| 摘要 |
PROBLEM TO BE SOLVED: To provide a refraction index distribution measuring method of pre form and a measuring device used for this capable of measuring a refraction index distribution in an extremely short time even preform has a large diameter. SOLUTION: In this method, light perpendicular to an axis of the preform 2 is made incident on the columnar preform 2 for optical fiber, a position of the light after transmitting through the preform is measured, and the diffraction index distribution inside the preform is measured from an incident position of the light and the position of the transmitted light. It is characterized by that an arithmetic unit 8 calculating positions of the light before and after transmission on the basis of an intensity distribution of the light after transmission and an arithmetic unit 9 calculating a diffraction index are provided separately. |
