Simple dynamic energy core equivalent rays method to design freeform surface for extended source

doi:10.1007/s12200-016-0619-y

Front. Optoelectron.

2016, Vol. 9

Issue (2) : 330-337 https://doi.org/10.1007/s12200-016-0619-y

RESEARCH ARTICLE

Simple dynamic energy core equivalent rays method to design freeform surface for extended source

Kun WANG,Yanjun HAN,Hongtao LI,Yi LUO(

),Zhibiao HAO,Lai WANG,Changzheng SUN,Bing XIONG,Jian WANG

Tsinghua National Lab on Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

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Abstract

A simple method is proposed to design freeform surface for Lambertian extended source. In this method, it can take advantage of the designing method for point source via substituting each incident ray with a dynamically calculated equivalent ray. For each facet on the freeform surface, the equivalent ray emits from the energy weighted average-emitting-position for the corresponding incident beam, and redirects into the direction which is determined by a source-to-target mapping. The results of the designing examples show that the light distributions’ uniformities can be improved by this method, e.g., even the improvement of 59% can be achieved.

Keywords nonimaging optics illumination design light emitting diodes (LEDs)

Corresponding Author(s): Yanjun HAN,Yi LUO

Just Accepted Date: 26 February 2016 Online First Date: 29 March 2016 Issue Date: 05 April 2016

Cite this article:

Kun WANG,Yanjun HAN,Hongtao LI, et al. Simple dynamic energy core equivalent rays method to design freeform surface for extended source[J]. Front. Optoelectron., 2016, 9(2): 330-337.

URL:

https://academic.hep.com.cn/foe/EN/10.1007/s12200-016-0619-y
https://academic.hep.com.cn/foe/EN/Y2016/V9/I2/330

Fig.1 (a) Illustration of a θ ~ r mapping for point source; (b) when the source is an Lambertian extended source, each facet of the freeform surface will form a light spot

Fig.2 An incident beam is formed by a large number of rays, which are emitting from different source positions and passing through a specific small facet of freeform surface

Fig.3 (a) Construction of the freeform surface contour for point source; (b) ECER method is using the equivalent ray to substitute the incident ray from the point source during each facet construction, and each equivalent ray is obtained by several times iteration

Fig.4 Flow chart of the ECER method

Tab.1 Results of this uniform-illuminance-distribution designing example

Fig.5 When the source radius is 3 mm in the designing example, (a) illuminance distributions achieved by the traditional method; (b) illuminance distributions achieved by ECER method; (c) line chart of the illuminance distributions achieved by the traditional method; (d) line chart of the illuminance distributions achieved by ECER method, (e) x coordinates of the ECER emitting positions for each facet of the freeform surface profile

Fig.6 Results of the intensity distributions of the optical systems which are designed by ECER method and the traditional method, respectively. (a) RSD values of the intensity distributions; (b) energy utilization ratio of the intensity distributions

Tab.2 Results of this uniform-intensity-distribution designing example

Fig.7 When the source radius is 10 mm, (a) intensity distributions designed with ECER method; (b) intensity distributions designed with the traditional method; (c) line chart of the two intensity distributions; (d) designed lens shape by ECER method and the source

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