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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 2m. RM&TdB  
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。 EubR] ckB  
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模型 Hj ]$  
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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。 L(!4e  
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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. w?CbATQ   
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光源 tB.;T0n  
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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。 &d`T~fl|  
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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。 !mFo:nQ)}  
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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。 >Bp%~8f  
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图2. 字母F光源的设定方法光 ];Whvdnv  
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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 g!n1]- 1  
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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。 a?'3  
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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。 7=XQgbY/  
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图5. 视网膜重点采样规格设定
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脚本  N>`+{  
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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： ))c;DJc  
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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。 Qv8#{y@U  
余下的脚本计算与屈光度有关的所有参数。 W9 y8dw.  
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分析 t )Z2"_5  
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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。 nR/; uTTz  
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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 iM2 EEC  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. pALB[;9g  
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Dim entity As T_ENTITY ^a; V-US  
Dim op As T_OPERATION hx4!P(o1  
Dim mat As T_MODELMATERIAL S "oUE_>  
Dim A As Double qNHS 1  
Dim pupilDiam As Double <6<uO\B\  
Dim eID As Long d1e'!y}R5  
Dim parID As Long )I]E%ut{4,  
Dim count As Integer +lJuF/sS8m  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double $Fz/&;KX!  
Dim tlens As Double, nlens As Double \!ESmxSa;  
Dim curv As Double, conic As Double ~b\7 qx_a9  
Dim ok As Long ?y<n^`  
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Sub Main 2DQ'h}BI  
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    '用户输入对话框 H[@}ri<  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 F/j=rs,*|D  
        TextBox 220,21,40,21,.TextBox1 'default: 0 3\=8tg p  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 O#O~A |  
        OKButton 40,91,90,21 1\YX|  
        CancelButton 190,91,90,21 <eN>X:_N  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ^\N2 Iu>6  
        TextBox 220,49,40,21,.TextBox2 'default: 4 @mP@~  
    End Dialog 0O-p(L=  
    Dim dlg As UserDialog H'gPGOd  
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    ok = Dialog (dlg) |D]jdd@!a2  
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    If ok=0 Then    'cancel button was pressed DP^{T/G  
        Print "Execution cancelled." { w!}:8p  
        End w41#? VC/  
    End If .6O>P2m]a_  
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    'Assign accommodation and pupil diameter & use defaults if field left empty v@>hjie  
    If dlg.TextBox1 = "" Then ! FHNKh  
        A = 0           'Default accommodation d,<ctd  
    Else YY7:WQS  
        A = CDbl(dlg.TextBox1) ~fCD#D2KU  
    End If J=zZGd%  
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    If dlg.TextBox2 = "" Then Q]6nW[@j'  
        pupilDiam = 4   'Default pupil diameter 9HTb  
    Else -8 &f=J)  
        pupilDiam = CDbl(dlg.TextBox2) |:!0`p{R  
    End If &OI=r vDmo  
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    Print " " Mqc[IAcd]  
    Print "Accommodation = " & A & " Diopters" @.0jC=!l  
    Print "Pupil Diameter = " & pupilDiam & " mm" uaU!V4-  
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    ' Calculate new parameters with accommodation 2Y wV}  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness ke3=s  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ).tZMLM/-  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens H>M%5bj  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens kOtC(\]5  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens m k -" U7;  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 3tr?-l[N\  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 3I"&Qp%2  
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    'Adjust parameters to account for accommodation m%Ef]({I  
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    '************************************************************************* ie$=3nZJ}  
    'Aqueous thickness (Position of Lens) l>qCT  
    '************************************************************************* l,v:[N  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) JWn9&WK  
    GetCustomElement eID, entity QT|mN  
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    parID = FindFullName( "Geometry.Arizona Eye" ) {Or|] 0  
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    ' Delete any shift(s) in z *:&fw'vd,  
    count = 0 aB'<#X$x  
    While GetOperationCount(eID)>count !o.g2  
        GetOperation eID, count, op o1n c.2/0J  
        If op.Type="ShiftZ" Then Hy `r}+  
            DeleteOperation eID,count ZnJnjW PQ  
            count=count-1 D6ck1pxkx  
        End If .qVdo+M%F  
        count=count+1 @{ nT4{  
    Wend mB1)!  
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    'Set new shift in k"sL.}$  
    op.Type = "ShiftZ" 0c3G_I=  
    op.val1 = taq Jx{,x-I  
    op.parent = parID SA/0Z=  
    AddOperation eID, op ?v")Z 0 ~  
    Print "Set aqueous humor thickness = " & taq-0.55 @C!q S7k)  
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    '************************************************************************* [ 0~qs|27  
    'Radius and conic constant of anterior lens ]7VK&YfN  
    '************************************************************************* x`lBG%Y[-v  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ntF(K/~Y  
    GetConic eID, entity, curv, conic P0z "Eq0S  
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    SetConic eID, entity, 1/Rant, CCant ~P/G^cV3s  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant N9*$'  
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    '************************************************************************* ~cZ1=,P  
    'Radius and conic constant of posterior lens kh5V&%>?  
    '************************************************************************* t*<c+Ixu  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 9<YB &:<  
    GetConic eID, entity, curv, conic 4({=(O  
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    SetConic eID, entity, 1/Rpost, CCpost % idnm  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ZHF@k'vm/9  
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    '************************************************************************* 9z-"JnM  
    'Lens thickness (Position of posterior lens surface) m0#hG x  
    '************************************************************************* *o>E{  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) j=gbUXv/  
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    ' Delete any z-shift(s) 6 S&#8l  
    count = 0 ~ACB #D%  
    While GetOperationCount(eID)>count /;lk.-yU  
        GetOperation eID, count, op vx4& ;2  
        If op.Type="ShiftZ" Then  qJK^i.e  
            DeleteOperation eID,count bHMlh^{`%  
            count=count-1 6%'{Cq1DE  
        End If "d#s|_n,d)  
        count=count+1 EtL=_D-  
    Wend l-Xxv  
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    'Set new z-shift q3[LnmH  
    op.Type = "ShiftZ" B8nXWi  
    op.val1 = tlens f>'7~69  
    op.parent = parID -@73"w/  
    AddOperation eID, op 6RF01z|~_  
    Print "Set lens thickness = " & tlens PQ[TTLG\&  
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    '************************************************************************* d-* 9tit  
    'Lens index of refraction 'l}3Iua6qk  
    '************************************************************************* .dygp"*  
    eID = FindMaterial( "Lens" ) ;klDt|%3j  
    GetModelMaterial eID, mat .SsIU\[)  
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    mat.Nd = nlens b'&pJ1]]}  
    SetModelMaterial eID, mat $ -y+97  
    Print "Set lens index of refraction = " & nlens L=p.@VSZ  
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    '************************************************************************* <hea%6  
    'Pupil diameter 0g+@WK6y  
    '************************************************************************* ~ U1iB  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) /X:lt^?%I  
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    'Adjust pupil diameter (trimming volume inner hole) YO Y+z\Q  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Q\oUZnD$=  
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    ' Adjust pupil location to just in front of the lens A`r9"([-A  
    parID = FindFullName( "Geometry.Arizona Eye" ) j@ "`!uPz  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) =.%ZF]Oe+#  
    count = 0 q5 A+%#  
    While GetOperationCount(eID)>count 1D`RR/g&  
        GetOperation eID, count, op wx!*fy4hL  
        If op.Type="ShiftZ" Then `~}7k)F(  
            DeleteOperation eID,count sV6A& Aw  
            count=count-1 }.'%gJrS  
        End If 1Q%.-vs  
        count=count+1 ^Pf&C0xXv  
    Wend 4"2/"D0  
    op.Type = "ShiftZ" W>~%6K>p  
    op.val1 = taq-0.01 ^M9oTNk2  
    op.parent = parID GKSy|z  
    AddOperation eID, op So^`L s;S  
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    Print "Set pupil diameter = " & pupilDiam IX(yajc[~M  
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    'Update AZ Eye subassembly Description n96gDH*  
    eID = FindFullName( "Geometry.Arizona Eye" ) ;?!rpj  
    GetEntity eID, entity p^:Lj9Qax  
    entity.Description = "Accommodation = " & A & "D" z|<oxF.  
    SetEntity eID, entity =tNiIU  
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    Update qWpCe*C  
    Print "DONE!" v6VhXV6$|  
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End Sub ZX;k*OrW  
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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： Yel(}Ny  
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Accommodation = 4 Diopters #[W[ |m  
Pupil Diameter = 4 mm &-:yn&f7  
Set aqueous humor thickness = 2.81 G7;}309s  
Set anterior lens radius = 10.4 and conic constant = -2.375869 LPn }QzH  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 xW9 s[X  
Set lens thickness = 3.927 `Cf en8  
Set lens index of refraction = 1.42672 LwPM7S~ *  
Set pupil diameter = 4 0_ \ g  
DONE! f B96Q  
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（文章来源：讯技光电）
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