Design and Construction of a Line-Confocal Raman Microscope for Sensitive Molecules

Surface enhanced Raman spectroscopy (SERS) has great potential for investigating the secondary structure of biomolecules. While enhancements of many orders of magnitude are possible in SERS, the excitation powers required for adequate signal to noise may still be damaging for sensitive protein molecules. Here, we describe the design and construction of a line-confocal Raman micro-spectrometer, which allows investigations at much lower powers compared to a commercial Raman microscope, which uses a point-confocal design. Our design combines a commercial Raman spectrometer and a fluorescence microscope, and achieves simultaneous spectrometry over 400 pixels. This can be used for multiplexed probing of a homogeneous sample, using much lower power for each pixel at comparable signal-to-noise ratios.