Variable-wavelength detectors

Detectors which allow the selection of the operating wavelength called variable wavelength detectors and they are are particularly useful in three cases:

offer best sensitivity for any absorptive component by selecting an appropriate wavelength;
individual sample components have high absorptivity at different wavelengths and thus, operation at a single wavelength would reduce the system's sensitivity;

Depending on the sophistication of the detector, wavelength change is done manually or programmed on a time basis into the memory of the system.