Apparatus for determining physical parameters in an object using simultaneous microwave and ultrasound radiation and measurement

• US 7,040,168 B1
• Filed: 11/12/2004
• Issued: 05/09/2006
• Est. Priority Date: 11/12/2004
• Status: Expired due to Fees

• Current Assignee: John Bean Technologies AB (John Bean Technologies Corporation)
• Original Assignee: Frigoscandia Equipment AB (FMC Corporation)
• Inventors: Merkel, Harald
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US10/986,223
• Publication Number:
  US 20060101917A1
• Time in Patent Office: 543 Days
• Field of Search: 736/01
• US Class Current: 73/601
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 29/0672 by acoustic tomography medical tomography A61B8/13
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/2456 Focusing probes focusing arrangements G01N29/221
• CPC Class Codes: G01N 33/02 Food

Abstract

The present invention relates to an apparatus for determining a dielectric function in an object. The apparatus includes one transmit antenna for transmitting microwave radiation through the object, and one receive antenna for receiving the transmitted microwave radiation, one ultrasound transmitter for emitting ultrasound radiation through the object to generate a density variation in the object, means to analyse the microwave radiation transmitted through the density variation to determine the acousto-electric interaction in the object, and a device to calculate the dielectric function in the object from the acousto-electric interaction. The invention also relates to a method for determining the dielectric function in an object.

Claims

1. An apparatus for determining a dielectric function in an object, said apparatus comprising:

at least one transmit antenna for transmitting microwave radiation through said object,

at least one receive antenna for receiving the transmitted microwave radiation,

at least one ultrasound transmitter for emitting ultrasound radiation through said object to generate a density variation in the object,

means to analyse the microwave radiation transmitted through the density variation to determine the acousto-electric interaction in the object, and

means to calculate the dielectric function in the object from the acousto-electric interaction.

2. The apparatus according to claim 1, wherein said at least one transmit antenna is connected to a first microwave generator generating a transmit signal having a first fixed microwave frequency which is transmitted from said first antenna.

3. The apparatus according to claim 1, wherein apparatus further comprises a means to determine the attenuation comprising:

a mixer producing an intermediate frequency signal by mixing the received transmitted microwave radiation from said receive antenna with a local oscillator signal having a second fixed microwave frequency, said local oscillator signal is generated by a second microwave generator, and

an evaluation unit determining the acousto-electric interaction by evaluating phase and amplitude of the IF signal.

4. The apparatus according to claim 1, wherein said emitted microwave radiation and ultrasound radiation are arranged to be moved in relation to said object.

5. The apparatus according to claim 4, wherein said apparatus is stationary and the object is moved on a conveyor means.

6. The apparatus according to claim 4, wherein the apparatus is moved in relation to a stationary object.

7. The apparatus according to claim 1, wherein said ultrasound radiation is an ultrasound signal having a third fixed frequency, generated by an ultrasound generator.

8. The apparatus according to claim 1, wherein the apparatus further comprises at least one ultrasound receive antenna for receiving ultrasound radiation to determine an ultrasound runtime and damping mapping, referred to as metric for the object, which is used to determine the acousto-electric interaction in the object.

9. The apparatus according to claim 8, wherein the apparatus further comprises means to determine the phase of the ultrasound radiation for each focal point that is a part of the ultrasound metric.

10. A method for determining a dielectric function in an object comprising the steps of:

transmitting microwave radiation through said object from at least one transmit antenna,

receiving the transmitted microwave radiation in at least one receive antenna,

emitting ultrasound radiation, from at least one ultrasound transmit antenna, through said object to generate a density variation in the object,

analysing the microwave radiation transmitted through the density variation to determine the acousto-electric interaction in the object, and

calculating the dielectric function in the object from the acousto-electric interaction.

11. The method according to claim 10, wherein the step of analysing the microwave radiation to determine the acousto-electric interaction in the object comprises the step of obtaining an ultrasound metric of the object.

12. The method according to claim 11, wherein the ultrasound metric is obtained by:

a) focusing emitted ultrasound radiation to a point in the object b) adjusting the phase of the ultrasound radiation while measuring an acousto-electric efficiency signal to obtain a maximum of the acousto-electric efficiency signal,

c) storing the value of the phase together with position of the focal point in a memory, and

d) repeating steps a)–

c) until the metric for the object is completed.

13. The method according to claim 11, wherein the step of calculating the dielectric function in the object comprises the steps of:

selecting at least one point inside the object,

focusing the ultrasound on the point,

determining the damping of the received transmitted microwave radiation, and

determining the dielectric function using the ultrasound metric.

14. The method according to claim 11, wherein the step of calculating the dielectric function in the object comprises the steps of:

selecting at least one pair of point inside the object,

focusing the ultrasound on both points,

determining the damping of the received transmitted microwave radiation for both points, and

determining damping and the dielectric function between the two points using the ultrasound metric.

15. An apparatus for determining local distribution of temperature in a food product, said apparatus comprising:

at least one transmit antenna for transmitting microwave radiation through said food product,

at least one receive antenna for receiving the transmitted microwave radiation,

at least one ultrasound transmit antenna for emitting ultrasound radiation through said food product to generate a density variation in the food product,

means to analyse the microwave radiation transmitted through the density variation to determine the acousto-electric interaction (δ

) in the food product, and

means to calculate the dielectric function in the food product from the acousto-electric interaction and to calculate the local distribution of temperature in the food product based on the calculated dielectric function.