Most of the prevalent spectroscopy techniques which use dual channel collection take advantage of this effect to see small signals in the way that polarized light interacts with surfaces. Many examples exist such as the molecular orientation of monolayer deposits or the subtle spectral differences that may be used to detect chirality (or handedness in molecules). 

Applications for multiple channel data collection techniques include:

The experiments above require the use of an infrared photoelastic modulator, which may be included as a part of an experiment configuration from Thermo Scientific. A range of sampling optics and electronics is available for double modulation experiments on the Nicolet^TM Nexus^TM 870 spectrometer. The three techniques, PM-IRRAS, VCD and VLD, are most commonly used for thin layers on metal substrates such as lubricant layers on hard disks, chirality of molecules (handedness) especially in biological or pharmaceutical applications and molecular orientation in polymer films, respectively.