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Recent increasing interest in light guide plates (LGPs) based on the advanced manufacturing towards optoelectronics applications has emerged as a potential technology. The aim of this study was to estimate the optical characteristics on practical verification of laser-engraved glass light guide plate with concave microstructures. The case study can use the industrial ability of picosecond laser (pico-laser) technique, a type of ultrafast laser pulses, to directly engrave a glass sheet (Corning Iris® Glass) with functional concave microstructures for fabricating an LGP. Eight small pieces of samples with array of microstructures engraved on different processing conditions were made for measuring optical characteristics before and after the samples were etched by hydrofluoric acid. Here, the engraved 6-inch LGP structures can make light exit from the LGP uniformly. Additionally, the two optimized LGPs were put in a 7.8-inch backlight module where the measured results showed the uniformity of spatial luminance was 0.9. The study demonstrated the one-step process utilizing pico-laser technique, yielding for the design of microstructures of thinner large-sized liquid crystal display (LCD) products in the manufacturing of LGPs for lighted-up in a backlight unit (BLU).

This study proposed a method to improve the efficiency and recognizability of the spectroscopy method for measuring nanofluid stability. The 0.2 wt% and 0.4 wt% carbon-based nanofluids (CBNFs) were used as samples. The volumes of three test types of samples in the cuvette were 2.5 mL (Case 1), 1.8 mL (Case 2), and 1.8 mL (Case 3), respectively. In addition, an opaque black tape covered the lower half of the original area spotted by the probe beam in Case 3. The spectrometer was used to measure absorbance at wavelengths of 400–800 nm at fixed time interval. The results indicate that reducing the distance between the area spotted by the probe beam and the liquid level can improve the efficiency and recognizability of CBNF stability detection. For the optimal condition, the time to detect CBNF settling reduces by 50% and recognizability improves by 34.9% in the design of Case 2.

This paper proposes an ultrafast-laser process for ablating multilayer graphene film to form the conductive electrodes for a gas sensor module with wireless circuits. In this study, a picosecond laser source was directly used to perform double scanning for precisely fabricating the spiral electrode pattern as the sensing test region. The ablated surface of multilayer graphene structures fabricated using sufficiently strong pulses with a pulse width of 7 ps and a wavelength of 532 nm was investigated through scanning electron microscopy. The graphene-based electrode was integrated with wireless circuits to form a gas sensor module. The relationship between the spiral electrode design and sensitivity to gas detection was analyzed. Electrical detection of gas was studied by employing different electrode designs, and change in the detection limit at room temperature with change in resistance was examined. Furthermore, the role of graphene-based devices comprising spiral electrodes fabricated using the laser process and integrated with wireless circuits to form a module in gas detection was analyzed.

In this study, we proposed a two-staged, transparent, planar solar concentrator composed of stacked waveguide sheets with an arc-segment structure array and movable receiving assemblies, which operated in a hybrid tracking approach. The stacked waveguide sheets carrying the arc-segment structures as TIR collectors could provide high concentration ratios and coupling efficiency with wide angular tolerance in the first stage. The following movable receiving assembly composed of light guide channels (LGCs) and compound parabolic collectors (CPCs) laterally slid according to the incidence angles to receive the earlier concentrated light for further concentration and provide the PV cells on the ends of CPCs with uniform irradiance in the second stage. The simulation results demonstrated that the optimal model could provide an average efficiency of 0.87, an average uniformity of 0.875, and an average concentration ratio of 738 over a whole year regarding the light source with AM 1.5D wavelengths in the working range of PV cells.

In this study, polyethylene naphthalate (PEN) was investigated as a flexible substrate because, compared with polyethylene terephthalate, it achieves a lower root mean square roughness and transmittance, which is favorable for reducing leakage from the bottom of flexible substrates. A flexible device structure composed of tungsten oxide/indium-doped tin oxide/PEN was used in an electrochromic (EC) test. The experimental results show that the flexible EC display device achieved a high transmittance difference of > 40% and color efficiency of 70.2 cm 2 /C at 560 nm. The transmittance difference was degraded in the visible range after 200 cycles of continuous bending. Furthermore, compared with flat fresh devices, the WO 3 device exhibited poor retention properties in a colored state after being subjected to longer bending cycles.

In this paper, we propose a novel feasible method `digital laser-blastering' (DLB) to fabricate a large-sized LED light guide plate (LGP) of high luminance and efficiency for TV application, which can be hardly achieved by other technologies. Both principle model and experimental measurement are demonstrated, and the comparisons between the experiment group and control group adopting other fabrication technology are also presented. We adopted CO2 laser to engrave the surface of a bare PMMA plate with numbers of micro-concavities. Subsequently, we used Conoscope and BM7 to measure angular luminance and spatial luminance of the backlight unit with the DLB LGP, respectively. In the experimental results, the average spatial luminance of the experiment group with DLB LGPs increases 103-122% at most as compared to the control group, and the feasibility to be applied for the LCD TV of the size over 37 inches is demonstrated. In addition, the DLB LGP adopting an inverted-prism film (IPF) has a very narrow angular distribution in the vertical direction but a much wider in the horizontal, which is suitable especially for TV application.

In this study, a new type of fluorescent lamp is proposed, and it is demonstrated that the fluorescent lamp with a well-designed filter can provide higher illuminance and air cleaning function without consuming extra electricity power. The filter with high reflectance is used to cover the vents of the lampshade and the heat from the lamp is utilized to drive the air up and through the filter such that the air can be filtered and cleaned. The results show that the fluorescent lamp indeed provides higher illuminance and the increased rate of the illuminance due to the filters is far much higher than that of the power consumption of the fluorescent lamp due to the filters. Meanwhile, after the 14-week test on the filter, the light transmittance of the filters reduces below 50% but the illuminance just decreases 3.2%. Therefore, the filter can indeed capture the contaminants in the air but does not diminish the entire illuminance for the long time use. Furthermore, this concept can also be applied to design t...

In this study, we used two-step synthesis method to prepare nano-coating containing multi-walled carbon nanotubes (MWCNTs) of different concentrations and applied the MWCNTs to heat dissipation for the projection lamp fixtures. We quantitatively coated the nano-coating on the inner surface of the housing of the fixture and evaluated its effects on the internal temperature, power consumption, and luminous output of the fixture for different conditions. The results show that both concentration of the MWCNT nano-coating and the projecting angle of the fixture affect the internal temperature and power consumption. With the MWCNT nano-coating of concentration at 1.328 wt.% and the projecting angle of 0°, the internal temperature of the fixture adopting the halogen lamp and that adopting the LED lamp reduce 5.4% ± 2.1% and 3.2% ± 2.1% at most, respectively; the power consumption reduces 12.9% ± 2.1% at most for the LED lamp; the luminous output has no significant difference for either the halogen or LED lamp. This study demonstrates MWCNT Nano-coating has great feasibility for heat dissipation of the lighting fixture. Further, this concept can also be applied to the cases requiring non-contact heat dissipation. Therefore, this study can widely contributes to energy saving and carbon emission reduction.

This study proposed a slim coupler to collimate the light emitted from an LED, which can be used as a collimated light source. The coupler is substantially a 2-D compound parabolic collector (CPC); its bottom surface has longitudinally extending V-groove microstructures thereon. The parabolic side walls reflect the propagating light to converge only in the transverse direction, but the V-groove microstructures reflect the light and make its propagating direction gradually rotates around a central axis of the CPC. Therefore, the angular distribution of the light finally converges after several times of reflection on both side walls and V-groove microstructures. Moreover, the illuminance distribution on the outlet of the V-groove CPC becomes more uniform than a CPC without V-groove microstructures. The effects of V-groove microstructures on both angular and illuminance distributions of the light emerging from the outlet of the CPC is analyzed, and the feasibility of providing a uniform collimated light source is verified by conducting simulation.

In this study, we implemented optimization for the coupler inlets of the planar solar concentrator, which was proposed in our prior work. The planar solar concentrator had a waveguide slab to carry an array of light-collecting elements thereon. The light entering the elements is focused on the coupler inlets and guided into the slab with propagating therein through total internal reflection (TIR). Thus, all the light from the elements is guided to the ends of the slab and highly concentrated. Because the coupler inlets couple light into the slab and also decouple the light propagating in the slab in subsequent interactions, they must be optimized to balance between coupling efficiency and decoupling loss. The optimized arrangements of coupler inlets included three types here: uniform-thickness platform, stepped-thickness platform, and stepped-width platform. In the simulation, the three types have the same area of the inlet to keep the concentrator with the same tolerance of the incident angle of light. We analyzed both the optical efficiency and range of the vertical angular distribution of the light reaching the outlet end of the slab; then made a comparison for the three inlet arrangements. The simulation results demonstrate the stepped-thickness and stepped-width platforms provide higher efficiency and concentrated irradiance.

A thermal management system that governs the operating temperature is crucial to green energy/power sources. This paper evaluated the feasibility of alumina (Al 2 O 3 )/water nanofluid for these cooling systems using an air-cooled heat exchanger for heat dissipation. The Al 2 O 3 /water nanofluid was produced by the direct synthesis method at the concentrations of 0.5, 1.0, and 1.5 wt.%. The experiment aimed for measuring the heat dissipation performance at the above weight fractions, fluid flow rates (1.8, 2.1, and 2.4 L/min), and sample temperatures (30, 40, 50, and 60 °C) within the operating range of green energy/power sources. Firstly, the thermal conductivity was measured to prove the enhancement of heat dissipation. After formulating the solid/water parameters and uncertainty analysis, key issues were investigated by controlling the fluid temperatures, flow rates, and weight fractions of nanoparticles. The experiments show that the maximum enhancement of heat exchange compared with distilled water is of 40% at high weight fraction of nanoparticles (1.5 wt.%) and low nanofluid temperature (30 °C). Moreover, the maximum enhanced ratio of pumping power occurs at high temperature of 60 °C and high weight fraction of nanoparticles (1.5 wt.%). Through the experiments, one can obtain the key factors to optimize a thermal management system of green energy/power sources in the near future.

We propose a new scheme to enhance the longitudinal Bragg selectivity of a volume hologram with use of a light pipe. Longitudinal shifting selectivity of the system is shown to be obviously enhanced in both experimental measurement and theoretical calculation. Such a technique is not only useful in the volume holographic 3-D imaging but also useful in the shift multiplexing holographic optical storage system.

In this paper, a two-step method is adopted to add titania (TiO2) nanoparticle and silica (SiO2) nanoparticle in commercial water-based paint to form the nano-paint with various concentrations of the added nanoparticle. The paint is sprayed onto the steel plate to form a coated film as the test samples. The experiments are implemented in order to investigate the effects of the nanoparticle on reflection spectra, surface hydrophobic and heat transfer performance of the coated film. The experimental results show that adding the nanoparticle indeed has positive effects on the above properties. This research contributes to the development of the functional paint for various applications.

This study examines the effect of particle size, temperature, and weight fraction on the thermal conductivity ratio of alumina(Al 2 O 3 )/water nanofluids. A Al 2 O 3 /water nanofluid produced by the direct synthesis method served as the experimental sample, and nanoparticles, each of a different nominal diameter (20, 50, and 100 nm), were dispersed into four different concentrations (0.5, 1.0, 1.5, and 2.0 wt%). This experiment measured the thermal conductivity of nanofluids with different particle sizes, weight fractions, and working temperatures (10, 30, 50 °C). The results showed a correlation between high thermal conductivity ratios and enhanced sensitivity, and small nanoparticle size and higher temperature. This research utilized experimental data to construct a new empirical equation, taking the nanoparticle size, temperature, and lower weight fraction of the nanofluid into consideration. Comparing the regression results with the experimental values, the margin of error was within −3.5% to +2.7%. The proposed empirical equation showed reasonably good agreement with our experimental results.

A paraxial equation for calculating pixel-based 2-D shifting selectivity of collinear holographic storage system is proposed. The equation shows that the broader reference pattern makes high shifting selectivity. In addition, both amplitude and phase modulation make no obvious change in shifting selectivity so shifting selectivity is not affected through advanced design of reference pattern. Besides, a simplified formula based on a point signal is proposed, which shows a clear physical insight that the shifting selectivity is the square of Fourier transform of the intensity distribution of reference pattern and does not depend on thickness of the disc when a point signal is applied.

This study employs a direct-synthesis method to produce titania (TiO2)/water nanofluid, which is a working fluid involved in the electrophoretic deposition (EPD) of nanophotocatalytic films. In general, using organic solvents and water as the bulk liquids in EPD produces environmental pollution and defective films due to the electrolysis of water. To mitigate water electrolysis, the fabrication method proposed in this study adds an anionic dispersant to the TiO2/water nanofluid. The anionic dispersant changes the surface charge of TiO2 nanoparticles to facilitate their deposition on the anode. For low voltage EPD processes, this method effectively improves defective nanophotocatalytic films. These defects are caused by bubbles from the water electrolysis, as the volume of oxygen produced at the anode amounts to half of the hydrogen produced at the cathode. The objective of this study is to propose empirical equations describing the relationship between film thickness and electric parameters.

We propose and demonstrate a volume holographic optical element (VHOE) for signal-mode fiber coupling and the sending of conjugate waves of reference light for the construction of holographic elements. Given the inherent Bragg conditions of the VHOE, the angular tolerances of the conjugate reading light in both the horizontal and vertical directions are studied under different conditions.

With progress in the LED luminous efficiency, the LED gradually expands the scope of application from the backlight to general lighting. In the application of the backlight, a light guide plate (LGP) is used to guide the LED light and emits the light uniformly from its surface to achieve a uniform planar light source. Except for the merit of slim volume, the LGP can prevent the LED light from directly entering the eyes resulting in glare; thereby the LGP is also used for general lighting applications, especially for the high-directionality lighting with slim volume. For the illumination, the prescribed distribution of the light emitted from the LGP had better modulated by both the microstructure on the LGP surface and a LED lens/coupler. In general, distribution of the light emitted from the LED is partially adjusted by the LED lens/coupler before the light entering the LGP. In this study we designed a LED coupler to collocate with two types of LGPs so that the LGP can uniformly emits the highly-collimated light or the light with the prescribed intensity distribution, which can be used for the backlight or lighting application, respectively.

In this paper, we proposed a novel optical film 'Collimation Film with Equivalent Focal Reflective Aperture' (CFEFRA) that can collocate with the proper light guide plate (LGP) to provide a highly collimated planar light source (HCPLS) that not only has high intensity peak but also good uniformity. The CFEFRA has micro-cylindrical lenses and inverted-prism-like micro-teeth on its upper surface and lower surface, respectively. The lower micro-teeth that are aligned with the upper lenses can deflect the light emitting from the LGP at large declination into the normal, and then the deflected light with transverse fan-out is further converged by the upper lens to become the collimated light. The exact alignment between the upper and lower micro-structures is fulfilled by the method 'auto-secure-alignment by focusing of a collimated exposure beam'. The vertical and horizontal full width at half maximum (FWHM) of angular intensity of the HCPLS for the optimal case are of 14 and 6 degrees, respectively. Moreover, it still has high optical efficiency with light output of over 90% despite the resultant emitting light is such collimated. Most importantly, CFEFRA just needs to collocate with a relatively low-cost and easily-manufactured LGP so the HCPLS adopting the CFEFRA can be extended for large-sized application. Both optical model and experimental samples are demonstrated in this paper, and the simulation results are consistent with the experimental results. The consistency proves our design concept and optical model are convincible and feasible.

In this paper, we investigated the optical output characteristic of the light guide plate (LGP) with microstructures engraved by a CO2 laser, which is for edge-lit backlight of liquid crystal display or illumination. Especially, the laser-engraving method is suitable for the slim large-sized LGP used in LED TV backlight, and the engraved microstructure has polished surface to contribute to better optical efficiency. For seeking higher optical efficiency, we adopted a LGP with lenticular-arrayed surface (LAS LGP) as the experimental substrate. In order to investigate the effect of the lenticular-arrayed surface on optical output characteristic for the different kinds of the engraved microstructures, we used the laser to directly engrave the flat surface (opposite to the lenticular-arrayed surface) of the LAS LGP with different kinds of microstructures as experimental samples; each sample has one kind of the engraved microstructures on its flat surface. Similarly, we also engraved the same kinds of the microstructures on the flat LGP as a controlled group for comparison. The cross-section profiles of the engraved microstructures on both LAS LGP and flat LGP were measured by a laser confocal microscope. All the samples were further measured for spatial and angular luminance by the BM7 and Conoscope, respectively. In addition, both the experimental data and simulation results were demonstrated and compared to each other in this paper.

In this paper, we investigated the optical characteristic of the light guide plate (LGP) with microstructures engraved by a CO 2 laser. The LGP is for edge-lit backlighting of liquid crystal display. Traditionally, the microstructures on largescaled LGP are formed by screen-printing, which are hardly formed by inject molding. However, the screen-printed LGP highly scatters light and has lower optical efficiency. Therefore, a method was proposed to use the laser to directly engrave the flat surface of a bare LGP with microstructures. The engraved LGP has better optical performance due to the polished surface of the engraved-microstructures, and can be used for large-scaled application such LCD TV backlighting. We used different processing parameters to engrave the microstructures of 11 different shapes on a bare LGP and measured the cross-sectional dimensions of the microstructure. Among them, five kinds of shapes were chosen to be engraved on the bare LGPs respectively as samples. The five LGP samples were measured for spatial and angular luminance by the BM7 and Conoscope. With difference in the profiles of the microstructures, the angular distributions of light emitting from the LGP also differ. All the experimental data of the samples were compared with one another and the on-axis luminance of the best LGP sample could potentially increase 50% more than the reference sample if a proper optical film was chosen to accompany it.

Volume holographic optical disc (VHOD) technology is simpler than the angular multiplexing holographic system. However, disc rotation usually causes pixel migration, thus reducing signal quality. This study proposes a special geometrical arrangement to counteract pixel migration. Using paraxial approximation analysis, an optimal geometrical distance ratio, K, is calculated to compensate for pixel migration and improve image quality during disc rotation. The results of approximation analysis are confirmed by both simulation and experimental results.

This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration.

In this paper, a method is proposed for highly precisely simulating the optical behavior of a light guide plate, which has microstructures of rough texture and rugged edges thereon. By adopting the 'equivalent medium-immersed measurement' to establish precise optical characteristic of the light guide plate, the simulated results of luminance distribution are much accordant with experimental measurement. This method will be useful in luminance uniformity evaluation and hot-spot check in advance, and it will greatly contribute to save time and cost of product development.

A novel design for a volume holographic optical disc to reduce radial cross talk is proposed. By adopting a proper spatial filter, the radial cross talk can be reduced and the radial selectivity increases so that the multiplexing capacity can increase effectively. The theory and the corresponding experiment are demonstrated.

We propose a paraxial solution for pixel shift selectivity, which can simulate the pixel shift selectivity in two dimensions and in wide range easily. Thus, the effect of different reference patterns can be calculated in detail. From the simulation result, we conclude that the pixel shift selectivity get worse for amplitude modulation reference patterns. Making no modulation is the best reference pattern for pixel shift selectivity, however the point spread function will be worst in this case. To get an optimum system in both pixel shift selectivity and point spread function, the reference pattern with phase modulation will be the best choice.

In the paper, we design a sub-wavelength level polarizer to replace the traditional polarizer in various optical applications. The structure of the polarizer is a one-dimension periodic grating. It has three layers with different materials. We do the basic design by using "Effective Medium Theorem." And we verify and improve the result by using rigorous couple-wave analysis (RCWA). In the range of visible wavelength, the polarizer has high contrast and high tolerance of incident angle in three-dimension space.

An out-of-plane angular detection scheme with random phase encoding is proposed. A ground glass is attached on a rod, which is rotated around a center point, so that the rotation of the rod induces the displacement of the ground glass in a circular path. To enhance the rotational sensitivity we adjust the Bragg selectivity of the volume holographic optical element encoded by random phase. Therefore, the rotational sensitivity can be tuned over a large range from several degrees to ten thousandth degrees by changing the radius of rotation. The theoretical calculation, as well as experiment, is demonstrated.

A highly precise rotational filter based on a volume-holographic optical element is proposed and demonstrated. We present a clear theoretical calculation of the rotation sensitivity of the volume-holographic filter used to sense the rotation of a spherical ground glass object. By introducing the longitudinal displacement of the scattering point across the sphere, the sensitivity of the filter is greatly improved to 350 times that of a general case for a planar ground glass.

A paraxial solution of the coaxial holographic storage algorithm is proposed, which can be applied to calculate the pixel response and shift selectivity. The pixel response shows that the reference pattern is a key issue.

We propose a novel way to enhance the Bragg selectivity of a volume hologram with use of a light pipe. Longitudinal shifting selectivity of the system is shown obviously enhanced experimentally and theoretically.

In this paper we propose a new way to fix the diffracted pattern on the original output plane by a specific geometrical arrangement during the rotation of the holographic disk. The behaviors on bit error rate (BER) and signal-to-noise ratio (SNR) are calculated and discussed.

This study proposes a slim planar apparatus that can function as a color-separation backlight for the color-filter-free liquid-crystal display (LCD) system. It has a two-level folded configuration comprising a composite light-guide plate (LGP) and light-emitting diode (LED) couplers. The LED couplers generate the highly collimated beams of the three primaries (R, G, and B) that enter the composite LGP at their separate angles; then the three primaries were uniformly extracted out of the top surface of the LGP at their respective angles differing in the longitudinal direction. In the simulation, a lenticular lens array was used to focus the three primaries onto their respective subpixels; each pixel of the LC panel comprised three subpixels, identical to the traditional layout. The proposed apparatus can be applied in backlight modules with a maximal diagonal dimension of 39 inches and a thickness of 15.5 mm. The simulation results indicated that the spatial uniformities of the three primaries ranged between 84% and 87%, the area of the color gamut of the LCD system was 99.5% of that defined by the National Television System Committee, and the total optical efficiency was 41%, as the double of a traditional LCD system. Thus, the proposed apparatus improved the total optical efficiency markedly and provided the LCD system with a wide color gamut.

We propose a novel imaging structure based on a volume holographic optical element that allows one-dimensional optical imaging through a specific Bragg window. The lateral magnification is shown to be linear and negative. Lateral magnifications of 2.5, 5, and 10 of the imaging element are demonstrated theoretically and experimentally.

We proposed a new model to analyze Bragg selectivity of volume holograms in spatial domain as well as in temporal domain. The applications of volume holographic filters to surface variation detection and high dense wavelength filtering are presented.

Two volume holographic storage schemes using random phase multiplexing technique are presented. A ground glass is spatially shifted to multiplex the signals for both storage schemes. The diffraction selectivity of the ground glass is experimental investigated and theoretically analyzed.

This paper proposes a design of a bidirectional backlight using a pair of stacked light guide plates (LGPs) for large displays employed in time-multiplexing dual-view and 3D applications. The LGPs with superficial microconcavities can emit very concentrated light and prevent the light emitted by an LGP from being disturbed by another LGP. In order to demonstrate the feasibility of the design in large dual-view and 3D displays, the transverse width of the designed bidirectional backlight in the simulation was set 500 mm, equivalent to the size of a 23-in. monitor. Moreover, the design of two stacked wedged LGPs reduced its thickness to only 2 mm. According to the simulation results, the bidirectional backlight emits concentrated light in two directions from the upper and lower LGPs. Before an optical film was put on the backlight, the intensity peaks of the emitted light were at 71° and −76° with respect to the normal; angular distributions of the emitted light were 20° and 22.5°; uniformity was 84%; and optical efficiency was 87%. For dual-view application, an optical film with prisms of a 100° apex angle was designed to deflect the light emitted from the upper and lower LGPs into the directions at −40° and 40°, respectively; the cross talk was below 10%. For 3D application, an optical film with asymmetric multifaceted, inverted prisms was designed to concentrate the light emitted separately from the two LGPs and deflect the emitted light into the left and right eyes. The intensity peaks of the light emitted from the optical film were at 5° and −4° with respect to the normal; angular distributions of the light emitted from the optical film were 13° and 11°; and the cross talk for the left and right eyes was 5% and 7%, respectively.

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).

This study proposes a slim planar apparatus for converting nonpolarized light from a light-emitting diode (LED) into an ultra-collimated linearly polarized beam uniformly emitted from its top surface. The apparatus was designed based on a folded-bilayer configuration comprising a light-mixing collimation element, polarization conversion element, and polarization-preserving light guide plate (PPLGP) with an overall thickness of 5 mm. Moreover, the apparatus can be extended transversally by connecting multiple light-mixing collimation elements and polarization conversion elements in a side-by-side configuration to share a considerably wider PPLGP, so the apparatus can have theoretically unlimited width. The simulation results indicate that the proposed apparatus is feasible for the maximal backlight modules in 39-inch liquid crystal panels. In the case of an apparatus with a 480 × 80 mm emission area and two 8-lumen LED light sources, the average head-on polarized luminance and spatial uniformity over the emission area was 5000 nit and 83%, respectively; the vertical and transverse angular distributions of the emitting light were only 5° and 10°, respectively. Moreover, the average degree of polarization and energy efficiency of the apparatus were 82% and 72%, respectively. As compared with the high-performance ultra-collimated nonpolarized backlight module proposed in our prior work, not only did the apparatus exhibit outstanding optical performance, but also the highly polarized light emissions actually increased the energy efficiency by 100%.

In this study, we investigate the grain size effect of high electron mobility transistor devices with ohmic contact metals of stacked Ti/Al/Ni/Au and Ti/Al/Mo/Au. In addition to a comparison of electrical characteristics, the ohmic contacts were also examined by a scratch test for the observation of adhesion behavior. The experimental results demonstrate that the metal grain size is strongly dependent on metal adhesion, which may lead to bonding issues. Moreover, the grain-induced lateral stress lowers the drive current and increases the off-state current owing to the degraded gate swing and transconductance of transistor switching characteristics.

A paraxial solution to the coaxial holographic storage algorithm is proposed based on the scalar diffraction theory and a VOHIL model (volume hologram being an integrator of the lights emitted from elementary light sources), which can give insight into the optical characteristics of the collinear holographic storage system in an effective way, including the point spread function and shift selectivity. The paraxial solution shows that the reference pattern is the key issue in the point spread function. Thus, the bit error rate of the system can be improved by changing the reference pattern. The proposed solution will be useful in the design of a new reference pattern to perform a high-quality readout pattern in the coaxial holographic storage system.