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Acousto-Acoustic Microscopy

IP.com Disclosure Number: IPCOM000039011D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Imaino, W: AUTHOR [+3]

Abstract

A new type of acoustic microscope or imaging device, to be called an acousto-acoustic microscope or imager, resolves the opposing requirements of high resolution and high detection sensitivity by exciting and detecting at different wavelengths. Also acoustic absorptions are detected with zero background. The principle of the acousto-acoustic microscope is indicated in the figure. A high-frequency acoustic transducer is excited by a high frequency electrical wave that is slowly amplitude-modulated. Using an acoustic lens, the high frequency amplitude-modulated acoustic wave emitted from the transducer can be tightly focused onto the sample, since the wavelength is short and diffraction is small. This provides high spatial resolution.

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Acousto-Acoustic Microscopy

A new type of acoustic microscope or imaging device, to be called an acousto- acoustic microscope or imager, resolves the opposing requirements of high resolution and high detection sensitivity by exciting and detecting at different wavelengths. Also acoustic absorptions are detected with zero background. The principle of the acousto-acoustic microscope is indicated in the figure. A high- frequency acoustic transducer is excited by a high frequency electrical wave that is slowly amplitude-modulated. Using an acoustic lens, the high frequency amplitude-modulated acoustic wave emitted from the transducer can be tightly focused onto the sample, since the wavelength is short and diffraction is small. This provides high spatial resolution. Any acoustic absorption in the incident region of the sample results in modulated heating and thus acoustic emission at the slow modulation frequency of the incident wave. This emitted slow or low frequency acoustic wave has poor spatial definition, but this does not ruin spatial resolution of the whole device since this is determined by the focusing of the excitation beam. The low frequency wave can be detected with a slow risetime detector with high sensitivity. This detection scheme is also zero-background, since no acoustic absorption (at the high frequency) means no signal (at the low frequency). Scanning the focused excitation beam on the sample provides an image of excessive acoustic absorption in...