Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Integral Imaging System Enabling Enhanced Depth of Field Incorporating a Birefringent Liquid Crystal Lens Array

복굴절 특성을 갖는 액정 렌즈어레이를 이용한 깊이감이 향상된 집적영상 시스템

  • Park, Chan-Kyu (Department of Electronic Engineering, Kwangwoon University) ;
  • Hwang, Yong-Seok (Department of Electronic Engineering, Kwangwoon University) ;
  • Lee, Sang-Shin (Department of Electronic Engineering, Kwangwoon University)
  • Published : 2008.12.31
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Abstract

An integral imaging system enabling enhanced depth of field by incorporating a pair of liquid-crystal (LC) lens arrays was proposed and demonstrated. The lens arrays exhibit two different refractive indexes depending on the light polarization. The proposed LC lens array I and II were implemented by depositing a ZLI-4119 LC and an E-7 LC, respectively, on top of a lens-array substrate in glass. When the two LC lens arrays were aligned appropriately, a birefringence was obtained for a specific light polarization in such a way that the incoming light sees different refractive indexes for them. As a result, the focal length associated with the imaging system utilizing the LC lens arrays was adaptively varied, thereby enhancing the depth of field for the image reconstruction. We have theoretically analyzed the proposed integral imaging system with the $LightTools^{(R)}$ to confirm that the focal length could be adjusted with the help of the birefringent lens array. Finally the proposed imaging system successfully reconstructed the objects. The birefringent lens array employing the ZLI-4119 LC produced a real image with the focal length of 680 mm, while the other using the E-7 LC yielded a virtual image with the focal length of -29 mm.

본 논문에서는 집적영상의 문제점인 깊이감 제한 문제를 해결하기 위해서 편광된 광과 복굴절 매질인 액정 렌즈어레이를 이용한 집적영상 시스템을 제안하고 구현하였다. 제안된 렌즈어레이는 두 개의 유리 렌즈어레이 위에 서로 다른 ZLI-4119와 E-7 액정을 증착하여 구현하였다. 액정은 편광 방향에 따라서 굴절률이 서로 다르기 때문에 두 개의 중심깊이 평면을 얻을 수 있다. 이로 인하여 초점 영역의 변화를 얻을 수 있으며 이로 인해 복원 시 깊이감을 향상시킬 수 있다. $LightTools^{(R)}$ 프로그램을 이용하여 집적영상 시스템을 구현하였고, 굴절률 차에 의한 초점거리 변화를 확인하였다. 액정 디스플레이 공정을 이용하여 소자를 제작하였고, 광학 실험을 통하여 초점거리의 변화를 측정하였다. ZLI-4119 액정 렌즈어레이의 굴절률은 기본 렌즈어레이의 굴절률보다 작기 때문에 실상이 맺히게 되고, 초점거리는 약 680 mm였다. 반면에 E-7 액정 렌즈어레이의 경우에는 허상이 맺히게 되고, 이론적인 초점거리는 -29 mm였다.

Keywords

References

  1. G. Lippmann, “La photograhie integrale,” Compt. -Rend. Acad. Sci., vol. 146, pp. 446-451, 1908
  2. F. Okano, H. Hoshino, J. Arai, and I. Yuyama, “Real-time pickup method for a three-dimensional image based on integral photography,” Appl. Opt., vol. 36, no. 7, pp. 1598-1603, 1997 https://doi.org/10.1364/AO.36.001598
  3. N. Davies, M. McCormick, and L. Yang, “Three-dimensional imaging systems: a new development,” Appl. Opt., vol. 27, no. 21, pp. 4520-4528, 1988 https://doi.org/10.1364/AO.27.004520
  4. B. Lee, S, Jung, and J.-H Park, “Viewing-angle-enhanced integral imaging by lens switching,” Opt. Lett., vol. 27, no. 10, pp. 818-820, 2002 https://doi.org/10.1364/OL.27.000818
  5. Y. Kim, J. Park, H. Choi, J. Kim, S. Cho, and B. Lee, “Depth-enhanced three- dimensional integral imaging by use of multilayered display devices,” Appl. Opt., vol. 45, no. 18, pp. 4334-4343, 2006 https://doi.org/10.1364/AO.45.004334
  6. J. Park, S. Jung, H. Choi, and B. Lee, “Integral imaging with multiple image planes using a uniaxial crystal plate,” Opt. Exp., vol. 11, no. 16, pp. 1862-1875, 2003 https://doi.org/10.1364/OE.11.001862
  7. Y. Kim, H. Choi, J. Kim, S.-W. Cho, Y. Kim, G. Park, and B. Lee, “Depth-enhanced integral imaging display system with electrically variable image planes using polymer-dispersed liquid crystal layers,” Appl. Opt., vol. 46, no. 18, pp. 3766-3773, 2007 https://doi.org/10.1364/AO.46.003766
  8. C. K. Park, Y. S. Hwang, and S. S. Lee, “Integral imaging system with enhanced depth of field using birefringence lens array,” Proc. IMID, vol. 8, pp. 1135-1137, 2008
  9. J. Lee, S. Kim, and E. Kim, “Reconstruction of a threedimensional object and system analysis using ray tracing in practical integral imaging system,” Proc. SPIE, vol. 6695, pp. 19-27, 2007 https://doi.org/10.1117/12.733361
  10. Y. S. Hwang, T. H. Yoon, J. C. Kim, “Design and fabrication of variable focusing lens arrays using liquid crystal for integral photography,” Jpn. J. Appl. Phys., vol. 42, no. 5, pp. 6434-6440, 2003 https://doi.org/10.1143/JJAP.42.6434