Work by MIT researchers may make drones, robots and self-driving cars both more affordable and also improve their performance. Successful commercialization of a new lidar-on-a-chip could bring the cost of improved 3D scanning within the range of Makers.
Most of us are fortunate enough to take for granted the ability to automatically absorb information about the world around us and navigate through whatever landscape we find ourselves in. Whether the environment is a crowded city street or an uneven costal path, the combination of our senses and brain ensure we (mainly) avoid objects and stay upright.
Recreating this ability in machines is a challenge that advancements in silicon photonics may help address this.
In an article for IEEE Spectrum’s Tech Talk blog MIT researchers, Christopher V. Poulton and Prof. Mike R. Watts describe silicon photonics as:
“A chip technology that uses silicon waveguides a few hundred nanometers in cross section to create “wires for light,” with properties similar to optical fibers except on a much smaller scale.”
These waveguides can be built into a chip and perform a similar function to the wires and connectors seen in traditional electrical engineering. The difference is that light, rather than electricity, transmits data, switches circuits and performs the other tasks commonly carried out by a chip.
The advantage of using light is the lower power requirement when compared to sending data with electricity via copper connectors. Photonic applications are still emerging and widespread use is increasingly likely now traditional microchip manufacturers are adapting mass production facilities for the technology.
These manufacturers include companies such as Intel and Luxtera who have spent almost 15 years developing silicon photonics. Luxtera were the first to bring a mass-produced product to market and the company refer to the technology as CMOS photonics.
Work done at MIT’s Photonic Microsystems Group by Poulton and Watts, “develops microphotonic elements, circuits, and systems for a variety of applications, including communications, sensing, and coupled microwave-photonic circuits.” Earlier this month the group announced success in a DARPA backed project to use silicon photonics to enable lidar-on-a-chip.
Lidar vs. radar and Google vs. Tesla
Radar uses radio waves to build a picture of the surrounding environment. Solid objects in the path of the radio wave may reflect or disrupt the wave and detection of these events can be used to build up a picture of the environment.
Lidar uses a similar concept, the reflection of a transmitted signal, but rather than a radio wave a lidar unit sends out a light wave. The systems full name is “LIght Detection and Ranging.” The light can be infrared, ultraviolet, laser or from another source.
Both methods can be used to identify the location of an object in a space. Through harnessing the Doppler shift a calculation of the object’s speed and direction of travel can also be performed. The police have used lidar speed guns since 1989 for that very purpose.
“Radio waves are created by the acceleration of electrons in a radio antenna, and light waves are created by the oscillations of the electrons within atoms,” writes Frank Wolfs on the differences between the two. Furthermore, because light waves operate at smaller wavelengths, approximately 100,000 times smaller, a greater level of detail in describing an environment or object is possible.
For this reason Lidar is acknowledged as offering greater precision, but the technology can be disadvantaged by adverse weather conditions such as rain or fog.
Google’s self-driving cars depend upon lidar to understand their surroundings. The lidar unit is mounted in a distinctive beacon on the car’s roof and scans 60 meters in all directions. The equipment in use by Google can cost up to $70,000 per unit according to The Guardian newspaper.
3D printing has grown to another level with 3D food printing which is the future of 3D printing.
