Raman Grating Polychromator with Multichannel Detector

Recent achievements in the design of near-infrared diode lasers, of volume-phase transmission multiplexed holographic gratings and of sensitive CCD arrays allow 

A multi-channel spectrometer has a light source with shutter, a sample and reference compartment, a grating polychromator and a diode array detector (Fig. 4.9). 

All spectral elements are recorded simultaneously by the array detector, i. e. the measuring time with the shutter in its open position is very short The short illumination time permits the sample and reference positions to be positioned immediately after the light source. Multi-channel spectrometers may also be constructed as double beam instruments. For special measurements, e. g. rapid kinetic investigations, when the chopper frequency is too low with respect to the rate of 

UV/VIS absorption spectra may also be obtained with single beam instruments. In single beam spectrometers the background and sample spectra are measured one after the other. Since a chopper and reference chamber are not needed, single beam instmments are usually cheaper than double beam instruments. 

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