Prism Sheets Research Articles

Time-of-flight measurement-based three-dimensional profiler system employing a lightweight Fresnel-type Risley prism scanner

A time-of-flight measurement-based three-dimensional (3D) profiler system employing a lightweight scanning system is demonstrated. To reduce the weight of the scanning system, and thereby achieve faster scanning speeds, two Fresnel prism sheets were employed as the scanning optics and installed to work as a pair of Risley prisms. Each Fresnel prism sheet has a diameter of 102 mm and mass of 15 g, which is about 12 times lighter than ordinary bulky prism. By scanning the laser beam with the developed scanning system, a 3D point cloud image of a target object located 8 m away could be successfully obtained. The image distortion was removable by correcting six geometrical parameters of the scanner using a simple optimization algorithm. It was confirmed by the experiment that once the distortion has been corrected, it is valid for other scanning speeds (and trajectories), enabling 3D profile measurements that do not require postprocessing of measured data. Measurement results for a standard target composed of square extrusions were in good agreement with the reference values, with deviations of <1 mm.

A theoretical analysis on sensitivity improvement of an SPR refractive index sensor with graphene and barium titanate nanosheets

The sensitivity of the surface plasmons resonance (SPR) refractive index sensor is investigated using angle interrogation. The modified configuration is presented to enhance the performance of the sensor. A multilayer SPR Sensor is proposed with the BK7 prism, silver (Ag), barium titanate, and graphene sheets. The thickness of both the Ag layer is 50 nm and 10 nm, respectively. A layer of BaTiO3 is sandwiched between two thin layers of Ag. The sensitivity is high as 280°/RIU has been achieved with four thin layers of BaTiO3 and mono layer of graphene, which is 108 % higher than the conventional sensor. The graphene layer is used as a bio-compatible reagent, which improves the sensitivity of the sensor. The investigated sensor is susceptible to a 1.358 refractive index. This sensor has the potential for biomedical and biochemical sensing applications.

Synthesis of Nano-Zirconia by Chemical Process and Its Application to Optical Display

3 mol% yttria-doped stabilized zirconia (3YSZ) is synthesized by a solvothermal process, and its characteristics are investigated using various methods. Also, the dispersibility of synthesized 3YSZ nanoparticles is observed with the species of surface modifier. The 3YSZ nano sol prepared with an optimum condition is employed in prism coating and its properties are evaluated. The synthesized 3YSZ nanoparticles show a globular shape with about 10 to 20 nm crystallite size. The mixed phases with the nano sol show a high specific surface of 178 m2/g. The prism sheet coated with the 3YSZ nano sol present an excellent refractive index, transmittance, and luminance; refractive index is 1.603, transmittance is 90.2 %, and luminance of coating film is improved by 5.9 % compared to that of the film without 3YSZ nano sol. It is verified that the surface modified 3YSZ is suitable as the prism sheet for optical displays.

Performance Evaluation of External Light Shelves by Applying a Prism Sheet

To address the increased use of lighting energy in the building sector, research on the use of light shelves has been increasing. Previous studies have focused on applying operating techniques to improve daylighting performance, which reduces the economic efficiency of light shelves and the building energy savings. This study proposes the use of prism sheets to improve the performance of light shelves, a concept which was validated by evaluating the performance related to saving building energy and improving indoor light uniformity through a full-scale testbed. This study used an external light shelf with no prism sheet, a window with a prism sheet applied, and a window with both an external light shelf and prism sheet applied as Case 1, Case 2, and Case 3, respectively, and analyzed the illuminance distribution and lighting energy consumption required to maintain the optimal indoor illumination for each case. This study also derived the optimal specifications for each case to save building energy and considered the flow of natural light to analyze the performance evaluation results. The main findings are as follows: (1) the optimal specifications to improve daylighting performance were derived for Case 1, requiring the application of operating techniques; (2) Case 2 was not suitable for saving energy and improving light uniformity when compared to Case 1; and (3) Case 3 was effective in saving building energy. In Case 3, even when the light shelf was fixed at 20° without moving, it saved building energy and improved light uniformity compared to Case 1. However, the prism sheet in Case 3 should be detached during winter to maximize building energy savings.

광선반 채광성능 개선을 위한 프리즘시트 적용 방안 연구

Recently, there has been an increase in the number of studies on the performance of light shelf with an aim of solving the issue of increasing lighting energy consumption in the building sector. However, the efficiency of the light shelf is limited in terms of building energy saving as operating technologies are applied to improve the daylighting performance in response to the external environment. Therefore, this study proposes a light shelf using a prism sheet and aims to verify its effectiveness based on performance evaluation through a full-scale test bed. The conclusions of the study are as follows : 1) This study derived the optimal variables for light shelf installation (Case 1), prism sheet attachment (Case 2), and light shelf with prism sheet (Case 3). 2) Based on the optimal variables, saving lighting energy was achieved in Case 3 compared to Case 1 and Case 2 by 2.6% and 14.9%, respectively. In addition, the fixed type of Case 3 at the angle of 0° led to saving of lighting energy compared to Case 2 and Case 3 by 2.6% and 14.9%, respectively. The results reveal that Case 3 proposed in this study is effective in terms of using the prism sheet to obtain the daylighting efficiency of a movable light shelf. 3) Based on the optimal angles derived for each case, the uniformity of Case 3 can be improved by 11.4% and 12.1% in the summer, and 0% and 6.3% in the mid-season, compared to Case 1 and Case 2, respectively. However, the application of the prism sheet during winter reduces the uniformity, so it is preferable to remove the prism sheet during winter.

Edge-lit LCD backlight unit for 2D local dimming.

Local dimming technology has been highly desired for integration with liquid crystal displays (LCDs) in order to improve their contrast ratios (CRs) as well as to overcome power efficiency bottlenecks. In this paper, we propose and demonstrate a slim (~1 mm) edge-lit LCD backlight unit (BLU) capable of 2D local dimming. We designed a semi-partitioned light guide plate (LGP) patterned with inverse-trapezoidal microstructures, which allows the ultra-slim BLU to function without prism sheets. Since light emitting diodes (LEDs) are placed in the middle of the LGP, the BLU can freely define illuminated areas and the whole BLU can be modularly expanded like a tile canvas. The fabricated BLU achieves uniformity in both local and global luminance distributions, as well as in high local dimming performance. Experimentally, the BLU increases the CR of the display up to two orders of magnitude compared to conventional BLUs.

A Basic Study on the Application of Prism Sheets to Double-Skin Facades to Improve Indoor Light Environments

A Basic Study on the Application of Prism Sheets to Double-Skin Facades to Improve Indoor Light Environments

Surface Profile Measurement of Micro-Optics by Using a Long Stroke Atomic Force Microscope

In this study, a long stroke atomic force microscope (LS-AFM) has been developed for the measurement of the micro-optics which have micrometric amplitude surface structures. An electrochemically polished tungsten wire is used as the AFM probe tip. Since the effective length of the tungsten probe is more than 100 μm, the probe tip can access valley part without the interference between the steep slope and the sidewall of the probe tip. By using the long stroke PZT Z scanner whose long stroke of 70 μm and a resolution of 1 nm, micrometric amplitude of the optical elements can be measured. A linear encoder is employed to measure the displacement of Z scanner in Z direction. A well-detected result of a prism sheet film profile has been obtained by the LS-AFM and its tapping mode.

Integration of Prism Sheet on Quantum Dot Film With Bridge Patterns to Enhance Luminance of LED Backlight Unit

An integrated prism sheet on quantum dot (QD) film with bridge patterns has been proposed to increase the optical efficiency of an LED backlight unit. The bridge patterns were designed, such that they not only extract the light trapped in a QD film but also change the optical path effectively toward the vertical direction. We verified our design concept and geometrical parameters by optical simulation, and fabricated the integrated optical sheet using a lithography and UV imprinting process. The simulation results show the luminance enhancement of 33.6% after applying the bridge patterns while keeping the same Commission Internationale de l'Éclairage (CIE) after careful controlling the concentration of QDs. The enhancement of luminance toward the vertical directionwas also confirmed experimentally after the fabrication of an integrated prism sheet on a QD enhancement film.

Planar solar concentrator featuring alignment-free total-internal-reflection collectors and an innovative compound tracker.

This study proposed a planar solar concentrator featuring alignment-free total-internal-reflection (TIR) collectors and an innovative compound tracker. The compound tracker, combining a mechanical single-axis tracker and scrollable prism sheets, can achieve a performance on a par with dual-axis tracking while reducing the cost of the tracking system and increasing its robustness. The alignment-free TIR collectors are assembled on the waveguide without requiring alignment, so the planar concentrator is relatively easily manufactured and markedly increases the feasibility for use in large concentrators. Further, the identical TIR collector is applicable to various-sized waveguide slab without requiring modification, which facilitates flexibility regarding the size of the waveguide slab. In the simulation model, the thickness of the slab was 2 mm, and its maximal length reached 6 m. With an average angular tolerance of ±0.6°, and after considering both the Fresnel loss and the angular spread of the sun, the simulation indicates that the waveguide concentrator of a 1000-mm length provides the optical efficiencies of 62-77% at the irradiance concentrations of 387-688, and the one of a 2000-mm length provides the optical efficiencies of 52-64.5% at the irradiance concentrations of 645-1148. Alternatively, if a 100-mm horizontally staggered waveguide slab is collocated with the alignment-free TIR collectors, the optical efficiency would be greatly improved up to 91.5% at an irradiance concentration of 1098 (C(geo) = 1200X).

Measurements of maxillary sinus volume and dimensions by computed tomography scan for gender determination

IntroductionHumans are sexually dimorphic. Identification of remnants of skeletal and decomposing parts of human is one of the most difficult skills in forensic medicine. Forensic anthropologists often receive an incomplete skeleton, which are recovered fragmented but some bones are often recovered intact e.g. maxilla. However, typical identification methods may be inconclusive, especially when certain extreme post-mortem changes have developed.The aim of this study is to compare the size and volume of the maxillary sinus between males and females by CT Scan for gender determination. Methods102 cases (61 males & 41 females) were studied from Gwalior region. The sinus measurements were taken from series of CT Head images on DICOM viewing software using inbuilt electronic caliper. Independent sample t-test & discriminant function analysis were done using Graph pad prism & Word Excel Sheet windows 2007 version. ResultsThe dimensions & volume of the maxillary sinus of male was found to be larger than those of female & this difference was statistically significant (p < 0.05) for sinus AP & Volume. 65.16% of males & 68.9% of females were sexed correctly & the overall percentage for sexing maxillary sinuses correctly was 67.03% & sinus AP was the best discriminant parameter with an overall accuracy of 69.81%. DiscussionWe can conclude that CT measurements of maxillary sinus dimensions & volume may be useful for identification of gender in forensic anthropology to some extent when other methods are inconclusive.

Volumetric display using rotating prism sheets arranged in a symmetrical configuration

A volumetric display that creates a distortion-free three-dimensional (3D) image in midair is described. The proposed system consists of rotating prism sheets used as an optical scanner and a dihedral corner reflector array (DCRA), which is a distortion-free imaging element. Two prism sheets are arranged in a symmetrical configuration to reduce an unnatural motion parallax caused by optical aberrations. A cross-section of the 3D image is formed by the DCRA in midair and moved by the rotating prism sheets to create a 3D displayable space. A 3D volume image was displayed without image distortion or unnatural motion parallax.

9.3: “Round View Display”, Motion Parallax Based 3D Display with Super Wide Viewing Angle

Abstract“Round View Display (RVD)” achieves “Round View” perception by realizing the smooth expression of image rotation corresponding to the position of each member of the audience with super wide viewing angle and smooth motion parallax. By adding a specially designed slanted prism sheet after a lenticular lens, 90 deg. viewing angle is achieved.

무전해 니켈도금 소재의 초정밀 가공에서 V-형상 미세 패턴 가공한계에 대한 실험적 평가

The continuing demand for increasingly slimmer and brighter liquid crystal display (LCD) panels has led to an increased focus on the role of light guide panels (LGPs) or optical films that are used to obtain diffuse, uniform light from the backlight unit (BLU). The most basic process in the production of such BLU components is the micromachining of V-shaped grooves. Thus, given the current trend, micromachining of V-shaped grooves is expected to play increasingly important roles in today's manufacturing technology. LCD BLUs comprise various optical elements such as a LGP, diffuser sheet, prism sheet, and protector sheet with V-shaped grooves. High-aspect-ratio patterns are required to reduce the number of sheets and enhance light efficiency, but there is a limit to the aspect ratio achievable for a given material and cutting tool. Therefore, this study comprised a series of experimental evaluations conducted to determine the machining limit in microcutting V-shaped grooves on electroless nickel plated die materials when using single-crystal diamond tools with point angles of <TEX>$20^{\circ}-80^{\circ}$</TEX>. Cutting performance was evaluated at various cutting speeds and depths of cut using different machining methods and machine tools. The experimental results are that V-shaped patterns with angles of <TEX>$80^{\circ}$</TEX> or up can be realized regardless of the machining conditions and equipment. Moreover, the feed rate has little effect on machinability, and it is thought that the fly-cut method is more efficient for shallow patterns.

대면적 엣지형 LED 디스플레이의 광특성 향상을 위한 도광판설계

Through the rapid development of LED TV, a large-area edge-lit backlight unit is widely researched in the display industry for enhancing the optical efficiency, luminous uniformity and slim design. In addition, an edge-lit backlight unit includes many optical sheets such as reflection sheet, prism sheet and diffuser sheet. However the function can be replaced by the carefully patterned light guide plate (LGP). Micro patterns which located on the top and bottom surface of light guide plate was designed by ray-tracing optical simulation. The designed patterns improved the light characteristics of LGP, including optical extraction efficiency and intensity distribution uniformity. These results suggest that it is very effective method to design edge-lit LGP with micro-patterns on both sides for large-area display and to reduce the fabrication cost.

Volumetric display using a rotating prism sheet as an optical image scanner

We developed a volumetric display that uses a rotating prism sheet as an optical scanner. A cross-sectional image of a three-dimensional (3D) object was moved laterally by the rotating prism sheet. A stack of the cross-sectional images constructed a 3D volume image that satisfies all requirements of stereoscopic vision. Since the mechanical load of the proposed scanning method was small, it is easy to enlarge the effective area of the scanner and its scanning area. We used a concave mirror to collimate rays emitted from each point to reduce the aberration caused at the prism sheet. A displayed 3D image had a size of 7 cm × 5 cm × 7 cm and a resolution of 1024 × 768 × 200 voxels.

Optimization of polymer light emitting devices using TiOx electron transport layers and prism sheets

The internal and external efficiency of polymer light emitting devices were found can be simultaneously improved by insertion a high refractive index material, titanium oxide (TiOx), to the emission layer and a prism sheet attached to the substrate. The TiOx layer increased the internal efficiency due to a better electron injection and hole confinement. However, it led a wider angular emission profile with more photons trapped in the substrate. By using the prism sheet, those trapped light was efficiently coupled to the air. The extraction efficiency enhancement was increased from 33.1% to 54.4% and the overall current efficiency was improved up to 86%.

Improvement of Optical Extraction Efficiency of Organic Light-Emitting Diode Using a Large Area Nano-Pattern

In order to improve optical extraction efficiencies, we propose a nano-patterned organic light-emitting diode (OLED) which doesn't rely on high precision lithography nor rigorous periodicity. The nano-pattern is fabricated by spin-coating PS (poly-styrene) spheres on the substrate and carrying out reactive ion etching and flattening using dielectric material. The verification of the optical properties of the nano patterns was carried out by fabricating OLED-like structures using quantum dot and distributed Bragg reflector (DBR). As a result, the nano-patterned structure showed a 28% increase in optical efficiency compared to the non-patterned sample. In addition, the use of a prism sheet on the backside of a glass substrate also showed a 23% increase in optical efficiency by disturbing the total internal reflection between glass and air. In this way, the large area nano-patterns can be fabricated and applied to increasing the optical extraction in OLED.

Micro Reverse-pyramid Array를 이용한 일체형 Sheetless LCD Backlight의 광학적 특성

LCD backlight unit (BLU)에서 도광판 상부에 micro reverse-pyramid array (MRPA) 또는 micro reverse-cone array (MRCA)을 설치함으로써 기존의 확산 시트와 프리즘 시트를 없애고 구조를 단순화하였으며, 광학적 시뮬레이션을 통하여 새로운 도광판의 최적 조건을 얻었다. MRPA와 MRCA의 측면각과 높이, 윗변의 반지름이나 윗변의 길이에 따라 휘도와 시야각의 변화를 구하였다. MRPA와 MRCA 구조물의 최적의 형상은 측면각이 각각 59도와 57도이었으며, 시야각은 68도와 64도이었다. 구조물의 높이는 큰 영향을 주지 않았다. The structure of an LCD backlight unit (BLU) was simplified by installing a micro reverse-pyramid array (MRPA) or a micro reverse-cone array (MRCA) on the top surface of the light guide panel (LGP) in order to eliminate the conventional diffuser sheet and the prism sheet. The optimum conditions of the MRPA and the MRCA in the new light guide panel were obtained through optical simulation. The change of the luminance and view angle that depend on the side angle, the height, and the length at the top of the MRPA and MRCA were studied. The optimized side angle and the view angle of the MRPA and MRCA were 59 and 57 degrees for the side angles and 68 and 64 degrees for the view angles, respectively.

Low‐voltage and high‐transmittance blue‐phase liquid‐crystal device with slanted electrodes

Abstract— A low‐voltage (∼10 Vrms) and high‐transmittance (∼90%) polymer‐stabilized blue‐phase liquid‐crystal (BPLC) device with a slanted‐electrodes structure is proposed. Unlike the vertical‐field‐switching (VFS) mode in which oblique incident light and a vertical field are employed, the proposed device utilizes normal incident light and an oblique field. The slanted electrodes generate a strong and uniform oblique electric field, which contributes in obtaining low voltage and high transmittance. Moreover, no couple films or prism sheets are needed, which helps to enhance the optical efficiency and simplify of the device structure. This device has great potential application for emerging BPLC displays and photonic devices.