Advances in Mechanically Scanned Acoustic Microscopy,

A scanning acoustic microscope, using the design we have previously described, can now be routinely operated at a frequency of 1 GHz with a corresponding resolution of nearly 1 micron. Operating in transmission a number of biological samples have been imaged. With this high resolution, variations in the elastic properties within individual cells can be seen. Moreover, clear distinctions have been demonstrated between the acoustic images and corresponding optical micrographs. Several alternative imaging modes have also been demonstrated with this instrument. One of these is a phase contrast technique in which the phase of the output signal is compared directly to the phase of the input signal. Another mode is reflection imaging which allows specimens on thick substrates to be viewed. This technique has been applied profitably to an investigation of integrated circuits. Author