M. Delhaye

Characteristics of Raman Microscopy

Publisher Summary This chapter focuses on those characteristics which differentiate Raman microspectroscopy from the more conventional techniques. The important characteristics of Raman microscopy are directly related to two fundamental optical considerations: (1) the focusing of the incident laser excitation on the sample and (2) the collection of the scattered light. The chapter analyzes the specific problem of coupling a microscope to a Raman spectrometer. The confocal effect is described, as it the basis of recent advances in Raman instrumentation, including imaging techniques. The total Raman intensity depends on the solid angle Ω in which the scattered light is collected. In the backscattering configuration Ω describes approximately the cones of both the incident and scattered light. The optimum use of the Raman light flux o collected from a sample requires it to be transmitted from sample to detector via the successive apertures of the instrument. The invariance conditions of the optical extent can be fulfilled with the use of coupling optics which result in good matching between all of the apertures along the entire light path, from microscope to the spectrometer detector.