Current Optics and Photonics

  • 제1권6호
  • /
  • Pages.604-612
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  • 2017
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  • 2508-7266(pISSN)
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  • 2508-7274(eISSN)
한국광학회 (Optical Society of Korea)
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Accurate Roughness Measurement Using a Method for Evaluation and Interpolation of the Validity of Height Data from a Scanning White-light Interferometer

  • Kim, Namyoon (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Lee, Seung Woo (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • I, Yongjun (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Pahk, Heui-Jae (School of Mechanical and Aerospace Engineering, Seoul National University)
  • 투고 : 2017.08.07
  • 심사 : 2017.10.27
  • 발행 : 2017.12.25
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초록

An effective and precise method using a scanning white-light interferometer (SWLI) for three-dimensional surface measurements, in particular for roughness measurements, has been proposed. The measurement of a microscopically sloped area using an interferometer has limitations, due to the numerical aperture of the lens. In particular, for roughness measurements, it is challenging to obtain accurate height data for a sloped area using the interferometer, due to diffraction of the light. Owing to these optical limitations of the interferometer for roughness measurements, the Ra measurements performed using an interferometer contain errors. To overcome the limitations, we propose a method consisting of the following two steps. First, we evaluate the height data and set the invalid height area to be blank, using the characteristics of the modulus peak, which has a low peak value for signals that have low reliability in the interferogram. Next, we interpolate the blank area using the adjacent reliable area. Rubert roughness standards are used to verify the proposed method. The results obtained by the proposed method are compared to those obtained with a stylus profilometer. For the considered sinusoidal samples, Ra ranges from $0.053{\mu}m$ to $6.303{\mu}m$, and we show that the interpolation method is effective. In addition, the method can be applied to a random surface where Ra ranges from $0.011{\mu}m$ to $0.164{\mu}m$. We show that the roughness results obtained using the proposed method agree well with profilometer results. The $R^2$ values for both sinusoidal and random samples are greater than 0.995.

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참고문헌

  1. T. C. Bristow, A. Bouzid, and J. Bietry, "Surface measurements and applications for manufactured parts using noncontact profilometer," Proc. SPIE 954, 217-226 (1989).
  2. B. Bowe, "White light interferometric surface profiler," Opt. Eng. 37, 1796 (1998). https://doi.org/10.1117/1.601727
  3. P. de Groot and L. Deck, "Surface profiling by analysis of white-light interferograms in the spatial frequency domain," J. Mod. Opt. 42, 389-401 (1995). https://doi.org/10.1080/09500349514550341
  4. K. Creath and J. C. Wyant, "Absolute measurement of surface roughness," Appl. Opt. 29, 3823-3827 (1990). https://doi.org/10.1364/AO.29.003823
  5. P. J. Caber, "Interferometric profiler for rough surfaces," Appl. Opt. 32, 3438 (1993). https://doi.org/10.1364/AO.32.003438
  6. R. Windecker and H. J. Tiziani, "Optical roughness measurements using extended white-light interferometry," Opt. Eng. 38, 1081-1087 (1999). https://doi.org/10.1117/1.602154
  7. F. Gao and R. Leach, "Surface measurement errors using commercial scanning white light interferometers," Meas. Sci. Technol. 19, 13 (2008).
  8. D. Malacara, Optical Shop Testing (John Wiley & Sons, 2007), Vol. 59.
  9. H.-G. Rhee, Y.-W. Lee, I.-W. Lee, and T. V. Vorburger, "Roughness measurement performance obtained with optical interferometry and stylus method," J. Opt. Soc. Korea 10, 48-54 (2006). https://doi.org/10.3807/JOSK.2006.10.1.048
  10. V. G. Badami, J. Liesener, C. J. Evans, and P. De Groot, "Evaluation of the measurement performance of a coherence scanning microscope using roughness specimens," in Proc. ASPE Annual Meeting (Denver, CO, USA, Nov. 2011), pp. 23-26.
  11. A. Harasaki, J. Schmit, and J. C. Wyant, "Improved verticalscanning interferometry," Appl. Opt. 39, 2107-2115 (2000). https://doi.org/10.1364/AO.39.002107
  12. K. G. Larkin, "Efficient nonlinear algorithm for envelope detection in white light interferometry," J. Opt. Soc. Am. A 13, 832 (1996). https://doi.org/10.1364/JOSAA.13.000832
  13. DE BOOR, Carl, A practical guide to splines (New York: Springer-Verlag, 1978).