Regensburg 2013 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 10: Scanning Probe Microscopy

MI 10.6: Vortrag

Donnerstag, 14. März 2013, 11:00–11:15, H5

Confocal Raman Microscopy: True Surface and 3D Raman Imaging — Ute Schmidt, •Max Stadler, Thomas Dieing, and Olaf Hollricher — WITec GmbH, 89081 Ulm, Germany

Confocal microscopy has been used to reconstruct three-dimensional images of micro-objects by using a spatial pinhole to eliminate out-of focus light in specimens thicker than the focal plane. Raman spectroscopy on the other hand is used to unequivocally determine the chemical composition of a material. Confocal Raman microscopy combines the chemically sensitive Raman spectroscopy with high resolution confocal microscopy leading to chemical images with diffraction limited resolution. The discrimination of out of focus information used in confocal microscopy is particularly beneficial for confocal Raman imaging since it reduces the volume from which the Raman spectrum is collected. This leads to a diffraction limited resolution in chemical imaging of samples. However, the high confocality always results in high focus sensitivity. Therefore, Confocal Raman imaging of rough opaque samples was so far very challenging due to the inability to keep the samples in focus. The true surface confocal Raman imaging method combines confocal Raman imaging and optical profilometry. An integrated profilometer is used to acquire topographic scans of several square millimeters, similar to very large AFM topographic images. The coordinates of this large topographic image are used to trace the surface contours while acquiring the confocal Raman image. Therefore, topographic and diffraction limited Raman images of heavily inclined and rough samples can be obtained in one instrument.