Fall 2013 IAB & Research Review
September 18 - 19
3D Imaging: Sub-mm Resolution Ranging using a Chip-scale MEMS FMCW LIDAR Source
3D imaging systems have recently obtained increased publicity by their use in consumer electronics devices. Applications include gesture recognition or 3D mapping in autonomous cars. Today’s commercially available miniaturized 3D imaging systems are most commonly based on time-of-flight measurements. They are several cm3 in size and offer 10s of cm ranging resolution at a typical object distance of 10m. Frequency Modulated Continuous Wave (FMCW) Light Detection and Ranging (LIDAR) offers significantly better ranging resolution at typical distances of a few meters, without the need of high speed detectors and electronics.
We present recent ranging results with sub-mm resolution in indoor environments using a miniaturized FMCW LIDAR source. Our chip-scale source employs MEMS tunable infrared Vertical Cavity Surface Emitting Lasers (VCSEL), silicon photonics, and control electronics. Using an optoelectronic phase-locked loop employing an integrated silicon photonics chip, we demonstrate generation of linear frequency chirps as frequency modulated ranging signal, exhibiting a tunable VCSEL source frequency excursion of 50GHz at a center wavelength of λ0=1548nm. Design and performance of the source components as well as experimental ranging results will be discussed.
Exploring a modular integration strategy based on wafer level microfabrication technologies potentially offers volume production of tightly integrated low cost 3D imaging systems. The heterogeneous integration platform will combine CMOS electronics with passive and active photonic components. It can be expected, that a fully integrated FMCW LIDAR source chip will exhibit a volume of less than one cubic millimeter. Such a tightly integrated, compact chip-scale LIDAR source has the potential to revolutionize 3D-imaging in mobile applications.