Sensitivity enhancement and fringe reduction in tunable diode laser spectroscopy using hemispherical diffusers

The use of diffuse, highly reflective optical components, in particular, a hemispherical BaSO₄ diffuser, at the point of light injection into non-transparent or turbid media was evaluated as a means to increase the measurement sensitivity of spectroscopic absorption measurements. By performing the light injection from, e.g., an optical fiber through a component designed to make the light diffuse and to reflect (and thereby re-inject) light scattered from the sample, the total amount of light delivered into the sample is increased. Further, the occurrence of possible interference fringes is strongly reduced.