Peter Kipfer

Sol-gel replication of optical components suited for surface mount assembly

Optical microsystems, which can be fabricated using replication technology and assembled using optical surface mounting techniques, can offer compact, cost-effective solutions for applications in optical communication, metrology, sensors, illumination and displays. Especially adapted to the needs of mid-size volume production of a few hundred to thousands modules is wafer-scale replication. The fabrication of single micro lenses or lenslet arrays on wafer substrates and the wafer-scale replication of such lens arrays for optical microsystems in sol-gel materials is under development as a cost-effective alternative to lens fabrication in glass. For an optical microsystem with a compact module for laser beam forming, wafer-scale, singlesided and double-sided replication has been developed to fabricate refractive or diffractive optical elements onto glass substrates. Combined opto-mechanical modules have been UV-cast-replicated from a sol-gel master in a single step. In addition, step & repeat replication can be employed for the fabrication of large arrays of custom specific lenses. Replication accuracy of better than a wavelength has already been achieved for refractive lenses with 50 μm SAG. Finally, diced optical components from the replicated wafers will be used for the manufacturing of micro-optic systems. A six-axis robot motion, automated optical alignment and laser-reflow soldering method is used to assemble the photonics modules. This method, called TRIMO-SMD (three-dimensional miniaturized optical surface-mounted device), is currently being made commercially available by Leica Geosystems AG.