APPARATUS AND METHOD FOR MEASURING CONNECTION TOLERANCE OF MULTI-MODE OPTICAL FIBER

• Main Authors: KAIZU KATSUMI, KOIKE SHINJI
• Format: Patent
• Language: English
• Published: 15.08.1997
• Edition: 6
• Subjects: MEASURING; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; TESTING; TESTING STATIC OR DYNAMIC BALANCE OF MACHINES ORSTRUCTURES; TESTING STRUCTURES OR APPARATUS NOT OTHERWISE PROVIDED FOR

PROBLEM TO BE SOLVED: To provide an apparatus and a method whereby a connection tolerance of various kinds of multi-mode optical fibers can be evaluated in a short distance while speckle noises generated by a light source of high coherence are taken into consideration. SOLUTION: A relative positional relationship of connection end faces of first and second multi-mode optical fibers 4, 6 is registered by a fine adjustment stage 5 so that an output signal from the second multi-mode optical fiber 6 is detected to have a maximum amplitude by a transmission waveform-measuring device 11. A position where the amplitude becomes maximum is set to be a position where a relative positional shift of the first and second multi-mode optical fibers is zero. An average photodetecting level necessary for obtaining a constant signal to noise ratio at this time is obtained. Thereafter, the multi-mode optical fibers are optionally shifted relatively by the fine adjustment stage 5. An average photodetecting level necessary for obtaining the constant signal to noise ratio to each amount of the positional shift is obtained. A connecting positional shift allowable to a constant increasing amount of the photodetecting level is obtained for each amount of the positional shift from a relation of an increase of the amount of the positional shift and the increasing amount of the average photodetecting level based on the necessary average photodetecting level when the positional shift is not generated.