Evidence of a millimeter size virtual light source for acousto-optical tomography in scattering media using a chirp modulation of the ultrasound

摘要

The Acousto-optical imaging technique in scattering media can be explained by using the concept of a virtual light source moving inside the medium. Its emission depends on the local optical properties of the insonified area, making it an interesting candidate for in-depth tissue (several centimeters) probing. Evidence of this statement in the restrictive case of a chirp-reduced-size virtual source is shown using a technique that records a film during one chirp modulation of the imaging system. A Fast Fourier Transform treatment correlates the Fourier spectrum of time-sampled transmitted light to the position of the source along the ultrasonic beam, revealing its millimetric size.