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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 B2vh-%63  
人眼光学模型可用来设计眼科用设备，光学系统注定了要与人眼一起使用。本文演示了这样一个模型：Arizona眼睛模型，在Jim Schwiegerling教授的书中有详细描述：《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源，并包括一个基于想要的屈光度来调整模型的内嵌脚本。 ^$jb7HMObI  
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模型 :K,i\  
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模型的定义如表1种所示，由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度（A）来决定。 8U"v6S~A%Q  
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Table 1. AZ眼睛模型的定义
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在FRED中使用0屈光度来创建的，光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. 9!\B6=r y4  
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光源 ?pmHFlx  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 N0Lw}@p  
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图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 *I.f1lz%*  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 zT]8KA   
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图2. 字母F光源的设定方法光 dt]-,Y  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 &i6mW8l  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 n5NsmVW\x  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 `iNSr?N.  
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图5. 视网膜重点采样规格设定
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脚本 n M*%o-  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： ,!y$qVg'\f  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 1};Stai'  
余下的脚本计算与屈光度有关的所有参数。 ,T$U'&;  
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分析 24*XL,  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 ChPmX+.i_  
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图7. 字母F在视网膜上颜色分析
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脚本代码 ]MitOkX  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. .jE{3^  
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Dim entity As T_ENTITY /]Md~=yNp  
Dim op As T_OPERATION &.Qrs :U  
Dim mat As T_MODELMATERIAL Yu^4VXp~M%  
Dim A As Double qiBVG H  
Dim pupilDiam As Double @9RM9zK.q  
Dim eID As Long 6}Ci>_i4#  
Dim parID As Long ,Uqs1#r  
Dim count As Integer ?X<eV1a   
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double nT$SfGFj8  
Dim tlens As Double, nlens As Double H3=qe I  
Dim curv As Double, conic As Double A[{yCn`tM  
Dim ok As Long 'yEHI  
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Sub Main D.u{~  
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    '用户输入对话框 _|I#{jK  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 Flm%T-Dl  
        TextBox 220,21,40,21,.TextBox1 'default: 0 2-v%`fA  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 |3"KK  
        OKButton 40,91,90,21 %pL''R9VF  
        CancelButton 190,91,90,21 )}Kf=  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 qt"m  
        TextBox 220,49,40,21,.TextBox2 'default: 4 wE`]7mA  
    End Dialog p]+Pkxz]'  
    Dim dlg As UserDialog "`e{/7I  
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    ok = Dialog (dlg) I-(zaqp@  
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    If ok=0 Then    'cancel button was pressed qqY"*uJ'  
        Print "Execution cancelled." Wt-GjxGi  
        End `d`T*_  
    End If 3bH'H*2  
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    'Assign accommodation and pupil diameter & use defaults if field left empty !z3jTv  
    If dlg.TextBox1 = "" Then ZKTz ,  
        A = 0           'Default accommodation E*K;H8}s  
    Else dkTX  
        A = CDbl(dlg.TextBox1) -C]5>& W  
    End If }|NCboM^_  
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    If dlg.TextBox2 = "" Then r[iflBP  
        pupilDiam = 4   'Default pupil diameter 5Yq@;e  
    Else {cVEmvE8  
        pupilDiam = CDbl(dlg.TextBox2) `b7t4d*  
    End If +iRh  
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    Print " " meO:@Z0  
    Print "Accommodation = " & A & " Diopters" 7~.9=I'A  
    Print "Pupil Diameter = " & pupilDiam & " mm" ;iL#7NG-R  
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    ' Calculate new parameters with accommodation F{;((VboN  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness RMu~l@  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens y}ev ,j  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens g*C7 '  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens `Eo.v#<  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens w%jII{@,  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ^8N}9a  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 56kI 5:  
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    'Adjust parameters to account for accommodation @<EO`L)Z  
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    '*************************************************************************  S9FE  
    'Aqueous thickness (Position of Lens) k=T\\]KxC  
    '************************************************************************* M&9+6e'-F  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) $}<e|3_  
    GetCustomElement eID, entity '!~)?C<  
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    parID = FindFullName( "Geometry.Arizona Eye" ) u>a5GkG.  
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    ' Delete any shift(s) in z Yufc{M00  
    count = 0 59;KQ  
    While GetOperationCount(eID)>count T%*D~=fQ'  
        GetOperation eID, count, op d)Y}>@:W  
        If op.Type="ShiftZ" Then \bvfEP  
            DeleteOperation eID,count |[b{)s?x  
            count=count-1 5vnrA'BhBU  
        End If <bEbweQrgm  
        count=count+1 ^v7gIC  
    Wend RPL:-  
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    'Set new shift in hf&9uHN%7m  
    op.Type = "ShiftZ" ml }{|Yz  
    op.val1 = taq }`m/bgtFX  
    op.parent = parID /R wjCUf  
    AddOperation eID, op p>8D;#Hm L  
    Print "Set aqueous humor thickness = " & taq-0.55 LyFN.2qw  
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    '************************************************************************* WX3-\Y5E  
    'Radius and conic constant of anterior lens 89(Q1R ?:  
    '************************************************************************* Z=vU}S>r|v  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) =]0&i]z[.  
    GetConic eID, entity, curv, conic !'*-$e  
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    SetConic eID, entity, 1/Rant, CCant /aZ`[m2  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant WCixKYq  
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    '************************************************************************* u;2[AQ.  
    'Radius and conic constant of posterior lens XVZ   
    '************************************************************************* {;6`_-As%  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) a<bwzX|.  
    GetConic eID, entity, curv, conic u.xnOcOH!  
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    SetConic eID, entity, 1/Rpost, CCpost 2`=7_v  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost v):Or'$~M  
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    '************************************************************************* NqWdRU  
    'Lens thickness (Position of posterior lens surface) E+;7>ja  
    '************************************************************************* 9~[Y-cpoi  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) &0JI!bR(  
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    ' Delete any z-shift(s) hM@>q&q_  
    count = 0 [MY|T<q  
    While GetOperationCount(eID)>count 9p(. A$  
        GetOperation eID, count, op ., 6-u  
        If op.Type="ShiftZ" Then vUM4S26"NT  
            DeleteOperation eID,count Wvf ^N(  
            count=count-1 $1`2 kM5  
        End If '/s)%bc  
        count=count+1 SO0PF|{\r  
    Wend k;FUs[  
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    'Set new z-shift 1p=]hC  
    op.Type = "ShiftZ" -ZLJeY L  
    op.val1 = tlens vy I!]p  
    op.parent = parID 97!;.f-  
    AddOperation eID, op 8bld3p"^  
    Print "Set lens thickness = " & tlens U # qK.  
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    '************************************************************************* }*]-jWt1J\  
    'Lens index of refraction O :Tj"@h  
    '************************************************************************* TOQP'/   
    eID = FindMaterial( "Lens" ) TuaBm1S{f  
    GetModelMaterial eID, mat i=2N;sAl  
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    mat.Nd = nlens CzrC%xy  
    SetModelMaterial eID, mat Mb*?5R6;  
    Print "Set lens index of refraction = " & nlens g[4WzDF*  
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    '************************************************************************* 13x p_j  
    'Pupil diameter ncT&Gr   
    '************************************************************************* NK H@+,+V  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) #o#H?Vo9b  
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    'Adjust pupil diameter (trimming volume inner hole) QoT;WM Z  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" |P?*5xPB  
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    ' Adjust pupil location to just in front of the lens + v:SM 9  
    parID = FindFullName( "Geometry.Arizona Eye" ) O0H.C0}  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) FfT`;j  
    count = 0 (TT}6j  
    While GetOperationCount(eID)>count 5\VWCI  
        GetOperation eID, count, op DZtsy!xA  
        If op.Type="ShiftZ" Then  a0)QH  
            DeleteOperation eID,count 8Z=R)asGS  
            count=count-1 ,r_Gf5c  
        End If 5]:U9ts#  
        count=count+1 +9sQZB# (  
    Wend dioGAai'  
    op.Type = "ShiftZ" [v!f<zSQK  
    op.val1 = taq-0.01 G$('-3@i`w  
    op.parent = parID @-`*m+$U6  
    AddOperation eID, op 'PW5ux@`<  
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    Print "Set pupil diameter = " & pupilDiam ('+d.F[109  
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    'Update AZ Eye subassembly Description <t!W5q  
    eID = FindFullName( "Geometry.Arizona Eye" ) h^P#{W!e\  
    GetEntity eID, entity YKK*ER0  
    entity.Description = "Accommodation = " & A & "D" Q\sK"~@3  
    SetEntity eID, entity ]\HvKCN}  
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    Update Z*6IW7#  
    Print "DONE!" N?`' /e  
     ;*2Cm'8E  
End Sub l,aay-E  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： <qt|d&  
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Accommodation = 4 Diopters &_8 947  
Pupil Diameter = 4 mm {R{=+2K!|k  
Set aqueous humor thickness = 2.81 a(ZcmYzXU  
Set anterior lens radius = 10.4 and conic constant = -2.375869 )%fH(ns(  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 @_{=V0  
Set lens thickness = 3.927 b" [|:F>P  
Set lens index of refraction = 1.42672 HTTC TR  
Set pupil diameter = 4 {?7Uj  
DONE! %E;'ln4h&,  
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（文章来源：讯技光电）
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