Optical fiber for transmitting ultraviolet ray, optical fiber probe, and method of manufacturing the optical fiber probe
View Patent ↗It is an object of the present invention to provide an optical fiber for transmitting ultraviolet ray which has an improve transmittance and is prevented from deterioration by ultraviolet ray with which it is irradiated. It is another object of the present invention to provide an optical fiber probe which can propagate vacuum ultraviolet ray and deep ultraviolet ray at a high transmittance, is deteriorated only to a limited extent when irradiated with ultraviolet ray and can be etched to have a desired shape of the sharpened section at the fiber end. The present invention provides the optical fiber for transmitting ultraviolet ray which has a core 5 of silica glass containing a given content of fluorine and a clad 6 a of silica glass containing a given content of fluorine or boron, a clad 6 b of a resin which transmits ultraviolet ray or a clad 6 c having air holes H. The clad may be coated with a protective layer and further with a covered layer for protection. In particular, the core, clad and protective layer have a high transmittance for ultraviolet ray and resistance to ultraviolet ray with which they are irradiated, when treated with hydrogen. An optical fiber probe 1 has an optical fiber 2 provided with a sharpened section 3 at the end, which is sharpened with an etchant solution, the sharpened section 3 being coated with a light-shielding metallic film 4.
1. An optical fiber for transmitting ultraviolet rays, comprising a core of silica glass impregnated with hydrogen and containing 100 to 1,000 ppm fluorine and 4 to 7 ppm hydroxyl groups.
2. The optical fiber for transmitting ultraviolet rays according to claim 1 , wherein said optical fiber further comprises a cladding of silica glass containing 1,000 to 7,000 ppm fluorine or 2,000 to 10,000 ppm boron.
3. The optical fiber for transmitting ultraviolet rays according to claim 1 , wherein said optical fiber further comprises a cladding of resin which transmits ultraviolet rays.
4. The optical fiber for transmitting ultraviolet rays according to claim 1 , wherein said optical fiber further comprises a cladding having two or more air holes arranged in parallel to the optical axis.
5. The optical fiber for transmitting ultraviolet rays according to claim 1 , wherein said cladding is coated with a protective layer.
6. The optical fiber for transmitting ultraviolet rays according to claim 1 , wherein said protective layer is coated with a covering layer for protection.
7. A method of producing an optical fiber for transmitting ultraviolet rays, comprising drawing an optical fiber having a core of silica glass containing 100 to 1,000 ppm fluorine and 4 to 7 ppm hydroxyl groups and then impregnating the drawn optical fiber with hydrogen.
8. The method of producing an optical fiber for transmitting ultraviolet rays ray according to claim 7 further comprising arranging capillaries, each having a central lumen, on the core, coating the core with the capillaries to integrate them with each other, then subjecting the capillary-coated core to said drawing.
9. The method of producing an optical fiber for transmitting ultraviolet rays according to claim 7 , further comprising:
forming a cladding on said core; and
coating said cladding with a covering layer for protection during said drawing.
10. The method of producing an optical fiber for transmitting ultraviolet rays according to claim 9 , wherein said coating with the covering layer for protection is conducted after the hydrogen impregnation treatment.
11. An optical fiber probe having an optical fiber sharpened at the end, characterized in that the optical fiber comprises a core of silica glass containing 100 to 1,000 ppm fluorine.
12. The optical fiber probe according to claim 11 , wherein said optical fiber further comprises a cladding of silica glass containing 1,000 to 7,000 ppm fluorine or 2,000 to 10,000 ppm boron.
13. The optical fiber probe according to claim 11 , wherein said core is coated with a cladding of resin which transmits ultraviolet rays.
14. The optical fiber probe according to claim 11 , wherein said core is coated with a cladding having two or more air holes arranged in parallel to the optical axis.
15. The optical fiber probe according to claim 12 , wherein said cladding is coated with a protective layer.
16. The optical fiber probe according to claim 15 , wherein said protective layer is further coated with a covering layer for protection.
17. A method of producing the optical fiber probe of claim 11 , wherein said optical fiber end is sharpened with an etchant solution.
18. The method of producing the optical fiber probe according to claim 17 , wherein said etchant solution is a 2 to 46% aqueous solution of hydrofluoric acid.