• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1080-1082
• /
• 2008

An ultra-thin reflective flexible LCD film has been demonstrated. The 30% thickness of the display can be reduced by applying a quarter-wave-plate film as upper substrate. A low temperature alignment material and special designed photo spacer were applied in this new display. The bending behavior was improved by reduced thickness.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.365-365
• /
• 2006

The wavelength dispersion of birefringence (or retardation) is very important property for optical use of polymer films. Birefringence free film and retardation film have been widely used for applications such as liquid crystal display (LCD). In this study, miscible polymer blends which consist of polymers of positive and negative birefringence were found. By operating composition and orientation of molecules in the transparent blend films, the behavior of wavelength dispersion of birefringence (retardation) was controlled. The applicability to wideband birefringence free film and quarter wave (retardation) film was discussed.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.6
• /
• pp.577-582
• /
• 2003

This paper describes a new technique for thickness measurement of a very thin layer less than one-quarter of the wavelength of ultrasonic wave used in the ultrasonic pulse-echo measurements. The technique determines the thickness of a thin layer in a tapered medium from constructive interference of multiple reflection waves. The interference characteristics are derived and investigated in theoretical and experimental approaches. Modified total reflection wave g(t) defined as difference between total and first reflection waves increases in amplitude as the interfacial layer thickness decreases down to zero. A layer thickness less than one-tenth of the ultrasonic wavelength is measured using the maximum amplitude of g(t) with a good accuracy and sensitivity. The method also requires no inversion process to extract the thickness information from the waveforms of reflected waves, so that it makes possible to have the on-line thickness measurement of a thin layer such as a lubricating oil film in thrust bearings and journal bearings during manufacturing process.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.292-294
• /
• 2008

We have developed new reflective LCD for Mixed twist nematic LC mode with high quality image. We have found out an optimal twist angle of LC and optical film's axis by simulation. Also we measured electro-optic characteristics for new design panel. As a result, high reflectance and wide viewing angle characteristics were achieved.

• Current Optics and Photonics
• /
• v.2 no.5
• /
• pp.474-481
• /
• 2018

We propose a polarization phase-shifting technique to investigate the thickness of $Ta_2O_5$ thin films deposited on BK7 substrates, using a modified Sagnac interferometer. Incident light is split by a polarizing beam splitter into two orthogonal linearly polarized beams traveling in opposite directions, and a quarter-wave plate is inserted into the common path to create an unbalanced phase condition. The linearly polarized light beams are transformed into two circularly polarized beams by transmission through a quarter-wave plate placed at the output of the interferometer. The proposed setup, therefore, yields rotating polarized light that can be used to extract a relative phase via the self-reference system. A thin-film sample inserted into the cyclic path modifies the output signal, in terms of the phase retardation. This technique utilizes three phase-shifted intensities to evaluate the phase retardation via simple signal processing, without manual adjustment of the output polarizer, which subsequently allows the thin film's thickness to be determined. Experimental results show that the thicknesses obtained from the proposed setup are in good agreement with those acquired by a field-emission scanning electron microscope and a spectroscopic ellipsometer. Thus, the proposed interferometric arrangement can be utilized reliably for non-contact thickness measurements of transparent thin films and characterization of optical devices.

• Korean Journal of Optics and Photonics
• /
• v.13 no.2
• /
• pp.162-165
• /
• 2002

We propose an optical configuration for a transflective display mode using a transflective film and a half-wave AFLC cell whose in-plane tilt angle is 22.5。. It provides high brightness and high contrast in the reflective mode as well as in the transmissive mode.

• Journal of the Korean Ceramic Society
• /
• v.40 no.4
• /
• pp.375-379
• /
• 2003

In this paper, a novel design of multilayer ceramic-based Transmit/Receive (T/R) switch using Low Temperature Co-fired Ceramic (LTCC) technology have been presented. Compact T/R switch has been designed by transforming quarter-wave transmission line to its lumped equivalent circuit. Especially, high-Q three dimensional inductors with double strip have been proposed and incorporated. The proposed inductor has been modeled by multi-conductor coupled lines. A measured inductor quality factor (Q) of 80 and a Self-Resonance Frequency (SRF) of 6.6 GHz have been demonstrated. The inductor library has been incorporated into the design of WCDMA T/R switch.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.9
• /
• pp.983-987
• /
• 2004

We have studied electro-optic characteristics of reflective optically compensated splay (R-OCS) cell. The initial configuration of this cell is in splay form such that a mid director lies parallel to the substrate and around it hybrid structure is formed symmetrically so the optically compensation effect exists. Optimized optical configurations could be achieved by using a single polarizer, a quarter-wave film and a cell with quarter-wane retardation. The optimal cell retardation is 0.34 ${\mu}$m, allowing to have large cell gap. The cell provides high contrast ratio of 80:1 at normal direction and the region with contrast ratio over 5:1 covert up to 160$^{\circ}$ horizontally and vertically at all wavelength range.

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.02a
• /
• pp.409-410
• /
• 2009

In this paper, we report an experimental study of a linear polarization-discriminatory state inverter made of three-layer sculpture thin film fabricated by glancing angle deposition technique. The first and third layers are quarter-wave plates of zigzag structure and the middle of them is a circular Bragg reflector of left-handed helical structure.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.905-909
• /
• 2002

Characteristics of reflective LCDs, which have gained a lot of notice in recent years, rely largely on optical design of circular polarizers and the quarter-wave plates, as a component. Important design includes wavelength dispersion, viewing angle, uniformity of display and matching of refractive index. Our work has contributed to improving performance of reflective LCDs by enhancing the characteristics of polymer film using stretching and optical lamination technologies. To design that offers higher contrast and wider viewing angle, we have discovered that it is necessary to control viewing angle variation of the polarizing axis in order to compensate for the viewing angle of the polarizing film as well as the optical anisotropic properties of liquid crystal. Applying this technology to circular polarizers used for reflective LCDs enables design of wide viewing angle circular polarizers. In order to realize higher contrast for reflective LCDs, it is also necessary to design other optical materials including polarizing films. For design of hybrid optical film, it is particularly necessary to reduce surface reflection and interface reflection. This paper also reports our findings concerning this topic.