There is provided an optical connector configured to receive a plurality of MT ferrules attached to terminal ends of multi-fiber cables. The tube body is provided with a plurality of holes for accommodation of a locking hook respectively and the resilient retainer is peripherally equipped with several pairs of vertical flexible ribs with an expansion space defined therebetween. In addition, the closing andor opening times should be independent of possible changes in properties of the spring device. The expandable engagement wall defines a passage, and the fastener extends through aligned openings in the first member and the head portion of the connector member, into the passage defined by the expandable engagement wall of the second member. An external channel is vertically spaced from the internal channel and is defined by the exterior surfaces of the sidewalls. The rotation driving means rotates the light deflecting means so as to direct the laser beam toward the measurement range.