LiDAR Beam Steering and Optics

There are many ways to steer optical beams. Historically, steering an optical beam meant moving a mirror or a transmissive optical element. Over the last few decades, other approaches have been developed that involve creating an optical path difference (OPD) or a phase difference. We can group beam steering methods into mechanical and nonmechanical approaches. Nonmechanical approaches are sometimes called optical phased arrays (OPAs) because they change the angle of an optical beam based on changing the phase profile of that optical beam. Microwave phased-array radars, which have been around for decades, use this approach of changing the phase of an outgoing or incoming beam. The much-shorter wavelength associated with optical systems makes this approach more difficult. Following the discussion of mechanical and nonmechanical approaches to beam steering, a few relevant optical design parameters for a LiDAR are presented. This topic includes a brief discussion of adaptive optics, as well as how to use some of the presented nonmechanical techniques to make dynamically adaptive optical elements. If it is possible to change a phase profile across an optical element to steer a beam, then it is also possible to change a phase profile to make a lens or another optical element. The future era of flexible optical elements will be an enabler.