White light LEDs become more and more important in display and lighting in various structures. Here a new modeling algorithm for phosphor-converted white light-emitting diodes (pcW-LEDs) is proposed, aiming to perform accurate simulation for color appearance, where potentially enabling optical designers to remove yellowish/bluish spots in LED lighting. The proposed modeling method is applied to simulate a pcW-LED with a hemi spherical lens. The simulation accurately predicts the blue and yellow light distribution. The model is further verified by applying a total internal reflector lens to the pcW-LED. In the midfield region, the blue and yellow light distribution exhibit large variations as the observation distance changed; this varying light pattern for both the blue and yellow lights can be accurately predicted by using the proposed model. The well-established optical model should facilitate designing a pcW-LED that features high-quality illumination and enhances color uniformity.
In this paper, we present a luminaire design with anti-glare and energy-saving effects for sports hall. Compared with traditional lamps using in a badminton court, the average illuminance on the ground of the proposed LED luminaire is enhanced about 300%. Besides, the uniformity is obviously enhanced and improved. The switch-on speed of lighting in sports hall is greatly reduced from 5-10 minutes to 1 second. The simulation analysis and the corresponding experiment results are demonstrated.
In this study, a low glare and high-efficient tunnel lighting design which consists of a cluster light-emitting diode and a
free-form lens is presented. Most of the energy emitted from the proposed luminaire is transmitted onto the surface of
the road in front of drivers, and the probability that the energy is emitted directly into drivers’ eyes is low. Compared
with traditional fluorescent lamps, the proposed luminaire, of which the optical utilization factor, optical efficiency, and
uniformity are, respectively, 44%, 92.5%, and 0.72, performs favorably in traffic safety, energy saving, and glare
A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. We performed an experimental study to find a balance between optical efficiency and color uniformity by changing light recycling and color mixing.
In the paper, we design a focal adjustable flashlight, which can provide the spotlight and the wide-angle illumination in
different modes. For most users, they two request two illumination modes. In such two modes, one is high density energy
of the light pattern and the other is the uniform light pattern in a wide view field. In designing the focal adjustable
flashlight, we first build a precise optical model for the high-power LED produced by CREE Inc. in mid-field
verification to make sure the accuracy of our simulation. Typically, the lens is useful to be the key component of the
adjustable flashlight, but the optical efficiency is low. Here, we introduce a concept of so-called total internal refraction
(TIR) lens into the design of flashlight. By defocusing the TIR lens, the flashlight can quickly change the beam size and
energy density to various applications. We design two segments of the side of the TIR lens so that they can be applied to
the two modes, and the flashlight provides a high optical efficiency for each mode. The illuminance of the center of light
pattern at a distance of 2 m from the lamp is also higher than using the lens in the spotlight and wide-angle illumination.
It provides good lighting functions for users.
In this letter, we present a new design for a light-emitting diode- based bike headlamp. The optical design contains two horizontal reflectors and a light pipe with two horizontal parallel mirrors. The designed illumination pattern in our simulations performs a contrast of 250 in the K-mark regulation, and it was measured to be 21 in the experiment with a not well-finished prototype, which was operated at 1 W. The contrast is higher than 5 as requested in the regulation.
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