Design Of Optical System For LED Off - Road Vehicle Assisted Driving Lamp With Free Surface Method

An off-road vehicle is a specially designed vehicle for off-road driving. It can handle all kinds of roads in the wild field as well as give people a mighty feeling, which makes it popular with drivers. With the living standard rising, more and more people choose off-road vehicles in order to better enjoy the fun of driving in the wild. As the main tools for lighting, off-road vehicle lights have huge impact on drivers’ safety. There are plenty of off-road lights in the market, which provide consumers with many different choices. Nevertheless, the lighting standard of off-road vehicle lights is in the state of deficiency, which has cast a shadow over the safety of the drivers.To address this safety problem of off-road lighting, this dissertation focuses on the research of lighting standard of off-road auxiliary driving lights, the most common lights of off-road vehicle lights. From the comprehensive consideration of situation of different roads in the wild, a minimum lighting range can be drawn from the minimum range of visibility under different turning radius of off-road vehicles. After measuring the luminance reflectance of different types of roads, a minimum flux requirement in the minimum lighting range, as well as the lighting standard for off-road auxiliary driving lights, is proposed. To ensure the practical usefulness of the proposed lighting standard, a sampling test requirement is proposed as well. Auxiliary driving lights should fulfill the sampling test proposed.Meanwhile, to fulfill the proposed lighting standard as well as to make innovation of the off-road light optical design method, the freeform surface method is used in this dissertation to design the auxiliary driving lamp with LED as the light source. After a thorough description of the freeform surface method and a design sample, a lens for the auxiliary driving lamp is designed using the freeform surface method. The proposed minimum lighting range is split into several parts. According to these parts, the lens is designed in two different sections, one of which is set to be achieved via refraction method and the other one internal reflection method. After the surfaces are got from the computer programming, the points of the surfaces can be used to grow freeform surfaces with model software. Finally the lens can be done with the surfaces grown in the last step. An optical simulation software can be used to test the result.The simulation result has shown that the designed lens can fulfill the proposed lighting standard well and has high efficiency.