One or more optical signals (wherein at least some of a plurality of optical signals are at different angles of travel with respect to one another and are directed towards an area comprising a movable barrier-controlled point of passage) create reflections when striking passageway boundaries as correspond to a given movable barrier. Obstacles in the pathway also give rise to reflections. By determining a time-of-flight for such reflections, one can detect a likely presence of an obstacle in such a pathway. Pursuant to one approach, such time-of-flight information can further provide information regarding a likely size of such an obstacle.