3. Hybrid process

Components often must meet requirements that cannot be satisfied by a single material (Figure 7 ). In particular, when it is necessary to reconcile conflicting properties such as hard/soft, hydrophilic/hydrophobic, or conductive/non-conductive, it is preferable to use combinations of materials. As with hot-forming, the process starts with a semi-finished product in the form of multilayer sheets obtained by coextrusion. When the materials have different refractive indices, it is advantageous to use composite sheets for the manufacture of optical waveguides