of the sample. A Michelson interferometer, that incorporates a high power microscope objective, is used to detect the acoustic disturbance. Detection near the source combined with high frequency generation ($0.1 GHz) facilitates investigation of fundamental processes of harmonic generation on length scales comparable to grain size dimensions. Published by Elsevier Science B.V.
Page 1. Observation of Flexural Modes in FBAR Resonators at MHz Frequencies John D. Larson III (S... more Page 1. Observation of Flexural Modes in FBAR Resonators at MHz Frequencies John D. Larson III (SM) Electronic Research Laboratories, Agilent Laboratories, 3500 Deer Creek Road, Palo Alto, CA, 94304 Richard C. Ruby ...
Review of Progress in Quantitative Nondestructive Evaluation, 1988
Localized heating produced by absorption from a pulsed laser provides an efficient noncontacting ... more Localized heating produced by absorption from a pulsed laser provides an efficient noncontacting source of ultrasonic waves in materials. This paper describes the results of experiments conducted to illustrate the feasibility of this type of source for microstructure characterization in metal and ceramic materials. Piezoelectric and capacitive wide bandwidth detection transducers have been used to record attenuation and scattering in these materials for comparison with the conventional pulse echo technique. The laser source was found to be an efficient, versatile, and wide bandwidth noncontacting source.
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Papers by Ken Telschow