The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 25, 1996
Filed:
Dec. 27, 1994
Peter M Baumgart, San Jose, CA (US);
Karl A Flechsig, Los Gatos, CA (US);
Michael F Lee, Los Altos, CA (US);
Wing P Leung, Arcadia, CA (US);
Ullal V Nayak, San Jose, CA (US);
Thao A Nguyen, San Jose, CA (US);
Timothy C O'Sullivan, San Jose, CA (US);
Andrew C Tam, Saratoga, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method is provided for making crater shaped bumps on a calibration disk which can be used for calibrating a PZT slider, the PZT slider in turn being used for detecting predetermined asperities on a production run magnetic disk. The crater shaped bumps emulate predetermined asperities of production run magnetic disks and especially asperities which are undesirable and would cause the production run disk to be discarded after testing by the PZT slider. Crater shaped bumps which emulate undesirable asperities on current production runs of magnetic disks have a diameter in the range of 10 to 25 .mu.m and a peripheral ridge with a height h.sub.r above a nominal surface of the calibration disk in the range of 75 to 120 nm. Close tolerance crater shaped bumps with this configuration can be made by impinging two or more pulses of laser energy on the same location of a calibration disk. By increasing the number of pulses the height of the peripheral ridge progressively increases. By employing multiple pulses, the height of the peripheral ridge is increased while the diameter of the crater shaped bump stays substantially constant. Further, by employing multiple pulses diameters and heights of crater shaped bumps can be produced with close tolerances within a diameter range of 5 to 20 .mu.m and a height range of 2 to 120 nm. Different arrangements of the crater shaped bumps on a calibration disk are provided for increasing the range of calibration of the PZT slider.