| 摘要 |
PURPOSE:To reduce the unnecessary insertion loss and protect a light-detector element from saturation as well as to make it possible to easily measure the loss distribution at any desired wavelength, by combining a high-output single-wavelength light pulse source with a multilayer film wavelength filter. CONSTITUTION:The light pulse from a light pulse source 12 driven by a pulse signal generator 11 is made incident on a light-branching filter 19 employing a dielectric multilayer film wavelength filter. The light pulse having a wavelength of 1.06mum is totally reflected by the light branching filter 19 and condensed by a lens 21 and is then made incident on an optical fiber 14 to be inspected, to advance while exciting Raman light. In this case, a Rayleigh back scattered light is generated which goes backward toward the incident end of the optical fiber 14. This back scattered light reaches the light branching filter 19 from the incident end of the optical fiber 14 through the lens 21. Since the Raman light includes a light component having a wavelength (1.2-1.6mum) longer than that of the incident pulse light, only the light component having a wavelength within the transmitting range of the light branching filter 19 passes therethrough. The transmitted light is condensed by a lens 22, and the intensity of the light is converted into an electric signal by a light detector element 15, e.g., an avalanche light multiplier element and is processed by a signal analyzer 16. |
