Supersonic turbulent mixing layer requires high spatiotemporal resolution of measuring techniques to study its aero-optical effects. However, the spatiotemporal resolution of existing techniques is not high enough. NPLS-WT (NPLS based wavefront technique) is a new aero-optics measuring technique developed in 2010. Its time resolution is 6ns, and spatial resolution and time correction resolution can reach up to micrometers and 200ns respectively. NPLS-WT was used in this paper to study aero-optical effects induced by Mc=0.5 supersonic mixing layer. The fine wavefront aberration information is revealed by the OPD of high resolution. The results show that the wavefront in near field is not sensitive to the resolution, and large-scale structures play a dominant role on the wavefront in near field. The cumulative effects analysis show us that the density difference between large-scale structures and free stream is the main reason to wavefront aberration, and the larger the vortex is, the more obvious the effect to wavefront aberration is.