Authentication of a user initiating a communication may be achieved using a visual indicator of the user. The gear member is axially fixed to the outer member and freely rotatable with respect to the outer member and the gear member threadedly engages a threaded portion of the inner member to translate inner member along the axis. A processor receives the image data from the detector, and executes a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.