The stable light power guide system is useful problem in the medical laser apparatus. The light communication use quartz fiber is powerful light guide for near infrared radiation with YAG laser. However, in contract to low power propagation at the light communication, light power propagation is a prerequisite for the medical laser. In the case of high power propagation, the occurrence of thermal damage was confirmed on the both end surfaces of quartz fiber. Therefore, the method to overcome this defect was investigated. In our present experiments, we found that the effective method was the forced water cooling at the both end part of fiber.
In our present experiments, a fiber of diameter 0.6mm and length ca.4 m was used as test fiber.
From the our experimental results, this confirms that the method of forced water cooling on coupling parts has made it possible to YAG laser power transmission (ca. cw 80W) and the efficency dose not decrease after a long time continuous operation (above a hour).
On the other hand, we have investigated on the light guide for CO₂ laser. As the light guide was used rectangular hollow metal tube. The present experimental results show that,in the coupling, the most suitable condition is one dimensional focus.