【作者】 李明；

【导师】 郑晓东； 刘向东；

【作者基本信息】 浙江大学 ， 光学工程， 2007， 硕士

【摘要】 发光二极管(LED，Light Emitting Diode)被认为是人类发展历史上继火焰、白炽灯、放电灯之后的第四代光源。和前三代光源相比较，LED的突出特点是：其发光芯片的面积非常小，通常只有几百微米到1mm；发光源，即芯片与被照射对象之间有光学系统，如传统的LED通常制作成炮弹型；其亮度远高于传统光源。随着LED的亮度不断提高，功率不断增大，LED在使用中的安全性问题成为越来越现实的问题，应该得到人们的足够重视。由于安全性所涉及问题非常复杂，明确LED的安全问题非常困难，国际上还没有关于此问题的公认的标准。但照明是人类生活中不可或缺的环境，预测LED照明对人眼可能造成的伤害并正确评价和测量危险的程度，对于保证人类健康具有非常重要的意义。关于评价方法ICNIRP、IEC、CIE这三个标准组织都有关于LED安全性的相关规定，我们根据IEC 60825-1中的分类方法来确定LED的安全阈值，通过计算LED的对于人眼的AEL(Accessible emission limit)值来评估LED的安全性。这种评价方法是建立在对LED的表观光源的对向角进行测量的基础上的。在研究中我们首先使用ASAP软件对LED的出射光束进行了仿真，发现光束的发散角随芯片的位置和LED封装的外形有规律的变化，于是推测LED的表观光源的大小与LED的光束发散角和封装的外形有关。之后我们通过透镜成像、CCD接收的方法测量了十一种不同类型的LED的正面和侧面表观光源大小，在最危险观察距离(即距离光源100mm的位置)计算出相应的对向角，并且根据IEC标准中的计算方法算出了各种类型LED的AEL值，为实际的生产测试提供了有用的参考数据。从测得的数据中我们发现，眼睛的视网膜热危害的AEL值与LED的发散角和直径分别成线性关系，普通的非大功率LED一般不足以造成视网膜热伤害，但是其中光谱中拥有蓝光成分的很容易造成视网膜光化学伤害，特别是纯蓝光LED在实验中所有大小的电流驱动下都超过了1类光源的视网膜光化学伤害的AEL值。人们在生产和使用这些LED时需要多加小心。更多还原

【Abstract】 As the rapid development of Light Emitting Diode (LED), its brightness become more and more dazzling, its power become higher and higher. The ocular safety problem when using LED should be paid enough attention. Unfortunately, due to the widely use and rapid progress of LEDs, there is still no such a acknowledged safety standard for LEDs.To predict the hazard done to human eyes by LEDs and assess the level of hazard correctly is significant to human health.After comparing the regulation about LED by ICNIRP IEC and CIE, we decide to assess the safety property of LED by calculating its Accessible Emission Limit (AEL) according to the method of classification defined in IEC 60825-1. In this method, the angular subtense of the apparent source size is the essential quantity for optical hazard assessment.In the research, we use a software called ASAP to simulate the output beam of LEDs at first. We found the divergence angle of the beam changed regularly with the change of the location of the chip or the shape of the LED’s package, hence there must be some relationship between the apparent source size and the divergence angle or the diameter of LED. And then the apparent source size is measured by the image formed through lens and received by CCD. The angular subtense is calculated from the apparent source size and the specified most hazardous viewing distance. At last, the AEL of each type of LED is calculated according the formula in IEC60825.Through the data we got, it can be found that the AEL of retinal thermal hazard has a linear relationship with divergence angle and the diameter of LED respectively. The ordinary non high power LEDs will not cause retinal thermal hazard, but they will probably cause retinal photochemical hazard, especially the ones whose spectrum composed mainly by blue rays.更多还原