Abstract

Spatially resolved Raman spectroscopy employing 2-D detection is used to map the chemical and physical properties of materials. Scattered light from a laser-illuminated line on the sample is projected on the entrance slit of a spectrometer and the dispersed light is collected by a 2-D detector, yielding a 2-D data matrix (up to 1024 × 1024 with x = wavelength and y = position along the illuminated line). Up to 1024 Raman spectra, each corresponding to a unique position along the line, are acquired simultaneously. Analysis of the spectra in each row of the data matrix yields a 1-D spatial profile of the property of interest. We find that fluctuations in the 1-D property profile depend linearly upon the signal-to-noise ratio (SNR) of the spectra in the data matrix. For photon-limited spectra the SNR in the data matrix varies as the square root of the quantum efficiency (QE) of the detector. A charge coupled device with QE = 50% will yield comparable quality maps to those obtained with an imaging microchannel plate photomultiplier (Mepsicron) with QE = 12% in one quarter of the time.

© 1991 Optical Society of America