Self-driving cars often use LiDAR — think of it as radar using light beams. One limitation of existing systems is they need some method of scanning the light source around, and that means moving parts. Researchers at the University of Washington have created a laser on a chip that uses acoustic waves to bend the laser, avoiding physically moving parts. The paper is behind a paywall, but the University has a summary poster, and you can also find an overview over on [Geekwire].
The resulting IC uses surface acoustic waves and can image objects more than 100 feet away. We would imagine this could be helpful for other applications like 3D scanning, too. The system weighs less than a conventional setup, too, so that would be valuable in drones and similar applications.
The high-frequency acoustic pulses create phonons that deflect the photons in the laser beam. By varying the frequency of the pulses, the beam will sweep over a 20-degree field of view. The phonons are similar to a diffraction grating. They not only alter the direction of the beam but also change its wavelength.
This effect simplifies the receiver setup. When laser energy returns to the receiver, the measured wavelength informs the receiver of the angle corresponding to the transmitted beam. To be practical, the system needs to have a greater range, and this is due to the system’s poor efficiency of about 5%. To reach 300 meters — a number making it practical for autonomous cars — will require 50% efficiency, something the team thinks they’ll achieve soon.