The project involved the design, development, construction and testing of a high resolution acoustic microscope. A 220 MHz ultrasonic pulser/receiver was designed and developed as part of the effort. The pulser/receiver unit could be used as a stand-alone instrument controlled through the front panel. Alternately, the instrument can be controlled remotely through a personal computer. The pulse repetitive frequency can be set anywhere from 500Hz to 125 kHz using either an internal clock or triggered via an external source. A choice of 16 preset energy levels together with the ability to choose three different peak amplitudes is offered. The damping level can be set between 10 and 1000 ohms. The receiver gain (7-70 dB), attenuation (0-63dB) and damping (10 -1000 ohms) can be set via the front panel or remotely from a computer. A number of filter and signal rectification options are available to the user.
The acoustic microscope is interfaced to a personal computer which is equipped with a suite of user friendly, state-of-the-art pattern recognition as well as signal/image processing packages. Powerful 2D and 3D computer graphics packages for displaying and manipulating images are included. The software package includes algorithms for controlling an X-Y-Z mechanical scanner. The software is capable of detecting the boundaries of the test specimen, conduct a scan with the desired spatial resolution and display the processed c-scan image automatically. The signal/image processing package can subsequently be used to extract information of interest to the user.
The resolution of the microscope is better than 5 micrometers. The instrument has been used to study the structure of metallic as well as ceramic components.
The scanning acoustic microscope system was designed in 1992 and the technology was transferred to Takano in 1993. As in the case of the single frequency eddyscope, the acoustic microscope system incorporated state-of-the-art technologies and offered many features that were not available in acoustic microscopes on the market at that time.