A material screening apparatus is adaptable between a reduced-bearing mode and an additional-bearing mode. A supercell is coupled between each transistor and ground. The time period for plasma treating the titanium nitride layer is controlled so that penetration of nitrogen into the underlying titanium contact layer is substantially prevented, preserving the titanium contact layer for subsequently forming a titanium silicide at the bottom of the contact. Various metric and analysis techniques can be applied to the signals to determine the media type. When a bending impact load acts on the swivel shaft, the yoke and mount press against each other at the bend prevention gap to support the bending impact force. The two optical waveguides are arranged such that they respectively receive a measurement light portion of the measurement light and that the measurement light portions are superimposed after passing through the optical waveguides.