Basic studies on optical imaging of biological tissues using optical speckle patterns modulated by ultrasound

摘要

Ultrasound-modulated light has recently been utilized to improve a spatial resolution of optical imaging of biological tissues. This paper describes a new method for detecting the ultrasound-modulated light by using variations in speckle patterns. A pulsed laser beam was injected into a turbid medium and modulated by an ultrasound pulse. The pulsed light was synchronized with the ultrasound, and a phase inversion technique was used so that a modulated component could be detected using a conventional CCD's shutter speed. In order to evaluate the performance of this technique, one-dimensional imaging of absorbed object embedded in a turbid medium was carried out in both of the transmission and reflection methods. It was found that a modulated component can be successfully extracted from scattered light by using the proposed technique in both cases.