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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 / 3eGt7x#  
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。 v%rmfIU  
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模型 nW)?cQ 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。 7KesfH?  
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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. U&i#cF   
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光源 zLgc j(;  
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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。 2vTO>*t  
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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。 )DmydyQ'  
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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。 r?itd)WC<X  
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图2. 字母F光源的设定方法光 uwQgu!|x  
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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 ^&D5J\][  
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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。 eL>wKu:r  
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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。 4[i 3ckFT,  
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图5. 视网膜重点采样规格设定
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脚本 Q7<Y5+  
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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： ~n8UN<  
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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。 r95 ,X!  
余下的脚本计算与屈光度有关的所有参数。 /Yb8= eM  
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分析 i6P}MtC1  
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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。 k;jl3GV  
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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 |||m5(`S  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. uB^"A ;0v  
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Dim entity As T_ENTITY VQ,5&-9Y3  
Dim op As T_OPERATION @sG*u >   
Dim mat As T_MODELMATERIAL yZ{N$ch5b  
Dim A As Double ?FNgJx*\S  
Dim pupilDiam As Double CVvl &on  
Dim eID As Long B8eZ}9X  
Dim parID As Long bl&9O  
Dim count As Integer &"W gO!pzD  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double p+<qI~  
Dim tlens As Double, nlens As Double P5h*RV>oS  
Dim curv As Double, conic As Double 2+I5VPf  
Dim ok As Long L-)ZjXzk  
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Sub Main y\j[\UZKO  
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    '用户输入对话框 ovOV&Zt  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 \BH?GMoP  
        TextBox 220,21,40,21,.TextBox1 'default: 0 x1Y/^ks@2  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 kssRwe%>;  
        OKButton 40,91,90,21 BJ]L@L%  
        CancelButton 190,91,90,21 0 LXu!iix  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 5x|$q kI  
        TextBox 220,49,40,21,.TextBox2 'default: 4 IJKdVb~   
    End Dialog m' S{P:TK  
    Dim dlg As UserDialog `),U+  
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    ok = Dialog (dlg) I L7kpH+y  
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    If ok=0 Then    'cancel button was pressed 6w? GeJ  
        Print "Execution cancelled." 9{U@s  
        End lK/4"&  
    End If TghT{h@  
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    'Assign accommodation and pupil diameter & use defaults if field left empty o/ 51 RH  
    If dlg.TextBox1 = "" Then aCH;l~+U  
        A = 0           'Default accommodation 3QKBuo  
    Else @aN~97 H\  
        A = CDbl(dlg.TextBox1) cAGM|%  
    End If olr#3te  
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    If dlg.TextBox2 = "" Then f3n^Sw&Q(Q  
        pupilDiam = 4   'Default pupil diameter +w(6#R8u5  
    Else nC !NZ  
        pupilDiam = CDbl(dlg.TextBox2) 7p\&D?  
    End If %scIZCrI~  
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    Print " " `Ix`/k}  
    Print "Accommodation = " & A & " Diopters" bC"h7$3  
    Print "Pupil Diameter = " & pupilDiam & " mm" pg!oi?Jn  
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    ' Calculate new parameters with accommodation -IVWkA)7  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness =bP<cC=3b  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens Z_dL@\#|  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens %-$ :/ N  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens t~dK\>L  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens b?cO+PY01  
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    tlens = 3.767 + 0.04*A                  'Lens thickness P.Cn[64a+@  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction q&3(yhx  
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    'Adjust parameters to account for accommodation <Piq?&VX[  
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    '************************************************************************* [-"ZuUG  
    'Aqueous thickness (Position of Lens) vfj{j= G  
    '************************************************************************* eHKb`K7C.  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) S76MY&Vx23  
    GetCustomElement eID, entity pRxVsOb  
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    parID = FindFullName( "Geometry.Arizona Eye" ) X{i>Q_8>  
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    ' Delete any shift(s) in z o(> #}[N}  
    count = 0 wpC .!T  
    While GetOperationCount(eID)>count ts_|7Ev  
        GetOperation eID, count, op Eb6cL`#N  
        If op.Type="ShiftZ" Then {*g{9`   
            DeleteOperation eID,count ]oz>/\!  
            count=count-1 xzfugW  
        End If (nBh6u*  
        count=count+1 ;gu4~LQw  
    Wend FqGMHM\J  
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    'Set new shift in B<Cg_C  
    op.Type = "ShiftZ" m~W[,7NE0&  
    op.val1 = taq Unq~lt%2  
    op.parent = parID g2^{+,/^K  
    AddOperation eID, op 2h]CZD4  
    Print "Set aqueous humor thickness = " & taq-0.55 -vc$I=b;  
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    '************************************************************************* LH @B\ mS  
    'Radius and conic constant of anterior lens "|Yy "iB[  
    '************************************************************************* @x A^F%(  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" )  @e\ @EW  
    GetConic eID, entity, curv, conic ^ r(]S%  
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    SetConic eID, entity, 1/Rant, CCant i| ,}y`C#  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant U7g,@/Qx  
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    '************************************************************************* N7}3?wS  
    'Radius and conic constant of posterior lens =;Co0Q`  
    '************************************************************************* kD1Nq~h2  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) o$U{.#  
    GetConic eID, entity, curv, conic Z!fbc#L6  
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    SetConic eID, entity, 1/Rpost, CCpost +eKLwM  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost }.WO=IZ  
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    '************************************************************************* 0Y0`$   
    'Lens thickness (Position of posterior lens surface) X&rsWk  
    '************************************************************************* MF*4E9Ue.  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) *> Be w  
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    ' Delete any z-shift(s) :9x]5;ma  
    count = 0 |f1^&97=+  
    While GetOperationCount(eID)>count hgDFhbHtd6  
        GetOperation eID, count, op cH|J  
        If op.Type="ShiftZ" Then ![vy{U.:`  
            DeleteOperation eID,count $nIE;idk  
            count=count-1 hcYqiM@8>  
        End If ~ oq.yn/1  
        count=count+1 >zw@!1{1  
    Wend KjF8T7%  
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    'Set new z-shift =`N 0  
    op.Type = "ShiftZ" \`2EfYJ{  
    op.val1 = tlens <pKOFN%m  
    op.parent = parID 55] MRv  
    AddOperation eID, op 'gD./|Z0  
    Print "Set lens thickness = " & tlens ,VUOsNN4\  
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    '************************************************************************* +<V$G/"  
    'Lens index of refraction )#hR}|  
    '************************************************************************* <m{#u4FC'  
    eID = FindMaterial( "Lens" ) 'Ce?!U O  
    GetModelMaterial eID, mat \'('HFr,  
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    mat.Nd = nlens RX^8`}N  
    SetModelMaterial eID, mat I1dOMu9  
    Print "Set lens index of refraction = " & nlens -=UvOzw  
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    '************************************************************************* 4R8Qn^  
    'Pupil diameter IeA/<'U s  
    '************************************************************************* Ytqx 0  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) R6z *!W{  
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    'Adjust pupil diameter (trimming volume inner hole) ,qV7$u  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Kg /,  
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    ' Adjust pupil location to just in front of the lens  _PwPLSg  
    parID = FindFullName( "Geometry.Arizona Eye" ) i/!KUbt  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) pV 8U`T  
    count = 0 e~,+rM  
    While GetOperationCount(eID)>count B !rb*"[  
        GetOperation eID, count, op L7xiq{t`Y  
        If op.Type="ShiftZ" Then B(eiRr3  
            DeleteOperation eID,count =0;njL(7;  
            count=count-1 -sDl[  
        End If n3eWqwQ$5  
        count=count+1 4[%_Bnv#AJ  
    Wend 43,*.1;sz  
    op.Type = "ShiftZ" +~ Y.m8  
    op.val1 = taq-0.01 Klu0m~X@  
    op.parent = parID 30sA\TZ  
    AddOperation eID, op g@?R"  
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    Print "Set pupil diameter = " & pupilDiam 8W7ET@`  
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    'Update AZ Eye subassembly Description j~9Y0jz_  
    eID = FindFullName( "Geometry.Arizona Eye" ) c0X1})q$  
    GetEntity eID, entity Ia{t/IX\[  
    entity.Description = "Accommodation = " & A & "D" @.G;dL.f{  
    SetEntity eID, entity 'fzJw  
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    Update GQjU="+  
    Print "DONE!" {aopGu?i  
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End Sub N!\1O,  
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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： 4Y G\<Zf  
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Accommodation = 4 Diopters *N6sxFs  
Pupil Diameter = 4 mm *W 04$N  
Set aqueous humor thickness = 2.81 ^0I"  
Set anterior lens radius = 10.4 and conic constant = -2.375869 ChNT; G<6$  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 6]HMhv  
Set lens thickness = 3.927 "0z4mQ}>N  
Set lens index of refraction = 1.42672 y^ st T^  
Set pupil diameter = 4 aHitPPlq  
DONE! ybIqn0&[  
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（文章来源：讯技光电）
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