Acoustical Holography Using Temporally Modulated Optical Holography

ARMA Processing for NDE Ultrasonic Imaging

“…The received signal at point (x,y) is Figure 1. Geometry of Imaging System sr(x,y,f,t) = kIll O(x,y,z )exp(j2wf(t-t d »dx dy dz (2) n n n n n n object where O(x,y,z) is the object distribution function, n n n describing the object in terms of the reflection coefficients. In general, the object reflectivity is a function of the frequency of the illuminating wave, but this dependency when known can be taken care of and compensated for in the reconstruction process.…”

“…It is known that in continuous-wave acoustic holography [2] we can resolve objects separated in angle by AID, where A is the wavelength of the acoustic wave and D is the diameter of the hologram aperture. This imaging methodology although excellent for lateral resolution is insufficient for range resolution.…”