Diffraction-free acoustic detection for optoacoustic depth profiling of tissue using an optically transparent polyvinylidene fluoride pressure transducer operated in backward and forward mode.
An optoacoustic detection method suitable for depth profiling of optical absorption of layered or continuously varying tissue structures is presented. Detection of thermoelastically induced pressure transients allows reconstruction of optical properties of the sample to a depth of several millimeters with a spatial resolution of 24 mum. Acoustic detection is performed using a specially designed piezoelectric transducer, which is transparent for optical radiation. Thus, ultrasonic signals can be recorded at the same position the tissue is illuminated. Because the optoacoustical sound source is placed in the pulsed-acoustic near field of the pressure sensor, signal distortions commonly associated with acoustical diffraction are eliminated. Therefore, the acoustic signals mimic exactly the depth profile of the absorbed energy. This is illustrated by imaging the absorption profile of a two-layered sample with different absorption coefficients, and of a dye distribution while diffusing into a gelatin phantom.
Jaeger
Michael
M
University of Berne, Institute of Applied Physics, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
Niederhauser
Joël J
JJ
Hejazi
Marjaneh
M
Frenz
Martin
M
D000042:Absorption; D000162:Acoustics / Q000295:instrumentation; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008027:Light; D008567:Membranes, Artificial; D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation; D011145:Polyvinyls; D014160:Transducers, Pressure; D005465:Fluorocarbon Polymers
D008567:Membranes, Artificial; D011145:Polyvinyls; C024865:polyvinylidene fluoride; D005465:Fluorocarbon Polymers