PURPOSE: To improve the long-time reliability of an optical tape-type unit by irradiating only ultraviolet rays, whose wavelength is approximately equal to the peak wavelength of the absorption spectrum wavelength of a resin hardened by ultraviolet rays of a protective layer, to the protective layer consisting of said resin hardened by ultraviolet rays whose absorption spectrum wavelength is different from that of a coating layer around an optical fiber.
CONSTITUTION: Optical fiber strands 3 where coating layers 2 consisting of a resin hardened by ultraviolet rays are coated preliminarily around optical fibers 1 are supplied by bobbins 10 and are arranged in parallel into a plane by a guide roll 11, and a fused resin hardened by ultraviolet rays whose absorption spectrum wavelength is different from that of the resin hardened by ultraviolet rays of the coating layer 2 is supplied from a material supply tank 12 and is applied to these arranged optical fiber strands 3 to coat them, and the whole of optical fiber strands is formed into a tape shape. This tape is allowed to pass an ultraviolet lamp 14, and only ultraviolet rays whose wavelength is approximately equal to the peak wavelength of the absorption spectrum wavelength of said fused resin hardened by ultraviolet rays to harden this resin, thus forming a protective layer 4.
OOMAE KAZUYA
KOKAYU MIKIO
