Finding the Optimal Focus Position Using the Cora 5X00 Sampling Inserts

Only samples which are in the optimal focus position will provide a good Raman signal. This is especially important for solid and opaque liquid samples. Glass vials and other packaging can create an unwanted fluorescent background.


Raman spectrometers using a backscattering geometry, such as the Cora 5X00 series, are well suited for the characterization of opaque solids, powders, and liquids. This includes various solid samples such as gemstones, semiconductors, carbon materials, liquids like red wine, diesel and ink.

For optimal measurement conditions, the laser focus has to be at the sample interface for fully opaque samples or slightly below the surface inside the sample for more transparent samples. Any deeper focusing will result in absorption of both the laser light as well as the created Raman signal. Even for materials that are mostly transparent a decreasing Raman signal can be observed when the focus position is too deep inside the sample.

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