| 摘要 |
PURPOSE:To control the extent of higher-order mode excitation to an optimum quantity of incident light, and use an optical fiber in a maximum transmission band state by providing an adjusting mechanism for the incidence conditions of the optical fiber between a condenser lens and an optical fiber end part. CONSTITUTION:Light emitted by a light emitting element 14 is incident on a lens 11 to obtain a parallel beam P, which strikes a pinhole 13. The striking beam is made incident to a lens 12 through the hole 131 of the pinhole 13. Therefore, the quantity of the incident light beam between the pinhole 13 and lens 12 is small depending upon how large the angles of incidence to spaces A and B encircled with broken lines and solid lines are large. Then, adjusted light beam is converged by the lens 12 and incident on the optical fiber 15. Thus, incidence NA to the optical fiber 15 is adjusted. |
