Abstract: A resin coated optical fiber 1 comprising a bare optical fiber 2 and sequentially provided on its circumference with a primary coating layer 3a and a secondary coating layer 3b both made of an ultaviolet-curing urethane resin. The primary coating layer 3a and the secondary coating layer 3b have respective thicknesses of 60 to 200 ?m and 20 to 300 ?m. The pulling force for simultaneously removing the primary and secondary coating layers 3a and 3b is 100 gf or less. The primary coating layer 3a has a tensile strength of 0.5 to 1 MPa. The primary coating layer 3a after immersed in a solvent has a swelling ratio of 5 to 150%. The secondary coating layer 3b has a Young's modulus of 100 to 1,500 MPa. This resin coated optical fiber allows its coatings to be removed without deteriorating the strength or other properties of the bare optical fiber and without leaving any coating waste on the surface of the bare optical fiber after the coatings were removed.

Abstract: 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 6a of silica glass containing a given content of fluorine or boron, a clad 6b of a resin which transmits ultraviolet ray or a clad 6c having air holes H. The clad may be coated with a protective layer and further with a covered layer for protection.