Raman Confocal MicroscopyAmpliar
INL has one Witec Alpha 300R confocal Raman system, with three possible laser excitation wavelengths at 532, 633 and 785 nm. The microscope is equipped with three selectable Zeiss objectives (100x, 50x, 10x) that operate in air, with numerical apertures NA=0.9, 0.7, 0.2, respectively. The 100x and 50x are from the series EC Epiplan and are fit for Raman signal acquisition. The 10x lens is used for video image acquisition. The UHTS300 spectrometers coupled to the Andor Peltier cooled CCD detectors provide cutting-edge resolution at the highest sensitivity.
Because of the confocal setup, it is not only possible to collect information from the sample surface, but also to look deep inside transparent samples. Raman imaging is possible with the acquisition of a complete Raman spectrum at each image pixel, resulting in images consisting of tens of thousands of spectra. The acquisition time for one spectrum is in the range of milliseconds, resulting in complete images being collected typically in a time frame of minutes. When analyzing dedicated peak characteristics of the spectra, a variety of images can be generated using only a single set of data. This allows not only for imaging the distribution of chemical compounds, but also for analyzing, for example crystallinity or material intrinsic stress distributions.