请教一个一直没有搞懂的问题：edge thickness是如何定义的

<P>在zemax的手册中关于edge thickness的定义一直没有搞懂，在这请教各位。</P>
<P>我把这段话写在这里：</P>
<P>zemax uses two different definitions for the term "edge thickness". Usually, the edge thickness is computed foa seecific surface by:</P>
<P>E(i)=Z(i+1)-Z(i)+T(i) （这里括号里的字符表示下标）</P>
<P>where Z(i) is the sag of the surface at the +y semi-diameter（是指半径为+y处吗？）of the surface, Z(i+1) is the sag of the next surface at the +y semi-diameter of the next surface, and T(i) is the axial thickness of the surface(这个thickness of the surface又是怎么定义的呀？). Note that the edge thickness are computed accounting for the sag at he respective semi-diameter of each surface, which in general are different.</P>
<P>主要是edge thickness要加上那个T(i)，实在是搞不懂。</P>
<P>还有一个没搞懂的是edge thickness solve，感觉看上去也是一头雾水啊。</P>

<P>它就是二个光学面边缘之间的厚度</P>

<P>哦。</P><P>看来Zi是以第i面为坐标原点衡量的，而Z(i+1)是以第i+1面衡量的。</P><P>没注意到沿光轴方向坐标原点是在不断改变的。</P><P>谢谢了^_^</P>

<P 0cm 0cm 0pt; mso-layout-grid-align: none"><FONT size=2>请问在air上是怎么去作定义</FONT><p></p></P>

Z是第i面边缘与中心的高度差，T是中心厚度

好 谢谢