High-average-power tunable laser system and its long-term performance for photodynamic therapy

Abstract

Performance characteristics of a high average power tunable laser system designed for clinical photodynamic therapy (PDT) are described. Seventeen watts of TEM<SUB>00</SUB> average power at 630 nm with sulforhodamine 640 dye has been achieved. The time*power pump laser product for the dye laser's output power to degrade to one half of its initial power was recorded to be thousands of watt*hours or hundreds of thousands of photons per molecule. The system had a wall plug efficiency of .33%. The system utilizes the high efficiency KTiOPO<SUB>4</SUB> (KTP) frequency doubled Nd:YAG laser to pump a tunable dye laser system designed specifically for the low maintenance and high reliability required in PDT. Performance at other wavelengths of interest in investigational and clinical PDT is described. Comparative results obtained with sulforhodamine 640 versus rhodamine 6G under identical conditions are described. Performance of various manufacturer's preparations of sulforhodamine 640 was assessed. Comparison to other high average power tunable systems as well as long term system performance including dye stability data are presented.