A mobile storage having a mobile storage unit having a detection side; an opposing component having an aisle side facing the detection side; the mobile storage unit being movable between a closed position and an open position wherein an aisle is defined; at least one detection module having an optical pulse emitter and an optical detector both provided at an end, facing the aisle, the optical pulse emitter emitting a light pulse, the optical detector detecting a reflection of the light pulse. An object detection method for a mobile storage comprising comparing a temporal reflection signal to a background temporal reflection signal to detect the presence of an object; and indicating a status of the aisle to be presence of an object if the object is detected to be present.