Patent ID: 7817286

Claim:
An optical interference fly height (FH) test apparatus for measuring FH comprising: a slider; a transparent disk; means for directing a light beam, with an intensity associated therewith, between the slider and the disk; computer-controlled means for iteratively measuring an estimated FH, during calibration, and averaging the estimated FH, the computer-controlled means further for iteratively measuring the FH by using at least two points of measurement on the slider when the slider is moved away from the disk at a pitch angle, the intensity of the light beam being measured as the slider is retracted relative to the disk thereby causing FH to increase and to travel through maximum and minimum light beam intensities, wherein the estimated FH is computed as a function of the pitch angle, during calibration, and during each iteration of estimating FH, a previously-estimated FH is used to converge the estimated FH so that the estimated FH is within a predetermined range from the actual FH.