Lightweight, non-mechanical, polarization-independent LiDAR beam steering system

During Phase I of this project, two approaches for achieving polarization-independent non-mechanical lidar beam steering were demonstrated, and a demonstrator system was fabricated and testing. The demonstrated technology based on spatial modulation of geometrical phase has been reduced to a well-understood method for switching the pointing direction of laser beams and receiver fields of view. The Phase II project will extend these results to allow future NASA beam steering systems to electronically steer lidar transmitter, receiver, and transceiver pointing directions for any polarization of lidar radiation, and will develop the supporting technology needed to enable such systems to operate in relevant environments, especially the thermal and radiation environments likely to be encountered in future space missions. Adding polarization independence will extend the applicability of non-mechanical beam steering to additional classes of lidar, since such independence can increase the received signal by up to a factor of four with some types of lidars. The weight reduction that is obtained in future lidar systems using the developed technology will be maximized by identifying optical components with the minimum possible weight that still meet wavefront quality requirements. Previous developments have allowed the complete elimination of moving parts in some beam steering systems for LiDARs. One of the major advantages of this elimination of moving parts has been a potential reduction in weight and increase in reliability of future LiDAR systems. However, some previous non-mechanical beam steering systems for LiDARs have been sensitive to the polarization of light, and in particular, have been capable of utilizing only one polarization of the optical return to the LiDAR receiver. This wastes up to half of the optical energy returned from a target. If the laser source is unpolarized, it also wastes half of the laser output. The power reaching the receiver can therefore be increased by up to a factor of four by eliminating polarization sensitivity in the steering system. The opportunity to employ all polarizations of light in the LiDAR receiver could significantly reduce the overall weight of the system since it would allow a reduction in transmitter power and/or reduction in the size of the LiDAR optics. The main technical objectives are to take the polarization-independent beam steering technology developed in Phase I to the point where it has been demonstrated to perform with the required optical efficiency, low weight, and wavefront quality needed in future NASA LiDAR applications in relevant environments, and to deliver a prototype beam steering system that incorporates this advance in non-mechanical beam steering technology. The architecture will be selected based on the results of the Phase I study. A major focus of the Phase II effort will be to design the delivered system to be compatible with the environment in future spacecraft. In particular, components and materials will be selected for compatibility with the ionizing radiation environment in space. Due to previous experience on other programs, BEAM Co. has an extensive database of radiation effects on optical materials, and this information will be used in the design of the deliverable demonstrator beam steering system. BEAM Co. has also developed methods of both thermal control and thermal compensation, and we will use these methods to assure acceptable performance of the likely operating temperature ranges.
Benefits: Compact, low SWaP, non-mechanical, hence, robust, LiDARs with reliable and fast data acquisition capability that meet requirements for a space landing vehicle could be used for other NASA missions including asteroid flybys, swarms of cubesats, etc. due to higher precision guidance and navigation systems. An additional potential application of this technology is to transceiver steering for free-space optical communications systems. Numerous non-NASA applications include autonomous navigation systems for ground and air vehicles and robots, and commercial free-space optical communications.