Optical design of an LED motorcycle headlamp with compound reflectors and a toric lens

Collimating illumination of a refractive lens using an annularly stitched surface for extended LED sources

We report a design method based on an annularly stitched aspherical surface for highly collimated optical systems with extended light sources. The annularly stitched aspherical surface is constructed as a circular central zone and one or more annular zones, which are rotationally symmetric and provide flexibility to satisfy the requirements of a practical design. An extended LED light source can be considered, and a backward ray-tracing process is used to construct the initial lens model. The specific optimization has been added step by step to modify the stitched surface to redistribute the light rays emitted from the extended source. The smoothness of the stitched surface is considered in the design and optimization process to guarantee the processability of the system. A prototype has been fabricated and tested, which demonstrates the validity of this method.

Design and optical performance research of a fully customizable collimating lens based on total internal reflection

An optical design method of a fully customizable collimating lens is proposed. The initial model of the complete lens is constructed by two parts. One part is calculated by the total internal reflection algorithm; the other part is constructed by trial-and-error method. The lens is further optimized by normal vector correction and high- and low-angle compensation. The optical performance of the fully customizable collimating lens is studied. It is proven to have good collimation performance with a divergence angle of 1.8° at 50% of the maximum luminous intensity; the uniformity is as high as 98.4%.

GaN-based mini-LED matrix applied to multi-functional forward lighting

In this paper, we propose and demonstrate to use of 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 5 × 6 LED die 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. Besides, to extend the functionality of the headlamp module, we propose to dispense IR phosphor on LED dies in the high-beam zone of the GaN-based mini-LED matrix. Thus the vehicle can emit IR high beam, which can be imaged through a camera and can be incorporated with machine vision for an autonomous vehicle without using a complicated adaptive headlight to avoid glare. The proposed multi-function in spatial and spectral domains will be helpful to various applications with use of a mini-LED matrix.

Design of a reflective LED automotive headlamp lighting system based on a free-form surface

In this paper, a design scheme of an automobile low-beam light illumination system with a reflector free-form surface is presented. Per the energy grid mapping theory and edge ray theory, an oblique triangular energy mapping scheme was proposed, and the free-form reflector was obtained by geometric iterative calculation. The Monte Carlo ray tracing method was used to simulate the system. The simulation results met the regulatory requirements of ECE R112, and the light efficiency could reach 81%. The length, width, and height of the reflector were 55.61mm×22.02mm×23.70mm. The reflector achieves a special light type through precise light distribution, does not need other shielding objects, and has the advantage of small size.

Freeform optical design of beam shaping systems with variable illumination properties

Freeform optics constitutes a new technology that is currently driving substantial changes in beam shaping. Most of the current beam shaping systems are elaborately tailored for fixed optical properties, which means the output light distribution of a beam shaping system usually cannot be changed. What we present here is a class of beam shaping systems, the optical properties of which can be changed to meet the requirements for different applications. The proposed beam shaping system is composed of a freeform lens and a non-classical zoom system which is designed by ray aiming and the conservation of energy instead of aberration control. The freeform lens includes two elaborately designed freeform optical surfaces, by which both the intensity distribution and wave-front of an incident light beam are manipulated in a desired manner. The light beam after propagating through the non-classical zoom system produces an illumination pattern on a fixed observation plane with a variable pattern size and an unchanged irradiance distribution at different zoom positions. Two design examples are presented to demonstrate the effectiveness of the proposed beam shaping systems.

Design and prototyping of highly-collimated long-distance optical systems with an LED light source

Electrical lighting design is usually based on the illumination design. Its main task is to ensure that the electricity and optical system can be normal, safe, reliable, and economically viable. In this paper, we propose a design and optimization method for outdoor illumination systems to generate relatively powerful light beams for far distances. The illumination systems are based on highly integrated LED modules instead of high intensity discharge lamps. The size of the LED light-emitting surface is 2.5mm×2.1mm, and the secondary optical elements are composed of a basic plano-convex lens and a Fresnel lens. The results of simulation demonstrate that the emission angle of the system is 1.1°, and the central illumination at 2500 m away is more than 1 lx. The total system is simple but practical, and several groups can be combined into a larger system. Two proof-of-concept prototypes producing acceptable illuminance are developed, and one is composed of four groups whose light is visible from 5000 m away. Both are fully waterproof and in a high degree of protection. The systems can provide up to 12 h of continuous lighting, and the operating temperature rise is less than 25°C. The results indicate that our design can be applicable for practical wild working sites.

Design of a Bicycle Head Lamp Using an Atypical White Light-Emitting Diode with Separate Dies

To the best of our knowledge, this is the first demonstration of a design for a bicycle head lamp with a high-contrast cutoff line using an atypical white light-emitting diode (LED) with two separate dies. The precise optical model was created by setting the weighting factor on the emitting surface. The downward reflector was designed and fabricated to produce a high-contrast cutoff line in both short- and long-axis orientations, but a yellowish outer pattern was observed. A modified two-color optical model was created to describe the yellowish patterns in both orientations and explain the yellowish effect. Such an effect was caused by the larger coverage area of the phosphor than that by the blue dies. To reduce the yellowish effect near the cutoff line, a specific phosphor area was blocked in the experiment. The yellowish effect was greatly reduced, and the contrast across the cutoff line was enhanced. The presented technology is useful for designing a high-contrast light pattern with such an atypical white LED.