In life, interference and diffraction of light can produce some interesting geometic patterns. In this study a mask and optical equipment were used to produce interesting patterns in the liquid crystal sample. The mechanism is the photoisomerization effect of azo dye, which influences the orientation of liquid crystal molecules and results in a special diffraction pattern in the cell. First a green laser(532nm) though a mask irradiated onto the azo dye-doped liquid crystal sample. Ten plane waves from different directions super positioned on the sample. Therefore, special pattern were record in the sample by the adsorption of azo dye. The diffraction pattern and diffraction efficiencies of the sample were inrestigared, Besides, the characteristic of the polarization-independence were also studied.