• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.281-287
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• 2009

The optical anisotropy of rubbed PI(polyimide) film on patterned LCD glass substrate is analyzed using polarimetry. The direction of the optic axis and the magnitude of the very small retardation ($\sim$ 0.4 nm or less) is precisely measured by using a transmission ellipsometer. The variation of the optical anisotropy is presented as the curve of the optic axis versus the magnitude of the phase retardation and it is explained by using a simple optical model.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.248-249
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• 2002

The gaseous molecular condensation retardation by laser excitation has been known, but with limited success. Condensation inhibition between the gas phase molecules by laser excitation was clearly shown in many experiments.(1)-(2) However, surface condensation inhibition of the excited molecules has been controversial for the last several decades.(3)-(4) In 1994, S. J, Sibener and Y. T. Lee published an experimental evidence of the internal energy dependence of the surface condensation of gaseous $SF_{6}$ and $CCl_4$ molecules. (omitted)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.140-141
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• 2001

반사형 STN-LCD (supertwisted nematic liquid crystal display) 는 많은 display에서 사용되고 있는 LCD mode 중의 하나이다. 그러나 현재 많이 사용되는 반사형 STN-LCD는 그림 1과 같이 한 장의 polarizer와 두장의 retardation film을 사용하는 구조이므로 각각의 component에 대한 parameter들에 의해 display의 표시 성능이 좌우된다. 먼저 Reflective STN-LCD의 보상에 필요한 parameter를 살펴보면, 그림 1과 같이 5개 ( $\alpha$, ø$_1$, ø$_2$, 각 retarder의 retardation : Δnd$_1$, Δnd$_2$)의 parameter의 결정이 필요하다. (중략)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.209-212
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• 2012

In this paper, we have studied on the optimal design of the optical compensation film for the TN-LCDs. To have wide viewing angle panels, several methods such as multi-domain method, optical path method, and phase compensation method have been proposed. Among these methods, this paper focused on the phase compensation method. In the phase compensation method, the phase retardation generated from the optical birefringence for the off-axis incident is compensated by using optical films with refractive anisotropy. To compensate the phase retardation of the TN-LCDs, we have proposed design concept for the biaxial optical films and analyzed the optical performance for the proposed structures. The calculation of the dynamic motion of the liquid crystals was based on the Ericksen-Leslie theory and the optical performance of the TN-LCD was calculated from the Extended Jones Matrix Method. From the results, we have confirmed that the optical characteristics of the TN-LCDs with the biaxial films have been improved considerably compared with the TN-LCDs compensated by the combination of the uniaxial films.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.828-834
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• 2005

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in optical plastic parts using R-G-B separation of white light. The main idea of an analysis comes from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. A complete system to give the quantitative values of retardation covering high order 2-D birefringence will be demonstrated. Further investigation is under way to improve the accuracy of the system using diodes as light sources.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.290-293
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• 2004

Recently, injection molded plastic optical products are widely used, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique measuring birefringence in optical plastic parts using R-G-B separation of white light. The main idea of an analysis comes from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. A complete system to give the quantitative values of retardation covering high order 2-D birefringence will be demonstrated. Further investigation is under way to improve the accuracy of the system using diodes as light sources.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.47-48
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• 2000

Parameters of a biaxial compensation film and a liquid crystal cell for the optically compensated bend mode LCD with wide viewing angle were optimized. For practical approach, we calculated the optical refractive indices of a retardation film when thickness of a retardation film was fixed at 50 ${\mu}m$. Furthermore, we also optimized optical parameters of LC cell when parameters of a retardation film were different with designed values, because the biaxial compensation film with exact designed values was very difficult to fabricate. In experiments, we achieved the wide viewing angle of over the ${\pm}$ 60 degrees by using a biaxial compensation film with a practical thickness value.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.430-432
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• 2005

Although color characteristics of IPS mode are much better than TN or VA mode, there still remains a room for improvement of the color characteristics of IPS mode compared with the conventional CRT. It has been generally as sumed that inherent color variation of IPS mode is entirely owing to dependence of the effective retardation on wavelength and role of optical axis of IPS mode has been little considered. In this study, we investigated the effects of driving voltages on the effective retardation and the effective optical axis by a computer simulation. The result shows that rotation of effective optical axis is dependent on wavelength and tends to be smaller for larger wavelength.

• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.288-293
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• 2009

Polarization characteristics of a composite film composed of two optically anisotropic films are analyzed. The procedure to determine the effective optics axis and the equivalent retardation of the composite film is suggested in conjuction with the related ellipsometric expressions. The explicit expressions of the effective optic axis and the equivalent retardation of a non-uniform anisotropic film are derived when all optic axes are parallel. Those expressions of the composite film where optic axes of two constituting anisotropic films are not parallel are also derived. Dependence of those expressions on the polarization state of the incident light or the azimuth angle of the linearly polarized light and their limit when applied to practical use are discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.20-21
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• 2009