OPTICAL FIBER

PURPOSE:To guide visible rays also coaxially with a working light by inserting an optical fiber core, which guides the working light, into a metallic tube to suppress heating by effects of reflection, heat conduction, or the like of the metal and forming a visible-ray guide path on the outside circumference of the metallic tube. CONSTITUTION:The CO2 laser light transmitted by an optical fiber core 1 is condensed by the second condenser lens 8 to perform the work. Even if the CO2 laser light is leaked a little to the outside from the outside circumference of the optical fiber core 1 by phenomena of scattering or the like on the way of transmission in the optical fiber core 1, heating is suppressed by actions of reflection, heat conduction, etc. of the metallic surface because the optical fiber core 1 is stored in a metallic tube 2. Meanwhile, the He-Ne laser light of visible rays emitted from an He-Ne laser oscillator 9 is converted to an annular beam by a conical prism 10. This laser light is reflected on a Ge mirror 7 and is made incident on a visible-ray guide path 4 and is condensed by the condenser lens 8 to indicate the condensation point of the working light.