Appropriate characterization of soluble aggregates is an important aspect of biologics development and manufacturing, and sedimentation velocity analytical ultracentrifugation (SV-AUC) is often used an orthogonal technique to size-exclusion chromatography (SEC) for this purpose. Precise quantification of low levels of soluble aggregates by SV-AUC can be adversely impacted by improper cell alignment. This report describes the development of an optical system capable of quantifying cell alignment that affords a substantial improvement compared to historical approaches.