Scanning Spectrometers: Controlling All Variables Over Time
Scanning spectrometers are often used to collect high resolution spectra to measure very small concentrations of substances. These types of spectrometers provide exceptional resolution; however, both of these come at a significant cost to the collected spectrum. Any change in the collection system over the period of one scan can affect the quality of collected data. For high quality spectra in a scanning spectrometer, it is exceptionally important to control the stability of the illumination source, detector, and of the sample. All environmental variables such as sample temperature or stability also have to be fixed. Most importantly, it is impossible to acquire reliable spectra for dynamically changing systems, as the information obtained at the beginning of a scan corresponds to a different state than when the end of the scan occurs.
Non-Scanning Spectrometers: Entire Spectrum Obtained Simultaneously
The most significant advantage of non-scanning spectrometers is that the entire spectrum of a sample is obtained simultaneously. This means that even though the sample might by dynamically changing or the measurement system has time dependent behaviour, the variations in the signal are collected for all wavelengths at the same time. This is extremely important for any spectral collection for dynamically changing systems such as biological tissues or on-line processes.