Raman spectroscopy with intensified vidicon detectors: A study of intact bovine lens proteins

Abstract

Abstract Raman spectra of intact ocular lenses contain important structural information related to aging and cataract formation. However, the direct application of Raman spectroscopy to human eyes for cataract diagnosis has been considered unsafe because of the high laser power (∼100 mW) required to generate Raman spectra using the photomultiplier‐photon counting (PMT‐PC) detection method. The clinical application of Raman spectroscopy has become more likely with the development of sensitive multichannel optical detectors such as the ‘silicon intensified target’ (SIT) coupled to an optical multichannel analyzer (OMA). We have incorporated the SIT in a novel mismatched subtractive dispersion double monochromator that has optimum stray light (<5×10 −9 ), throughput, and resolution for these experiments. It is demonstrated that the new SIT–OMA detection method is capable of obtaining high‐quality Raman spectra of an intact bovine lens with a laser power (∼1 mW) significantly below the threshold for retinal damage. The multichannel and photon counting detection systems have been carefully compared under high and low light level conditions so that the advantages of the SIT‐OMA system for other Raman experiments may be easily evaluated.