Measuring and testing – Vibration – By mechanical waves
Patent
1997-03-06
1999-11-16
Brock, Michael
Measuring and testing
Vibration
By mechanical waves
73634, 73579, G01N 2900
Patent
active
059837233
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention is based on an ultrasonic measurement apparatus and relates in particular to a device (termed ultrasonic resonator in the following), with the aid of which plane ultrasonic wave fields are generated in fluid specimens by means of electrical systems known in general (e.g. network analyzers) and with which the frequency dependency of the amplitude and/or the phase of these resonances may be analyzed. Such devices are employed mainly in determining the speed and absorption of sound by specimens in the ultrasound range.
DESCRIPTION OF THE RELATED ART
In known ultrasonic resonators the specimen is disposed directly between the highly precise parallel arrangement of the planar end surfaces of electroacoustic transducers. These transducers are inserted fluid-tight in openings of the walls of a cavity accommodating the specimen. This forms the so-called resonator cavity and the transducers form the acoustically active walls of the resonator in which the plane wave field materializes between the transducers.
one major problem, hitherto awaiting a satisfactory solution, as regards this known arrangement is securing the transducers in a highly accurate parallel position free of tension, but sealing the specimen. Especially in the case of aggressive specimen fluids this problem can hardly be solved. Apart from this, there is the risk of gas bubbles sticking persistently in the region of the seal with most of the sealing methods involved. The presence of such gas inclusions in the resonator heavily interfers with the propagation of the wave field.
SUMMARY OF THE INVENTION
The object of the present invention is thus based on providing ultrasonic measurement apparatuses having ultrasonic resonators in which the problem of sealing off the sound-active resonator wall is eliminated.
This object is achieved by an ultrasonic measurement apparatus having the characterizing features of claim 1.
Due to the ultrasonic transducers in the ultrasonic resonators of the present ultrasonic measurement apparatus being coupled externally (to an external side of the body containing the resonator cavity) acoustically to the resonator chamber body or specimen chamber body, no sealing problems whatsoever are encountered. Thus, the resonator chamber body may totally consist of a non-piezoelectric material and be produced from any suitable material. In the same way, the geometry of the internally located resonator cavity and the outer shape are restricted only by the acoustical requirements, it thus being possible e.g. to directly employ commercially available glass or quartz-glass cuvettes, as used in spectralphotometric applications.
Useful materials are all solid-stats materials resistant to the corresponding specimens. By suitably selecting the resonator chamber bodies according to their geometry (e.g. wall thickness) and their acoustical parameters the acoustic properties of the resonator calls thus formed may be optimized within broad limits and adapted to the requirements of the ultrasonic resonance measurement. In this way it is also easily possible to combine ultrasonic resonance measurements with other, e.g. optical, potentiometric, conductometric, etc. methods of analysis.
The transducers(s) of the present ultrasonic measurement apparatus is(are) preferably disposed movable, so that they may be moved, e.g. translatorically shifted or pivoted from a resting position, in which they are distant from the resonator chamber body, into a working position, in which they come into contact with the outside of the resonator chamber body. The transducers may also be applied durably to the external surfaces of the resonator chamber body (e.g. cuvettes for the measurement of light absorption or the fluorescence, flow cuvettes) and then replaced, together with the cuvettes as necessary. The transducers may be moved in a direction parallel to the plane active surface being formed by the transducers.
All transducers known in general (piezoelectric, capacitive, electrostatic) may be employed as the ultrason
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patent: 3974681 (1976-08-01), Namery
patent: 4607520 (1986-08-01), Dam
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patent: 5141331 (1992-08-01), Oehler et al.
patent: 5351527 (1994-10-01), Blackburn et al.
Buckin Vitaly
De Maeyer Leo
Funck Theodor
Brock Michael
Buckin Vitaly
Moller Richard A.
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