机械工程学报

WANG Wei

LAI Wuxing

SHI Tielin
School of Mechanical Science and Engineering,
Huazhong University of Science and Technology,
Wuhan 430074, China

TAO Wei

CHENG Xinjian
Tribology & Mechanical
Characterization Division,
SAE Magnetics (H.K.) Ltd.,
Dongguan 523087, China

LOW FLYING HEIGHT MEASUREMENT WITH MULTI-WAVELENGTH INTERFEROMETRY*

Abstract: A method for measurement of ultra-low flying height in head-disk spacing is described. Three different wavelengths are selected out from white light by filters to measure the spacing simultaneously. Besides solving the ambiguity problem, a more reliable result is achieved by using weighted average of measurement results from three different wavelengths, where the weight is dependent upon spacing. Fringe-bunching correction algorithm (FBC) and spot-tilling technique are adopted to suppress calibration and random errors. Moreover, incident bandwidth correction (IBC) method is introduced to compensate the error caused by low monochromaticity of incident light. Based on dynamic flying height tester (DFHT II), with the redesigned of photo-electric conversion and signal acquirement module, an instrument has been developed. And comparing the experimental data from the instrument with those from a KLA-FHT D6, the discrepancy is less than 5%. It indicates that the instrument is suitable to perform ultra-low flying height measurement and satisfies the requirement of magnetic heads manufacturing.

Key words: Flying height measurement Multi-wavelength interferometry Incident bandwidth

* This project is supported by National Basic Research Program of China (973 Program, No. 2003CB716207) and National Natural Science Foundation of China (No. 50775091). Received October 10, 2007; received in revised form March 14, 2008; accepted April 18, 2008

浏览（下载）论文全文（PDF格式）

Biographical notes

WANG Wei, born in 1975, is currently a PhD candidate in School of Mechanical Science and Engineering, Huazhong University of Science and Technology, China. His research interests include technique of micro-nano measurement and machine vision.
Tel: +86-27-87792150; E-mail: alvinwang@smail.hust.edu.cn

LAI Wuxing, corresponding author, born in 1972, is currently an assistant professor in School of Mechanical Science and Engineering, Huazhong University of Science and Technology, China. He received his PhD degree from School of Mechanical Science and Engineering, Huazhong University of Science and Engineering, China, in 2002. His research interests include signal analyzing, digital image processing, MEMS testing, encapsulation testing.
Tel: +86-27-61253985; E-mail: wxlai@tom.com

SHI Tielin, born in 1964, is currently a professor, an advisor of doctoral candidate and the vice-director in School of Mechanical Science and Engineering, Huazhong University of Science and Technology, China. He received his PhD degree from School of Mechanical Science and Engineering, Huazhong University of Science and Engineering, China, in 1991. He has been engaged in the teaching and research of state monitoring and fault diagnosing, signal analyzing, artificial intelligence, specialist system, telemonitoring and diagnosing, etc, for a long time.
Tel: +86-27-87556835; E-mail: tlshi@public.wh.hb.cn

TAO Wei, born in 1972, is currently a senior engineer in Tribology & Mechanical Characterization Division, SAE Magnetics (H.K., China) Ltd., is also a master candidate in Harbin Institute of Technology, China. His research interests include technique of flying height measurement, technology innovation & management, and management information system.
Tel: +86-76922810033-2020; E-mail: taoweite@sae.com.hk

CHENG Xinjian, born in 1972, is currently a principal engineer in Tribology & Mechanical Characterization Division, SAE Magnetics (H.K., China) Ltd. His research interests include technique of flying height measurement, tribology & mechanical characterization and technology innovation & management.
Tel: +86-27-22810033-2089; E-mail: xjcheng@sae.com.hk

References

[1] DURAN C A. Error analysis of a multiwavelength dynamic flying height tester [J]. IEEE Transe. Magn., 1996, 32: 3 720-3 722.
[2] LACEY C, ROSS E W. Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings: US, 5457534[P]. 1995-10-10.
[3] MITSUYA Y, OHSHIMA Y. Error analysis of head–disk spacing measurements made by using optical interferometry[J]. ASME J. Tribol., 2001, 123: 358-362.
[4] MITSUYA Y, KAWAMOTO Y, ZHANG H, et al. Head–disk spacing measurement using Michelson laser interferometry as observed through glass disk [J]. ASME J. Tribol., 2004, 126: 360-366.
[5] KARL M H, VOLKER B, AHMED A Z. Profilometry with a multi- wavelength diode laser interferometer[J]. Meas. Sci. Technol., 2004, 15: 741-746.
[6] ZHU J, BAUGH E, TALKE F E. Simultaneous five-wavelength interferometry for head/tape spacing measurement[J]. Tribology
International, 2000, 33: 409-414.
[7] YAMAMOTO S Y, SHI R F. Flying height measurement technology below 10 nm [C]//IEEE Magnetic Recording Conference, Digest of the Asia-Pacific, 2002: TU-P-26-01-TU-P-26-02.