MEASUREMENT OF REFRACTIVE INDEX DISTRIBUTION FOR OPTICAL FIBER BASE MATERIAL WITH HIGH NUMERICAL APERTURE

摘要

PURPOSE:To enable measurement of a refractive index distribution in noway affected by high-order diffraction light without drawing an optical fiber base material with a high numerical aperture, by providing a slit on the emission side to withdraw and measure a specified diffraction light spot. CONSTITUTION:Light beam 12 from an He-Ne laser 10 is made incident into a base material 20 in a matching oil 18 through a lens 16. The base material 20 employs an optical fiber base material with a high numerical aperture sintered without being drawn. Light emitted from the base material 20 is bent at an angle phi by a refractive index distribution to be incident into a line sensor 26 passing through a lens 22 and cylindrical lens 24. Then, a slit 40 is provided between the lenses 22 and 24 to withdraw a specified diffraction light from among emission light patterns and the diffraction light is analyzed one- dimensionally. This enables measurement of angle phi of refraction of light beam in noway affected by a high-order diffraction light spot.