| 摘要 |
PURPOSE:To shorten a measuring time and to simplify a device by making light incident on a single mode optical fiber to be measured and changing the position of a slit located on an image formation part of a lens system for expanding a near field pattern (NFP) from the projection end of the optical fiber to measure the quantity of passed light. CONSTITUTION:Light from a light source 1 is condensed by a lens 2 and made incident on the single mode (SM) optical fiber 3 and the NFP on the projection end is expanded by lenses 4, 5. The slit 10 movable in the rectangular direction to the optical axis is arranged on the image formation surface of the lenses 4, 5 and the passed light is photoelectrically converted by a photodetector 12 and displayed on a display part 13. The quantity of passed light is measured respectively by changing the position of the slit 10 to find out the spot size. Thus, the measuring time can be shortened from ordinary 10min to 2-3min. |
