In this work the authors have added an additional sensor to the traditional Phase Doppler Interferometry (PDI) configuration yielding three independent measures of phase shift between detectors. This seemingly minor enhance-ment has a profound impact on the limitations of the PDI technique in two important areas: the minimum laser beam diameters and the ability of the technique to discriminate liquid droplets from solid particles. Phase Doppler measurements can be impacted by reflection/refraction errors in which a droplets measured diameter is substantially different from its actual size. This is most critical when small droplets are measured as very large but the converse is possible as well. Consideration for this error source places a major constraint on the minimum laser beam diameter at the measurement volume. The addition of a third independent measure of phase shift effectively eliminates reflection/refraction errors allowing PDI measurements with smaller laser beams than would ordinarily be recommend-ed. The authors demonstrate this ability by measuring the same location of a spray with decreasing laser beam waists. Since the droplet number density limit of the Phase Doppler technique scales inverse to the square of the laser beam diameter, such an optical configuration would substantially enhance the instruments performance in dense sprays ap-plications. For applications such as icing cloud measurements, the ability to discriminate and size only liquid droplets in a mixed-phase environment is an important capability of the PDI technique. The relationship between the phase shifts of Phase Doppler signals can be used to differentiate liquid droplets or other spherical particles from irregularly-shaped solids. The authors demonstrate that the addition of a third independent measure of phase shift reduces the number of false positives (solids measuring as droplets) by a large factor from 11.7% to 0.33% in one example. Artium PDI-FP 雙量程可機(jī)載飛行探頭 激光相位多普勒干涉儀LDV，PDI，PDPA，PDA 激光誘導(dǎo)白熾光（LII）煙氣分析儀