Subjective speckle is widely used in various fields such as optical imaging and object detection, especially in the field of in-plane displacement measurement which has attracted much attention, and illumination laser is one of the key factors affecting its measurement. Firstly, based on the theory of information optics, the principle of lens imaging under spherical wave and plane wave illuminations is studied; Then an optical system of subjective speckle is constructed, and the in-plane displacements of scattered object are measured using digital image correlation method under spherical wave and plane wave illuminations, respectively. Finally, the influence of the two types of waves on the in-plane displacement measurement is analyzed and discussed based on the above principle. It is found that the two types of waves have little effect on the measurement error, but have a significant impact on the measurement limit, that is, the measurement limit of in-plane displacement under spherical wave illumination is much lower than that under plane wave illumination.