R&D Of Optics For High Power cw CO[sub]2[/sub] Lasers In The Japanese National Program

Substrate material preparation, surface finishing and coating techniques as well as optical evaluation methodology were developed to design and manufacture metal reflective optics and transmissive optics made of ZnSe and KC1 substrate. These optics were used successfully for high power cw CO 2 laser of up to 20 KW. On the basis of these technologies, the triple layer AR coating for KRS-5 infrared fibers was developed. Maximum transmitted power of a cw CO 2 laser beam through the fiber was found to exceed 90 W. The operating life exceeding 1000 hours in 40 W continuous irradiation test was achieved with the AR coated 1500 mm long KRS-5 fiber with 0.5 mm diameter.