【作者】 刘鹏；

【导师】 郑臻荣； 刘旭；

【作者基本信息】 浙江大学 ， 光学工程， 2014， 博士

【摘要】 随着LED技术的成熟和医疗照明需求的日益复杂化,有关LED在手术无影灯中应用的研究越来越多,并开始出现商业化的LED无影灯产品。跟传统的卤素无影灯系统相比较,虽然LED手术无影灯具有明显的优势,但是其设计理论还没有形成成熟的体系。本文从无影灯的发展历程出发,对比了目前LED无影灯产品的技术参数,提出了LED无影灯设计的两个关键问题,LED光谱的视觉感知和光学设计。结合LED在医疗中的应用,本文提出了采用光谱可调的LED无影灯增强医生视觉感知的可能；针对无影灯日益复杂的照明要求,提出了用多个自由曲面去解决LED手术无影灯在实际应用中所遇到的光学难题。在光学设计方面,本文分析了现有光学多自由曲面理论的原理和局限性,提出了序列多自由曲面设计方法。该方法可以将较为复杂的照明需求子目标化,根据子目标化之后的照明要求和前置曲面的光学特性,选取合理的映射关系,分步去实现最终的照明要求,降低了自由曲面的设计难度。针对扩展光源的引入,本文还提出了序列自由曲面的优化方法,并针对扩展光源实现了一款用于圆形均匀照明的全内反射透镜,验证了该优化理论的实用性。在视觉感知方面,本文着重研究了LED照明光谱与生物样品组织对比度之间的关系。为此,我们建立了一套大型LED测试平台,该平台可以为颜色生理、颜色心理相关实验提供光谱多样的照明支持。为了提高LED测试平台输出光斑的颜色均匀性,本文通过光斑拼接和对自由曲面透镜的优化实现了针对阵列LED光源的大面积混色。为了量化生物样品的组织对比度,本文提出了一种对比度评价模型,该模型不仅可以衡量整个组织样品的对比度信息,同时也可以反映特定区域的细节信息。基于LED测试平台和组织对比度评价模型,通过一系列的实验,得到了用于组织对比度增强的局部最优LED光谱,为光谱可调的LED无影灯在光源选择、光谱优化方面提供了有力的数据支持。基于序列光学多自由曲面设计方法以及对LED照明视觉效应的进一步认识,本文提出了两套自由曲面LED无影灯。为了解决手术室中普遍存在的气流扰动问题,本文提出了天吊式LED手术无影灯,并采用基于序列多自由曲面设计方法的光学系统,实现了其苛刻的照明设计要求。为了改进吊塔式无影灯的光学性能,本文提出了卫星式LED多光谱无影灯的概念,结合LED的排布和自由曲面准直透镜的设计,保证了该无影灯系统良好的照明输出,并通过模拟和实验研究了该系统的性能。最后,本文对光谱可调LED自由曲面无影灯的研究进行了总结,并提出在今后研究中应该注意的问题。更多还原

【Abstract】 With the development of LED technology and higher requirements of medical illumination, people try to study the application of LED in surgical lighting, and commercial LED surgical lighting products emerges in recent years. Compared with the traditional surgical lighting which based on the halogen lamps, LED surgical lamps have many advantages while there are still no recognized standards for LED surgical lighting design.Based on the history of surgical lighting and specifications of the current LED surgical lamps, optical design and visual perception of LED lighting, are considered as two key aspects of the LED surgical lighting. Because of the complicated illumination requirements, multiple freeform surfaces are suggested to be employed in the optical design. According to the LED’s application in previous medical use, the possibility of enhancing the visual perception by LED multi-spectral surgical lamps was studied.As for the optical design aspect, a sequential multiple surfaces (SEMS) design method is proposed. This method can reduce the optical design difficulties by dividing the design target into several subtarget, which can be easily obtained by single freefrom surfaces. According to the first subtarget, first partial differential equation about the freeform surface can be easily solved by the mapping relationship between the emiting angle of the light source and the target area. Based on the previous surfaces, the incident rays of the present freeform surface can be updated to estabilish a new differentail equation. Then, a lens with multiple freeform surfaces can be achieved by solving these equations. In order to make this method feasible to the extended light sources, optimization theory of freeform surface was proposed. Based on this optimization design method, a TIR freeform lens which can produce circular uniform irradiance pattern by use of a LED source is obtained.As for the aspect of visual perception, the relationship between LED spectral and the contrast of tissue was studied. To provide various spectral mode for the following experiments, a LED lighting platform is proposed. In the designing of the LED lighting module, a large scale color mixing method by configuration of the LED units and the optimized design of the freeform lens was applied. Also, an entropy based contrast evaluation model is constructed for quantify the tissue texture while the contrast of the regieons of interest. Based on the LED lighting platform and the evaluation model, the LED lighting with appropriate spectral distributoon are proposed for enhancing the tissue contrast. This provided the fundamental data for LED surgical lighting on the LED selection and the spectral optimization.Based on the previous study of this paper, two LED surgical lighting systems were proposed. In order to allievate the air disturbance exisited in the operation rooms, a LED ceiling embedded surgical lighting system, which lead to extremly complicated optical challenge, is proposed. By using of the SEMS design method, the optical performance of the surgical lighting system was ensured. After that, a satellite sugical lamp is proposed to optimize the optical performance of the tower crane based surgical lamps. By the configuration of the LEDs and the freeform techniques, the optical output of the proposed lamp was satifying, which is also validated by the results of both the simulation and experiments.At last, we summrized the previous study on the freeform based LED surgical lighting with multiple spectral, and proposed the direction of future study.更多还原