Lasers are used in microscopy to excite fluorescence in molecules either naturally occurring in biological matter or added by preparation of the sample with special dyes.
Cytometry means to detect specific properties of single cells out of a large volume of cells. The cells can be detected and sorted according to special criteria like the presence of blood cells, cell core material or similar.
Raman Spectroscopy uses the Raman effect which is named after the Indian physicist C.V. Raman who discovered this effect in the year 1928 together with his colleague K.S. Krishnan.