High-power He-Ne laser and its application to photodynamic therapy of cancer

A high-power He-Ne laser with a flat discharge tube has been realized and used for the photodynamic therapy (PDT) of cancer. Its output power can be enhanced by increasing the transverse size of the discharge tube. To obtain higher output power. two or four of the laser tubes mentioned above are placed into one laser box. Their laser beams are coupled into a quartz optic fiber; the output power from the end of the optic fiber is above 280 or 480mW, respectively. This optic fiber can pass though the endoscopic tube to enter the human body to irradiate cancer for PDT. The effective rate of PDT is above 80%. The design principle, characteristics and structure of this He-Ne laser and its clinical effects in PDT are introduced in this paper.