Improved interferometric detection of scattered light with a 4f imaging system

We analyze the performance of three imaging systems to detect near-forward scattered light interferometrically by using a Mach-Zehnder geometry. The alignment of each system is demonstrated by measurement of the heterodyne efficiency and correlation of the angular width and field 1/e radius measurements of the sample beam. Measurements of angular-scattering data demonstrate the range of angles over which each system is effective. Of the three systems analyzed, the 4f imaging system is determined to be most effective, because it accurately reproduces both the phase and the amplitude of the scattered field at the detector.