Packaging and characterization of miniaturized spectral sensing devices

In modern optical diagnostics there is an increasing interest in compact and cost-effective devices, i.e. for the analysis of surfaces, thin films, solids, powders, pastes, gels, liquids and alike. Therefore fast and non-invasive measurements are necessary. For the realization of such devices, micro system technology especially Micro-Opto-Electro-Mechanical System (MOEMS) technology is suitable. Hence two main miniaturized optical analyzer modules employing MOEMS have been developed. They are based on the principle of spectral sensing in the infrared range by means of a scanning micro mirror with an integrated diffraction grating or in combination with a separate grating. Using these configurations it is possible to project a specific wavelength onto an exit slit in front of an infrared detector. The first packaging approach is based on assembled laser-cut stainless steel sheets and optical standard components. During the further development different setups with improved reliability and accuracy have been realized. Due to the requirement of compact dimensions and short optical paths modern methods e.g. rapid prototyping were utilized to optimize packaging and optical setup and therefore the performance of the complete system. In this work the characteristics and the measurement results of different development levels will be reviewed. Furthermore we address issues, challenges and performance optimization of MOEMS packaging with respect to ultra compact micro mirror spectrometers. Finally, the applications and the feasibility of such miniaturized spectrometer systems are discussed.