Most recently, lidar has been embodied in slightly gawky units atop cars that just scream, “Something is different about this vehicle!” Using rotating mirrors, a beam can be steered 360° around the vehicle and up and down (to some extent) to map out everything that’s within range. But there’s some thought that, if we’re serious about letting the neighbors see us inside one of those, we need to improve the aesthetics.
This came up in a presentation by MicroVision at last fall’s MEMS Executive Congress. They have a MEMS mirror setup that we saw a couple of years ago as used in their pico-projector application. They use the same basic setup for heads-up displays and for lidar (which uses one extra ASIC); they adapt to the application by changing out the laser diodes and software.
Rather than rotating 360°, their MEMS mirror waves back and forth in a sinusoidal scan, controlled by a 27-Hz resonator; individual pixels are defined by turning the laser diode on and off. The faster the scan, the faster you can get an overview of what’s nearby. By slowing the scan, you get more detail. It sounds simple in principle, but they say that they have to battle jitter in the mirror and temperature effects on the laser. Control and compensation are the tough parts.