To provide an optical irradiation fiber outputting light to the side part and improving the directivity of the light to be outputted.
The optical irradiation fiber 1 comprises: an optical fiber 10 extended in one direction, for propagating light made incident from an incidence end 10b and emitting it from an emission end 10a; an optical irradiation part 20 attached to the side of the emission end 10a of the optical fiber 10 and extended in the extending direction of the optical fiber 10, for scattering the light outputted from the side of the emission end 10a of the optical fiber and emitting it from a side face; and a tubular member (pipe 70) for which the optical irradiation part 20 is inserted to the inner side, and which has a light shielding property for the light L emitted from the optical irradiation part 20. The tubular member (pipe 70) is provided with an output part 70B for making the light L emitted from the optical irradiation part 20 pass through, and the ratio of the inner diameter of the tubular member (pipe 70) to the outer diameter is 0.65.
HATTORI TOMOYUKI
Shiro Terasaki
Masatoshi Shibata