TY - JOUR
T1 - A highly phase-sensitive heterodyne polariscope for the full-field measurement of twisted-nematic liquid crystal
AU - Yu, Tsung Chih
AU - Lo, Yu Lung
N1 - Funding Information:
Manuscript received July 17, 2008. First published August 22, 2008; current version published October 15, 2008. This work was supported by the National Science Council, Taiwan, under Grant NSC96-2628-E-006-005-MY3. The authors are with the Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (e-mail: [email protected]). Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LPT.2008.2004677
PY - 2008
Y1 - 2008
N2 - This study proposes a highly phase-sensitive imaging polariscope with a common-path heterodyne configuration for the mapping of spatially distributed cell gap of a twisted-nematic liquid crystal (TNLC). The polariscope adopts an electrooptic modulator incorporated with a quarter-wave plate to modulate the linear polarized light. By applying an integrating-bucket method, the two-dimensional (2-D) phase distribution of the detected heterodyne signal is extracted for the inverse calculation of the TNLC cell thickness. The proposing system has no need to remove or to rotate any optical elements in the measuring process and makes it possible to perform high-speed 2-D mapping. The dynamic range of retardation is around 0.7 μm without ambiguity in the proposing method. By using a standard 8-bit gray level charged-coupled device (CCD), the experimental result shows that the standard deviation of 1.8 nm in the 2-D measurement of cell thickness has been obtained. The retardation resolution of 0.5 nm of the proposed method is also achieved and is better than that of the Stokes parameters determination method with high gray level CCD.
AB - This study proposes a highly phase-sensitive imaging polariscope with a common-path heterodyne configuration for the mapping of spatially distributed cell gap of a twisted-nematic liquid crystal (TNLC). The polariscope adopts an electrooptic modulator incorporated with a quarter-wave plate to modulate the linear polarized light. By applying an integrating-bucket method, the two-dimensional (2-D) phase distribution of the detected heterodyne signal is extracted for the inverse calculation of the TNLC cell thickness. The proposing system has no need to remove or to rotate any optical elements in the measuring process and makes it possible to perform high-speed 2-D mapping. The dynamic range of retardation is around 0.7 μm without ambiguity in the proposing method. By using a standard 8-bit gray level charged-coupled device (CCD), the experimental result shows that the standard deviation of 1.8 nm in the 2-D measurement of cell thickness has been obtained. The retardation resolution of 0.5 nm of the proposed method is also achieved and is better than that of the Stokes parameters determination method with high gray level CCD.
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U2 - 10.1109/LPT.2008.2004677
DO - 10.1109/LPT.2008.2004677
M3 - Article
AN - SCOPUS:77953126947
SN - 1041-1135
VL - 20
SP - 1778
EP - 1780
JO - IEEE Photonics Technology Letters
JF - IEEE Photonics Technology Letters
IS - 21
ER -