| 摘要 |
PURPOSE:To measure the wavelength characteristics of the degree of coupling of an optical fiber coupler in a short time by using a heat ray generated by heating an incidence-side optical fiber as a light source, branching it at a welding and elongation part, and measuring the intensity of projection light appearing on a projection side and inspecting the coupling rate. CONSTITUTION:The optical fiber is heated from its side face and then the optical fiber reaches certain constant temperature and considered to be a kind of black body to become a light source which has a spectrum based on the Planck's rule of thermal radiation. When the temperature of the optical fiber is sufficiently high, it becomes a light source which generates light in a wavelength range (0.6-1.6mum) used for optical fiber transmission. This light is propagated in the core part of the optical fiber coupler, branched at the welding and elongation part, and projected from core parts 3 and 4 in the end surfaces of the fibers 1 and 2. This method allows the heating length of the optical fiber to be set optionally long and the energy generated by the heating is found by using the Planck's expression and Wien's displacement law and proportional to the value obtained by raising the heating temperature to the 5th power, so light with high energy is made incident on the optical fiber. Consequently, the light can easily be made incident on the optical fiber as compared with a conventional inspecting method, the measurement time can be shortened, and the measurement accuracy is excellent.
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