Resolution beyond the diffraction limit in the acoustic microscope: A nonlinear effect

摘要: By operating the reflection mode scanning acoustic microscope at nonlinear power levels, resolution beyond linear diffraction limit can be achieved. To demonstrate this effect, imaging experiments were performed in liquid nitrogen, argon, and water frequencies between 2000 2800 MHz. The spatial frequency response of system was found to have a cutoff which is least 1.4 times higher than system. It proposed that improvement result interaction transmitted fundamental beam harmonics. harmonics are generated converging portion focal spots significantly smaller spot beam. harmonic reflected by object influences detected due (parametric) results improved resolution. A simple physical model gaussian analysis presented elucidate energy exchange focused