Design of Diffuse Reflection Freeform Surface for Uniform Illumination

Zhu, Zhaoda; Jin, Xiaolong; Yang, Hui; Zhong, Lipeng

doi:10.1109/jdt.2013.2273073

Cited by 21 publications

(22 citation statements)

References 27 publications

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“…Similarly, the authors of [9] studied the benefits of applying different LED lamp deployment patterns on the ceiling to achieve a better coverage uniformity in the room. However, in all these VLC scenarios in which direct illumination is used, over-exposure problems may emerge on those room areas in which the LED light beams are focused, or the eyes of the VLC users may suffer from the glare effect that strong directive light generates if not properly distributed [10].…”

Section: Introductionmentioning

confidence: 99%

Visible Light Communication System in Presence of Indirect Lighting and Illumination Constraints

Dowhuszko

Ilter

Hämäläinen

2020

ICC 2020 - 2020 IEEE International Conference on Communications (ICC)

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Visible Light Communication (VLC) systems are designed to provide illumination and data services simultaneously. To achieve this goal, LED lamps are usually deployed on the room ceilings, in order to maximize the chances of having Line-of-Sight (LoS) connectivity between the VLC transmitter and the random locations that the VLC receiver can take. In an early stage of adoption, where the cost of LED lighting fixtures enabled with VLC technology will not be suitable for ultra-dense deployments, it is expected that only one VLC transmitter is placed per room. In this situation, the use of direct illumination may have serious problems to satisfy the illumination constraints and provide a homogeneous data rate coverage. Moreover, the use of a single powerful LED lamp per room may create discomfort glare effect to users and over-exposure problems in areas of the room at which the light beam is directed. In order to address these problems, this paper studies the data rate that VLC technology can achieve with indirect illumination. That is, when the LED lamp is pointing upwards, and the VLC user receives the optical signal that is reflected back from the ceiling. Obtained simulation results show that indirect illumination provides a more homogeneous data rate coverage when compared to direct case, while simultaneously verifying the illumination constraints in most of the places that the VLC receiver may take in the room.

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Section: Introductionmentioning

confidence: 99%

Visible Light Communication System in Presence of Indirect Lighting and Illumination Constraints

Dowhuszko

Ilter

Hämäläinen

2020

ICC 2020 - 2020 IEEE International Conference on Communications (ICC)

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“…Whang et al presented different configurations of LED arrays to achieve uniform illumination distributions and the desired beam angle [19]. zhu et al designed the configuration of LED array and diffuse reflection surface to realized uniform illumination [20], [21]. In these work, the researchers only focus on the improvement of illumination uniformity, and the ACU is not considered.…”

Section: Introductionmentioning

confidence: 99%

Angular Color Uniformity Enhancement for Color-Mixed LEDs by Introducing a Diffusing Coating Layer

et al. 2020

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In this study, a simple and low-cost method is proposed to enhance angular color uniformity (ACU) of color-mixed light-emitting diodes (cm-LEDs) by introducing a diffuse coating layer. Optical models of the proposed cm-LEDs packaging modules were constructed by Monte Carlo ray-tracing simulation. The simulation results demonstrate the ACU enhancement of the cm-LEDs packaging modules with the application of the diffuse coating layer on the reflection cup. Owing to the strong light scattering and diffuse reflection effects of the diffuse coating layer, the different color light emitted from the different chip are sufficiently mixed. The diffuse coating layer was fabricated by spraying method. Its optical performance was demonstrated by experiments. The correlated color temperature (CCT) deviations of the cm-LEDs applying the diffuse coating layer have been reduced from 1174 K to 138 K at viewing angles ranging from −80°to +80°. A lowest luminous flux loss of 3.54% is obtained. The diffuse coating layer could also maintain the excellent ACU performance when the average CCTs changes from about 2000 K to 5200 K. Extremely low CCT deviations were obtained, which are less than 300 K at average CCTs ranging from 2000 K to 5200 K. The results demonstrate that the diffuse coating layer is a feasible and effective method to enhance the ACU of the cm-LEDs.

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“…17 In addition, some researchers introduced diffuse reflection into the lighting design and diffuse reflection has some successful applications in different fields. [20][21][22][23] Zhu et al proposed a design method for a diffuse reflection freeform surface to replace the hemispherical scattering mirror. 20 Chakraborty et al demonstrated the feasibility of adapting the diffuse reflectance spectroscopy approach using the visible and near infrared spectra for detecting soil pollution.…”

Section: Introductionmentioning

confidence: 99%

Design method of double freeform surface lens with diffuse reflection

Zhu

Peng

Yuan

2019

Lighting Research & Technology

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The design method of a double freeform surface lens is being widely applied in non-imaging optical systems. In this paper, a diffuse reflection freeform surface is introduced into the design of a double freeform surface lens. Different from the universal double freeform surface lens, this double freeform surface lens is divided into a small-angle freeform surface and a large-angle diffuse reflection freeform surface. The small-angle freeform surface firstly limits and forms the lighting area. Then, the large-angle freeform surface is designed to improve the efficiency of lighting the area. And this front light diffuse reflection effectively avoids the influence of light source projection onto the lighting effects. Based on this design method, the double freeform surface lens is obtained. The results show that the efficiency of a circular lighting area reaches 81% and the uniformity of the irradiance distribution reaches 91%. And this design is also suitable for forming different shapes of lighting areas while maintaining a better lighting effect.

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Design of Diffuse Reflection Freeform Surface for Uniform Illumination

Cited by 21 publications

References 27 publications

Visible Light Communication System in Presence of Indirect Lighting and Illumination Constraints

Visible Light Communication System in Presence of Indirect Lighting and Illumination Constraints

Angular Color Uniformity Enhancement for Color-Mixed LEDs by Introducing a Diffusing Coating Layer

Design method of double freeform surface lens with diffuse reflection

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