Design, fabrication, and characterization of a multidimensional prism.

In this research, a novel multidimensional prism with three distinct 45°, 135°, and 225° inclined optical surfaces were realized by using inclined exposure technology and SU-8 polymer. To obtain a smooth surface, the solvent loss percentage and temperature of post-exposure bake (PEB) are two key factors that need to be well controlled during fabrication. The experimental results showed that surface roughness can achieve 42.9±7.6  nm, which is one-tenth of high-precision machining or molding processes, under the processes parameter combinations of PEB temperature, and solvent loss percentage is 95°C and 82.86%, respectively. The surface reflectivity of the prism was measured by using a He-Ne laser, and reflectivity of the prism surface without and with aluminum metal film was 90.8% and 91.8%, respectively. The slight difference of reflectivity means that a prism with a high-quality inclined surface can be realized. The functionality of the prism for three lasers was also verified with RGB lasers, and it successfully demonstrated the feasibility of application of a multidimensional prism on the optical system. Finally, the utilization of inclined exposure technology not only monolithically integrates three 45° inclined surfaces into one prism without precision assembly but also greatly simplifies the fabrication processes to further reduce the cost. This component and technology can also be applied to medical endoscope systems if the SU-8 is replaced by PDMS or other biocompatible materials using a molding process. These results provide the potential for mass manufacturing, which is of considerable value to the optical markets.