High-resolution, high-speed confocal Raman imaging

Typical confocal Raman images consist of thousands of individual spectra from which various pieces of information can be extracted in order to display certain chemical information as an image. In order to acquire these images in a reasonable amount of time, the time required for a single spectrum must be minimized. This can be achieved through the optimization of various parts of the confocal Raman microscope. This article describes the usage of an ultra-high throughput spectrometer in combination with a spectroscopic electron multiplying CCD (EMCCD) camera as a detector. The spectrometer is compared to a standard mirror-based Czerny-Turner spectrometer and shows twice the throughput over virtually the entire visible spectral range as well as an improvement in the line shape of recorded Raman bands. The ultra-high throughput spectrometer and the EMCCD camera in combination with a high throughput Raman microscope reduces the acquisition time for single spectra to a matter of milliseconds and significantly enhances the sensitivity of the instrument. Example measurements are presented to illustrate the speed and sensitivity of the system. (C) 2008 Elsevier B.V. All rights reserved.