Micro scanning mirrors with laser diode for pattern generation

A novel micro scanning mirror based on MEMS technology with a laser diode could be used in the projection of Lissajous patterns. Two micro scanning mirrors twisted in X-axis and Y-axis are used to deflect the laser beam onto the desired projection area to draw a 2-dimensional pattern. The optical scanning angle of the mirror can reach ±12° in 15 V square wave driving signal at twice the mirror's resonant frequency. Given the sinusoidal movement of the mirrors in each axis, the laser beam follows a Lissajous pattern. Through analyzing the principle of the generated patterns and simulating them with Matlab, oscillation frequency combination of 2400 Hz (X-axis) and 2425 Hz (Y-axis) for image generation is chosen. This combination can achieve 194×192 pixels at refresh frequency 25 Hz which is enough for movie frames. A method of projecting arbitrary images by modulating the laser diode through FPGA is given, which provides the basis for developing micro projectors.