Compact Diode-Pumped Laser System for Biomedical Imaging

We will develop a compact diode-pumped laser system for non-ionizing imaging of soft tissue. The following paragraph describes this concept. Two single-frequency lasers, when aligned and overlapping onto a photodiode, create a heterodyne signal in the detector proportional to each beam's amplitude. A scattering medium placed in one beam's path scatters light outside of the beam, so the heterodyne signal results only from unscattered light. If a dense embedded object attenuates the beam, the heterodyne signal decreases and the object can be imaged. Additionally, the frequency of the heterodyne signal allows the use of an extremely sensitive detection system, which allows for imaging through thicker samples. Lightwave has demonstrated this concept in a simple setup using two single frequency diode-pumped Nd:YAG lasers. The goals of Phase I are to explore the limits of this system by optimizing the signal detection system, exploring other possible laser systems or configurations, and measuring systems characteristics such as spatial resolution, signal-to-noise ratio, and data acquisition rates. At the completion of the Phase I, we expect to be able to generate two dimensional images through tissue samples. During Phase II, we expect to develop a complete prototype imaging system.