Phase detection in acoustic microscopy.
The scanning laser acoustic microscope provides a relatively simple means by which speed of sound data can be collected from biological specimens. By employing a phase detection circuit, phase-contour lines can be superimposed on acoustic micrographs and digitized for direct speed of sound calculations. Because of the existence of mild field non-uniformities, the phase reference must be mathematically modeled. This is accomplished by employing a polynomial function and simple linear regression. Scattering can be studied by using a frequency-selective "dark field" approach. Speed of sound maps are readily produced from the phase data by applying the simple geometric relationships of wave propagation; however the theoretical limitations of the technique must be kept in mind. Using this approach, useful data have been obtained.
Levinson
S F
SF
Indianapolis Center for Advanced Research, IN 46204.
D000162:Acoustics; D000818:Animals; D001001:Anura; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007834:Lasers; D008853:Microscopy / Q000379:methods*; D008962:Models, Theoretical; D009132:Muscles / Q000648:ultrastructure; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D014465:Ultrasonics; D014463:Ultrasonography / Q000379:methods*