Laser projection device based on a 2D resonant micro scanning mirror

Laser scanning is an interesting technology for projection displays. It promises light-weight, compact systems, productions yields independent of display resolution and low prices. The critical components of a laser projector are the modulator-laser unit and a deflection unit. Both must meet great demands. We propose micro mechanically fabricated resonant 2D scanning mirrors for the deflection unit. They are quiet, compact, have low power consumption and are practically free of wear. The deflected laser beam of a resonant 2D scanning mirror however scans a Lissajous pattern instead of a raster as in a cathode ray tube. The advantages are no need for a forced linearity of the scan and no need for a slow vertical axis. Thus, stability issues are avoided. This paper presents a demonstrator of a projection device based on a projection method that enables using micro scanning mirrors with similar frequencies for both axes. The deflection frequencies of the micro scanning mirror are adjusted in a way that the laser beam describes a Lissajous pattern with high density on the projection screen. Generation of driving signals, determining the actual beam position and laser modulation is done by a control circuit realized with a FPGA. A USB 2.0 interface is responsible for the image transfer from the control PC to the projection device. This enables displaying moving images