Simultaneous double-beam concept

A double-beam spectrometer consists of both sample and reference channels and measures both channels simultaneously. The separation of the light beam from the source is accomplished using a beam splitter so that approximately 50% of the source-emitted energy is divided to both sample and reference channels. The use of the dual-beam concept compensates for instrument instabilities inherent to all spectrometers. The resultant spectrum is the ratio of the sample and reference channels in transmission. As in the case of single-beam instruments, in practice the final spectrum from this device is given as... 

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