Optimization of magnetic force microscopy for retrieval of data from an erased or altered audiotape

Abstract

Magnetic force microscopy (MFM) has been used to investigate the potential for retrieving information from an erased or altered audiotape. The audiotape recording process, the reasons for the distortion of signals during the recording process are presented. An in-depth study has been conducted to investigate the effects of MFM operation parameters on the data retrieval process. Most importantly, these include interleave height and tip speed. Interleave height (i.e., the height of the MFM tip above the surface) has been optimized for maximum clarity of MFM images. Tip speed studies have been carried out to optimize the data retrieval time and suggestions to further reduce the retrieval time are also made. A study has also been performed using MFM to determine the maximum frequency that could be recorded on an audiotape. This optimization of MFM suggests a novel technique for the retrieval of data from erased or altered audiotape. DEDICATION To her, whose very thought creates a strong vigour in my mind and instills a hope of that which is auspicious. To her, who had taught me all the good qualities that I possess. To her, who showered unconditional love and rendered support during the most demanding times of my life. To the natural bond between us which serves as a constant source of inspiration and guidance, even today. Words fail to express the memories with her that produce unspeakable happiness in my heart. To my late mother, I dedicate this thesis. iii ACKNOWLEDGEMENTS First of all I would like to express my deepest gratitude to my advisor Dr.Charter D. Stinespring, without whose continuous guidance, encouragement and support, none of this research would have been possible. My sincere thanks, also, to the chemical engineering department of West Virginia University (WVU) for providing me such a wonderful opportunity to pursue masters by research program. My thesis would be incomplete without my immediate mentor, Dr.Andrew Woodworth, who taught me the experimental setup, struggled with me in aligning the laser and focusing the camera, took care of me like a little brother, showed tremendous patience and guided me in all possible ways. I would also like to express my reverence towards my father, P S Subramanian, for his affection, encouragement and support throughout my life. My earnest thanks and appreciation to my brother, P S Shyaam Prasad, for boosting my confidence and passing valuable remarks. I also want to thank my grandmother and aunt for their love and enthusiasm. Appreciation is also due to my other lab mates Srikanth Raghavan and Tobias Denig for their witty and inspiring comments during the experimental sessions. I cannot thank enough, my fellow students, particularly Adam Finniss, Ashish Bambal, Christopher Yurchick, Jason Hissam and Steve Markovich for the endless conversations in the graduate lounge which made me feel at home. I wish you all the very best for a fantastic research and a wonderful life. My thanks to Dr. Alfred H. Stiller and Dr. John W. Zondlo for agreeing to be a part of my thesis ...