An illumination device comprises a laser source, a beam expander, a micromirror array having a first control system, a fast steering mirror having a second control system, a diaphragm array, a microlens array, an illumination lens group, and a reflection mirror sequentially along the propagation direction of the laser beam. The first control system comprises a first computer controlling each micromirror on the micro-mirror array through the micromirror array controller to rotate in two-dimensional directions so expanded beam forms desired intensity patterns on the diaphragm array after reflected by the micromirror array and fast reflection mirror and a micromirror array controller; the second control system comprises a second computer controlling the reflection mirror of the fast steering mirror to rotate through fast steering mirror controller so created intensity pattern moves relative to the diaphragm array and a fast steering mirror controller. Method for using the illumination device is provided.