Design method of double freeform surface lens with diffuse reflection

Abstract

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.

A design of compound tailored illumination by a total-internal-reflection lens for machine vision

“…The method disclosed in previous research 13 is based on a collimation method, which has efficient illumination but cannot be used to obtain uniform illumination, and another vulnerability is the process of the structure, resulting in a limitation. The method by Zhu et al 18 also has a structure that may not favour processing, and energy loss is another limitation. The MA method 22 may have advantages in the process compared with our method; however, the ability to adjust the contrast between irradiance of different regions were not shown in this method, and some details, such as light efficiency, were not disclosed.…”

“…Therefore, a lighting system that generates tailored irradiance in different regions should be considered in machine vision to enhance useful information and weaken the useless information of targets. Tailored illumination has always been a frontier topic of nonimaging optical design, and several mathematical models and structures have been previously disclosed by researchers, 18–22 the objectives of which were all achieved theoretically or practically. Zhu et al .…”

“…Zhu et al . 18 employed an edge-ray-based method for producing tailored faculae (rectangle, triangle) on the target surface. The produced faculae are patterns formed by light on a target surface, which are directly determined by the irradiance distribution.…”

Mini-LEDs with Diffuse Reflection Cavity Arrays and Quantum Dot Film for Thin, Large-Area, High-Luminance Flat Light Source

“…Zhu et al proposed double freeform surface lens with diffuse reflection applied in non-imaging optical systems [ 45 ]. Zhu et al proposed diffuse reflective Off-Axis surface for noncircular LED arrays [ 46 ].…”

Opto-Electronics Review

“…The shape of such a distribution should be constantly controlled during the optical system design process. It is not enough to perform many time-consuming analytical and geometrical operations and, then, control the obtained distribution using computer simulations [7][8][9]. This leads to a danger of creating unacceptable designs and starting work from the beginning.…”