OSA's Digital Library

Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Vol. 41, Iss. 22 — Aug. 1, 2002
  • pp: 4497–4502

Digital Hilbert Transformation for Separation Measurement of Thicknesses and Refractive Indices of Layered Objects by Use of a Wavelength-Scanning Heterodyne Interference Confocal Microscope

Yuuki Watanabe and Ichirou Yamaguchi  »View Author Affiliations


Applied Optics, Vol. 41, Issue 22, pp. 4497-4502 (2002)
http://dx.doi.org/10.1364/AO.41.004497


View Full Text Article

Acrobat PDF (955 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

A wavelength-scanning heterodyne interference confocal microscope quickly accomplishes the simultaneous measurement of the thickness and the refractive index of a sample by detection of the amplitude and the phase of the interference signal during a sample scan. However, the measurement range of the optical path difference (OPD) that is obtained from the phase changes is limited by the time response of the phase-locked loop circuit in the FM demodulator. To overcome this limitation and to improve the accuracy of the separation measurement, we propose an OPD detection using digital signal processing with a Hilbert transform. The measurement range is extended approximately five times, and the resolution of the OPD is improved to 5.5 from 9 μm without the electrical noise of the FM demodulator circuit. By applying this method for simultaneous measurement of thickness and the refractive index, we can measure samples 20–30-μm thick with refractive indices between 1 and 1.5.

© 2002 Optical Society of America

OCIS Codes
(040.2840) Detectors : Heterodyne
(110.6960) Imaging systems : Tomography
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(180.1790) Microscopy : Confocal microscopy

Citation
Yuuki Watanabe and Ichirou Yamaguchi, "Digital Hilbert Transformation for Separation Measurement of Thicknesses and Refractive Indices of Layered Objects by Use of a Wavelength-Scanning Heterodyne Interference Confocal Microscope," Appl. Opt. 41, 4497-4502 (2002)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-41-22-4497


Sort:  Author  |  Year  |  Journal  |  Reset

References

  1. T. Fukano and I. Yamaguchi, “Simultaneous measurement of thicknesses and refractive indices of multiple layers by a low-coherence confocal interference microscope,” Opt. Lett. 21, 1942–1944 (1996).
  2. M. Haruna, M. Ohmi, T. Mitsuyama, H. Tajiri, H. Maruyama, and M. Hashimoto, “Simultaneous measurement of the phase and group indices and the thickness of transparent plates by low-coherence interferometry,” Opt. Lett. 23, 966–968 (1998).
  3. K. Yoden, M. Ohmi, Y. Ohnishi, N. Kunizawa, and M. Haruna, “An approach to optical reflection tomography along the geometrical thickness,” Opt. Rev. 7, 402–405 (2000).
  4. T. Fukano and I. Yamaguchi, “Separation of measurement of the refractive index and the geometrical thickness by use of a wavelength-scanning interferometer with a confocal microscope,” Appl. Opt. 38, 4065–4073 (1999).
  5. T. Fukano and I. Yamaguchi, “Geometrical cross-sectional imaging by a heterodyne wavelength-scanning interference confocal microscope,” Opt. Lett. 25, 548–550 (2000).
  6. G. J. Tearney, M. E. Brezinski, J. F. Southern, B. E. Bouma, M. R. Hee, and J. G. Fujimoto, “Determination of the refractive index of highly scattering human tissue by optical coherence tomography,” Opt. Lett. 20, 2258–2260 (1995).
  7. M. Ohmi, Y. Ohnishi, K. Yoden, and M. Haruna, “In vitro simultaneous measurement of refractive index and thickness by low coherence interferometry,” IEEE Trans. Biomed. Eng. 47, 1266–1270 (2000).
  8. A. Knüttel and M. Boehlau-Godau, “Spatially confined and temporally resolved refractive index and scattering evaluation in human skin performed with optical coherence tomography,” J. Biomed. Opt. 5, 83–92 (2000).
  9. Y. Watanabe and I. Yamaguchi, “Geometrical tomographic imaging of refractive indices through turbid media by wavelength-scanning heterodyne interference confocal microscope,” Appl. Opt. 41, 2414–2419 (2002).
  10. A. J. den Boef, “Interferometric laser rangefinder using a frequency modulated diode laser,” Appl. Opt. 26, 4545–4550 (1987).
  11. O. Sasaki, T. Yoshida, and T. Suzuki, “Double sinusoidal phase-modulating laser diode interferometer for distance measurement,” Appl. Opt. 30, 3617–3621 (1991).
  12. M. Suematsu and M. Takeda, “Wavelength-shift interferometry for distance measurements using the Fourier transform technique for fringe analysis,” Appl. Opt. 30, 4046–4055 (1991).
  13. Y. Zhao, Z. Chen, C. Saxer, S. Xiang, J. F. de Boer, and J. S. Nelson, “Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning and high velocity sensitivity,” Opt. Lett. 25, 114–116 (2000).
  14. M. Sticker, C. K. Hitzenberger, R. Leitgeb, and A. F. Fercher, “Quantitative differential phase measurement and imaging in transparent and turbid media by optical coherence tomography,” Opt. Lett. 26, 518–520 (2001).
  15. T. Wilson, Confocal Microscopy (Academic, New York, 1990).
  16. H. Kikuta, K. Iwata, and R. Nagata, “Distance measurement by the wavelength shift of laser diode light,” Appl. Opt. 25, 2976–2980 (1986).
  17. E. Fischer, E. Dalhoff, S. Heim, U. Hofbauer, and H. J. Tiziani, “Absolute interferometric distance measurement using a FM-demodulation technique,” Appl. Opt. 34, 5589–5594 (1995).

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