Abstract

A new method for measuring the multiple parameters of a twisted nematic liquid crystal (TNLC) by applying a genetic algorithm is presented. This paper adopts an electrooptic modulator to modulate the linear polarized light which passed through a TNLC cell in a heterodyne polarimetric setup. The intensity ratio and the phase of the detected heterodyne signal are used for the inverse calculation in the LC cell parameters by applying a genetic algorithm approach. As a result, the multiparameter measurements in the entrance director angle of TNLC, twist angle, and cell thickness are achieved. The advantage of the heterodyne polarimeter introduces high sensitivity on intensity and phase detections, and the multiple parameters could be easily extracted through the genetic algorithm. Also, the ambiguity in the angle extraction could be uniquely solved in this paper. The experimental results show that the average deviation of 0.01° and 0.013 µm in the measurement of twist angle and cell thickness, respectively, have been obtained. The average deviation of 0.23° in the measurement of director angle has also been achieved.

© 2007 IEEE

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  1. Y. Zhou, Z. He, S. Sato, "A novel method determining the cell thickness and twist angle of a twisted nematic cell by Stokes parameter measurement," Jpn. J. Appl. Phys. 36, 2760-2764 (1997).
  2. S. H. Lee, W. S. Park, G. D. Lee, K. Y. Han, T. H. Yoon, J. C. Kim, "Low-cell-gap measurement by rotation of a wave retarder," Jpn. J. Appl. Phys. 1, Regul. Rap. Short Notes 41, 379-383 (2002).
  3. J. S. Gwag, K. H. Park, G. D. Lee, T. H. Yoon, J. C. Kim, "Simple cell gap measurement method for twisted-nematic liquid crystal cells," Jpn. J. Appl. Phys. 2, Lett. 43, L30 (2004).
  4. S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry ," J. Appl. Phys. 89, 80-85 (2001).
  5. J. S. Gwag, S. H. Lee, K. Y. Han, J. C. Kim, T. H. Yoon, "Novel cell gap measurement method for a liquid crystal cell," Jpn. J. Appl. Phys. 2, Lett. 41, L79-L82 (2002).
  6. J. S. Chae, S. G. Moon, "Cell parameter measurement of a twisted-nematic liquid crystal cell by the spectroscopic method ," J. Appl. Phys. 95, 3250-3254 (2004).
  7. Y. Zhou, Z. He, S. Sato, "An improved stokes parameter method for determination of the cell thickness and twist angle of TNLC cell," Jpn. J. Appl. Phys. 37, 2567-2571 (1998).
  8. V. Duran, J. Lancis, E. Tajahuerce, "Cell parameter determination of a twisted-nematic liquid crystal display by single-wavelength polarimetry," J. Appl. Phys. 97, 043101 (2005).
  9. M. Kawamura, Y. Goto, S. Sato, "Two-dimensional measurements of cell parameter distributions in reflective liquid crystal displays by using multiple wavelengths Stokes parameters," J. Appl. Phys. 95, 4371-4375 (2004).
  10. M. Kawamura, Y. Goto, S. Sato, "A two-dimensional pretilt angle distribution measurement of twisted nematic liquid crystal cells using stokes parameters at plural wavelengths," Jpn. J. Appl. Phys. 43, 709-714 (2004).
  11. H. B. Serreze, R. B. Goldner, "A phase-sensitive technique for measuring small birefringence changes," Rev. Sci. Instrum. 45, 1613-1614 (1974).
  12. Y. Shindo, H. Hanabusa, "Highly sensitive instrument for measuring optical birefringence," Polym. Commun. 24, 240-244 (1983).
  13. M. H. Chiu, C. D. Chen, D. C. Su, "Method for determining the fast axis and phase retardation of a wave plate," J. Opt. Soc. Amer. A, Opt. Image Sci. 13, 1924-1929 (1996).
  14. A. Márquez, M. Yamauchi, J. A. Davis, D. J. Franich, "Phase measurement of a twist nematic liquid crystal spatial light modulator with a common-path interferometer," Opt. Commun. 190, 129-133 (2001).
  15. Y. L. Lo, J. F. Lin, S. Y. Lee, "Polariscope for the simultaneous measurements of the principal axis and phase retardation using two phase-locked extractions," Appl. Opt. 43, 6248-6254 (2004).
  16. C. C. Tsai, C. Chou, C. Y. Han, C. H. Hsieh, K. Y. Liao, Y. F. Chao, "Determination of optical parameters of a twisted-nematic liquid crystal by phase-sensitive optical heterodyne interferometric ellipsometry," Appl. Opt. 44, 7509-7514 (2005).
  17. D. E. Goldberg, Genetic Algorithms in Search, Optimization and Machine Learning (Addison-Wesley, 1989).
  18. Y. L. Lo, T. C. Yu, "A polarimetric glucose sensor using a liquid crystal polarization modulator driven by a sinusoidal signal," Opt. Commun. 259, 40-48 (2006).
  19. P. Yeh, C. Gu, Optics of Liquid Crystal Displays (Wiley, 1999).
  20. Z. Michalewicz, Genetic algorithms + Data structures = Evolution Programs (Springer-Verlag, 1992).
  21. H. C. Cheng, Y. L. Lo, "Arbitrary strain distribution measurement using a genetic algorithm approach and two fiber Bragg grating intensity spectra," Opt. Commun. 239, 323-332 (2004).
  22. H. C. Cheng, Y. L. Lo, "The synthesis of multiple parameters of arbitrary FBGs via a genetic algorithm, and two thermally modulated intensity," J. Lightw. Technol. 23, 2158-2168 (2005).

2006

Y. L. Lo, T. C. Yu, "A polarimetric glucose sensor using a liquid crystal polarization modulator driven by a sinusoidal signal," Opt. Commun. 259, 40-48 (2006).

2005

H. C. Cheng, Y. L. Lo, "The synthesis of multiple parameters of arbitrary FBGs via a genetic algorithm, and two thermally modulated intensity," J. Lightw. Technol. 23, 2158-2168 (2005).

V. Duran, J. Lancis, E. Tajahuerce, "Cell parameter determination of a twisted-nematic liquid crystal display by single-wavelength polarimetry," J. Appl. Phys. 97, 043101 (2005).

C. C. Tsai, C. Chou, C. Y. Han, C. H. Hsieh, K. Y. Liao, Y. F. Chao, "Determination of optical parameters of a twisted-nematic liquid crystal by phase-sensitive optical heterodyne interferometric ellipsometry," Appl. Opt. 44, 7509-7514 (2005).

2004

Y. L. Lo, J. F. Lin, S. Y. Lee, "Polariscope for the simultaneous measurements of the principal axis and phase retardation using two phase-locked extractions," Appl. Opt. 43, 6248-6254 (2004).

J. S. Chae, S. G. Moon, "Cell parameter measurement of a twisted-nematic liquid crystal cell by the spectroscopic method ," J. Appl. Phys. 95, 3250-3254 (2004).

M. Kawamura, Y. Goto, S. Sato, "Two-dimensional measurements of cell parameter distributions in reflective liquid crystal displays by using multiple wavelengths Stokes parameters," J. Appl. Phys. 95, 4371-4375 (2004).

M. Kawamura, Y. Goto, S. Sato, "A two-dimensional pretilt angle distribution measurement of twisted nematic liquid crystal cells using stokes parameters at plural wavelengths," Jpn. J. Appl. Phys. 43, 709-714 (2004).

J. S. Gwag, K. H. Park, G. D. Lee, T. H. Yoon, J. C. Kim, "Simple cell gap measurement method for twisted-nematic liquid crystal cells," Jpn. J. Appl. Phys. 2, Lett. 43, L30 (2004).

H. C. Cheng, Y. L. Lo, "Arbitrary strain distribution measurement using a genetic algorithm approach and two fiber Bragg grating intensity spectra," Opt. Commun. 239, 323-332 (2004).

2002

S. H. Lee, W. S. Park, G. D. Lee, K. Y. Han, T. H. Yoon, J. C. Kim, "Low-cell-gap measurement by rotation of a wave retarder," Jpn. J. Appl. Phys. 1, Regul. Rap. Short Notes 41, 379-383 (2002).

J. S. Gwag, S. H. Lee, K. Y. Han, J. C. Kim, T. H. Yoon, "Novel cell gap measurement method for a liquid crystal cell," Jpn. J. Appl. Phys. 2, Lett. 41, L79-L82 (2002).

2001

A. Márquez, M. Yamauchi, J. A. Davis, D. J. Franich, "Phase measurement of a twist nematic liquid crystal spatial light modulator with a common-path interferometer," Opt. Commun. 190, 129-133 (2001).

S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry ," J. Appl. Phys. 89, 80-85 (2001).

1998

Y. Zhou, Z. He, S. Sato, "An improved stokes parameter method for determination of the cell thickness and twist angle of TNLC cell," Jpn. J. Appl. Phys. 37, 2567-2571 (1998).

1997

Y. Zhou, Z. He, S. Sato, "A novel method determining the cell thickness and twist angle of a twisted nematic cell by Stokes parameter measurement," Jpn. J. Appl. Phys. 36, 2760-2764 (1997).

1996

M. H. Chiu, C. D. Chen, D. C. Su, "Method for determining the fast axis and phase retardation of a wave plate," J. Opt. Soc. Amer. A, Opt. Image Sci. 13, 1924-1929 (1996).

1983

Y. Shindo, H. Hanabusa, "Highly sensitive instrument for measuring optical birefringence," Polym. Commun. 24, 240-244 (1983).

1974

H. B. Serreze, R. B. Goldner, "A phase-sensitive technique for measuring small birefringence changes," Rev. Sci. Instrum. 45, 1613-1614 (1974).

Appl. Opt.

J. Appl. Phys.

J. S. Chae, S. G. Moon, "Cell parameter measurement of a twisted-nematic liquid crystal cell by the spectroscopic method ," J. Appl. Phys. 95, 3250-3254 (2004).

S. T. Tang, H. S. Kwok, "Transmissive liquid crystal cell parameters measurement by spectroscopic ellipsometry ," J. Appl. Phys. 89, 80-85 (2001).

V. Duran, J. Lancis, E. Tajahuerce, "Cell parameter determination of a twisted-nematic liquid crystal display by single-wavelength polarimetry," J. Appl. Phys. 97, 043101 (2005).

M. Kawamura, Y. Goto, S. Sato, "Two-dimensional measurements of cell parameter distributions in reflective liquid crystal displays by using multiple wavelengths Stokes parameters," J. Appl. Phys. 95, 4371-4375 (2004).

J. Lightw. Technol.

H. C. Cheng, Y. L. Lo, "The synthesis of multiple parameters of arbitrary FBGs via a genetic algorithm, and two thermally modulated intensity," J. Lightw. Technol. 23, 2158-2168 (2005).

J. Opt. Soc. Amer. A, Opt. Image Sci.

M. H. Chiu, C. D. Chen, D. C. Su, "Method for determining the fast axis and phase retardation of a wave plate," J. Opt. Soc. Amer. A, Opt. Image Sci. 13, 1924-1929 (1996).

Jpn. J. Appl. Phys.

Y. Zhou, Z. He, S. Sato, "An improved stokes parameter method for determination of the cell thickness and twist angle of TNLC cell," Jpn. J. Appl. Phys. 37, 2567-2571 (1998).

M. Kawamura, Y. Goto, S. Sato, "A two-dimensional pretilt angle distribution measurement of twisted nematic liquid crystal cells using stokes parameters at plural wavelengths," Jpn. J. Appl. Phys. 43, 709-714 (2004).

Y. Zhou, Z. He, S. Sato, "A novel method determining the cell thickness and twist angle of a twisted nematic cell by Stokes parameter measurement," Jpn. J. Appl. Phys. 36, 2760-2764 (1997).

Jpn. J. Appl. Phys. 1, Regul. Rap. Short Notes

S. H. Lee, W. S. Park, G. D. Lee, K. Y. Han, T. H. Yoon, J. C. Kim, "Low-cell-gap measurement by rotation of a wave retarder," Jpn. J. Appl. Phys. 1, Regul. Rap. Short Notes 41, 379-383 (2002).

Jpn. J. Appl. Phys. 2, Lett.

J. S. Gwag, K. H. Park, G. D. Lee, T. H. Yoon, J. C. Kim, "Simple cell gap measurement method for twisted-nematic liquid crystal cells," Jpn. J. Appl. Phys. 2, Lett. 43, L30 (2004).

J. S. Gwag, S. H. Lee, K. Y. Han, J. C. Kim, T. H. Yoon, "Novel cell gap measurement method for a liquid crystal cell," Jpn. J. Appl. Phys. 2, Lett. 41, L79-L82 (2002).

Opt. Commun.

A. Márquez, M. Yamauchi, J. A. Davis, D. J. Franich, "Phase measurement of a twist nematic liquid crystal spatial light modulator with a common-path interferometer," Opt. Commun. 190, 129-133 (2001).

Y. L. Lo, T. C. Yu, "A polarimetric glucose sensor using a liquid crystal polarization modulator driven by a sinusoidal signal," Opt. Commun. 259, 40-48 (2006).

H. C. Cheng, Y. L. Lo, "Arbitrary strain distribution measurement using a genetic algorithm approach and two fiber Bragg grating intensity spectra," Opt. Commun. 239, 323-332 (2004).

Polym. Commun.

Y. Shindo, H. Hanabusa, "Highly sensitive instrument for measuring optical birefringence," Polym. Commun. 24, 240-244 (1983).

Rev. Sci. Instrum.

H. B. Serreze, R. B. Goldner, "A phase-sensitive technique for measuring small birefringence changes," Rev. Sci. Instrum. 45, 1613-1614 (1974).

Other

P. Yeh, C. Gu, Optics of Liquid Crystal Displays (Wiley, 1999).

Z. Michalewicz, Genetic algorithms + Data structures = Evolution Programs (Springer-Verlag, 1992).

D. E. Goldberg, Genetic Algorithms in Search, Optimization and Machine Learning (Addison-Wesley, 1989).

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