ABSTRACT
This chapter explains the physical basis behind the Raman effect before presenting the practical methods used to employ Raman scattering as a molecularly specific contrast mechanism in a wide range of samples. It looks at the development and application of non-linear Raman-based methods such as Coherent Anti-Stokes Raman Scattering (CARS). The effect is used in linear, beam scanned confocal Raman microscopy and more recently using complex non-linear excitation of the sample in methods such as CARS. In many optical techniques where CARS or other non-linear processes are used, a significant constraint is placed on the physical conditions including the beam alignment. A variation of CARS, in that it is a non-linear process using Raman transitions, is stimulated Raman scattering. In general though, practical Raman microscopes use a beam scanning technique to generate images and the core configuration is similar to that used in a confocal microscope.
