Antifungal effects of ultraviolet C (UV-C) irradiation have been considered a potential solution to reduce the severity of black spots on postharvest fruits. In this work, a 30 × 30 × 30 cm system was made based on UV-C light-emitting diodes (LEDs) to apply in reducing disease symptoms for bananas which could be used in industrial conveyor belts. The UV-C irradiance monitoring was carefully carried out for several sections at various box heights in simulation and measurement. The findings experienced a dominating range of 6 to 9 W/m2 in the central sections. Regarding in vivo conditions, the observation after a week from experiment showed that the disease symptoms on the UVC-treated banana peel, which was exposed under UV-C light around 5 s, dramatically decreased compared to a natural banana. Consequently, the UV-C dose range is proposed from 0.030 to 0.045 kJ/m2 with minimum damage in terms of sensory properties. Owing to the flexible shape and short exposure time, the system promises to provide many potential applications to prolong the quality of bananas.
In this study, we use 30 mini-LED arrays as the light source of the bike lamp. A single reflector with 68 segments to project vehicle low beam and high beam with the use of a GaN-based mini-LED matrix, which is a 30 LED dies array. The design of the reflector is based on light field technology in considering etendue from the light source across the segments. The group of the segments with smaller etendue from the LED dies in the bottom 2 rows are used to project low beams. When the other LED dies are turned on, the reflector will project light upward and form the high beam. The selection of the turn-on LED dies in the mini-LED matrix can adjust the width of the illumination pattern so that an adaptive low/high beam can be performed.
We perform the mid-field model of a UV-C LED with an arranged wavelength of around 275 nm by comparing the 2-dimension (2-D) gray-level image captured by a monochromatic CMOS and the corresponding simulated irradiance pattern. Owing to UV-C light, we propose using a fluorescent film to absorb UV-C light and re-emit light at a longer wavelength so that the 2-D gray level image can be captured. The calibration to approach the corrected gray level of image is presented. Consequently, we obtain the precise mid-field light source model. Moreover, the model is also applied for dome lens design and then compares the optical behavior with fabricated samples in measurement to evaluate its validity.
We introduce a current development in optical design for vehicle forward lighting based on solid-state lighting, in particular, phosphor-converted white LEDs. The vehicles include bicycles, bikes, and automobiles. Although the requirements regulating different vehicles are different, the low beam always requires a high-contrast cutoff line. Three optical design approaches are discussed; these include a projection lens incorporated with a baffle or beam shaper, multisegment reflectors, and complex lenses. A new design approach called light field management technology for the multisegment reflector is introduced. In addition, the possible related manufacturing errors and the robustness of different optical approaches are analyzed. Finally, we introduce three approaches to adaptive forward lighting that provide a driver with brighter and clearer vision without inducing glare to people on the roadway. The application of video projection technology to roadway illumination could be a trend of vehicle forward lighting based on solid-state lighting.
A design scheme for an aspherical lens including two step processes is proposed and demonstrated to direct appropriate flux to the expected target illumination. The first-step design is based on a point source and the surface geometry is determined. The flux deviation between the design and target illumination becomes the factor in the optimization process, and the angular flux compensation is done to adjust the light pattern. Finally, the experimental result shows that high similarity between the target and the measurement is observed and full width at half maximum angle error is within 3%, which are both better than those in the aspherical lens design based a point source and a real light-emitting diode without optimization by flux compensation.
We proposed a novel structure to perform photon recycling for a double-light-source illumination system pumped by a laser. In the design, two kinds of phosphor are located at the two focus of an elliptical reflective surface separately, after the phosphor on the first focus pumped by laser, the backward scattering light will refocus at the other phosphor layer at the second focus. The absorption spectrum of the second phosphor should fit that of the emission light by the first phosphor. When the emission spectrum covers red light, the whole system is a double-light-source module.
In this paper, an efficient lighting design for indoor sport field is presented. The average illuminance for the indoor sport field with eight playing courts can be achieve to 500 lx at a 11.2 m of the lamp's mounting height. Besides, because of specific arrangement of luminaires, the proposed lighting design can effectively reduced the glare effect and provide a comfortable illumination to players.
Two optical designs for marine beacon based on Direct In-line Package (DIP) LED is proposed and demonstrated. The luminous intensity of the marine beacon using DIP LED can achieve to the IALA recommendation’s requirement of 5 nautical miles. The measurement of color coordinates can also fit the IALA recommendation’s requirement. By the surface-structured TIR lens, we successfully keep the divergence angle to 68 degrees in the horizontal direction and converge to 8 degrees in the vertical direction.
In this thesis, on the basis of the phosphor optical models, green and red phosphor mixture optical model has been well established. Under some specific green to red phosphor doping proportions, this model can be utilized to simulate the chromatic properties, spatial CCT distributions, and packaging efficiency. There are some benefits of applying the phosphor optical model, one is that the confusion about mixture or layer phosphor configuration can perform better could be solved. Another is that the comparison and analysis of these phosphor configurations can be made not only in experiment but also in simulation, and will be more details to be discuss in the simulation. There are several types of packaging structures in high color quality applications. Consequently, the importance of phosphor optical model cannot be overestimated. After few steps above and with the help of experimental analysis and optimized in simulation, a packaging structure with high color quality and high efficiency has been approved. Finally, this light source with high performance will be utilized in the luminaire to improve the color and energy saving properties.
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