| 摘要 |
PURPOSE:To obtain a distribution of refractive index (RI) overall small in aberration by controlling diffusion velocity of a monomer and polymn. velocity of a base material in a process of diffusing a monomer into the base material polymerized incompletely and capable of holding its own shape in order to produce a polymer different in RI from the mother material. CONSTITUTION:A monomer Ma producing a reticular polymer Pa having an RI of Na is polymerized incompletely to form a base material 1 capable of holding its own shape, and a monomer Mb producing a polymer Pb having a RI of Nb different from Na of the material 1 is diffused into the inside from the surface of the material 1 and polymerized to obtain a synthetic resin light transmitting medium having an RI distribution. In such a monomer diffusion step, a stepwise or continuous temp. gradient is given to control the diffusion velocity of the monomer Mb and the polymn. velocity of the material 1. Such an operation can be executed not only batchwise but also by continuous extrusion molding using an extruder. The rod thus obtained has a parabolic RI distribution, and lenses having small aberration and various diameters from smaller ones can be obtained by cutting in prescribed lengths. |
