Abstract: In a method of manufacturing a transparent polymer material article having a refractive index gradient the polymer base material is caused to absorb a swelling agent including at least a monomer adapted to yield a polymer having a refractive index different than that of the polymer base material. A first preform having a first geometry is formed from the polymer base material sufficiently polymerized for the first preform to be self-supporting. A confinement space is defined between the first preform and an abutment member having facing it a second geometry at least partly different than the first geometry and having a greater volume than the latter. The first preform is brought into contact in the confinement space with a sufficient quantity of swelling agent for the swelling to which it is then subject to cause it to be urged actively into contact with all points of the second geometry.

Abstract: To produce a graded index polymer there is diffused into a base material formed of at least one partly polymerized monomer adapted to yield a homopolymer with refractive index N1 in the gel state an additive material formed of at least one monomer adapted to yield a homopolymer with refractive index N2 different from N1. The polymerization of the base material treated in this way is then completed. The additive material comprises a mixture of at least two monomers and the composition of this mixture is varied with time.