| 摘要 |
<p>PURPOSE:To lessen the dispersion of Stokes light and anti-Stokes light without any loss of light and heighten the precision of measurement by modulating a laser light source by a pseudo-random signal, extracting the Stokes light and anti-Stokes light caused by Raman scattering from backward scattering light of an optical fiber and finding fiber characteristics from a signal of a limited band after the pseudo-random signal is multiplied. CONSTITUTION:Light of wave length lambda0 is reflected on two-toned mirrors 4, 3 and input to an optical fiber 11. The mirror 3 transmits only Stokes light of returned scattering light and the other light is reflected on the mirror 4. The mirror 4 transmits anti-Stokes light alone and the other light is reflected. Accordingly, the Stokes light is input to an O/E convertor 12a and the anti- Stokes light is put into another O/E convertor 12b. The loss of light reflection passing a route described above can be nearly neglected and transmission light can be lowered in the case of a degree wherein a few dichroic mirrors are superposed on one another. In addition, the constitution takes effect at the time when pulse light from a light source of small peak power such as a pseudo- random light signal is made incident.</p> |
