ABSTRACT
Generally, for transflective liquid crystal displays with different modes and different cell gaps between the refractive and transmissive parts, precise process control to pattern the electrode and match the cell gaps may reduce the yield and thus, require high cost. This paper proposes a simple transflective liquid crystal display with a single-mode and single-cell thickness without a patterned electrode to achieve better productivity. The proposed transflective liquid crystal display consists of three half-wave retardation films, two quarter-wave retardation films, and an LC layer, whose optical performance was confirmed by both simulation and experiment. The optimal optical configuration to obtain an excellent dark state in the visible range was determined by the Mueller matrices calculus, which was applied to each optical component. The calculated and experimental results showed that the proposed transflective LC structure has excellent electro-optical properties and is expected to have many liquid crystal display applications.
ABSTRACT
It is demonstrated by numerical modeling that spectrally dispersed compound pumping diodes and low-loss pumping chamber reduced the temperature dependence of the output energy of quasi-continuous wave diode-pumped Nd:YAG lasers considerably. Several compound diodes with different spectral profiles were tested for pumping. The laser energy was calculated as a function of diode temperature from -30°C to 60°C. When a compound diode with a flat-top spectrum was used for pumping, the mean laser energy was 83% of the maximum energy of a Nd:YAG laser pumped by a diode with a narrow bandwidth. In addition, a compound diode with three emission lines was tested for pumping. When the wavelength gap between the adjacent emission lines of the pumping diode was in the range of 3-10 nm, the mean energy of the Nd:YAG laser became similar to that of a Nd:YAG laser pumped by a diode with a flat-top spectrum.
ABSTRACT
A reflective thermochromic display fabricated by a very simple method using three kinds of thermochromic pigments is produced and its thermo-optical characteristics are investigated. The display exhibits maximum red, green, and blue reflectances of 38%, 30%, and 35%, respectively. The reflective display cell shows continuous gray color with changing temperature, which is crucial for multicolor displays. It also shows an excellent viewing angle above 80° without any of the additional optical components that are required in liquid crystal displays. We expect that this display technology will be used for outdoor billboard information display applications.
ABSTRACT
We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality.
ABSTRACT
We present a single-cell gap-transflective liquid crystal display (LCD) characterized by a π cell having bulk-type liquid crystal (LC) bistability and an optical film configuration. The π cell has two stable states, which are a twisted and a nontwisted LC state. We used the twisted LC state for the reflective part connected with nonpatterned electrodes, producing a vertical field in the proposed transflective LCD. Also the nontwisted LC state was for the transmissive part with interdigitated patterned electrodes driving an in-plane field in the device. The simulated and experimental results show good electro-optical characteristics in both the reflective and transmissive parts.
ABSTRACT
We present a method that determines the actual surface azimuthal anchoring strength based on the torque balance. It is found by an optical technique of measuring simultaneously the cell thicknesses and twist angles at two regions of a wedge-type liquid crystal cell whose cell thickness varies continuously between different positions in the cell.
ABSTRACT
We developed a diode-pumped high-average-power Nd:YAG green laser. By use of a monolithic diffusive reflector having three slits and a rod with low doping concentration, uniform distribution of excited Nd ions could be achieved. Uniform distribution in the rod reduced thermal birefringence. We employed a Z-shaped cavity to have a constant beam size at the frequency-doubling crystal independent of thermal lensing in the rod. The pulse width and green power dependence on the pump power were analyzed. A maximum green power of 101 W was obtained when the total pump power was 398 W. The optical-to-optical conversion efficiency was as high as 25.4%.
