| 摘要 |
PURPOSE:To make it possible to reduce time required for production and precisely control dopant concentration distribution, by freeze-drying a dopant solution in a porous gel and sintering the solution in producing a lens by a molecular stuffing method. CONSTITUTION:A solution containing a dopant is permeated into a porous gel obtained from a sol prepared by dispersing fine silica particles in an acidic catalyst hydrolytic solution of a silicon alkoxide and the dopant is partially eluted to form concentration distribution. The dopant solution in the porous gel is then frozen, dried under reduced pressure and sintered to produce a refractive index distribution-type lens. Disturbance of the distribution while drying which has been a problem can be completely eliminated by this method. The time required for production can be remarkably reduced as opposed to fixation of distribution by solvent exchange as in a conventional method. |
