An optical waveguide mounting member for mounting to a substrate is disclosed. According to such a method, even when inexpensive carbon dioxide gas is used as shield gas, the amount of spatter can be reduced, and high weldability can be achieved in multipass welding. On the moving unit 41, there are mounted a loaded ring delivering unit 9 for holding and delivering a metal ring W on the loaded ring placement unit 8 and an unloaded ring delivering unit 10 for removing the metal ring W from support rollers 3, 4 and delivering the metal ring W to the unloaded ring placement unit 11. The concentric acoustic compressional wave diffracts the incident light, so that the diffraction optical device functions like a lens and converges the luminous flux.