Ultrafast confocal Raman imaging

Abstract

The use of an EM-CCD camera can greatly increase detection efficiency and speed, especially for the short integration times necessary with a confocal Raman microscope. The distribution of a 7.1 nm PMMA as well as a 4.2 nm alkane layer on a glass substrate could be easily detected and identified with an integration time of only 7 ms per spectrum, which reduced the overall acquisition time to 5.4 minutes for a 200 × 200 (= 40,000) spectra confocal Raman image. For very small signals that are dominated by the CCDs readout noise, the use of an EM-CCD can improve the S/N by a factor of 5-10 compared to the best available standard CCDs.