Design and construction of a light-delivery system for photodynamic therapy

We have developed a device to divide the output from a dye laser into as ma ny as eight beams of equal power with negligible total power loss. In this system, 630-nm s-plane polarized laser light was split by a series of highl y polarization-sensitive plate beamsplitters. Each of the beams was coupled to a 200, 400, or 600 mu m diameter optical fiber. Brewster-window-type at tenuators allowed the power of each beam to be individually set. It was pos sible to reconfigure the device to produce four, two, or one output(s). We discuss the design requirements of the beamsplitter device and describe its construction from mostly commercially available components. An apparatus f or positioning and stabilizing each optical fiber relative to the skin surf ace of a patient is also described. The illumination from the fiberoptic su pported by such an apparatus strikes a defined surface area and is independ ent of patient movement. Both the beamsplitter device and the optical fiber positioner are used routinely in photodynamic therapy (PDT) of malignant t umors in the clinic and in the laboratory. (C) 1999 American Association of Physicists in Medicine. [S0094-2405(99)01808-8].