The invention presents techniques for verifying patterns, such as time-based servo marks, recorded on magnetic media. An annular groove holding a seal ring is provided in the flange. The tunable front end module includes a Tx microelectromechanical system bandpass filter. The shrinkable sleeve is slid onto the at least one support member and located in a predetermined position around the exterior surface. At least some of the optical elements have at least one flat surface and at least one curved surface, and intersecting each other over an intersection volume of the intersecting optical elements.