Microstructured metallic moulding tools or mould inserts are needed for mass production of micro-optical components.
These tools are used for hot embossing or injection moulding of micro components in plastic. Because of the extremely
tight specifications like small sidewall roughness and high aspect ratios these tools are usually fabricated by lithographic
procedures followed by electroforming. In this case the structural geometry is limited to Manhattan-like structures and
only a limited number of technologies can be used to fabricate the master structures. Applicable techniques are e.g. X-ray
lithography (LIGA technology) or Deep Proton Writing (DPW). However these processes are not suitable for low-cost
mass production. They are limited by the exposure area and the design of the microstructures. To overcome these
limitations a new process has been developed which allows the transfer of micro-optical structures fabricated by other
technologies as well as assembled structures or structures with varying geometries into a moulding tool. The master
structures, either plastic, glass, metal or a combination of these materials, serve as sacrificial parts. With electroforming
technology, a negative copy of the microstructured master is built up in the metal subsequently used as a moulding tool.
Low-cost mass production is possible with these moulding tools.
We present the process chain in this paper and demonstrate its feasibility by producing reliable moulding tools from
three challenging and different components. The possibility of mass fabrication of the components by replication was
The aim of the presented LIGA-microspectrometer design is, to improve the spectral resolution and to achieve a high sensitivity covering at the same time a large spectral range. The footprint of the microspectrometer had to be increased to achieve these goals. To limit the increasing of the size of the system, the internal optical path was folded by introducing a mirror. The spectrometer is a grating spectrometer where the light is guided in a hollow waveguide. To improve the sensitivity of the spectrometer, the losses in the hollow waveguide had to be limited. As these losses increase with the number of reflections in the waveguide, a collimator lens in front of the entrance slit was introduced to realize a quasi free space propagation of the light in the waveguide. The concept of this microspectrometer, its characteristics, dimensions and key elements, such as entrance slit, collimator lens, hollow waveguide, optical path folding and decoupling mirror, are explained. Also the result of the photographic characterization of the microspectrometer is shown.