Heterodyne Holographic Interferometry for Visualization of Surface Acoustic Waves.
Abstract
A technique for recording and visualizing acoustic wavefronts over a finite field of view and with a resolution on the order of Angstroms has been developed. Multiple exposure holograms of an aluminum test block were used to record the surface displacements resulting from the detonation of a small explosive charge placed on the object surface. The primary wavefronts resulting from the explosive charge were sufficiently large as to be visible upon reconstruction of the holographic interferograms. In addition, details of the surface wavefronts which could not be deduced using conventional holographic interferometry were measured and displayed by modifying the pulsed recording geometry and subsequently applying heterodyne interferometric analysis to the holograms to interpolate between the observed interferometric fringes. Although theory predicts that still greater resolution is possible, fringe interpolation to 1/900 of a fringe (about 2A displacement) was demonstrated. Based on these experimental results and the mathematical relationships which have been developed to describe system performance, it appears likely that a practical system for studying sub-Angstrom transient phenomena may be realized using heterodyne holographic interferometry. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1984
- Accession Number
- ADA155405
Entities
People
- J. W. Wagner
Organizations
- Johns Hopkins University