【作者】 王恺；

【导师】 刘胜；

【作者基本信息】 华中科技大学 ， 光学工程， 2011， 博士

【摘要】 随着大功率LED流明效率不断提高、成本不断下降,大功率LED在通用照明与特种照明领域得到了越来越广泛的应用,如LED路灯、LED背光、LED汽车前照灯等等。高光效、光形可控与高空间颜色均匀度是实现高品质LED照明不可或缺的三个关键因素。为了克服现有光学设计方法的不足之处,提高LED照明品质,本论文围绕上述三个关键因素开展了LED封装与应用的自由曲面光学研究,并取得以下创新性成果：在光效与光形可控方面,对于圆对称光斑点光源情况,提出了一种新的任意配光曲线光源计算简单、任意出光角度准确可控的LED均匀照明自由曲面透镜设计算法。对于圆对称光斑扩展光源情况,提出了一套创新的基于反馈优化的扩展光源自由曲面透镜设计算法,包括优化目标平面面积网格划分、优化光源能量网格划分与两者协同优化三种设计方法。有效克服了扩展光源对照明效果的劣化,UE从0.53提高到0.90。对于圆光斑空间整体均匀照明问题,提出了一种新的逆向设计方法,包括优化配光曲线与实现任意配光曲线的新自由曲面透镜算法两部分。基于该方法,设计了两个集成自由曲面透镜的新型直下式背光用LED模块,在大距高比时显著提高了UE(从0.446提高到0.915)，同时大大减少了LED数量(1/4以下)。对于非圆对称光斑(例如常用的矩形光斑)点光源情况,提出了一种改进的非连续自由曲面透镜算法,具有任意配光曲线计算简单、能量对应灵活、光形可控度高等优点。同时,提出了两种新的连续自由曲面透镜算法,分别为基于中心辐射与基于矩形网格能量对应关系。新型自由曲面透镜出光效率高,能够实现均匀的近似矩形光斑,已成功应用于LED道路照明。对于非圆对称光斑扩展光源情况,基于同样的反馈优化设计思路,创新地提出了二次光学与一次光学相集成的应用导向型LED封装模块(ASLP),可实现均匀矩形光斑,能直接满足道路照明的需求。ASLP具有体积小(-1/8)、系统光效高(提高-8.1%)、成本低(降低17%)、方便客户使用等优点。同时,设计了一基于LED阵列光源的道路照明用多功能集成ASLP模组,具有系统光效高(提高-19.4%)、维护替换方便等优点。对于非圆对称光斑空间整体均匀照明问题,以实现亮度均匀道路照明为目标,提出了两种新的亮度均匀光学设计方法,分别为组合法与亮度均匀自由曲面透镜算法。这两种方法都显著提高了道路亮度均匀度,UL从0.30迅速提升到0.70,并已经成功应用于实际LED道路照明。同时,提出了一种新的亮度均匀非对称自由曲面透镜设计算法以提高道路照明利用率,平均亮度提高了25%。除了光效与光形可控方面,对LED照明空间颜色均匀度(SCU)也进行了研究。提出了一种采用自由曲面透镜来提高LED照明SCU的新方法。集成自由曲面透镜的新型LED封装模组的SCU从0.334增加到了0.957,并且对不同荧光粉层结构具有较好的稳定性与一致性。同时,采用空间颜色均匀自由曲面透镜能够大大降低LED的(?)u’v’值,提高LED照明品质。该新方法具有工艺简单、成本低、光效高、效果显著等优点。本文提出了一系列创新的自由曲面透镜设计算法与空间整体均匀照明设计方法,并基于这些算法设计了多种新型自由曲面透镜与新型LED封装模块,为实现光效高、光形可控、空间颜色均匀的高品质LED照明提供了一套有效的光学解决方案,将可以在LED通用照明与特种照明中得到广泛应用。更多还原

【Abstract】 High power light-emitting diodes (LEDs), with increasing luminous efficiency and cost performance in recent years, have more and more applications in general lighting and special lighting, such as LED road lighting, backlighting for LED TV, LED headlamp of automotive, etc.. High optical efficiency, controllable radiation pattern (RP) and high spatial color uniformity (SCU) are three key issues to realize high quality LED lighting. To overcome drawbacks of current optical design methods and to enhance the quality of LED lighting, this dissertation mainly focuses on the research of freeform optics design for LED packages and applications based on these three key issues. Achievements are as follows:In the aspect of optical efficiency and controllable radiation pattern, for the condition of circular-symmetry RP and point source, we propose a new freeform lens algorithm for LED uniform illumination, which makes the calculation simpler for light source with arbitrary light intensity distribution curve (LIDC) and is able to have an accurate control of emitting angles.For the condition of circular-symmetry RP and extended source, we develop a novel freeform lens algorithm based on feedback optimization for extended source problem, including three sub-methods of optimizing the division of target grid, optimizing the division of light source grid and co-optimization design methods. These three methods provide effective ways to overcome the deterioration of RP caused by extended source and enhance the UE significantly from 0.53 to 0.90.For the condition of whole lighting performance of circular-symmetry RP, we develop a new reversing design method for LED uniform illumination, including optimization of LIDC and a new algorithm of freeform lens to generate the required LIDC. According to this design method, two novel LED modules integrated with freeform lenses for direct-lit backlighting are successfully designed to enhance the UE from 0.446 to 0.915 in the situation of large distance-height-ratio, and the quantity of new LED modules dramatically decrease to less than 1/4 quantity of traditional LED modules.For the condition of non-circular-symmetry RP (e.g. rectangular RP) and point source, we propose an improved discontinuous freeform lens algorithm with advantages of arbitrary LIDC available, flexible light energy mapping relationship and shape of RP highly controllable. Moreover, we also develop two new algorithms for continuous freeform lenses, which are the design methods based on the radiate grid and the rectangular grid light energy mapping relationship respectively. Uniform rectangular RPs are able to be achieved by these freeform lenses, which have been applied in LED road lighting successfully.For the condition of non-circular-symmetry RP and extended source, based on the feedback optimization design concept and the integration of secondary optics with the primary optics of LED package, we develop a novel application specific LED package (ASLP) module, which is able to achieve rectangular RP meeting the requirement of road lighting directly. ASLP has advantages of small size (～1/8), high system optical efficiency (enhanced～8.1%), low cost (decline～17%) and easy for customer to use. In addition, a new ASLP module integrated with multi-functions, with advantages of higher system optical efficiency (enhanced～19.4%) and easy to maintain, also has been designed for road lighting.For the condition of whole lighting performance of non-circular-symmetry RP, we propose two new optical design methods for road lighting with high luminance uniformity, which are the combinatorial design method and the freeform lens algorithm for uniform luminance. Both of these two methods are able to enhance the ULof road lighting significantly from 0.30 to 0.70, and have been successfully applied in LED road lighting. Moreover, we also develop a novel asymmetrical freeform lens algorithm to enhance the utilization ratio of road lighting. Average luminance on the road is enhanced 25%by this design method.Except for the aspects of optical efficiency and controllable RP, SCU of LED lighting also has been studied. We propose a novel method to enhance the SCU of LED package by introducing the freeform lens. The SCU of a new LED module integrated with a freeform lens increases from 0.334 to 0.957 significantly. Moreover, the SCU of the new LED module is stable when the parameters of phosphor changing.⊿υ’ν’ of LED could be decreased and the illumination quality of RP could be enhanced by the freeform lens designed to achieve high SCU. This method has advantages of simple process, low cost, high optical efficiency and remarkable performance.This dissertation develops a series of novel algorithms for freeform lenses and design methods for good whole lighting performance. Kinds of new freeform lenses and LED modules are designed according to these advanced algorithms. These algorithms and freeform optics provide an effective optical solution for high quality LED lighting with high optical efficiency, controllable RP and high SCU, and could have a widely application in various LED applications.更多还原