Holmarc's Confocal Laser Raman Spectrometer couples a Raman spectrometer to a standard optical microscope, allowing highly magnified visualization of a sample and Raman analysis with a microscopic laser spot. In this equipment, sample is placed on the top of the microscope (Inverse confocal method)and is focused and then the measurement is taken. We can also analyze the sample output intensity vs. Raman shift spectrum which is connected via USB on a computer screen.
Confocal means having the same focus. Unlike a normal microscope, where the whole sample is illuminated, the confocal microscope only measures the light from a small volume in the sample at any given time. Raman imaging, which combines Raman spectroscopy and imaging techniques, is an excellent method for obtaining information about the spatial distribution of molecular species. The principle on which Raman Imaging is based, is that the spatial distribution of a molecular species is obtained by isolating the Raman scattered photons from a Raman line of the specific molecular species. Raman Imaging is a 3-dimensional problem (1 spectral and 2 spatial dimensions). In Confocal microscopy we use series-imaging method in which, point illumination technique is used. A laser spot is scanned across the sample. At each resolved position, the light is collected, spectrally filtered and detected by a detector. Confocal Raman microscopy refers to the ability to spatially filter the analysis volume of the sample, in the XY (lateral) and Z (depth) axes.