A robot system includes a robot linkage (202) having one or more arms connected by two joints (220, 222). The joints each including a joint axis of rotation (206 or 208) and a light source (128) aligned with the respective joint axis. The light sources are configured to direct light along the respective joint axis such that light from the light sources intersects at a position along an instrument (204) being held in an operational position by the robot linkage to define a remote center of motion (RCM) for the robot linkage.
