| 摘要 |
PURPOSE:To provide the optical fiber for illumination transmission which has a uniform projection speed pattern. CONSTITUTION:This optical fiber consists of a core composed of a 1st part having a constant refractive index n1 and a 2nd part which is formed around it and decreases in refractive index from n1 to n2, and a clad which is formed around the 2nd part and has a refractive index n3 less than n2. The diameter of the 1st part in the center of the core is 50-90%, preferably, 60-80% of the core diameter; and the specific refractive index difference between the refractive index n1 of the 1st part and the refractive index n2 of the 2nd part is 0.2-0.6% and the specific refractive index difference between the refractive index n1 of the 1st part and the refractive index n3 of the clad is 0.5-1.9%. This constitution makes the projection light intensity pattern uniform. |
