This paper presents an improvement approach to realize tracking on smooth glass surface based on
subjective speckle. The scattering mechanism on glass surface is analyzed and the affection on tracking
precise and range for tracking with subjective speckle is researched. The speckle captured by CCD just
from the upper surface of the glass is achieved by grazing incidence of the laser beam and the noise
mixed with the signal is eliminated by a barrier above the surface. Based on the apparatus of subjective
speckle tracking, the speckle contrast is improved from 0.25 to 1.25 by non-Gauss effect and the range
of the tracking has been increased from 200 μm to 400 μm compared with the objective speckle
method on the same condition.