Systems and methods for detection of micron-scale inhomogeneities using ultrasound

A system for detecting one or more inhomogeneities in a material sample, wherein the one or more inhomogeneities have one or more predetermined resonant frequencies, the system comprising:

• a pulser-receiver configured to generate one or more electrical pulses;
• a first ultrasound transducer configured to be arranged on a first side of the material sample, wherein the first ultrasound transducer is configured to generate one or more high frequency ultrasound (HFU) signals in response to receiving the one or more electrical pulses, wherein the one or more HFU signals propagate through the material sample and undergo scattering therein;
• a second ultrasound transducer configured to be arranged on a second side of the material sample opposite the first side, wherein the second ultrasound transducer is configured to receive the one or more scattered HFU signals from the material sample and transmit one or more electronic signals indicative of the one or more scattered HFU signals to the pulser-receiver;
• a processor;
• and
• a non-transitory, computer-readable medium storing instructions that, when executed, cause the processor to:
• receive the one or more electronic signals from the pulser-receiver,
• generate a windowed signal based on the one or more electronic signals by applying a window function,
• convert the windowed signal to frequency domain via fast Fourier transform, determine, for the converted signal, one or more peak frequencies within one or more resonant frequency bands associated with the one or more predetermined resonant frequencies, and
• compare the one or more peak frequencies to a baseline spectrum, wherein a peak frequency present in the converted signal and absent in the baseline spectrum is indicative of a presence of the one or more inhomogeneities in the material sample.

A method for detecting one or more inhomogeneities in a material sample, wherein the one or more inhomogeneities have one or more predetermined resonant frequencies, the method comprising:

• transmitting, by a pulser-receiver, one or more electrical pulses to a first ultrasound transducer arranged on a first side of the material sample;
• generating, by the first ultrasound transducer, one or more one or more high frequency ultrasound (HFU) signals in response to the one or more electrical pulses, wherein the HFU signals propagate through the material sample and undergo scattering;
• receiving, by a second ultrasound transducer a second side of the material sample opposite the first side, the one or more scattered HFU signals from the material sample;
• transmitting, by the second ultrasound transducer, one or more electronic signals indicative of the one or more scattered HFU signals to a processor via the pulser-receiver;
• generating, by the processor, a windowed signal based on the one or more electronic signals by applying a window function;
• converting the windowed signal to frequency domain via fast Fourier transform;
• determining, for the converted signal, a peak quantity within one or more resonant frequency bands associated with the one or more predetermined resonant frequencies;
• and
• comparing the peak quantity to a baseline value, wherein a peak quantity greater than the baseline value is indicative of a presence of the one or more inhomogeneities in the material sample.