OSA's Digital Library

Applied Optics

Applied Optics


  • Vol. 37, Iss. 28 — Oct. 1, 1998
  • pp: 6654–6663

Optical properties of alumina titanium carbide sliders used in rigid disk drives

Peter de Groot  »View Author Affiliations

Applied Optics, Vol. 37, Issue 28, pp. 6654-6663 (1998)

View Full Text Article

Enhanced HTML    Acrobat PDF (204 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



A common material for read–write sliders is a composite of alumina (Al2O3) and titanium carbide (TiC), with a grain size of the order of 1 μm. I derive the effective complex reflectivity of this material, using scalar diffraction theory and the known indices of refraction of Al2O3 and TiC. The effective reflectivity is a function of the relative surface area of the exposed TiC grains as well as of the numerical aperture of the collection optics. The theory resolves several known discrepancies between ellipsometry and reflectometry of Al2O3–TiC. The theory also predicts a systematic error in the phase shift on reflection calculation. These results are of considerable interest for surface shape metrology of the slider as well as for optical flying-height testing and control of pole-tip recession.

© 1998 Optical Society of America

OCIS Codes
(120.2130) Instrumentation, measurement, and metrology : Ellipsometry and polarimetry
(120.2830) Instrumentation, measurement, and metrology : Height measurements
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.4530) Instrumentation, measurement, and metrology : Optical constants
(120.4640) Instrumentation, measurement, and metrology : Optical instruments
(120.5410) Instrumentation, measurement, and metrology : Polarimetry

Original Manuscript: April 3, 1998
Revised Manuscript: June 10, 1998
Published: October 1, 1998

Peter de Groot, "Optical properties of alumina titanium carbide sliders used in rigid disk drives," Appl. Opt. 37, 6654-6663 (1998)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. F. Muranushi, K. Tanaka, Y. Takeuchi, “Estimation of zero-spacing error due to a phase shift of reflected light in measuring a magnetic head slider’s flying height by light interference” Adv. Inf. Storage Syst. 4, 371–379 (1992); The same paper was presented at the American Society of Mechanical Engineers Winter Annual Meeting, Atlanta, Ga., 1991.
  2. D. M. Wood, N. W. Ashcroft, “Effective medium theory of optical properties of small particle composites,” Phil Mag. 35, 269–280 (1977). [CrossRef]
  3. G. A. Niklasson, C. G. Granqvist, O. Hunderi, “Effective medium models for the optical properties of inhomogeneous materials,” Appl. Opt. 20, 26–30 (1981). [CrossRef] [PubMed]
  4. C. Lacey, C. Durán, K. Womack, R. Simmons, “Optical measurement of flying height,” in Proceedings of the Future Dimensions in Storage Symposium (International Disk Drive Equipment and Materials Association, Santa Clara, Calif., 1997), pp. 81–88.
  5. R. Synowicki, “Difficulties associated with analysis of composite head structures using ellipsometry,” applications note (J. A. Woollam Company, Lincoln, Neb., 1997).
  6. R. M. A. Azzam, “Ellipsometry,” in Handbook of Optics, M. Bass, ed. (McGraw-Hill, New York, 1995), Vol. 2, Chap. 27, p. 275.
  7. M. Born, E. Wolf, Principles of Optics, 6th ed. (Pergamon, Oxford, 1987), p. 40.
  8. H. G. Tompkins, A User’s Guide to Ellipsometry (Academic, Boston, Mass., 1993), p. 28.
  9. J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, New York, 1968), p. 14.
  10. R. Smythe, L. Selberg, L. Deck, “Pole tip recession measurements of transducers on thin film sliders for rigid disk drives,” in Proceedings of the International Disk Conference in Tokyo, Japan (International Disk Drive Equipment and Materials Association, Santa Clara, Calif., 1992).
  11. E. W. Rogala, H. H. Barrett, “Phase-shifting interferometer/ellipsometer capable of measuring the complex index of refraction and the surface profile of a test surface,” J. Opt. Soc. Am. A 15, 538–548 (1998). [CrossRef]
  12. G. D. Feke, D. P. Snow, R. D. Grober, P. J. de Groot, L. Deck, “Interferometric back focal plane microellipsometry,” Appl. Opt. 37, 1796–1802 (1998). [CrossRef]
  13. W. Stone, “A proposed method for solving some problems in lubrication,” Commonw. Eng. 1921, 115–122.
  14. J. M. Fleischer, C. Lin, “Infrared laser interferometer for measuring air-bearing separation,” IBM J. Res. Devel. 18, 529–533 (1974). [CrossRef]
  15. P. de Groot, L. Deck, J. Soobitsky, J. Biegen, “Polarization interferometer for measuring the flying height of magnetic read-write heads,” Opt. Lett. 21, 441–443 (1996). [CrossRef] [PubMed]
  16. P. de Groot, “Optical gap measuring apparatus and method,” U.S. patent5,557,399 (17September1996).
  17. K. Lue, C. Lacey, F. E. Talke, “Measurement of flying height with carbon overcoated sliders,” IEEE Trans. Magn. 30, 4167–4169 (1994). [CrossRef]
  18. Carbon overcoats are crystalline thin films that have a columnar microstructure that can cause significant optical scatter. This additional light loss can be accommodated by an empirical measurement of the scatter-loss coefficient μ.
  19. An alternative approach is to correlate the reflectance of the slider to the index of refraction by using an empirically derived equation. See K. H. Womack, A. Butler, “Determining the complex refractive index phase offset in interferometric flying height testing,” U.S. patent5,781,299 (14July1998).

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited