Aiming Ge

Hybrid daylight/light-emitting diode illumination system for indoor lighting.

A hybrid illumination method using both daylight and light-emitting diodes (LEDs) for indoor lighting is presented in this study. The daylight can be introduced into the indoor space by a panel-integration system. The daylight part and LEDs are combined within a specific luminaire that can provide uniform illumination. The LEDs can be turned on and dimmed through closed-loop control when the daylight illuminance is inadequate. We simulated the illumination and calculated the indoor lighting efficiency of our hybrid daylight and LED lighting system, and compared this with that of LED and fluorescent lighting systems. Simulation results show that the efficiency of the hybrid daylight/LED illumination method is better than that of LED and traditional lighting systems, under the same lighting conditions and lighting time; the method has hybrid lighting average energy savings of T5 66.28%, and that of the LEDs is 41.62%.

Optical design of a street lamp based on dual-module chip-on-board LED arrays

We design and propose a compact street lamp based on dual-module chip-on-board LED. The street lamp is composed of six faceted reflectors. It can direct the luminous flux and form uniform illumination on the target area, and it effectively reduces power consumption. We have conducted both simulations and prototype measurements. The test results show good optical performance in that the uniformity of luminance reaches 0.58 for LED lamp zigzag arrangements and 0.60 for LED lamp double-side arrangements. The average luminance can fulfill the requirements in Chinese road lighting Standard CJJ45-2006.

A composite optical system for a LED based headlamp low beam module

In this paper, we propose a composite optical system for automotive headlamps. The system is composed of a paraboloid collimating reflector, an off-axis paraboloid reflector, a baffle and an imaging len. By using a LED as the light source, precise light distribution can be achieved. When making ray-tracing simulation for the composite optical system in TracePro, a clear cut-off line can be seen on the measuring screen, as well as a hotspot at the centre. The power consumption for the LED light sources in this system is less than 10 W, resulting in an energy efficiency of more than 58% and a maximum illumination of 26.76 lux at the centre hotspot.

Optical design of a road lighting luminaire using a chip-on-board LED array

Compared to traditional street lighting technologies, light emitting diode (LED) luminaires have the potential advantages of increased energy efficiency, longer operating life and better light distribution. In this paper, we present a new high-quality LED road lighting luminaire. The luminaire shows high optical efficiency, high optical utilization factor and low glare, and illuminates the street with high uniformity. We verify its feasibility by Monte Carlo ray-tracing and test its real performance through a prototype model of the luminaire. The results show that it can achieve the expected performance.

Design of an LED-based headlamp low-beam system using combined prisms

An effective high-efficiency LED headlamp system for automotive low-beam lighting which consists of parabolic reflector, compound lenses and combined prisms, is introduced in this paper. Using a single, high-brightness LED, the illumination requirements for a headlamp low beam specified by UNECE regulation ‘Addendum 111: Regulation No. 112 Revision 2’ can be achieved. On the test screen at a distance of 25 m, simulation results as well as testing results for the prototype meet the requirements of the UNECE regulation for all specified regions and key points.

A new way to measure the luminous intensity distribution of LEDs based on Luneburg lens

The use of LEDs is increasing rapidly in both the commercial and residential markets. Nowadays, the main way to measure the luminous intensity distribution of a LED is by using a goniophotometer. This takes a long time which means its test efficiency is low. In this paper, we will propose a new way to measure the luminous intensity distribution of LEDs based on the Luneburg lens, which is a kind of dielectric lens with continuously changed index of refraction, with high efficiency and low cost. We also develop a complete test system and give the result of a simulation of the test system.

A Fresnel freeform surface collimating lens for LEDs

This paper proposes a freeform surface lens design based on the Fresnel model to achieve a compact structure and good collimation. A simulation indicates the lens enjoys an efficiency as high as 88.43% within a half view angle of 2° for 1 × 1 mm2 size LED. This paper makes a comparison of three types of lens, among which the Fresnel freeform lens achieves the best performance when the LED size is smaller than 2.5 × 2.5 mm2. The influence of the LED size and the manufacturing tolerances are discussed.

Optical design of a high-mast luminaire based on four COB LED light source modules:

Light-emitting diodes (LEDs) have been widely used in road lighting. This study investigates the optical design of a high-mast luminaire based on four chips-on-board LED light source modules and applies it to road lighting. The model of the high-mast luminaire is built with Solidworks, and then the optical simulations are analysed by Tracepro and Dialux. We also make a physical prototype of the high-mast luminaire to test its performance in practice. The illuminance distribution of the test area is nearly rectangular. The interior of the rectangle forms a smaller highlighted rectangular illumination area with uniform illumination. The outer edges of the rectangular illumination area will overlap the outer edges of the illumination area of other high-mast luminaires. The desired illuminance distribution and the uniform illumination can be obtained. Both the simulations and the experimental results meet the requirements of road lighting standards and the high-mast lamp can even achieve a better optical performance.

Research on a method to measure the optical parameters of a precision approach path indicator

The precision approach path indicator (PAPI) system is installed alongside a runway or at a heliport to provide accurate visual approach path information to pilots of landing aircraft, either day or night. The indicator sends the information through different color combinations. The international standards have very rigid requirements for the intensity distribution and the transition angle from red light to white light of the indicator. These two parameters are the main parameters to judge the accuracy of the indicator. We propose a new method to measure these two optical parameters, which can improve the accuracy of the signals and guarantee safe landing of the aircraft.