Scanning acoustic microscope



A Scanning Acoustic Microscope (SAM) is a device which uses focused sound to investigate, measure, or image an object. It is commonly used in failure analysis and non-destructive evaluation. It also has applications in biological and medical research. The semiconductor industry has found the Scanning Acoustic Microscope useful in detecting voids, cracks, and delaminations within microelectronic packages.

History
The first scanning acoustic microscope was developed in 1974 by C. F. Lemons and R. A. Quate at the Microwave Laboratory of Stanford University.

Principles of operation
Scanning Acoustic Microscopy works by directing focused sound from a transducer at a small point on a target object. Sound hitting the object is either scattered, absorbed, reflected (scattered at 180°) or transmitted (scattered at 0°). Typically, either the reflected or transmitted sound is gathered and measured. Based on the measurement, a value is assigned to the location investigated. The transducer (or object) is moved slightly and then insonified again. This process is repeated in a systematic pattern until the entire region of interest has been investigated. Often the values for each point are assembled into an image of the object. The contrast seen in the image is based either on the object's geometry or material composition. The resolution of the image is limited either by the physical scanning resolution or the width of the sound beam (which in turn is determined by the frequency of the sound).

Medicine and Biology
SAM can provide data on the elasticity of cells and tissues, which can give useful information on the physical forces holding structures in a particular shape and the mechanics of structures such as the cytoskeleton. These studies are particularly valuable in investigating processes such as cell motility.


 * Flaw Detection


 * Internal stress investigation


 * Elastic property characterization

Ultrasonic Direct Microscopy
Ultrasonic Direct Microscope (UDM) base on measuring the ultrasonic signal directly. The conventional sensor include a level sensor that means that the measurement instrument attitude of the signal. ADM technique deal with ultrasonic signal as is. That make possible to produce modulate ultrasonic signal and to check not only the main frequency, and enable wide range in order to examine little chances in to material in test.