Diode Array Spectrometer

The illustration here shows a schematic diagram of a diode array spectrophotometer, in which we replace a single photomultiplier detector with an array of photodiodes. The source radiation passes through the sample and is dispersed by a grating. The photodiode array is situated at the grating’s focal plane, with each diode recording the radiant power over a narrow range of wavelengths. Because we monitor simultaneously the individual diode detectors, we can record an entire spectrum simultaneously in as little as 0.1 s. The photographic insert shows a typical instrument. Note that the 50-mL beaker provides a sense of scale.