| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and apparatus for easily and quickly measuring the out of roundness of a core of an optical fiber blank. SOLUTION: The out of roundness measuring apparatus 1 comprises a container 2 for dipping an optical fiber blank 10 in a liquid, a light source 3 for irradiating the blank 10 with parallel rays of light, a photodetector 4 for receiving the light passed through the blank, hold rotators 5a, 5b for holding and rotating the blank 10, and a core out of roundness measuring unit 6. When the refractive indices of a clad part 10b and a liquid are approximately equal, the light passing through the clad 10b travels straightly without refraction, while the light passing through the core 10a is refracted to arrive at the photodetector due to the refractive index difference between the core 10a and the clad 10b. Hence, an image obtained by the photodetector 4 has specified bright and dark portions. The measuring unit 6 calculates the out of roundness of the core, based on the light intensity distribution of the image.
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