| 摘要 |
PROBLEM TO BE SOLVED: To stably generate a ring beam with high accuracy. SOLUTION: A ring beam generator is composed of a laser 2 as the beam source of electromagnetic waves and a fiber 3 as a cylindrical waveguide. On its incident end face 30, a perpendicular coordinate is estimated with a straight line located inside a meridian plane and vertical to an optical axis C as a Y coordinate axis, a straight line respectively vertical to this Y coordinate axis and the said optical axis C as an X coordinate axis, the surface of the optical axis C as a Z coordinate axis, and a point crossing the optical axis C on the incident end face 30 of the said fiber 3 as an origin. A reference beam X0 incident to the said origin is advanced inside a meridian plane M and radiated from an emission end face 31 after fully reflected five times on the boundary surface of the core and clad of the fiber 3, namely, on a reflection plane R of a radius (r). Then, the incident end face 30 is irradiated with the laser within the range of from +x to -x so as to satisfy|x|= resin(180/2N) (N is the number of times of reflection).
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