Acoustic emission (AE) measurements to determine the dynamic flying characteristics of optical sliders

Abstract

Flying heads carrying a magnetic coil and a high numerical aperture lens for magneto-optic recording or a solid immersion lens for optical phase change recording, respectively, are promising approaches for increasing the data density. A classic approach to dynamically evaluate the flight attitude of flying heads in data storage is acoustic emission (AE) testing of the head/disk interaction using special glide heads. In our paper we introduce the application of AE test heads for measuring the flying characteristics of optical far field and near field sliders. In comparison to conventional external AE sensors, i.e. sensors mounted somewhere in the drive, these AE elements are directly mounted on the sliders thus yielding a higher pulse shape and a better signal to noise ratio. This set-up allows a clear identification of the head disk contact. To calibrate the sensor a bump disk was fabricated and used for AE measurements.

Contact recording review

“…• AE technology: slider/disk contact is detected by an acoustic emission (AE) sensor installed on the arm (Khurshudov 1998;Muenter et al 2007) which links the suspension to the voice coil motor, and the AE signal is assumed to be proportional to the contact force and the disk velocity (Khurshudov and Talke 1998). Some concerns include that the AE sensor is far away from the contact detection point, and may not be sufficiently sensitive to detect light contact.…”