DE102009025464A1 - Assembly for determining sonic speeds and distances in e.g. fluid media, using ultrasound of ultrasonic imaging system, has evaluation unit determining variable sonic speed by determining parameters of point reflector at various locations - Google Patents

Abstract

The assembly (10) has a transmission signal generator (1) generating an electrical transmission signal on a channel (14). A transceiver switch (2) provides communication between transmission and receiving signals. Controlled elements (31-33) of an ultrasonic transducer (3) transmit ultrasonic waves into a detected medium (4). An evaluation unit (8) determines an average sonic speed in the medium to a point reflector (5) and distance of the reflector from the transducer, and determines a variable sonic speed by determining reflector's parameters at various locations. An independent claim is also included for a method for determining variable sonic speeds and distances in media using ultrasound.

Description

• – einem Sendesignalgenerator, der auf m ≥ 1 Kanälen elektrische Sendesignale erzeugt,
• – einer Sende-Empfangs-Weiche,
• – einem Ultraschallwandler mit n ≥ 1 Elementen, der die elektrischen Sendesignale vom Sendesignalgenerator über die Sende-Empfangs-Weiche erhält, wobei die angesteuerten Elemente des Ultraschallwandlers eine Ultraschallwelle in das zu untersuchende Medium mit konstanter oder ortsveränderlicher Schallgeschwindigkeit senden und wobei nach Umschaltung der Sende-Empfangs-Weiche die reflektierte Ultraschallwelle mit den Elementen des Ultraschallwandlers empfangen wird, und
• – einer Verstärkungseinheit, die die elektrischen Empfangssignale von den einzelnen Elementen des Ultraschallwandlers über die Sende-Empfangs-Weiche erhält und verstärkt, und
• – einer Aufnahmeeinheit, in der eine Analog-Digital-Wandlung der Empfangssignale in digitale Signale erfolgt und
• – einer Auswerteeinheit, die die aus der Aufnahmeeinheit weitergeleiteten digitalen Signale zur Auswertung erhält.

The invention relates to an arrangement and a method for the combined determination of sound velocities and distances in liquid and solid media by means of ultrasound, consisting of

• A transmission signal generator which generates electrical transmission signals on m ≥ 1 channels,
• A transmitting-receiving switch,
• An ultrasonic transducer with n ≥ 1 elements, which receives the electrical transmission signals from the transmission signal generator via the transceiver, wherein the controlled elements of the ultrasonic transducer transmit an ultrasonic wave into the medium to be examined at a constant or spatially variable speed of sound and wherein after switching the transmission Reception switch the reflected ultrasonic wave is received with the elements of the ultrasonic transducer, and
• - An amplification unit, which receives and amplifies the received electrical signals from the individual elements of the ultrasonic transducer via the transceiver, and
• - A recording unit in which an analog-to-digital conversion of the received signals into digital signals takes place and
• - An evaluation, which receives the forwarded from the recording unit digital signals for evaluation.

measurements in solids are carried out by ultrasound, to detect defects in materials, to measure layer thicknesses or structures in technical fields or in medicine, such as Visualize tissue structures and organ boundaries. It is the knowledge of the speed of sound is a necessary condition to measure sizes and distances.

on the other hand is the speed of sound or the speed of sound profile Of particular interest because this is important parameter for the solid or liquid substance or a mixture of substances. This is the case with many liquid solutions, for example or mix the speed of sound strongly from the concentration dependent and therefore advantageous for concentration measurement be used. The speed of sound is also material parameter and can be used for solid state characterization. Becomes the speed of sound by means of the ultrasonic echo principle measured to determine material parameters or concentrations, so is usually a comparison reflector on a predetermined position used to determine the sound path.

conventional technical measuring methods need for sound velocity measurement the knowledge of the length of the sound propagation path. To is either an external reference reflector or a receiving transducer to place at a predetermined position. In practice is However, this is not always possible, especially if lack of space for the measurement setup, chemically aggressive fluids exist present or the destruction of the test object in the solid state threatening.

A Determining sound velocity profiles is currently practical not possible or only with great effort. Mechanical is the spatially resolved determination of the speed of sound only in media accessible at all points and with optical Procedure only possible with transparent media.

Tomographic methods for the spatially resolved determination of the speed of sound are in the document M. Barth et al .: Acoustic tomography for the simultaneous detection of temperature and flow fields, 14th GALA Symposium: Laser Methods in Flow Measurement, 05.-07. September 2006 , Physikalisch-Technische Bundesanstalt Braunschweig, where the measurement of the speed of sound is carried out as sound transit time measurements between many pairs of transmitter and receiver in air. The process can in principle also be used in liquids and solids accessible on all sides. In liquids, the influence of the flow is compensated by measuring the speed of sound in both directions.

A method for determining the layer thickness and the speed of sound in a tube by means of ultrasonic pulses is in the document US2002134159 described in which the data for calculating the speed of sound and the layer thickness of a series of transmitted and reflected ultrasonic waves are determined, wherein at least one of the measurements is transmitted without the presence of the measurement object in the transmission path.

A device and a method for calibration and ultrasonic measurement of cylindrical test specimens is in the document DE 50 305 421 T described, wherein a plurality of parameters of the test pattern are determined simultaneously. There is the determination of multiple maturities for several distances in the Ka libration unit and the current speed of sound of the water by means of an optical or mechanical distance determination.

Of the Invention is based on the object, an arrangement and a method for the combined determination of sound velocities and distances indicate in liquid and solid media by means of ultrasound, which are designed so that the knowledge of one of both sizes need not be assumed to determine the other size, so that the effort to determine sound velocities and distances in liquid and solid media by means of ultrasound essential reduced.

• – einem Sendesignalgenerator, der auf m ≥ 1 Kanälen elektrische Sendesignale erzeugt,
• – einer Sende-Empfangs-Weiche,
• – einem Ultraschallwandler mit n ≥ 1 Elementen, der die elektrischen Sendesignale vom Sendesignalgenerator über die Sende-Empfangs-Weiche erhält, wobei die angesteuerten Elemente des Ultraschallwandlers eine Ultraschallwelle in das zu untersuchende Medium mit fester oder ortsveränderlicher Schallgeschwindigkeit senden und die Elemente des Ultraschallwandlers nach Umschaltung der Sende-Empfangs-Weiche die reflektierte Ultraschallwelle, und
• – einer Verstärkungseinheit, die die elektrischen Empfangssignale von den einzelnen Elementen des Ultraschallwandlers über die Sende-Empfangs-Weiche erhält und verstärkt, und
• – einer Aufnahmeeinheit, in der eine Analog-Digital-Wandlung der Empfangssignale in digitale Signale erfolgt, und
• – einer Auswerteeinheit, die die aus der Aufnahmeeinheit weitergeleiteten digitalen Signale zur Auswertung erhält,

wobei gemäß dem Kennzeichenteil des Patentanspruchs 1 der Sendesignalgenerator allein in Form von elektronischer Fokussierung oder in Zusammenarbeit mit der Aufnahmeeinheit in Form von synthetischer Fokussierung den erzeugten Ultraschallfokus schrittweise entlang der Achse des Ultraschallwandlers auf einzelne Fokuspunkte F_i im Abstand vom Ultraschallwandler fokussiert,
wobei eine Kalibriereinheit vorgesehen ist, die beim Erstellen der Kalibrierdaten entweder durch Simulationsrechnung oder durch Messung mit Hilfe der Aufnahmeeinheit für einen in einem Kalibriermedium W befindlichen Punktreflektor den Zusammenhang zwischen dem verwendeten Fokussierungsregime V_max(a_Wj), bei dem die Amplitude des reflektierten Ultraschalls maximal wird, und dem jeweils gewählten Abstand a_Wj des Punktreflektors vom Ultraschallwandler in einem Kalibriermedium liefert und als Tabelle T zusammenstellt,
wobei die Aufnahmeeinheit die Schalllaufzeit vom Ultraschallwandler zum Punktreflektor in dem Medium im Abstand a_Mj misst und durch schrittweise Fokussierung dasjenige Fokussierungsregime V_max(a_Mj), bestimmt, bei dem die Amplitude des reflektierten Schalls für diesen Punktreflektor maximal wird, und
wobei die Auswerteeinheit für einen im Medium befindlichen Punktreflektor das Fokussierungsregime V_max(a_Mj), bei dem die Amplitude des reflektierten Ultraschalls maximal wird, von der Aufnahmeeinheit erhält, und mit der von der Kalibriereinheit bereitgestellten Tabelle T den Abstand des Punktreflektors bezüglich des Kalibriermediums ermittelt, aus der von der Aufnahmeeinheit im Medium gemessenen Schalllaufzeit und dem ermittelten Reflektorabstand bezüglich des Kalibriermediums die mittlere Schallgeschwindigkeit im Medium bis zum Punktreflektor und den Abstand des Punktreflektors vom Ultraschallwandler ermittelt und durch Bestimmung dieser Parameter für Punktreflektoren an unterschiedlichen Orten die ortsveränderliche Schallgeschwindigkeit bestimmt.The object is solved by the features of claims 1 and 15. The arrangement for the combined determination of sound velocities and distances in liquid and solid media by means of ultrasound consists of

• A transmission signal generator which generates electrical transmission signals on m ≥ 1 channels,
• A transmitting-receiving switch,
• - An ultrasonic transducer with n ≥ 1 elements, which receives the electrical transmission signals from the transmission signal generator via the transmitting-receiving switch, the driven elements of the ultrasonic transducer to send an ultrasonic wave in the medium to be examined with fixed or spatially variable speed of sound and the elements of the ultrasonic transducer after switching the transmit-receive switch the reflected ultrasonic wave, and
• - An amplification unit, which receives and amplifies the received electrical signals from the individual elements of the ultrasonic transducer via the transceiver, and
• A recording unit in which an analog-to-digital conversion of the received signals into digital signals takes place, and
• An evaluation unit which receives the digital signals forwarded from the recording unit for evaluation,

wherein according to the characterizing part of patent claim 1, the transmission signal generator focused solely in the form of electronic focusing or in cooperation with the recording unit in the form of synthetic focusing the generated ultrasonic focus stepwise along the axis of the ultrasonic transducer to individual focus points F _i at a distance from the ultrasonic transducer,
wherein a calibration unit is provided which, when creating the calibration data either by simulation calculation or by measurement using the recording unit for a point in a calibration W _{spot reflector} the relationship between the used focusing _regime V _max (a _Wj ), in which the amplitude of the reflected ultrasound maximum is, and _supplies the selected distance a _{Wj of} the point _reflector from the ultrasonic transducer in a calibration _{medium and composes} table T,
wherein the recording _unit measures the sound propagation time from the ultrasound transducer to the point reflector in the medium at a distance a _Mj and determines by stepwise focusing that focusing _regime V _max (a _Mj ), at which the amplitude of the reflected sound for this point reflector becomes maximum, and
wherein the evaluation unit for a point _reflector located in the medium determines the focusing _regime V _max (a _Mj ) at which the amplitude of the reflected ultrasound becomes maximum, and with the table T provided by the calibration unit determines the distance of the point reflector with respect to the calibration medium , Determines the average sound velocity in the medium to the point reflector and the distance of the point reflector from the ultrasound transducer from the measured from the recording unit in the medium sound propagation time and the determined reflector distance with respect to the calibration and determined by determining these parameters for point reflectors at different locations, the spatially variable sound velocity.

Of the Reception of the sound can be on the central element of the ultrasonic transducer alone, on one of the remaining other elements or on a combination of several elements by means of electronic focusing or by means of synthetic focusing in the form of a time-delayed overlay the result on the individual elements echo signals.

The medium may consist of one or more layers, the layered medium containing point reflectors, wherein the speed of sound is determined in front of the respective point reflector with the calibration unit, the acquisition unit and the evaluation unit, and a repetition of the process for more distant point reflectors and thus detection The average sound velocity between the ultrasonic transducer and Punktreflektorort for each Punktreflektorort done, which can be created with sufficient dense distribution of point reflectors in the layers so a sound velocity profile and thus the speed of sound can be created in the individual layers, resulting from the determined sound velocities in the individual Layers and the sound propagation times between the individual Interfaces of the respective layer can calculate the layer thickness.

The Medium may be a liquid mixture that is distinguishable with Point reflectors is provided, with sound velocity differences may occur, with a determination of the distance from the ultrasonic transducer and the average sound velocity before the closest located in front of the ultrasonic transducer point reflector with the calibration unit, the receiving unit and the evaluation takes place, and a repetition the process for farther point reflectors and thus determination of the mean sound velocity between Ultrasonic transducer and spot reflector location for each spot reflector location takes place, with enough dense distribution of Point reflectors in the liquid mixture so a Sound velocity profile can be created.

The Medium can be a liquid mixture with random distribution Scattering particles which flow or diffuse, being Density variations and sound velocity differences occur can, with a determination of the distance from the ultrasonic transducer and the average sound velocity between the ultrasonic transducer and the focal point, d. H. the range of maximum sound pressure in the medium, with the calibration unit, the recording unit and the Evaluation unit takes place, and a repetition of the process for farther away focus points and thus finding the average sound velocity between ultrasonic transducer and Focus point takes place, with such a sound velocity profile can be created with support points at the focus points.

there send the driven elements of the ultrasonic transducer ultrasonic waves into a medium with a variable or constant ultrasonic speed. The interfaces and the point reflectors of the medium reflect Ultrasonic waves received by the ultrasonic transducer. Finally, the received ultrasonic signals in converted electrical signals and after amplification of Receiving and evaluation unit supplied.

• – der Laufzeit des Ultraschalls und
• – der durch das Fokussierungsregime vorgegebenen Fokuspunktlage.

The invention thus includes a measuring principle for the simultaneous determination of the distance between at least one point reflector or focal point in the medium to be examined and the ultrasonic transducer and the average speed of sound before the point reflector or focal point by means of ultrasound by the detection of two independent variables:

• - the duration of ultrasound and
• - The focus point position given by the focusing regime.

By Exploitation of the exact knowledge of the transit time and the ultrasonic field This way, information about the medium can be gained So far, only by introducing reference bodies can be determined at a predetermined position.

In the method for the combined determination of sound velocities and distances in liquid and solid media by means of Ultrasound using the previously described arrangement according to the characterizing part of the patent claim 15 completed the following steps:

A. Gradual focusing:

Of the Transmit signal generator focused solely by electronic focusing or in cooperation with the recording unit and the evaluation unit by synthetic focusing the ultrasound gradually along the axis of the ultrasonic transducer to individual focus points.

B. Calibration:

At the Creating the calibration data is done either by simulation calculation or by measuring with the help of the recording unit for a point located in a calibration medium W point reflector the Relationship between the focusing regime used, in which the amplitude of the reflected ultrasound becomes maximum, and the each selected distance of the point reflector from the ultrasonic transducer supplied in the calibration medium and compiled as a table.

C. Recording:

A recording unit detects the sound propagation time from the ultrasound transducer to a point reflector or focal point (in the case of "liquid mixture with randomly distributed scattering particles that flow or diffuse") in a medium, whereby the focusing regime determines the focusing regime by the stepwise focusing where the amplitude of the reflected ultrasound becomes maximum for that point reflector or focus point.

D. Evaluation:

In an evaluation unit for a point to be examined in the medium to be examined reflector from the determined focusing _regime V _max (a _Mj ), and provided by the calibration unit tabular relationship T between the focusing regime and the distance of the point reflector or focal point of the ultrasound transducer in a calibration medium Determining the distance of the point reflector or the focal point with respect to the calibration medium.

Farther takes place in the evaluation unit from the determined sound propagation time and from the determined point reflector distance or the focal point distance with regard to the calibration medium, the calculation of the mean Speed of sound in the medium to be examined up to the respective Point reflector location or focal point as well as the distance of the spot reflector location or the focal point of the ultrasonic transducer in the examined Medium.

Subsequently can by determining these parameters for several or all point reflectors or focus points at different Locate the mobile sound velocity in shape a sound velocity profile are performed.

• – dass sie die gleichzeitige Bestimmung des Abstandes der Punktreflektoren im zu untersuchenden Medium und der mittleren Schallgeschwindigkeit zwischen Ultraschallwandler und Punktreflektoren ermöglicht,
• – dass die nichtinvasive referenzlose Bestimmung der Schallgeschwindigkeit in Flüssigkeiten und Festkörpern, die Punktreflektoren oder Streuteilchen enthalten, mittels Ultraschall zur Erstellung eines Schallgeschwindigkeitsprofils zur Darstellung der ortsveränderlichen Schallgeschwindigkeit durchgeführt werden kann sowie
• – dass eine bessere Ortsbestimmung durch die Kenntnis der gleichzeitig gemessenen Schallgeschwindigkeit erreicht werden kann.

The advantages of the invention are

• - That it allows the simultaneous determination of the distance of the point reflectors in the medium to be examined and the average speed of sound between ultrasonic transducers and point reflectors,
• - that the non-invasive, non-referential determination of the speed of sound in liquids and solids containing point reflectors or scattering particles can be carried out by means of ultrasound to establish a sound velocity profile to represent the velocity of the satellite, and
• - That a better position determination can be achieved by the knowledge of the simultaneously measured speed of sound.

• – Flüssigkeiten oder Flüssigkeitsgemische mit Streuteilchen, die strömen oder diffundieren,
• – Flüssigkeitsgemische mit unterscheidbaren Punktreflektoren: Schallgeschwindigkeit vor dem Punktreflektor, Punktreflektorabstand, mittlere Schallgeschwindigkeit, Schallgeschwindigkeitsprofil,
• – geschichtete Medien mit Punktreflektoren: aus der Bestimmung der Schallgeschwindigkeit vor dem Punktreflektor und gleichzeitiger Bestimmung des Abstandes zwischen dem Ultraschallwandler und dem Punktreflektor erfolgt die Bestimmung der Schallgeschwindigkeit und die Bestimmung der Entfernungen der Punktreflektoren. Die Berechnung der Schichtdicke erfolgt durch die Messung der Schallgeschwindigkeit in dem Medium und der Schallaufzeit zwischen der vorderen Grenzfläche und hinteren Grenzfläche der jeweiligen Schicht.

With the arrangement according to the invention and the associated method according to the invention, the following media can be measured:

• - liquids or mixtures of liquids with scattering particles which flow or diffuse,
• - liquid mixtures with distinguishable point reflectors: speed of sound in front of the point reflector, point reflector distance, average speed of sound, speed of sound profile,
• - Layered media with point reflectors: from the determination of the speed of sound in front of the point reflector and simultaneous determination of the distance between the ultrasonic transducer and the point reflector, the determination of the speed of sound and the determination of the distances of the point reflectors. The calculation of the layer thickness is effected by the measurement of the speed of sound in the medium and the sound transit time between the front boundary surface and the rear boundary surface of the respective layer.

• – Prozessmesstechnik und Materialwissenschaften,
• – Konzentrationsbestimmung in Mischungen mit zwei oder mehr Komponenten, beispielsweise der Sättigungsgrad in Zuckerlösungen,
• – Bestimmung des Verschmutzungsgrades in Flüssigkeiten – Motoröl, Rohöl, Abwasser –,
• – Bestimmung von Materialparametern – Ölsorten –,
• – Ausmessen eines Schallgeschwindigkeitsprofils in strömenden Flüssigkeiten und Festkörpern, die Punktreflektoren enthalten, z. B. Bestimmung von Temperatur- und Dichtegradienten,
• – Bestimmung der Schallgeschwindigkeit als Funktion des Abstandes vom Ultraschallwandler ohne Eingriff in das Messmedium,
• – Eigenkalibrierung von Puls-Echo-Geräten bezüglich der Schallgeschwindigkeit z. B. bei Puls-Doppler-Messgeräten.

The following special fields of application can be specified:

• - process measurement and materials science,
• Concentration determination in mixtures with two or more components, for example the degree of saturation in sugar solutions,
• - determination of the degree of pollution in liquids - motor oil, crude oil, sewage -,
• - determination of material parameters - types of oil -,
• - Measuring a sound velocity profile in flowing liquids and solids containing point reflectors, z. B. determination of temperature and density gradients,
• Determination of the speed of sound as a function of the distance from the ultrasonic transducer without interfering with the measuring medium,
• - Self-calibration of pulse-echo devices with respect to the speed of sound z. B. in pulse Doppler measuring devices.

further developments and advantageous embodiments of the invention are set forth in further subclaims specified.

The invention will be explained in more detail by means of exemplary embodiments by means of several drawings. Show it:

1 an inventive arrangement for the determination of sound velocities and distances in liquid and solid media by means of ultrasound, wherein

1a a schematic representation of the entire arrangement in a single-layered medium,

1b an enlarged medium-ultrasound transducer assembly according to 1a .

1c a schematic representation of the arrangement for calibration in the calibration medium W and

1d a schematic representation of the arrangement according to 1a in the presence of several layers 41 and 42
demonstrate,

2 a sound field for an unfocused transducer (f = 20 MHz, d = 4.8 mm) in a solid after 20 mm water flow, where the (x, y, z) coordinate system is attached to the last interface passed by the ultrasound, so that the coordinate z in this case indicates the normal distance to the solid surface, and wherein

2a a longitudinal section,

2 B a cross section of the sound field in focus at z = 17 mm and

2c a transmit-receive field (SE field) for the same arrangement in focus at z = 17 mm,
demonstrate,

3 Longitudinal sections of the sound fields in water and in Plexiglas, each with the same ultrasonic transducer for the given ring element arrangement above in water, below in Plexiglas for comparison, the normalized maximum p for the sound field including its location in (x, y, z) coordinates is given, wherein Fok indicates the calculated distance with respect to water at which the focal point is in accordance with the driving times used, wherein the difference of the focal point positions in water and Plexiglas determined by simulation calculation is denoted by V, wherein

3a Fok = 7 mm, p = 385 (0,0,7.4) in water,

3b Fok = 10 mm, p = 543 (0,0,10.2) in water,

3c Fok = 13 mm, p = 558 (0,0,13.0) in water,

3d Fok = 7 mm, p = 320 (0,0,3.1), V = -4.3 mm in Plexiglas,

3e Fok = 10 mm, p = 762 (0,0,4.8), V = -5.4 mm in Plexiglas, and

3f Fok = 13 mm, p = 886 (0,0,6.4), V = -5.6 mm in Plexiglas, is achieved,

4 a sound field profile accordingly 2 and amplitude calculated by simulation calculations for different point reflector sizes with calculated sound pressure amplitude on the receiver for a spherical point reflector with a radius r = 0.4 mm ≈ λ and a spherical point reflector with a radius r = 1.2 mm ≈ 3λ at different distances from the axis, the spherical one Point reflector or the transducer is moved radially outward along a line,

5 a calibration curve for a spherical point reflector r = 0.05 mm in water at a distance a = 10 mm with the given ring element arrangement of the ultrasonic transducer, obtained from the sound field on the receiving elements,

6 Amplitude curves for each spherical point reflector with a radius of r = 0.05 mm in the second layer of a two-layer medium, wherein the first layer is a 5 mm thick water layer with the speed of sound c = 1500 m / s and the second medium a sound velocity of c = 1620 m / s, and wherein the first point reflector is at a distance of 5 mm after the water layer and the second point reflector at a distance of 8 mm from the water layer in the second medium.

7 7a Course of the normalized amplitude of the echo signal averaged over 500 seconds as a function of the measuring depth z of a pulse-echo method operating focussing ultrasonic transducer, wherein the propagation medium of the ultrasound provided with a point reflectors liquid metal (eutectic InGaSn) with the speed of sound c = 2740 m / s is used,

7b Calculated sound pressure amplitude of the ultrasonic transducer used for the arrangement used.

7c Shape of the ultrasonic lens used for the focusing.

The following are the 1a . 1b . 1c and 1d considered together.

• – einem Sendesignalgenerator 1, der auf drei Kanälen 14 elektrische Sendesignale erzeugt,
• – einer Sende-Empfangs-Weiche 2,
• – einem Ultraschallwandler 3 mit drei Elementen 31, 32, 33, der die elektrischen Sendesignale vom Sendesignalgenerator 1 über die Sende-Empfangs-Weiche 2 erhält, wobei die angesteuerten Elemente 31, 32, 33 des Ultraschallwandlers 3 eine Ultraschallwelle in das zu untersuchende Medium 4 senden und nach Umschaltung der Sende-Empfangs-Weiche 2 die von den im Medium 4 enthaltenen Punktreflektoren 5 reflektierte Ultraschallwelle mit den Elementen 31, 32, 33 des Ultraschallwandlers 3 empfangen, und
• – einer Verstärkungseinheit 6, die die elektrischen Empfangssignale von den einzelnen Elementen 31, 32, 33 des Ultraschallwandlers 3 über die Sende-Empfangs-Weiche 2 erhält und verstärkt, und
• – einer Aufnahmeeinheit 7, in der eine Analog-Digital-Wandlung die Empfangssignale in digitale Signale erfolgt, und
• – einer Auswerteeinheit 8, die die aus der Aufnahmeeinheit 7 weitergeleiteten digitalen Signale zur Auswertung erhält.

In 1a is a schematic representation of an arrangement 10 for the determination of sound velocities and distances in a single-layer medium 4 shown by ultrasound, the arrangement 10 consists

• A transmission signal generator 1 that on three channels fourteen generates electrical transmission signals,
• - A transmit-receive switch 2 .
• - an ultrasonic transducer 3 with three elements 31 . 32 . 33 receiving the electrical transmission signals from the transmission signal generator 1 via the send-receive switch 2 receives, with the driven elements 31 . 32 . 33 of the ultrasonic transducer 3 an ultrasonic wave in the medium to be examined 4 send and after switching the send-receive switch 2 those of the in the medium 4 contained point reflectors 5 reflected ultrasonic wave with the elements 31 . 32 . 33 of the ultrasonic transducer 3 receive, and
• - an amplification unit 6 that receive the electrical signals received from each element 31 . 32 . 33 of the ultrasonic transducer 3 via the send-receive switch 2 receives and reinforces, and
• - a recording unit 7 in which an analog-to-digital conversion of the received signals into digital signals takes place, and
• - an evaluation unit 8th taking out the recording unit 7 forwarded digital signals for evaluation receives.

According to the invention, the transmit signal generator focuses 1 in the form of electronic focusing or in cooperation with the recording unit 7 and the evaluation unit 9 in the form of synthetic focusing the generated ultrasound stepwise along the axis 12 of the ultrasonic transducer 3 to individual focus points F ₁ , F ₂ , F ₃ ,
the reception of the received signal takes place either through the middle element 31 alone, any other element 32 . 33 alone or by combining several elements 31 . 32 . 33 by means of synthetic focusing in the form of a time-delayed superposition of the on the individual elements 31 . 32 . 33 resulting echo signals,
is a calibration unit 9 provided when creating the calibration data either by simulation calculation or by measurement using the recording unit 7 for one in a calibration medium W ( 1c ) located point reflector 5 the relationship between the focusing _regime used V _max (a _Wj ), in which the amplitude of the reflected ultrasound is maximum, and the selected distance a _{Wj of} the point _reflector 5 from the ultrasonic transducer 3 in the calibration medium W and compiles as table T,
is a recording unit 7 provided that the sound propagation time of the ultrasonic transducer 3 to any point reflector 5 in the medium 4 measures at a distance a _Mj and, by stepwise focusing, determines the focusing _regime V _max (a _Mj ) at which the amplitude of the reflected ultrasound for this point reflector 5 becomes maximum,
wherein the evaluation unit 8th for one in the medium 4 located point reflector 5 the focusing regime V _max (a _Mj), in which the amplitude of the reflected sound becomes maximum is determined, and from the description provided by the calibration table T the distance of the point reflector 5 determined with respect to the calibration medium W, from the determined sound propagation time and the determined reflector distance with respect to the calibration medium W, the average speed of sound in the medium 4 to the point reflector 5 and the distance of the spot reflector 5 from the ultrasonic transducer 3 determined and by determining these parameters for point reflectors 5 determines the mobile velocity of sound C _Med at different locations,
where the time delay regimes are given n-tuples Δt ₁ , Δt ₂ , ..., Δt _n of times around which the individual elements 31 . 32 . 33 of the ultrasonic transducer 3 compared to the middle element 31 delayed, and
being a point reflector 5 an inhomogeneity in the medium 4 which is an extent in magnitude has an ultrasonic wavelength λ and at which the ultrasound is scattered.

In the case of an electronic focusing on focal points F, such a focusing regime is selected in which the ultrasound in calibration medium W is at the distance of the respective focal point F on the acoustic axis 12 from the ultrasonic transducer 3 is focused. With the same electronic focus, the actual focus point locations differ depending on the sound propagation speed in the media.

The simultaneous determination of the speed of sound and the distance of the spherical point reflector 5 from the sending elements / receiving elements 31 . 32 . 33 of the ultrasonic transducer 3 is based on the measurement of the sound propagation time t and the distance of the respective focal point F from the ultrasound transducer 3 ,

2a shows the longitudinal section of the sound field for an unfocused ultrasonic transducer 3 in a solid after a water supply VL. The sound field has a maximum at the end of the near field at z = 17 mm, which is also called a natural focus. The focus is not punctiform, but it forms an extended sensitive zone (eg 6-dB zone), which in longitudinal section in 2a and in cross section at z = 17 mm in 2 B you can see.

berechnet werden, wobei d der Element-Durchmesser, λ – die Wellenlänge in dem Medium 4, c – die Schallgeschwindigkeit und f – die Mittenfrequenz des Ultraschallwandlers 3 sind. Mithilfe der Gleichung (I) lässt sich der Fokusabstand z in verschiedenen Medien ineinander gemäß Gleichung (II) umrechnen

The distance z of the natural focus point depends on the element size of the ultrasonic transducer 3 , the ultrasound frequency and the medium 4 and can for a disc-shaped planar ultrasonic transducer 3 according to the equation (I) for the near field length N

where d is the element diameter, λ - the wavelength in the medium 4 , c - the speed of sound and f - the center frequency of the ultrasonic transducer 3 are. Using equation (I), the focal distance z in different media can be converted into one another according to equation (II)

By additional focusing by means of a lens or with ultrasonic transducers with several individual elements by electronic focusing, the focal point can be closer to the ultrasonic transducer 3 and significantly reduce the area of the sensitive zone. The position of the sound field maximum or the focal point results from the position of the natural focal point and the curvature of the lens or the electronically adjusted focusing. The exact position and extent of the sensitive zone for the resulting focus point can be determined by means of simulation calculations.

In 3 The sound fields in the media are water and plexiglass, each with the same ultrasonic transducer 3 and compared at the same electronic focusing. In the 3 the normalized maximum p for the sound field including its position in (x, y, z) coordinates is given. The (x, y, z) coordinate system is on the ultrasonic transducer 3 attached, so that in the coordinate z of the focal point distance, in this case, the distance of the focal point to the ultrasonic transducer 3 , is specified. 3 makes it clear that the position of the maximum depends on the material parameters of the medium 4 , in particular the speed of sound, changes greatly and that the evaluation of the focal point distance brings additional information at runtime.

4 shows the calculated sound pressure amplitude on the receiving elements for a spherical point reflector 51 with a radius r = 0.4 mm ≈ λ and a spherical point reflector with a radius r = 1.2 mm ≈ 3λ at different distances from the axis 12 , The spherical point reflector 51 or the ultrasonic transducer 3 will be along a line 13 radial to the axis 12 moved outward.

The curves for the amplitude level of the received reflected ultrasound signal for point reflectors 51 up to a size r = 0.4 mm, corresponds to approximately one wavelength λ, are congruent with each other and congruent with the profile line for the SE field of 2c , That is, in a liquid medium 4 can be the sound field with the help of a spherical point reflector 51 measure, and the height of the reflected signal from a point reflector 51 with a line scan or with a shift of the spherical point reflector 51 delivers the sound field in the medium to be examined 4 ,

This results in a spherical point reflector 51 the maximum in the reflected signal when the point reflector 51 in focus point F ₂ , as in 1b is shown is located. This fact can be reversed exploited to determine the point reflector location F ₂ by a shift of the focus point F.

In a transient transducer of the ultrasonic transducer 3 The focal point locations can only be adjusted by changing the position of the ultrasonic transducer 3 in relation to the medium to be examined 4 , z. B. with a water supply, set in the array transducer also by systematic change of the focusing regime by means of a time-delayed control of the elements or a time-delayed superposition of the echo signals.

In a calibration medium W with a known sound velocity, preferably for calibration water with a speed of sound c = 1500 m / s is included, the point reflector 51 on the Schallkopfachse 12 positioned at different distances a _Wj , and the electronic focusing is determined at which the reflected signal has a maximum.

This is a relationship between the electronic focus used and the distance of the point reflector 51 with respect to the calibration medium W obtained.

In the following Examples A and B, on the one hand, Example A is a point reflector 5 in a single-layered medium 4 unknown speed of sound ( 1a ) and on the other hand in example B of a two-layered medium 41 . 42 gone out, in which a point reflector 5 in the second layer 42 located ( 1d ),

According to Example B, the first layer 41 Water. For the second layer 42 should be the speed of sound and the distance of the point reflector 5 from an interface 11 be determined. For the simultaneous determination of the distance a _{M1 of} a point reflector 5 and the speed of sound in front of the point reflector 5 becomes an ultrasonic transducer 3 with annular elements 31 . 32 . 33 used, as well as in 1b is shown.

With the ring element arrangement 31 . 32 . 33 first, calibration curves will be appropriate 5 absorbed by adding water in a water bath 1c a point reflector 5 is placed at a defined distance a _W to the ring element arrangement. By a time-delayed control of the individual sending elements 31 . 32 . 33 becomes the focal point F along the axis 12 before (F ₁ ), on (F ₂ ) and behind (F ₃ ) the point reflector 5 and determines a curve for the amplitude as a function of the focusing regime. The focusing can be done directly by a time-delayed control of the transmitting elements with delay times corresponding to the respective focusing regime or by all transmitting elements 31 . 32 . 33 send one by one, the individual signals from the receiving elements 31 . 32 . 33 be registered and the signals for each sending elements 31 . 32 . 33 out of phase are superimposed according to the respective focusing regime. The process is for different distances, here in distance variations of a minimum of 0.1 mm of the point reflector 5 from the ring element arrangement 31 . 32 . 33 repeated. It is determined at which electronic focusing the maximum at the receiving elements 31 . 32 . 33 is registered. As focussing steps are made of a minimum of 0.1 mm, a spot reflector becomes 5 with a radius of r = 0.05 mm, that is in particular also smaller than the wavelength λ is used.

Tab. 1 shows the calibration curves, one of which is shown in 5 , determined maximum positions in the calibration medium W - water - for different point reflector distances within the water (c = 1500 m / s). Tab. 1: Calibration: correlation between geometric focus (electronic focusing) and position of the maximum for calibration medium W - water - c = 1500 m / s (determined from calibration curves according to FIG. 5 with a point reflector r = 0.05 mm) Point reflector position a _W 7.5 10.5 11.5 12.5 13.5 Fok. for Max 7.4 10.5 11.5 12.5 13.4

Example A

in the Example A is the following measurement situation according to line 1, Table 2 for a single-layered medium.

Example B

In example B, the following measurement situation is in accordance with the second and third lines of Tab. 2 and 1b before: A spherical point reflector 5 with a radius r = 0.05 mm is in the second layer 42 , z. B. tissue with a speed of sound of c = 1620 m / s, a two-layered medium 41 . 42 , The first shift 41 is a 5 mm thick water layer with a speed of sound of c = 1500 m / s. The thickness of the first layer 41 - The water flow VL = 5 mm - is given or previously determined according to the method described. The spherical point reflector 5 is in the second medium 42 , first at a distance of a _M1 = 10 mm (5 mm water layer + 5 mm distance from the interface 11 from the water to the second medium 42 ) and then at a distance of a _M1 = 13 mm (5 mm water layer + 8 mm distance from the interface 11 from the water to the second medium 42 ) on the axis 12 of the ultrasonic transducer 3 ,

From the electronic focusing and the measurement of the echo signal transit time, the speed of sound in the second layer 42 and the distance a _{M1 of} the spherical-type point reflector 5 from the ultrasonic transducer 3 certainly. For this purpose, first the signal propagation time t _j , which is the distance a _{M1 of} the point reflector 5 characterized, measured, as indicated in Tab. 2, Column 2. By electronic focusing then the focal point along the axis 12 systematically shifted and the amplitude measured for each electronic focus point. 6 shows the determined amplitude curves for the ultrasonic transducer 3 for the measurement situation described above, including the evaluation of the inner receiving element 31 with appropriate calibration is possible. From the measured curves in 6 the electronic focus point is determined at which the reflected signal has a maximum, as indicated in Tab. 2, Column 3.

wird die Schallgeschwindigkeit im zweiten Medium 42 berechnet gemäß Spalte 5, wobei t in diesem Fall die einfache Schallaufzeit im Medium 42 bis zum betrachteten Punktreflektor ist. Für das Beispiel B ist die Schichtdicke VL für das erste Medium 41 und VL = 5 mm, und die Schallgeschwindigkeit für das erste Medium 41 ist gleich der Schallgeschwindigkeit c_W des Kalibriermediums W – Wasser –, Mithilfe von Gleichung (IV)

wird anschließend der Abstand a_Med des kugelartigen Punktreflektors 5 gemäß Spalte 6 bestimmt. Zum Vergleich der Abweichung vom tatsächlichen Wert sind in Spalte 1 der verwendete Abstand des kugelartigen Punktreflektors 5 von der Grenzfläche 11 und die tatsächliche Schallgeschwindigkeit angegeben.Tab. 2 shows for different point reflector locations, characterized by different transit times t _j in column 2, the determined electronic focusing, in which the maximum occurs in column 3, and the value determined by interpolation of the values in Tab. 1 for the point reflector distance a _W on water in column 4. Using equation (III)

is the speed of sound in the second medium 42 calculated according to column 5, where t in this case the simple sound transit time in the medium 42 is up to the considered point reflector. For Example B, the layer thickness VL is for the first medium 41 and VL = 5 mm, and the sound velocity for the first medium 41 is equal to the speed of sound c _{W of} the calibration medium W - water -, using equation (IV)

is then the distance a _{Med of} the spherical-type point reflector 5 determined in accordance with column 6. For comparison of the deviation from the actual value, the distance used in column 1 of the spherical-type point reflector 5 from the interface 11 and the actual speed of sound indicated.

Tab. 2: Determination of the speed of sound C _Med in the medium 42 and the distance a _{med of} the point reflector 5 from the interface 11 from the sound field on the receiving elements (t _j - measured, simple signal transit time of interface 11 to the point reflector 5 ) Measurement situation t _j / 10 ^-6 s (measured) Electronic focusing for maximum a _W / mm (determined from Tab. 1) Calculated with equation (III), (IV) Corrected values with Tab. 4 C _Med / ms ^-1 c _med / ms ^-1 a _med / mm 1-layer system; Fluid, c = 1620 m / s Point reflector spacing of transmitting elements 9 mm 5.5556 Fok = 9.8 9.8 1627 2-layer system 5 mm water supply, 2nd layer c = 1620 m / s Point reflector spacing of transmitting elements 10 mm 3,086 Fok = 10.4 10.4 1620 2-layer system 5 mm water supply, 2nd layer c = 1620 m / s Point reflector spacing of transmitting elements 13 mm 4,938 Fok = 13.6 / 13.7 13.6 1616 1626 1-layer system c = 2730 m / s Point reflector spacing of transmitting elements 6 mm 2.198 Fok = 12.4 12.4 2909 6.39 2752 2732

The first three lines in Table 2 show that for tissue - with only a slight deviation of the speed of sound from the speed of sound of the calibration medium W - its speed of sound and the distance of the point reflector 5 can be determined with great accuracy. At Plexiglas 42 - At almost twice the speed of sound as in the calibration medium W - occurs a relative error of 7%. The cause and the increase in accuracy are discussed below.

liefert den Wert für die Lage des Maximums für einen kreisförmigen ebenen Ultraschallwandler 3. Bei der Fokussierung durch zeitverzögerte Ansteuerung mit dem Ultraschallwandler 3 treten zwischen dem berechneten Maximum mit der Gleichung (II)

wie in Tab. 3 – Spalte 4 angegeben, und den mit Schallfeldberechnungen, wie in Tab. 3 – Spalte 3 angegeben, ermittelten Werten Unterschiede auf. Das sind bei dem Gewebe 42, dessen Schallgeschwindigkeit nur wenig von dem Kalibriermedium W Wasser abweicht, nur 0.1 bis 0.2 mm, bei Plexiglas im Fokussierungsbereich jedoch immerhin ca. 0,75 mm. Deshalb ist es zweckmäßig, dass, wenn möglich, Kalibriermedien W mit nicht zu stark abweichenden Schallgeschwindigkeiten eingesetzt werden.The equation (I)

provides the value for the location of the maximum for a circular planar ultrasonic transducer 3 , When focusing by time-delayed control with the ultrasonic transducer 3 occur between the calculated maximum with the equation (II)

as shown in Table 3 - Column 4, and the values determined with sound field calculations, as indicated in Table 3 - Column 3, differences. That's the tissue 42 , whose sound velocity differs only slightly from the calibration medium W water, only 0.1 to 0.2 mm, with Plexiglas in the focusing area, however, after all, about 0.75 mm. Therefore, it is expedient that, if possible, calibration media W are used with not too different sound velocities.

Tab. 4 Aus dem Schaltfeld (Längsschnitt) ermittelte Fokuspunktlagen und zugehörige Schalllaufzeiten Elektronische Fok. Wasser c = 1500 m/s a_K Maximum für c = 1600 m/s Maximum für c = 1700 m/s Maximum für c = 2700 m/s c = 2800 m/s 1 Fok = 7 mm 7.4 6,8 6,3 3,1 3,0 2 Fok = 8 mm 8,3 7,7 7,1 3,7 3,5 3 Fok = 9 mm 9,3 8,6 (t = 5,375 μs) 8,0 (t = 4,706 μs) 4,3 4,0 gemittelte Werte für Fok = 9,8 mm, c = 5,5556 m/s (t = 5,825 μs) (t = 5,082 μs) 4 Fok = 10 mm 10.2 9,5 (t = 5,938 μs) 8,8 (t = 5,17 μs) 4,8 4,6 5 Fok = 11 mm 11,1 10,4 9,7 5,4 5,1 6 Fok = 12 mm 12,1 11,2 10,5 6 (t = 2,222 μs) 5,7 (t = 2,036 μs) 7 gemittelte Werte für Fok = 12,4 mm, t = 2,198 μs (t = 2,296 μs) (t = 2,107 μs) 8 Fok = 13 mm 13,0 12,1 11,3 6,5 (t = 2,407 μs) 6,2 (t = 2,214 μs) 9 Fok = 14 mm 12,9 12,1 7,1 6,7 10 Fok = 15 mm 13,8 12,9 7,6 7,3 11 Fok = 16 mm 14,6 13,7 8,1 7,8 In general, calibration for liquids can be done by means of spot reflector measurements. A possibility applicable for all media is the calculation of the sound field longitudinal section for the ultrasonic transducer used 3 at the corresponding focussing near the determined speed of sound (Table 4). Tab. 3 Deviation dv between the determined focal positions from sound field calculation and with the help of the approximation formula - Difference of 0.1 mm = error in focusing

Tab. 4 Focus point positions determined from the control panel (longitudinal section) and associated sound propagation times Electronic Fok. Water c = 1500 m / sa _K Maximum for c = 1600 m / s Maximum for c = 1700 m / s Maximum for c = 2700 m / s c = 2800 m / s 1 Foc = 7 mm 7.4 6.8 6.3 3.1 3.0 2 Foc = 8 mm 8.3 7.7 7.1 3.7 3.5 3 Foc = 9 mm 9.3 8.6 (t = 5.375 μs) 8.0 (t = 4.706 μs) 4.3 4.0 averaged values for Fok = 9.8 mm, c = 5.5556 m / s (t = 5.825 μs) (t = 5.082 μs) 4 Foc = 10 mm 10.2 9.5 (t = 5.938 μs) 8.8 (t = 5.17 μs) 4.8 4.6 5 Foc = 11 mm 11.1 10.4 9.7 5.4 5.1 6 Foc = 12 mm 12.1 11.2 10.5 6 (t = 2.222 μs) 5.7 (t = 2.036 μs) 7 averaged values for Fok = 12.4 mm, t = 2.198 μs (t = 2.296 μs) (t = 2.107 μs) 8th Foc = 13 mm 13.0 12.1 11.3 6.5 (t = 2.407 μs) 6.2 (t = 2.214 μs) 9 Foc = 14 mm 12.9 12.1 7.1 6.7 10 Foc = 15 mm 13.8 12.9 7.6 7.3 11 Foc = 16 mm 14.6 13.7 8.1 7.8

Tab. 4 shows the determined focal point distances for different media with different speeds of sound as a function of the electronic focusing with sound field calculations. If it is assumed that by shifting a point reflector, the maximum is found and the associated sound propagation time can be determined, from the focal position, ie the maximum position, for the respective speed of sound the transit time are determined, as the second value in the columns of Tab. 4 represents. If the focusing and the sound propagation time are determined for a medium to be examined with a roughly determined speed of sound, as indicated in line 7 of Table 4, the sound transit time up to the maximum for the two adjacent sound velocities can be determined from the focusing by interpolation. This results in interpolation the speed of sound of the medium to be examined.

For Plexiglas, which is the last example in Tab. 2, is given by This method according to line 7 of Tab. 4 a Sound velocity of c = 2752 m / s.

bestimmen, wobei der zur Fokussierung zugehörige Abstand im Kalibriermedium W aus Tab. 4 entnommen wird. Für Plexiglas 42 wird z. B. das Kalibriermedium W mit der Schallgeschwindigkeit von c = 2700 m/s verwendet. Dafür ergibt sich mit der Gleichung (III) eine korrigierte Schallgeschwindigkeit von c = 2736 m/s.Another possibility is that a material with approximately the already determined speed of sound is used as the calibration medium W. Then the speed of sound C _Med and the distance a _{Med of} the point reflector can be determined 52 from the interface also with the equations (III) and (IV)

determine the distance associated with the focusing in the calibration medium W from Tab. 4. For Plexiglas 42 is z. B. the calibration medium W with the speed of sound of c = 2700 m / s used. This results in the equation (III) a corrected sound velocity of c = 2736 m / s.

For a liquid mixture, for. B. with a variable mass density, analogous to a sound velocity profile can be determined by the water flow VL = 0 is set and for point reflectors 51 . 52 at different locations the distance from the ultrasonic transducer 3 and the mean speed of sound between point reflector 51 . 52 and ultrasonic transducers 3 be determined. The comparison of the determined sound velocities for two consecutive point reflectors 51 . 52 provides, along with the associated sonic delay, the change in average sound velocity between the point reflectors 51 . 52 ,

erfolgt, und eine Wiederholung des Vorgangs für weiter entfernt liegende Fokuspunkte F und damit Feststellung der mittleren Schallgeschwindigkeit zwischen Ultraschallwandler 3 und Fokuspunkt F für jeden Fokuspunkt F erfolgt, wobei die gemessene Schallaufzeit zwischen beiden Fokuspunkten und die bekannte Änderung des Fokussierungsregimes die mittlere Schallgeschwindigkeit zwischen den zwei Fokuspunkten liefert, wobei bei genügend dichter Verteilung von Punktreflektoren in der Flüssigkeit sich so ein Schallgeschwindigkeitsprofil erstellen lässt, wobei die Schallgeschwindigkeit des sich am dichtesten am Ultraschallwandler 3 befindlichen Punktreflektors 5 als Bezugs-Schallgeschwindigkeit dient.If there is a flow in the liquid, then the intensity maximum results by temporal averaging of the echo signals, wherein the determination of the distance and the sound velocity of the closest to the ultrasonic transducer 3 located focal point F with the equations (III) and (IV)

takes place, and a repetition of the process for farther away focus points F and thus determining the average speed of sound between ultrasonic transducer 3 and focal point F for each focal point F takes place, wherein the measured sound transit time between both focus points and the known change of the focusing regime provides the average velocity of sound between the two focus points, with sufficient dense distribution of point reflectors in the liquid can thus create a sound velocity profile, the Sound velocity of the closest to the ultrasonic transducer 3 located point reflector 5 serves as a reference sound velocity.

When Calibration medium W can also be a different liquid than Water are used.

7 shows on the basis of measured values that the location of the sound pressure maximum in flowing or diffusing liquids can be determined by averaging the echo signal amplitudes. It shows 7a the course of the echo signal amplitude, averaged over a period of 500 seconds, using as the propagation medium of the ultrasound a eutectic metal alloy made of InGaSn with room reflectors at room speed c = 2740 m / s and the maximum Max _{InGaSn of} the echo signal _amplitude for one Distance z = 33.55 mm from the ultrasonic transducer 3 results. 7b shows for comparison, the resulting for this arrangement by simulations SPL distribution in the propagation medium InGaSn, where the applicability of the method da shows that the distance resulting in the measurement z = 33.55 mm of the maximum Max _{InGaSn corresponding} to the range of the sound pressure maximum 7b matches. 7c shows a schematic diagram of the focusing ultrasonic ultrasound lens used in the ultrasonic transducer.

LIST OF REFERENCE NUMBERS

1

Transmission signal generator

2

Transmit-receive switch

3

ultrasound transducer

31

first element

32

second element

33

third element

4

medium

41

first medium

42

second medium

W

calibration

5

point reflectors

51

first point reflector

52

second point reflector

6

amplification unit

7

recording unit

8th

evaluation

9

calibration

10

invention arrangement

11

interface

12

axis of the ultrasonic transducer

13

line

14

channels

x

coordinate

y

coordinate

z

Coordinate / focus distance

r

radius a point reflector

v

Focus point distance

p

normalized maximum

Fi

focus point

Fok

electronic focus point

VL

On the calibration medium related distance from the ultrasonic transducer to to the interface upstream of the point reflector

d

diameter of the central element

Cd

speed of sound of the calibration medium

CMed

speed of sound of the medium to be examined

λ

wavelength of the ultrasound

f

center frequency of the ultrasound

t

Time

m

number the generated transmission signals

n

number the elements of the ultrasonic transducer

W

calibration

CMed

speed of sound in the medium to be examined

CMed

distance in the medium

Cd

speed of sound in the calibration medium

aW

distance in the calibration medium / distance converted to the calibration medium

AWJ

distance of the point reflector of the ultrasonic transducer during calibration, distance of the point reflector of the ultrasonic transducer converted to the calibration medium

Vmax (A min)

Focusing regime, where the maximum of the reflected by the point reflector ultrasound occurs in the unknown medium

Vmax (AWJ)

Focusing regime, where the maximum of the reflected by the point reflector ultrasound occurs in the calibration medium

T

tabular Relationship between the distance of the point reflector in the calibration medium and the focusing regime

Fok

calculated Distance with respect to the calibration medium, where the focus point is corresponding the drive times used is

V

difference the focal point positions in water and Plexiglas

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2002134159 [0007]
• - DE 50305421 [0008]

Cited non-patent literature

• - M. Barth et al .: Acoustic tomography for the simultaneous detection of temperature and flow fields, 14th GALA Symposium: Laser Methods in Flow Measurement, 05.-07. September 2006 [0006]

Claims (20)

Arrangement ( 10 ) for the combined determination of sound velocities and distances in liquid and solid media ( 4 . 41 . 42 , W) by means of ultrasound, consisting of - a transmission signal generator ( 1 ) on m ≥ 1 channels ( fourteen ) generates electrical transmission signals, - a transmit-receive switch ( 2 ), - an ultrasonic transducer ( 3 ) with n ≥ 1 elements ( 31 . 32 . 33 ), the electrical transmission signals from the transmission signal generator ( 1 ) via the transmit-receive switch ( 2 ), whereby the controlled elements ( 31 . 32 . 33 ) of the ultrasonic transducer ( 3 ) an ultrasonic wave into the medium to be examined ( 4 . 41 . 42 , W) with a fixed or spatially variable speed of sound and after switching the transceiver ( 2 ) receive the reflected ultrasonic wave, and - an amplification unit ( 6 ), which receive the received electrical signals from the individual elements ( 31 . 32 . 33 ) of the ultrasonic transducer ( 3 ) via the transmit-receive switch ( 2 ), and - a recording unit ( 7 ), in which an analog-to-digital conversion of the received signals takes place in digital signals, and - an evaluation unit ( 8th ) from the receiving unit ( 7 ) forwarded digital signals for evaluation, characterized in that the transmit signal generator ( 1 ) solely in the form of electronic focusing or in cooperation with the recording unit ( 7 ) in the form of synthetic focusing the generated ultrasonic focus stepwise along the axis ( 12 ) of the ultrasonic transducer ( 3 ) to individual focus points (F _i ) at a distance from the ultrasonic transducer ( 3 ) that a calibration unit ( 9 ) is provided when creating the calibration data either by simulation calculation or by measurement using the recording unit ( 7 ) for a point reflector in a calibration medium (W) ( 5 ) the relationship between the focusing _regime used (V _max (a _Wj )), at which the amplitude of the reflected ultrasound becomes maximum, and the selected distance (a _Wj ) of the point _reflector ( 5 ) from the ultrasonic transducer ( 3 ) in the calibration medium (W) and compiles as a table (T) that the recording unit ( 7 ) the sound propagation time from the ultrasonic transducer ( 3 ) to the point reflector ( 5 ) in the medium ( 4 ) measures at a distance (a _Mj ) and determines the amplitude of the reflected sound by stepwise focusing for each focusing _regime (V _i ), and that the evaluation unit ( 8th ) for a point located in the examination medium point reflector (5) of the receiving unit ( 7 ) receives the focusing _regime V _max (a _Mj )) at which the amplitude of the reflected ultrasound becomes maximum, and from the table (T) provided by the calibration unit the distance of the point reflector (FIG. 5 ) with respect to the calibration medium (W), from which the recording unit ( 7 ) in the medium ( 4 ) measured sound propagation time (t _j ) and the determined point _{reflector distance} (a _Wj ) with respect to the calibration medium (W) the average sound velocity (c _Med ) in the medium ( 4 ) to the point reflector ( 5 ) And the distance (a _Mj) of the spot reflector ( 5 ) from the ultrasonic transducer ( 3 ) and by determining these parameters for point reflectors ( 5 ) determines the variable velocity of sound at different locations, wherein the focusing regimes are n-tuples (Δt ₁ , Δt ₂ ,..., Δt _n ) of times by which the individual elements ( 31 . 32 . 33 ) of the ultrasonic transducer ( 3 ) compared to the middle element ( 31 ) are delayed or superimposed, and wherein a point reflector ( 5 ) an inhomogeneity in the medium ( 4 . 41 . 42 , W), which has an extension in the range of an ultrasonic wavelength (λ) and at which the ultrasound is scattered. Arrangement according to claim 1, characterized in that the medium to be examined ( 4 ) of one or more layers ( 41 . 42 ) with different speeds of sound and the medium ( 4 ) with point reflectors ( 5 . 51 . 52 ) for determining the speed of sound in front of the point reflector ( 5 ), the speed of sound (c _Med ) of the medium ( 4 ) according to equation (III)

is determined, a _W (the distance of the respective point of the reflector 5 . 51 . 52 ) from the ultrasonic transducer ( 3 ) with respect to the calibration medium (W), and wherein the distance (a _W ) from the focusing regime (V _max (a _W )) is determined, and wherein the lead (VL) the distance to the the point reflector ( 5 ) upstream interface ( 11 ) relative to the calibration medium (W), and where t is the simple sound propagation time of the point reflector ( 5 ) upstream interface ( 11 ) to the point reflector ( 5 ), and where c _{W is} the velocity of sound of the calibration medium (W). Arrangement according to claim 1, characterized in that the medium to be examined ( 4 ) is a liquid mixture that is compatible with distinguishable point reflectors ( 5 . 51 , 52 ), wherein sound velocity differences occur, whereby a determination of the distance of the on the axis closest to the ultrasonic transducer ( 3 ) point reflector ( 51 ) of ultrasonic transducers ( 3 ) and the mean velocity of sound (c _med ) between point reflector ( 5 ) and ultrasonic transducers ( 3 ) with the equations (V) and (VI)

where a _{W is} the distance of the point reflector ( 5 ) from the ultrasonic transducer ( 3 ) with respect to the calibration medium (W), and wherein the distance (a _W ) is determined by the focusing regime (V _max (a _W )), and where t is the simple sound transit time between ultrasonic transducers ( 3 ) and the respective point reflector ( 5 ), and where c _{W is} the speed of sound of the calibration medium (W), and a repetition of the process for farther point reflectors (FIG. 5 ) and thus a determination of the average sound velocity between ultrasonic transducers ( 3 ) and point reflector location for each point reflector location, where the mean velocity of sound (c _{j, j + 1} ) between two on the acoustic axis ( 12 ) (j, j + 1) point reflectors ( 51 . 52 ) via the equation (VII)

where t _{j + 1} -t _{j is} the simple sound transit time between the two point reflectors ( 51 . 52 ) and where a _{W (j + 1)} -a _{W (j) is} the distance between the two point reflectors ( 51 . 52 ) with respect to the calibration medium (W), and with sufficiently dense distribution of point reflectors ( 5 ) in the liquid mixture a sound velocity profile can be created. Arrangement according to claim 1, characterized in that the medium to be examined ( 4 ) is a liquid mixture which is provided with randomly distributed scattering particles which flow or diffuse, and thus, on averaged over time, at all locations in the medium ( 4 ) are sufficiently scattered particles are present, wherein the averaged over different transmission pulses echo signal amplitude of the focus point in the middle scattering particles for the selected focusing regime the propagation time proportional to the display position of the respective and thus the sound transit time from the ultrasonic transducer ( 3 ) to the focal point (F) in the medium ( 4 ) and wherein a determination of the average sound velocity (c _Med ) to the focal point (F) and the distance (c _Med ) between the ultrasonic transducer ( 3 ) and the focal point (F) with the equations (V) and (VI)

where the distance (a _W ) is determined by the focusing regime (V _max (a _W )), and where t is the simple sound transit time between ultrasonic transducers ( 3 ) and the respective focal point (F), and wherein c _{W is} the speed of sound of the calibration medium (W), and a repetition of the process for farther away focus points (F1, F2, F3) and thus a determination of the average sound velocity between ultrasonic transducers ( 3 ) and the respective focal point (F) and a determination of the distance of the respective focal point (F) from the ultrasonic transducer ( 3 ) for each focal point (F), wherein the mean velocity of sound (c _{j, j + 1} ) between two (j, j + 1) focus points (F) is given by the formula

where t _{j + 1} -t _{j is} the simple sound transit time between the two focus points (F), and where a _{Wj + 1} -a _{Wj is} the distance between the two focus points (F) with respect to the calibration _medium (W), wherein a sound velocity profile can be created. Arrangement according to claim 1, characterized in that the calibration unit ( 9 ) on the output side with the evaluation unit ( 8th ) and optionally on the input side with the recording unit ( 7 ), the calibration unit ( 9 ) when creating the calibration data either by simulation calculation or by measurement using the recording unit ( 7 ) for a point reflector in a calibration medium (W) ( 5 ) the relationship between the focusing _regime used (V _max (a _Wj )), at which the amplitude of the reflected ultrasound becomes maximum, and the selected distance (a _Wj ) of the point _reflector ( 5 ) from the ultrasonic transducer ( 3 ) in the calibration medium (W) and composes as a table (T). Arrangement according to claim 1, characterized in that the calibration unit ( 9 ) by calculation or measurement for a stationary point reflector ( 5 ) in the calibration _medium (W) at a distance (a _Wj ) at a defined sound velocity by stepwise displacement of the electronic focus point (F ₁ , F ₂ , F ₃ ...), the focusing (V _max (a _Wj )), determined in the the reflected ultrasound on a single element, or the entire element arrangement or the interconnection of several individual elements ( 31 . 32 . 33 ) has its maximum and thus the relationship between electronic focal point (Fok) and distance of the point reflector ( 5 ) (In the calibration W) delivers, and (the distance by a stepwise change _W1, a _{W2, W3} ... a) of the spot reflector ( 5 ) and repetition of the process provides a table (T) such that each distance (a _W1 , a _W2 , a _W3, ...) of the point reflector ( 5 ) an electronic focus point (Fok) is assigned, at which the maximum occurs. Arrangement according to claim 1, characterized in that the point reflectors ( 5 . 51 . 52 ) for calibration are objects in the order of the ultrasonic wavelength (λ) which are smaller than the selected focusing steps and with a different sound impedance than the medium to be examined ( 4 . 41 . 42 ) - metal or glass beads - are. Arrangement according to claim 1, characterized in that the evaluation unit ( 8th ) from the electronic focal point (Fok) the distance of the point reflector ( 5 ) Based on the calibration medium (W) and from this with the aid of the measured signal propagation time the distance (a _Med ) of the point reflector ( 5 ) and the speed of sound (C _Med ) in front of the point reflector ( 5 ) or between two point reflectors ( 51 . 52 ) in a layered medium ( 4 ) or liquid mixture according to equations (III) and (IV):

calculated. Arrangement according to claim 8, characterized in that in the case of a multilayered medium ( 4 ) a lead (VL) is present, wherein the distance of the last before the point reflector ( 5 ) ( 11 ) to the ultrasonic transducer ( 3 ) the speed of sound (c _Med ) after the interface ( 11 ), where a _{Med is} the distance of the point reflector ( 5 ) to the interface ( 11 ), t is the simple signal transit time between the spherical point reflector ( 5 ) and the interface ( 11 ), a _{W is} the distance with respect to the calibration medium (W) and c _{W is} the speed of sound in the calibration medium (W). Arrangement according to claim 8, characterized in that in the case of a point reflector ( 5 ) in a liquid mixture ( 4 ) the lead VL = 0, where C _{Med is} the mean velocity of sound from the point reflector ( 5 ) to the ultrasonic transducer ( 3 ), a _{Med is} the distance of the point reflector ( 5 ) of the ultrasonic transducer ( 3 ) and t is the simple sound transit time, whereby by repeating the process for point reflectors ( 5 ) With another distance and thus defined by a different Schallaufzeit a sound velocity profile can be created. Arrangement according to claim 9, characterized in that the ultrasonic transducer ( 3 ) Elements ( 31 . 32 . 33 ), which are designed as a ring element arrangement or as a matrix arrangement or as a linear arrangement, so that an electronic focus (Fok) or a synthetic focusing is possible. Arrangement according to claim 1, characterized in that for coupling the sound into a stratified or non-stratified medium ( 4 ) In addition, a liquid flow (VL) is provided. Arrangement according to claim 1, characterized in that the ultrasonic transducer ( 3 ) has a single element transducer or an element arrangement or a prefocused element arrangement, wherein the change of the focal point location alone or additionally by mechanical displacement of the ultrasonic transducer ( 3 ), wherein the ultrasonic transducer ( 3 ) is in communication with a displacement device, the ultrasonic transducer ( 3 ) along the acoustic axis ( 12 ) shifts. Arrangement according to claim 11, characterized in that in the ring element arrangement at least one annular element ( 31 . 32 . 33 ) to an inclination of the ultrasonic transducer ( 3 ) with respect to the interface ( 11 ) to adjust in order to adjust. Method for the combined determination of sound velocities and distances in liquid and solid media ( 4 . 41 . 42 , W) by means of ultrasound, using the arrangement ( 10 ) according to claims 1 to 14, characterized by the following steps: A. Stepwise focusing: the transmission signal generator ( 1 ) focused solely in the form of electronic focusing or in collaboration with the recording unit ( 6 ) and the evaluation unit ( 8th ) in the form of synthetic focusing the ultrasound stepwise along the axis ( 12 ) of the ultrasonic transducer ( 3 ) To individual focal points (F _1, F _2, F _3). B. Calibration: When the calibration data are generated, either by simulation calculation or by measurement with the aid of the recording unit for a point reflector located in a calibration medium (W) ( 5 . 51 . 52 ) the relationship between the used focusing _regime (V _max (a _Wj )), in which the amplitude of the reflected ultrasound is maximum, and the selected distance (a _Wj ) of the point _reflector ( 5 ) from the ultrasonic transducer ( 3 ) in the calibration medium (W) and compiled as a table (T). C. Recording: A recording unit ( 7 ) detects the sound propagation time from the ultrasonic transducer ( 3 ) to a point reflector ( 5 ) or to a focal point - in a liquid mixture with statistically distributed scattering particles which flow or diffuse, - in a medium ( 4 ), wherein the focusing regime (V _i ) is determined by the stepwise focusing, in which the amplitude of the reflected ultrasound for this point reflector ( 5 ) or focal point becomes maximum. D. Evaluation: In an evaluation unit ( 8th ) takes place for a medium to be examined ( 4 ) point reflector ( 5 ) from the determined focusing _regime (V _max (a _Mj )) and from that of the calibration unit ( 9 ) provided tabular relationship (T) between the focusing _regime (V _max (a _Mj )) and the distance of the point reflector ( 5 ) or the focal point of the ultrasonic transducer ( 3 ) in a calibration medium (W) the determination of the distance of the point reflector ( 5 ) or the focal point with respect to the calibration medium (W). A method according to claim 15, characterized in that from the determined sound propagation time and from the determined point reflector distance or focal point distance with respect to the calibration medium (W) the calculation of the average sound velocity in the medium to be examined ( 4 . 41 . 42 ) to the respective Punktreflektorort or focal point and the distance of the point reflector location or the focal point of the ultrasonic transducer ( 3 ) in the medium to be examined ( 4 . 41 . 42 ), and then by determining these parameters for multiple or all point reflectors ( 5 ) or the focal points at different locations the spatially variable speed of sound is performed in the form of a sound velocity profile, and wherein in the evaluation unit ( 8th ) from the determined focusing _regime V _max (a _Mj ) and from that of the calibration unit ( 7 ) Provided tabular connection (T) between the focusing regime (V _max (a _Wj)) and (the distance of the point reflector 5 ) from the ultrasonic transducer ( 3 ) in a calibration medium (W) the determination of the distance of the point reflector ( 5 ) with respect to the calibration medium (W) takes place, wherein the determined sound transit time (t) and from the determined distance of the point reflector ( 5 ) with respect to the calibration medium (W), the calculation of the mean velocity of sound in the medium to be examined ( 4 . 41 . 42 ) to the point reflector ( 5 ) and the distance of the point reflector ( 5 ) from the ultrasonic transducer ( 3 ) is carried out. Method according to claim 15 or 16, characterized in that subsequently by determining the distances for several or all point reflectors ( 5 ) At different locations the spatially variable speed of sound is determined in the form of a sound velocity profile. Method according to claims 15 to 17, characterized in that during the transmission the change of the focus point location is performed by one of the following method steps: a) by an electronic transmission focusing of the ultrasound, which is controlled by the focusing regime (V ₁ , V ₂ , V ₃ , ...) corresponding time-delayed control of the n individual elements ( 31 . 32 . 33 ) is carried out in such a way that that of the individual elements ( 31 . 32 . 33 ) outgoing ultrasonic waves in the distances of the focal points (F ₁ , F ₂ , F ₃ ...) constructively superimpose b) by a synthetic focusing of the ultrasound, which by recording of each individual transmitting element ( 31 . 32 . 33 ) on the respectively given receiving element ( 31 . 32 . 33 ) received echo signal and subsequent superposition of the echo signals of the transmitting elements ( 31 . 32 . 33 ) is realized according to the focusing regime (V ₁ , V ₂ , V ₃ , ...). A method according to claim 18, characterized in that, optionally or in addition to the transmission focusing, a focusing in the reception is carried out by the to the individual elements ( 31 . 32 . 33 ) Associated measured echo signals at said transmitting electronic focusing or by means of a bill superimposed echo signals in the synthetic focusing (corresponding to the focusing regime V ₁₎ are superposed with a time delay V _2, V _3, .... A method according to claim 18, characterized in that the reception of the received signal either by the middle element ( 31 ) alone or by another element ( 32 . 33 ) alone or by the combination of several elements ( 31 . 32 . 33 ) in the form of a time-delayed overlay of the individual elements ( 31 . 32 . 33 ) echo signals occur.

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