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The integrated amplitude and phase distribution of the sound field propagating from sinusoidally vibrating objects in air have been recorded by time-averaged TV holography. The behavior of the sound field is observed in real time by use of dynamic phase modulation. The magnitude and direction of the field are found by acoustic phase stepping and image processing. The field is three dimensional, and recordings of several cross sections are necessary for a complete description, but in many cases valuable information can be obtained by two-dimensional projections. The technique has been used to study sound propagation and details in the sound emission from extended sources.

The contours of constant phases across sinusoidally vibrating objects have been mapped using reference wave phase modulation in time-average electronic speckle pattern interferometry.

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We demonstrate low-coherence interferometry for diffusion measurements. We have measured the diffusion coefficient of a phthalocyanine dye in 1.5% agar gel with a two-wavelength interferometer; one wavelength was matched to the absorption peak of the dye at 675 nm, while the other, 805 nm, was not affected by the dye. The diffusion coefficient of the dye was found by fitting a mathematical model for the interferometer signal to the measured low-coherence interferometry amplitude. A 95% confidence interval for the diffusion coefficient was found to be D = (2.5 +/- 0.2) x 10(-10) m2/s. The influence of speckle averaging and experiment time on the determination of the diffusion coefficient has been studied. The presented technique allows in situ characterization of diffusion in semitransparent media.