Bubble Measuring Instrument and Method
Abstract
Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- October 2002
- Bibcode:
- 2002STIN...0315804K
- Keywords:
-
- Bubbles;
- Measuring Instruments;
- Detection;
- Counting;
- Size Determination;
- Patents;
- Frequencies;
- Image Transducers;
- Ultrasonic Radiation;
- Fluid Mechanics and Thermodynamics