R&D and demonstration were handled towards the main objectives. Specifications were established for the three demonstrators of the project: Fibre Optic Transceiver (FOT), Optical Encoder Head (OEH), and Back Light Units (BLU). Benchmarks were established based on competing products, or the state-of-the-art equipment and technologies when a direct competitor does not exist. Three research lines were developed in parallel: mould inserts micro structuring, injection moulding of optical components and in line quality control and alignment. Tooling technologies were optimized to fulfil the industrial requirements; the injection moulding process was optimized for the different demonstrators; and the assembly of the pilot line including the manufacturing equipment and the quality control systems was completed.
For inserts micro structuring, multiple technologies have been studied to achieve the requirements of the different products. Micromilling technology used for generating optical quality surfaces was also studied to manufacture gratings within the micrometric scale, obtaining excellent local homogeneity. Laser direct writing, Ion Implant Lithography (IIL) and multi-photon polymerization (MPP) have been used for generating patterns on steel mould inserts, which were replicated by injection moulding, providing advanced optical functionalities without increasing the final part size or the processing steps. Volume gratings on transparent materials was also analysed to manufacture diffraction gratings with promising results. These technologies have been completely validated within the demonstration activities.
Different injection moulding trials have been performed for the demonstrators: i) Hundreds of FOTs have been successfully injected without damaging the wires. ii) Diffraction gratings for the OEH have been reproduced in small areas, demonstrating good replication capabilities. iii) Large areas of the BLU have been overmoulded with different materials, showing the challenge of avoiding variability regarding the adhesion grade between the LEDs and the injected polymer.
Optical Coherence Tomography (OCT) and fibre optic interferometry have proven to be suitable technologies for the monitoring and quality assessment of the injection process. The OCT system has been tested with real FOT samples, allowing to detect anomalies within the injected material and to evaluate damage on the wires during the injection. Fibre optic interferometry was tested for measuring small displacements of a polymer, achieving resolutions better than one micron. A mechatronic device for assuring the automatic alignment of the components during the injection process, was designed and built. This system, along with the OCT, have been integrated in a mock-up mould for industrial validation.
The pilot line designed to manufacture the FOT has been installed, integrated and validated. All the equipment has been purchased and customized according to the manufacturing line requirements. The automated cell for the back-end processes has been assembled and validated. The front-end line, the injection station and the final processing robotic cell have been integrated into the accommodated clean room And ramping-up and commissioning actions have been successfully completed.
Regarding dissemination and communication, at the beginning efforts were put onto raising awareness of the project among target audiences. Lately, the results of the project have been presented on scientific publications, congresses and exhibitions. These results include the work performed by direct laser writing, MPP, fibre optic interferometry and mechatronic alignment, among others.
