A lightweight, rugged, solid state laser radar system enabled by non-mechanical electro-optic beam steerers

Abstract

There is currently a good deal of interest in developing laser radar (ladar) for autonomous navigation and collision avoidance in a wide variety of vehicles. In many of these applications, minimizing size, weight and power (SWaP) is of critical importance, particularly onboard aircraft and spacecraft where advanced imaging systems are also needed for location, alignment, and docking. In this paper, we describe the miniaturization of a powerful ladar system based on an electro-optic (EO) beamsteering device in which liquid crystal birefringence is exploited to achieve a 20° x 5º field of view (FOV) with no moving parts. This FOV will be significantly increased in future versions. In addition to scanning, the device is capable of operating in a "point and hold" mode where it locks onto a single moving object. The nonmechanical design leads to exceptionally favorable size and weight values: 1 L and < 1 kg respectively. Furthermore, these EO scanners operate without mechanical resonances or inertial effects. A demonstration was performed with a 50 kHz, 1 microjoule laser with a 2 mm beam diameter to image at a range of 100 m yielding a 2 fps frame rate limited by the pulse laser repetition rate. The fine control provided by the EO steerer results in an angle precision of 6x10 -4 degrees. This FOV can be increased with discreet, non-mechanical polarization grating beamsteerers. In this paper, we will present the design, preliminary results, and planned next generation improvements.

Swept Source Lidar: simultaneous FMCW ranging and nonmechanical beam steering with a wideband swept source

“…In recent years, solid-state lidar systems, which have no moving components, have attracted more attention in industries where robustness and stability are critical. Various nonmechanical beam steering methods have been studied; however, these methods still have limited performances or rely on complex immature technologies, including silicon-photonics optical phased arrays (OPAs) [2], liquid-crystal waveguides [3], vertical-cavity surface-emitting laser (VCSEL) based waveguides [4], and photonic-crystal waveguides [5]. Thus, simple solid-state beam steering mechanisms are desired for the realization of robust and stable lidar systems.…”

An Overview of the Latest Progress and Core Challenge of Autonomous Vehicle Technologies

“…However, its integrated design is more durable, compact and costeffective. Therefore, solid-state is one of the most important trends in this field [6][7].…”

Optimization of eyesafe avalanche photodiode lidar for automobile safety and autonomous navigation systems

“…Alternative solutions to mechanical beam steering that have been explored include microlens arrays, microelectromechanical systems, 24,25 liquid-crystal polarization gratings, 26 holographic glasses, and birefringent prisms. All of these approaches suffer from one or more of the following limitations: low throughput, scattering, small steering angle/aperture, high fabrication cost, and large size/weight.…”