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How LIDAR Is Improving Games, Phones and Cars

Tired of running over small children in the streets? Wish you didn’t have to get up to answer your phone from accross the room? Well, that’s all about to change. According to The Optical Society (OSA), researchers at University of California, Berkeley are working on a new system to remotely sense objects up to 30 feet away, which is about 10 times further than what we can sense with low-power laser systems currently being used. What does that mean for you and why should you care? Glad you asked! Basically, this means we’re closer to getting smaller, less expensive 3-D imaging systems that will ineviatably make your smartphone, your Kinect and even your future self-driving vehicle that much more awesome!

“While meter-level operating distance is adequate for many traditional metrology instruments, the sweet spot for emerging consumer and robotics applications is around 10 meters” or just over 30 feet, says UC Berkeley’s Behnam Behroozpour, who will present the team’s work at CLEO: 2014, being held June 8-13 in San Jose, California, USA. “This range covers the size of typical living spaces while avoiding excessive power dissipation and possible eye safety concerns.”

The new system relies on LIDAR (“light radar”), a 3-D imaging technology that uses light to provide feedback about the world around it. Basically, LIDAR emits a laser light that bounces off an object and can determine how far away that object is by measuring changes in the frequency that is emtted back. This means that a self-driving car can sense other vehicles and obstacles much quicker and be able to avoid collisions, something the previous sensors were unable to do well during the DARPA Grand Challenges. This could also be used in virtual environments, like say you wanted to play tennis in your back yard and have the game capture your motion and position on the “court”, thus changing the trajectory of the ball. Sounds pretty sweet to me. Current lasers used in high-resolution LIDAR imaging are bulky, expensive and consume too much power. Even the Microsoft Kinect requires a console you have to stand a few feet from to get it to work properly. Look at the current Google cars — They have these giant dumb-looking camera systems on top of them that weigh as much as another passenger, are exposed to the elements and are a total eye-sore. Researchers are working to decrease the size and power consumption of the LIDAR system while retaining optimal performance in terms of distance.

This is a conceptual vision for an integrated 3D camera with multiple pixels using the FMCW laser source. Credit: Behnam Behroozpour
This is a conceptual vision for an integrated 3D camera with multiple pixels using the FMCW laser source. Credit: Behnam Behroozpour

The new LIDAR system uses frequency-modulated continuous-wave (FMCW), which ensures the imager has good resolution with lower power consumption, Behroozpour says. This type of system emits “frequency-chirped” laser light (that is, whose frequency is either increasing or decreasing) on an object and then measures changes in the light frequency that is reflected back. The team is also utilizing a class of lasers called MEMS (micro-electrical-mechanical system) tunable VCSELs (vertical-cavity surface-emitting lasers). MEMS are tiny micro-scale machines that change the frequency of the laser light for the chirping while VCSELs are inexpensive integrable semiconductor lasers with low power consumption. By using the MEMS device at its resonance — the natural frequency at which the material vibrates — the researchers were able to amplify the system’s signal without a great expense of power. “Generally, increasing the signal amplitude results in increased power dissipation,” Behroozpour says. “Our solution avoids this tradeoff, thereby retaining the low power advantage of VCSELs for this application.” The team is now planning to integrate the VCSELs, photonics and electronics into a chip-scale package. Consolidating these parts should open up possibilities for “a host of new applications that have not even been invented yet,” Behroozpour says — including the ability to use your hand, Kinect-like, to silence your ringtone from 30 feet away.

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