ELECTROMAGNETIC DOSIMETER

Abstract

Certain embodiments are directed to an acoustograph or acoustic sensor configured as a thermometer or direct specific absorption rate (DSAR) sensor for the measurement of electromagnetic energy.

Claims

1. A device for measurement of the speed of an acoustic wave in a target medium comprising; a target medium in which acoustic waves can be generated; at least one probe beam source that can generate a probe beam that is capable of traveling through the target medium and being deflected by an acoustic wave traveling through the target medium; and at least one probe beam detector configured to detect deflection of a probe beam generated by the probe beam source.

2. The device of claim 1, further comprising at least one pump beam source.

3. The device of claim 2, wherein the at least one pump beam source is capable of generate a pump beam that can generate an acoustic wave in the target medium.

4. The device of any of claims 1 to 3, further comprising at least one electromagnetic source.

5. The device of claims 1 to 4, wherein the device is configured to enable the target medium to incur electromagnetic energy deposition.

6. The device of any of claims 1 to 5, further comprising a timer.

7. The device of claim 6, wherein the timer is configured to record or measure the time that the probe beam is disturbed or the time between disturbances of the probe beam.

8. The device of any of claims 1 to 7, wherein the at least one probe beam source is capable of generating two or more probe beams.

9. The device of any of claims 1 to 8, wherein the at least one probe beam source can generate an optical probe beam.

10. The device of any of claims 1 to 9, wherein the target medium, in different locations in the target medium, has two or more acoustic speeds for an acoustic wave.

11. The device of any of claims 1 to 10, wherein the target medium is water.

12. The device of any of claims 1 to 10, wherein the target medium is biological tissue or thermally coupled to a biologic tissue.

13. The device of any of claims 1 to 12, wherein the detector is configured to detect probe beam deflection in two dimensions.

14. The device of any of claims 1 to 13, wherein the detector is configured to determine acoustic wave speed, pressure amplitude of an acoustic wave, the distance of the acoustic source, and/or direction of the acoustic wave.

15. The device of any of claims 1 to 14, wherein the detector is a photodiode and/or a quadrant detector.

16. The device of any of claims 1 to 15, wherein the device is configured as an acoustograph or an acoustic sensor.

17. The device of any of claims 1 to 16, wherein the device is configured as a thermometer or a direct specific absorption rate sensor.

18. The device of any of claims 1 to 17, wherein the device is configured as an electromagnetic sensor, electromagnetic transducer, and/or electromagnetic converter.

19. A method of measuring electromagnetic energy comprising measuring a change in acoustic wave propagation in a medium exposed to an electromagnetic energy when compared to the medium not exposed to the electromagnetic energy.

20. A method for measuring the speed of an acoustic wave comprising: exposing a target medium to an excitation source to generate an acoustic wave; detecting at least one probe beam deflection of at least one probe beam traveling through the target medium; and calculating acoustic wave speed using information provided by detection of at least one probe beam deflection.

21. A method for measuring electromagnetic energy deposition in a target medium or temperature of a target medium comprising: exposing a target medium to an excitation source to generate an acoustic wave; detecting at least one probe beam deflection of at least one probe beam traveling through the target medium; calculating speed of the acoustic wave using information provided by detection of at least one probe beam deflection; and determining the electromagnetic energy deposition in the target medium or the temperature of the target medium using the speed of the acoustic wave.

22. The method of claim 21, further comprising: exposing the target medium to electromagnetic energy from an electromagnetic source; wherein detecting probe beam deflections occurs in the target medium after and/or both before and after exposure to the electromagnetic energy from the electromagnetic source; and wherein calculating speed of the acoustic wave uses information provided by detection of at least one probe beam deflection in the target medium after and/or both before and after exposure to the electromagnetic energy from the electromagnetic source.

23. The method of any of claims 21 to 22, wherein determining the electromagnetic energy deposition in the target medium and/or the temperature of the target medium comprises comparing the speed of the acoustic wave in the target medium to a standard, a calculated, or a measured acoustic wave speed and/or speed change of a same or similar medium with no or a known specific electromagnetic energy deposition in the same or similar medium and/or with a known temperature.

24. A method for measuring electromagnetic energy from and/or of an electromagnetic source comprising: exposing the target medium to electromagnetic energy from the electromagnetic source; exposing a target medium to a excitation source to generate an acoustic wave; detecting at least one probe beam deflection of at least one probe beam traveling through the target medium; calculating speed of the acoustic wave using information provided by detection of at least one probe beam deflection; determining the electromagnetic energy from and/or of the electromagnetic source; wherein detecting probe beam deflections occurs in the target medium after and/or both before and after exposure to the electromagnetic energy from the electromagnetic source; and wherein calculating speed of the acoustic wave uses information provided by detection of at least one probe beam deflection in the target medium after and/or both before and after exposure to the electromagnetic energy from the electromagnetic source.

25. The method of claim 24, wherein determining the electromagnetic energy from and/or of a source further comprises comparing the speed of the acoustic wave in the target medium to a standard, a calculated, or a measured acoustic wave speed and/or speed change of a same or similar medium with no or a known specific amount of exposure to a known electromagnetic energy from and/or of an electromagnetic energy source.

26. A method of setting a standard speed and/or change of speed of an acoustic wave in a medium correlated with a magnitude of electromagnetic deposition of the medium, a certain exposure time to a known electromagnetic energy from and/or of an electromagnetic source, and/or a temperature of the medium comprising: measuring the speed and/or speed change of an acoustic wave in a medium with a known magnitude of electromagnetic deposition of the medium, certain exposure time to a known electromagnetic energy from and/or of an electromagnetic source, and/or temperature.

Description

DESCRIPTION OF THE DRAWINGS

[0028] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of the specification embodiments presented herein.

[0029] FIG. 1. An example of an acoustograph or acoustic sensor configured as a thermometer or direct specific absorption rate (DSAR) sensor for the measurement of electromagnetic energy.

[0030] FIG. 2. Demonstrates the change of speed of an acoustic wave in a target medium as temperature of the target medium changes, which causes a change in how long it takes the acoustic wave to reach the probe beam (change in time of flight).

DESCRIPTION

[0031] FIG. 1 shows a target medium (13), a probe beam (15), a pump beam (11), an acoustic wave (12), an electromagnetic energy wave (19), an electromagnetic energy source (18), a probe beam source (14), a probe beam detector/sensor (16), an acquisition system (including a timer) (17) for collecting and analyzing data, a pump beam source (10), and a surface of the target medium or a surface capable of reflecting the acoustic wave (20). The target may be a readily available material whose thermodynamic properties are well-known and understood. An example of a target (13) may be liquid water at a temperature at or near ambient room temperature. The pump beam (11) may be a Q-switched laser beam focused to cause an acoustic wave (12) of sufficient amplitude that the probe beam (15) may be disturbed and the probe beam detector (16) may easily and readily detect the passage of the acoustic wave (12). The probe beam (15) may either be one or two or more laser beams. Whether one or two or more beams are used is indicative of the actual method used to determine the velocity of the acoustic wave (12) within the target media (13). For example, one probe beam (15) may be used if the distance is known from the disturbance causing the acoustic wave generation to the probe beam axis passing through the target media; therein, only the time required for the acoustic wave (12) to reach the axis of the probe beam may need to be measured. As another example, the single beam technique may be used by counting an initial detection of the acoustic wave by the probe beam as time zero, then measuring the time from time zero until the acoustic wave travels back to the probe beam (15) after being reflect off of surface (20), wherein the surface (20) is located at a known distance from the probe beam (15). If a two or more probe beam setup is utilized, the principle in measuring the period of time the acoustic wave (12) propagates through the target medium (13) can simply be the time that the acoustic wave (12) travels through a known distance between each probe beam.

[0032] FIG. 2 shows how a change in temperature of a target medium can change the speed of an acoustic wave in a target medium and therefore the time that the acoustic wave reaches a probe beam. FIG. 2 also shows that a known speed and/or change of speed of an acoustic wave in a target medium may be used to determine the temperature of the target medium.

[0033] This proposed method of measuring the energy absorbed by a target media offers a potential standard method of determining the energy emitted by an electromagnetic energy source whose wavelength is known, but whose power of emission is unknown. Furthermore, the apparatus and methods described herein provide a means of calibrating Narda probes used to measure the field strength of RF sources.

[0034] Optical sensors based on probe beam deflection technique (PBDT) are an accurate non-contact and non-destructive method of sensing acoustic wave and related phenomena. These optical sensors are insensitive to background noise, minimizing the need for acoustic isolation or shielding. Such optical probes have high axial resolution that allows the use multi of optic probes next to each other.

[0035] In the case of the PBDT method, a pressure wave is detected indirectly, as it propagates through the detection chamber or medium and interacts with the probe beam. The propagation of this pressure wave produces a local density gradient, which alters the refractive index of the medium, leading to beam deflection. When the front of the acoustic wave passes through the probe beam it causes an increase in the media refractive index, which consequently deflects the probe beam towards the higher density region, forming the negative lobe of the signal. During the trailing edge of the wave the probe beam bends in the opposite direction producing the positive lobe due to the decreasing density gradient. Subsequently the beam returns to its initial position as the wave propagates beyond the interaction region.