Stokes polarimeters and scanning slit optical beam profilers are used to measure the polarization properties and optical spot intensities of a laser beam, which go through the micromodulator by the $Z$-scanning method. The polarization properties of a $S$-polarized and a $P$-polarized light are researched. The optical intensities of laser beam are obtained for $S$-polarized light by the $Z$-scanning method. The results show that the groove films can affect the polarization properties of the $P$-polarized light but do not change the polarization properties of the $S$-polarized light. The optical spot intensity of $S$-polarized light can be changed with the help of groove films as the scattering effect.