Signal—to—Noise Ratios in Acousto—Photonic Imaging

摘要

The concept of tagging photons with ultrasound for medical imaging has been under development by several groups since the early 1990's. All the early attempts were plagued by low signals. The problem is very fundamental because the goal of good spatial resolution requires sampling only that light which has gone through a very small volume. It is compounded by the fact that the diverse paths of the photons result in signals which are not coherent with each other. Thus averaging over a large number of paths is of limited benefit. Recently, some new techniques have been developed for enhancing the signals. We will discuss the fundamental limits on signal-to-noise ratio which apply across all techniques.