Active Optical Tracking with Spatial Light Modulators

Two spatial light modulators (SLMs) are utilized for beam splitting, steering and tracking. Both linear and holographic phase screens are used in a demonstration of technology to allow real time tracking to communicate in a one-to-several type scenario. One SLM is used to apply a linear phase modulation to steer multiple beams onto a detector. The spots that are produced represent the targets as they move around the field of view of the central communication node. A Gerchberg-Saxton algorithm will subsequently use the detected spots as the desired pointing locations. Using this as input, the Gerchberg-Saxton algorithm yields a phase only map for multiple spot beam steering which is called the holographic phase. The holographic phase screens are then used on a second SLM to steer beams onto the same detector in near real time. As the target spots move about the detector's field of view, the holographic spots track them.