An objective lens for use in probe-forming particle-optical columns such as focused ion beam equipment, scanning electron microscopes, and helium microscopes is described. In one embodiment of the present invention, a wall unit is located at a customer premises which terminates a single analog phone line and adaptively encodes using Voice over Internet Protocol technology and multiplexes a plurality of telephonic and data calls over the single analog phone line. The vibrating beam includes the plurality of turned-down units and the plurality of coupling units coupled to the turned-down units, and the coupling units and the turned-down units are alternately disposed.