Method of making disk bumps with laser pulses for calibrating PZ

Details Method of making disk bumps with laser pulses for calibrating PZ Method of making disk bumps with laser pulses for calibrating PZ

1994-12-27

1996-06-25

Raevis, Robert

Measuring and testing

Instrument proving or calibrating

Volume of flow, speed of flow, volume rate of flow, or mass...

29557, B23K 2600

Patent

active

055289223

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.

REFERENCES:
patent: Re33777 (1991-12-01), Woodroffe
patent: 4608480 (1986-08-01), Bizot et al.
patent: 4931338 (1990-06-01), Toffle
patent: 5062021 (1991-10-01), Ranjan et al.

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