September 5, 2015

Self-sweeping laser could dramatically shrink 3D mapping systems

This self-sweeping laser couples an optical field with the mechanical motion of a
high-contrast grating (HCG) mirror. The HCG mirror is supported by mechanical springs
connected to layers of semiconductor material. The red layer represents the laser’s gain
(for light amplification), and the blue layers form the system’s second mirror.
The force of the light causes the top mirror to vibrate at high speed. The vibration allows
the laser to automatically change color as it scans. (Schematic by Weijian Yang)

(September 5, 2015)  A new approach that uses light to move mirrors could usher in a new generation of laser technology for a wide range of applications, including remote sensing, self-driving car navigation and 3D biomedical imaging.

A team of UC Berkeley engineers led by Connie Chang-Hasnain, a professor of electrical engineering and computer sciences, used a novel concept to automate the way a light source changes its wavelength as it sweeps the surrounding landscape. They report their findings in the journal Scientific Reports, published Thursday, Sept. 3.

The advance could have implications for imaging technology using LIDAR, or light detection and ranging, and OCT, or optical coherence tomography.

“Our paper describes a fast, self-sweeping laser that can dramatically reduce the power consumption, size, weight and cost of LIDAR and OCT devices on the market today,” said Chang-Hasnain, chair of the Nanoscale Science and Engineering Graduate Group at UC Berkeley. “The advance could shrink components that now take up the space of a shoebox down to something compact and lightweight enough for smartphones or small UAVs [unmanned aerial vehicles].”

LIDAR works by shining a beam of light at a target and measuring the amount of time it takes to bounce back. Because the speed of light is constant, this system can then be used to calculate distance. Self-driving vehicles and remote sensing technology use LIDAR for navigation and the creation of 3D maps.

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