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AssigneeInternational Business Machines Corporation
InventorsWayne I. Imaino, Andrew C. Tam
Estimating the term…
A method and device for detecting a narrow acoustic spectral feature in a sample as described. The method uses an electrical frequency modulated (FM) signal that is obtained from a voltage controlled oscillator. The Fourier spectrum of this wave is a main frequency f.sub.c with two small sidebands at frequencies f.sub.c .+-.f.sub.s. This whole triplet is slowly swept in frequency by a slow sawtooth generator. The electrical signal is fed into a flat acoustic transducer; the acoustic wave is then transmitted through an acoustically active medium, i.e. the sample, and detected by another flat acoustic transducer which produces an FM signal with a superposed amplitude modulated (AM) signal if one of the sidebands overlaps an acoustic feature. This electrical signal is then demodulated to give a pure AM signal which can be phase sensitive detected by using a lock-in amplifier. By suitable adjustment of the phase setting of the lock-in amplifier both the "in-phase" and "out-of-phase" signals of the detected acoustic signal can be detected.
A method of detecting a single spectral feature in the acoustic response of a sample under test, said method comprising the steps of:
A method of detecting and recovering information contained in a spectral feature of the acoustical response of a sample whose absorption and velocity of acoustical beams vary with time and frequency, said method comprising the steps of:
A device for detecting a spectral feature of a sample comprising:
Dependencies are inferred from the claim text.