In our lab we have several flow set-up to test the optical response of samples under different gas environment. As the name suggests, inside the cell a constant flow of gas is maintained while the pressure is kept constant. Up to four flow controllers are used to to mix up to four different gasses together in different ratios. For example, hydrogen can be mixed with Ar in various ratio’s to expose the sample to different hydrogen concentrations.
Optically transparent windows as well fiber feedthroughs allow one to measure the optical transmission/reflection/characteristics of samples on glass substrates as well as side and top-coated optical fibers. For example, the hydrogen concentration dependence of the optical transmission and reflection can be determined using a light source and spectrometer.
TU Delft Optical Hydrogen Sensing & Thin Film Energy Materials 