New detector technologies and their impact on Raman spectroscopy

The latest generation of solid state detectors including Charged- Coupled Devices (CCD) and Charge-Injection Devices will be reviewed. Over the last several years, these detectors have contributed to major advances in Raman spectroscopy. Compact Raman systems using diode laser excitation, fiber-optic probes, and new generations of imaging spectrometers have been developed. New approaches for implementing very high throughput monochromators will be discussed, and their impact on the overall Raman system considered. Detection sensitivities obtained using these new optical geometries and array detector technologies are truly astounding. Even at an analyte concentration of a few ppm, a spectrum with several identifiable peaks can be obtained in a mater of seconds. This high sensitivity coupled with the ability of fiber optics to provide remote as well as in-situ sampling now make Raman a technique appropriate for many medical, environmental, and industrial applications. An overview of combining proper optical systems with currently available and soon to be introduced detectors will be presented. A variety of operating parameters for today's and tomorrow's arrays including readout noise, quantum efficiency, dark current, cosmic ray noise, and readout modes will be considered.