A bed construction having a one-sided mattress assembly supported on a rigid foundation. The transverse component of the bias layer moment creates a balancing field in the free layer that counterbalances the coupling field in the free layer generated by the pinned layer. Access to the storage cells, and thus the data cartridges sitting therein, from the library’s exterior is blocked. A winding section is defined within the two side plates for winding a winding coil. The beam deflecting unit reflects at least one of the optical beams from the first and the second illumination module and couples the optical beams to form a multiplexed beam. In at least one other embodiment, a filter tuning technique may be provided and include providing trimming tabs on a resonator edge that may be disconnected or trimmed for filter tuning.