| 摘要 |
PROBLEM TO BE SOLVED: To estimate the presence or absence and the size of cracks by adjusting the focusing position of an optical system for flattening the brightness distribution of an optical fiber image and obtaining the brightness distribution of an end part for the optical fiber image. SOLUTION: An area value when there are cracks at a level for influencing a connection loss in the end face of an optical fiber is examined in advance. More specifically, a focusing position is kept as it is, an observation position is shifted to the end part of an optical fiber image, a window is set in a range where the crack parts can be fully accommodated, and a brightness distribution as shown in figure (c) is obtained for a plurality of cursors in the window. A, B, and D indicate a portion with lower brightness than a lower-limit threshold, while C indicates a portion with higher brightness than an upper-limit threshold. A and D indicate a portion with a low brightness even without any cracks. Therefore, the number of pixels included in B and C becomes that of pixels in the brightness distribution. By obtaining the total area value of the pixels of cracks in the brightness distribution of all cursors in the window, a connection loss after the fusion connection of a normal optical fiber is measured. |
