| 摘要 |
PURPOSE:To measure precisely the absolute value of the refractive index of a preform by covering the preform which contains no pure quartz layer with a transparent sheath type body whose refractive index is already known across refracting liquid and further covering its outside with refracting liquid. CONSTITUTION:The pure quartz pipe 15 which allows the refracting liquid 3 to be charged and held is fitted concentrically and detachably around the preform 1 which contains no pure quartz layer as a sample and a cell 5 which allows the refracting liquid 3 to be charged is fitted around the pipe 15. Then, a light beam from a light source 9 is passed through the cell 5, refracting liquid 3, pure quartz pipe 15, refracting liquid 3, preform 1, refracting liquid 3, pure quartz pipe 15, refracting liquid 3, and cell 5 and detected by a detector 13 through a lens 11. The refracting index of the pure quartz pipe 15 is already known, so the absolute value of the refracting index of the preform 1 is measured on the basis of it. |
