Philips Research - Technologies

Photoreplication

Photoreplication is a powerful technique for the replication shapes on a substrate. As compared to injection molding, this technique offers the possibility of rapid prototyping with low development costs and the integration of inorganic (brittle) substrates.

Example: Aspherical lenses

A thin aspherically shaped plastic coating is applied on a spherical glass substrate. The coating is obtained by filling the gap between the substrate and an aspherical mold with liquid monomer. The monomer is then turned into a glassy polymer by exposure to UV-light. This process is called photo-polymerization (2P). Next the product can be released.

Typical new passive applications are high accuracy lenses for optical storage, fiber collimators, fiber collimator arrays, replicated structures for biosensing applications, and lens arrays for telecom applications (1330 and 1500 nm). Examples of new active components using lenses are laser diode to fiber couplers, laser diode to waveguide couplers and variable focusing lenses, such as liquid crystal lenses.

To further enhance the performance of these systems, a replication coating with a higher refractive index than the currently used material (n = 1.56) is needed. Our current objective is to increase the refractive index to ca. 1.8. A permanent challenge is the control of reaction shrinkage of the resins. For this purpose + photorheology is a powerful tool in which the dynamic modulus development is monitored during the progress of the reaction in a rheometer equipped with a UV-light source.