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HPWA-MXOO 参数 Datasheet PDF下载

HPWA-MXOO图片预览
型号: HPWA-MXOO
PDF下载: 下载PDF文件 查看货源
内容描述: 二次光学设计考虑食人鱼LED灯 [Secondary Optics Design Considerations for SuperFlux LEDs]
分类和应用:
文件页数/大小: 23 页 / 2140 K
品牌: LUMILEDS [ LUMILEDS LIGHTING COMPANY ]
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For thin lenses, it is a good approximation to  
A cross-section through the center of a plano-  
convex lens, and its Fresnel counterpart are  
shown in Figure 5.32.  
measure f from the center of the lens.  
For thin, plano-convex lenses (R1 = ¥ ), the  
equation further simplifies to:  
The thickness of the Fresnel lens is reduced as  
the number of steps is increased. Typically Fresnel  
lenses are designed with the minimum number of  
steps needed to achieve the desired thickness,  
because additional light losses may occur at the  
internal faces and joining vertices. However, for  
plastic lenses, a thin design is desirable where  
excessive lens thickness will result in sink  
distortions. Therefore, the performance and  
moldability of a lens are traded-off when choosing  
the optimal number of steps.  
The above equations assume all rays arrive at  
shallow angles with respect to the optical axis  
(paraxial assumption). However, for SuperFlux  
LED applications, where much of the flux is  
contained at angles far from the optical axis,  
this is not the case. As a result, rays which are  
not close to the optical axis will be bent at too  
great an angle, a condition known as spherical  
aberration. A correction factor, C, can be added  
to the above equations to compensate for this  
effect as shown below:  
For most LED collimator designs, a correction  
factor of C @ 1.35 will produce the best results.  
The value of f chosen can be checked by  
tracing a ray from the source to the outer edge  
of the collimator lens (edge ray). If the edge ray  
is under collimated, the value of C used is too  
large. If the edge ray is over collimated, the  
value of C used is too small. Figure 5.29  
graphically depicts the edge ray method for  
checking f.  
Figure 5.28 Cross-section of an LED signal  
lamp using a dual-convex, collimator lens.  
Fresnel Lens Design  
A Fresnel lens can be visualized as a thick  
convex lens which has been collapsed about a  
series of circular, stepped setbacks. This type  
of lens takes on the properties of a much  
thicker lens and eliminates the difficulties  
involved with the manufacture of thick lenses.  
Figure 5.29 Edge ray method for checking f.  
18  
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