ANALYTICAL AND LABORATORY EQUIPMENT 27
Raman microscopy, AFM and piezo-based sample positioning
Fig.1. For high-precision and dynamic sample positioning, piezo-based scanning stages are a good solution: with their compact dimensions, they can easily be integrated in microscopes.
Gernot Hamann presents a combination of methods for high-precision optical, topographic and molecular analyses.
I
n pharmaceutical research, living cell investigations, nanophotonics or analyses in
photovoltaics or semiconductor technology, classical microscopic methods are often no longer sufficient in terms of optical resolution or information content. To obtain more extensive and more accurate measurement data of a sample, it is now possible to combine different microscopic methods with one another. However, this combination of methods not only makes high demands on the individual components of the microscopes, but also on the systems used for sample positioning.
For example, piezo-based positioning stages (Fig. 1.) achieve a position resolution in the sub-nanometer range and response times of less than 1ms. With this, dynamic operation
at scanning frequencies of up to 1,000Hz is possible. Te high dynamics in the Z axis for focusing processes or topography scans allow high- speed scanning of the sample in the X and Y directions. Tis shortens measuring times, increases throughput and reduces time-dependent impacts on the measurement. Moreover, they can be readily integrated into microscopes.
An application example of piezo-based scanning stages is a microscopic system of modular design, combining a Raman microscope with atomic force microcopy (AFM), see Fig. 2. Raman microscopy is based on a confocal, optical microscope and a Raman spectrometer. Te sample is scanned point by point and line by line. Te lateral resolution is about 200nm with green excitation light. During
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