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US 4,391,124 AGranted
Electroacoustic transducer calibration method and apparatus
AssigneeCornell Research Foundation, Inc.
InventorsCornelis J. Drost, G. Jan Milanowski
Life of this patent
Estimating the term…
Abstract
Methods and apparatus for calibrating terminated ultrasonic electroacoustic transducers are disclosed. The transducers are excited by a driving signal to emit an ultrasonic acoustic wave, which wave is received either by the same transducer after reflection or by a second transducer to produce an output signal. The driving signal and output signal are supplied to measuring circuitry deriving transd BACKGROUND OF THE INVENTION The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.
Claims33
A self-reciprocity calibration method for terminated ultrasonic transducers, comprising:
- supplying a driving signal from a driving source to a transducer in a transmit mode to cause said transducer to emit a burst of ultrasonic waves;
- switching said transducer to a receive mode to receive an echo of its emitted wave, said transducer responding to said echo wave to produce a transducer output signal;
- measuring the ideal source value of said driving signal source;
- measuring said transducer output signal, said driving signal and said output signal being fed through substantially identical impedance values;
- and
- deriving from the measures of said driving signal and said output signal a measure of transducer performance in absolute terms under conditions of actual termination.
3 more elements
A calibration method for terminated ultrasonic transducers comprising:
- continuously supplying from a drive signal source a driving signal to a first transducer to be tested in a transmit mode to cause said first transducer to emit ultrasonic waves;
- mounting a second transducer to be tested in the path of said ultrasonic waves, said second transducer operating in a receive mode to respond to said ultrasonic waves to produce a transducer output signal;
- measuring the ideal source value of said first transducer driving signal source;
- measuring said second transducer output signal, said driving signal and said transducer output signal being fed through substantially identical terminating impedance values connected to said transducers, whereby the performance characteristics of said transducers are measured in absolute terms as a function of the applied terminating impedances;
- and
- deriving from said measures of transducer driving signal and transducer output signal a transducer performance calibration signal under conditions of actual termination.
3 more elements
A self-reciprocity calibration circuit arrangement for terminated ultrasonic transducers, comprising:
- an ultrasonic transducer capable of operating in transmit and receive modes;
- a high frequency voltage source producing a drive signal;
- first circuit means for connecting said drive signal to said transducer to cause said transducer to operate in its transmit mode to emit acoustic waves;
- reflector means for reflecting at least a portion of said acoustic waves back to said transducer to cause said transducer to generate an output signal;
- second circuit means connectable to said transducer to cause said transducer to operate in its receive mode and for receiving said transducer output signal;
- terminating impedance means included in said first circuit means during the transmit mode of said transducer, and in said second circuit means during the receive mode of said transducer;
- measuring circuit means connected to said first circuit means and responsive to the ideal source value of said voltage source and connected to said second circuit means and responsive to said transducer output signal;
- and
- output circuit means responsive to said measuring circuit means to produce a transducer performance calibration signal which is a measure of transducer performance in absolute terms under conditions of actual termination.
6 more elements
A calibration circuit arrangement for terminated ultrasonic transducers, comprising:
- first and second ultrasonic transducers mounted in spaced apart relationship in an acoustic test fixture and defining an acoustic path;
- a high frequency drive voltage source;
- first circuit means having a transmit mode and including a first termination impedance, said first circuit means connecting said drive source through said first termination impedance to said first transducer to cause said first transducer to emit acoustic waves along said acoustic path to impact said second transducer and to cause said second transducer to produce an output signal;
- second circuit means having a receive mode and including a second termination impedance connected to said second transducer, said second termination impedance having a value substantially equal to the value of said first termination impedance, said second circuit means receiving said transducer output signal;
- measuring circuit means connectable to said first circuit means and responsive to the open circuit amplitude value of said drive source and connectable to said second circuit means and responsive to said transducer output signal;
- and
- output circuit means responsive to said measuring circuit means to produce a transducer performance calibration signal.
4 more elements
Dependencies are inferred from the claim text.