Laser Scanners - MEMS

A highly efficient solution for cell phone projection or pico projection comes by way of scanning red, green, and blue lasers really fast. In the case of micro electro mechanical systems (MEMS), the light is reflected off tiny mirrors that direct the right color to the right location at the right time. This technology has been around for a long time – think of bar code scanners. However, the challenge for projection is that rather than just scanning and tracking a “standard” color red laser for data input, cell phone projection will require a good image quality. The technology must be able to align the red, green, and blue lasers and scan them precisely and fast enough to trick the eye into believing it is seeing a seamless image. Companies such as Symbol (purchased by Motorola) and Microvision has demonstrated this at shows such as the Consumer Electronics Show. The exiting thing is that these companies have shown prototypes at small enough sizes with decent quality that the technology seems ready for launch.

The advantages for MEMS laser scanning are high efficiency, and small size. The big drawbacks so far today are the prohibitively high cost and technology challenge of the green laser component, and the inherent image problem that lasers produce called “speckle.” Laser speckle is a phenomenom present in all laser projection devices. This happens because the laser is a coherent light source, so as it reflects off any surface the light will appear to scatter slightly. This speckle appears as dark spots within the image and distort surrounding pixels.

Picture from http://www.elecdesign.com