Scanning near field ultrasound holography
AssigneeNorthwestern University
InventorsGajendra Shekhawat, Vinayak Dravid
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Abstract
A high spatial resolution phase-sensitive technique employs a scanning near field ultrasound holography (SNFUH) methodology for imaging elastic as well as viscoelastic variations across a sample surface. SNFUH uses a near-field approach to measure time-resolved variations in ultrasonic oscillations at a sample surface. As such, it overcomes the spatial resolution limitations of conventional phase-resolved acoustic microscopy (i.e. holography) by eliminating the need for far-field acoustic lenses.
Claims31
A scanning near field ultrasound holography method for surface and subsurface imaging comprising:
- vibrating a cantilevered tip at a first ultrasonic frequency;
- vibrating a sample at a second ultrasonic frequency;
- detecting movement of the cantilevered tip interacting with the vibrating sample to provide a tip deflection signal;
- and
- extracting surface acoustic wave (SAW) amplitude and phase information associated with the surface and subsurface of the sample using lock in detection.
A scanning near field holography method for surface and subsurface imaging comprising:
- vibrating a cantilevered tip at a first microwave frequency;
- vibrating a sample at a second microwave frequency;
- detecting movement of the cantilevered tip interacting with the vibrating sample to provide a tip deflection signal;
- and
- extracting surface acoustic wave (SAW) amplitude and phase information associated with the subsurface of the sample from the tip deflection signal using lock in detection.
An atomic force microscopy system, said system comprising:
- a cantilever, wherein said cantilever includes a tip at an end of said cantilever;
- a vibrating device for supplying vibrations at a first frequency to said cantilever to generate vibration at said tip;
- and
- a detector for detecting movement of said tip based on an atomic force between said tip and a surface of a sample, wherein said sample is vibrated at a second high frequency excitation different from said first frequency.
A scanning near field acoustic holography system, said system comprising:
- an acoustic wave generator configured to launch a first high frequency acoustic wave from the bottom of a specimen and a second acoustic wave from the base of said cantilever, wherein said cantilever includes a tip at one end, and wherein said tip serves as an antenna receiving phase and amplitude information from an acoustic signal;
- and
- a scanning near field acoustic holography module (SNFUH) electronic module capable of mixing the first and second acoustic waves to generate at least one of a product frequency, an addition frequency, and a difference frequency representative of a surface and subsurface of said specimen.
Dependencies are inferred from the claim text.