Full-field interferometric measurement of head-tape contact spacing

Abstract

Interferometry is the preferred measurement method for the contact spacing of the head-tape interface, due to its ease of use and high accuracy. Full-field techniques provide spacing data at all points in the field of view as opposed to a single measurement point. Dynamic interferometric measurement necessitates the use of a strobed illumination source, and thus prohibits the alteration of the fringe field to resolve the ill-constrained nature of the analysis problem. In addition, the head-tape contact problem is further complicated by the low phase gradient in the region of head-tape contact, which is often large in comparison to the field of view.

In this paper two algorithms are compared which do not require alteration of the fringe field and therefore can easily be applied to the dynamic head-tape interface. The first technique is a two-dimensional implementation of a biquadratic fit to the fringe extremes, while the second is a pseudo-spatial heterodyne technique using the two-dimensional Fourier transform. Theoretical implementation and results are presented.

Keywords

interferometry head-tape interface Fourier techniques Bernoulli interface

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References

Lacey

C. A.

Talke

F. E.

Measurement and simulation of partial contact at the head/tape interface

Trans. ASME, J. Tribology, 1992, 114 (4), 646–652.

Mizukawa

Hosaka

Hara

Study on spherical foil bearings

Bull. Jap. Soc. Mech. Engrs, 1985, 28 (243), 2105–2111.

Baugh

Talke

F. E.

Biquadratic surface fits for two-dimensional interferometric head/tape spacing

IEEE Trans. Magn., 1994, 30 (6), 4188–4190.

Takeda

Ina

Kobayashi

Fourier-transform method of fringe-pattern analysis for computer based topography and interferometry

J. Opt. Soc. Am., 1982, A72 (1), 156–160.

Macy

W. W.

Two-dimensional fringe-pattern analysis

Appl. Optics, 1983, 22 (23), 3898–3901.

Bone

D. J.

Bachor

H. A.

Sandeman

R. J.

Fringe-pattern analysis using a 2-D Fourier transform

Appl. Optics, 1986, 25 (10), 1653–1660.

Roddier

Interferogram analysis using Fourier transform techniques

Appl. Optics, 1987, 26 (9), 1668–1673.

Kreis

T. M.

Digital holographic interference-phase measurement using Fourier transform techniques

J. Opt. Soc. Am., 1986, A3 (6), 847–855.

Kujawiska

Wojciak

High accuracy Fourier transform fringe pattern analysis

Optics and Lasers in Engng, 1991, 14, 325–339.

10.

Reid

G. T.

Automatic fringe pattern analysis: A review

Optics and Lasers in Engng, 1986, 7 (1), 37–68.

11.

Schwider

Advanced evaluation techniques in interferometry In Progress in Optics, Vol. 28, 1990, pp. 273–359 (Elsevier Science Publishing Company, Oxford).

12.

Spik

Two-dimensional phase decoding from bounded fringe patterns by using the Fourier-transform method

Optica Applicata, 1987, 17 (4), 349–354.

13.

Huntley

J. M.

Speckle photography fringes analysis: Assessment of current algorithms

Appl. Optics, 1989, 28 (20), 4316–4322.

14.

Creath

Phase-measurement interferometry: Beware these errors

Proc. Soc. of Photo-Opt. and Instrum. Engrs, 1991, 1553, 213–220.

15.

Maas

A. A. M.

Phase shifting speckle interferometry. PhD thesis, Delft University of Technology, Netherlands, 1991.

16.

Huntley

J. M.

Noise-immune phase unwrapping algorithm

Appl. Optics, 1989, 28 (15), 3268–3270.

17.

Ghiglia

G. A.

Mastin

G. A.

Romero

L. A.

Cellular-automata method of phase unwrapping

J. Opt. Soc. Am., 1987, A4, 267–280.