引言
光学成像镜头的景深是重要的评价指标。
下面为大家讲解如何用ZEMAX光学设计软件来计算光学镜头的景深。
焦深=2*SPOT*F/D
其中SPOT为允许的弥散斑直径，F为理想像距，D为光瞳直径。
Through Focus 的MTF
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RSCE的详细解释如下
RMS spot radius with respect to the geometric image centroid in lens units. This operand uses a Gaussian quadrature method that is accurate for systems with unvignetted circular pupils.
ZEMAX本身可以计算宏语言，例如可以计算依赖于MTF等系统的景深。
下面是 文杰 写得ZPL语言计算景深的文件。
你可以在本文的下面的链接下载到ZPL文件，然后放入ZEMAX宏指令下面，执行即可。
[code]
! Depth of Field
! Calculate depth of field
!
! Wenjie Nong 11-11-06
!
FORMAT 8.3
INPUT "Focal length(mm)",effl
INPUT "F/#",fno
INPUT "Subject distance(m)(Input 0 for infinity)",distance
INPUT "Circle of confusion(mm)",CoC
distance = distance * 1000
! 0.00029 is limited resolution angle of human eye in radian
! elsa = 0.00029
enpd = effl / fno
mag = effl / distance
!delta1 = ( distance*distance * elsa ) / (effl/fno - distance*elsa)
!delta2 = ( distance*distance * elsa ) / (effl/fno + distance*elsa)
distance1 = mag*enpd*distance/(enpd*mag - CoC)
distance2 = mag*enpd*distance/(enpd*mag + CoC)
! distance == 0 means focus at infinity
IF distance == 0
distance2 = enpd / (CoC/effl)
distance1 = 0
ENDIF
PRINT ""
PRINT "Calculates Depth of Field..."
PRINT "Focal Length = ",effl," mm"
PRINT "F/# = ",fno
PRINT "Subject distance = ",distance/1000," m"
PRINT "Circle of confusion(mm)",CoC
PRINT "Depth of field in front of subject(m) : ",(distance-distance2)/1000
PRINT "Depth of field behind subject(m) : ",(distance1 - distance )/1000
PRINT "Total depth of field(m) : ",( distance1 - distance2)/1000
[/code]
输入参数说明：
Focal length(mm) 填入镜头焦距
F/# 填入镜头F/#
Subject distance(m)(Input 0 for infinity)", 填入物距，如果是无穷远则为0
INPUT "Circle of confusion(mm)", 填入允许的弥散圆大小, 如0.031mm
本文介绍了使用ZEMAX软件分析和评价成像镜头的焦深的方法。
提供了一个ZPL宏语言计算焦深的文件。
对于其详细的改变及讨论请参考一下文章：
http://www.optotek.com.cn/knowledge-item-77-Depth-of-Focus.html
更多问题，欢迎和我们联系.
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