Making Autonomous Vehicles More Affordable

A new approach to LIDAR – the combination of “light” and “radar” that enables such inventions as self-driving cars – could significantly reduce size, weight, power requirements and cost, making this technology practical for a broader range of applications.

Typical LIDARs work by shining a laser on an object and measuring the time it takes for the light to bounce back. Since the speed of light is constant, the system can then calculate the distance between the transmitter and the sensor. However, in order to differentiate incoming (reflected) light from outgoing (transmitted) light, the wavelength of the laser must be changed constantly using a mirror or series of mirrors to adjust the frequencies. It’s these mirror mechanisms that make LIDARs bulky, slow, power-hungry and costly.

Recently, researchers created what’s known as a self-sweeping laser in which the physical force of the light itself is used to move an ultra-thin, high contrast grating (HCG) mirror. Used in past experiments to create an artificial, chameleon-like skin, the HCG mirror consists of rows of tiny ridges which can move under an average force of only a few nano-newtons (about one-thousandth the weight of an ant), so that the energy exerted by the light alone is enough to cause it to vibrate. The mirror is mounted on mechanical springs which allow it to swing back and forth, sweeping across a wavelength range of 23 nanometers within the infrared spectrum, in cycles as short as a few hundred nanoseconds. The bottom line is that the new technique could be used to detect 3D surface profile features as small as 50 micrometers in size, at a distance of tens of meters, and capture them in real-time video. The whole thing can be powered by a AA battery, and takes up only a few hundred square micrometers of space.

In addition to making autonomous vehicles more affordable, the new LIDAR is faster, providing a more accurate picture of its surroundings. Its compact size and light weight make it suitable for smaller devices, such as smartphones or small drones. Other applications include optical coherence tomography for 3D medical imaging.