Spatial weighting in laboratory incoherent light scattering experiments.

Diffraction-based calculations of the relative spatial weighting of the observed volume in incoherent scattering experiments, applicable to both direct detection and heterodyne systems and arbitrary transmitter and receiver profiles, have been largely confirmed in laboratory measurements using a CO(2) laser. The results indicate that heterodyne systems have superior spatial resolution at small scattering angles for a given detector geometry and permit quantitative assessment of this and the greater sensitivity of coherent systems to misalignment.