Diode array detector photograph

Finally, the introduction of new detectors, such as diode arrays and charge-coupled devices (CCDs), has been a boon for Raman spectroscopy. CCDs permit the accumulation of light in the manner of photographic film additionally, their noise level is lower than that of the photomultiplier tube. In addition, by combining CCDs or diode arrays with optical dispersive elements, entire spectra mav be collected in fractions of a second. 

Spectrograph An optical instrument equipped with a dispersing element, such as a grating or a prism, that allows a range of wavelengths to strike a spatially sensitive detector such as a diode array, charge coupled device, or photographic plate. 

A spectrograph is similar in construction to the two monochromators shown in Figure 7-18 except that the slit arrangement is replaced with a large aperture that holds a detector or transducer that is continuously exposed to the entire spectrum of dispersed radiation. Historically, the detector was a photographic film or plate. Currently, however, diode arrays or CTDs are often used as transducers in spectrographs. 

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