| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for producing a plastic optical fiber which is small in the surface roughness at the inside surface of a clad and is less in transmission loss. SOLUTION: When the plastic optical fiber is produced by molding a thermoplastic resin to the tubular plastic optical fiber clad by an extruder, injecting a liquid core into this plastic optical fiber clad and solidifying the liquid core in this process for production, the land length 3 of the central mouthpiece of the extruder is specified to 18 to 300 mm, by which the surface roughness at the inside surface of the clad may be lowered and the plastic optical fiber having the less transmission loss may be obtained. In such a case the surface roughness Ra of the clad is within a range of 0.01μm<Ra<0.2μm and more particularly the land length 3 is most preferably in a range 20 to 40 mm. |
