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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 e>Q:j_?.e  
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。 !h&h;m/c  
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模型 &}gH!5L m  
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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。 -XECYwTh  
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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. -b%' K}.C  
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光源 1b=\l/2  
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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。 n\JSt}A  
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[attachment=67932]
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。 N}bZdE9F  
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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。 k:s86q  
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图2. 字母F光源的设定方法光 j~2t^Qz  
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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 7Il /+l(  
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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。 Se/]J<]  
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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。 mnMY)-6C  
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图5. 视网膜重点采样规格设定
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脚本 !]f:dWSLB  
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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： !ImtnU}  
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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。 )vur$RX  
余下的脚本计算与屈光度有关的所有参数。 ET]`  
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分析 EJrQ9"x&n  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 *O-si%@]  
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图7. 字母F在视网膜上颜色分析
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脚本代码 9%uJ:c?  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. 7+p=4i^@Zs  
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Dim entity As T_ENTITY V@>s]]HMq#  
Dim op As T_OPERATION *}i.,4+y   
Dim mat As T_MODELMATERIAL *C(XGX\?-  
Dim A As Double T*C]:=)  
Dim pupilDiam As Double zTt6L6:u  
Dim eID As Long n47v5.Wn  
Dim parID As Long ;lo!o9`<  
Dim count As Integer sz b],)|18  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ^RS`q+g  
Dim tlens As Double, nlens As Double Pd<>E*>}c.  
Dim curv As Double, conic As Double A[oxG;9xi  
Dim ok As Long 5AT[1@H(_  
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Sub Main <yrl_vl{  
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    '用户输入对话框 RV:%^=V-  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 P\H$*6v(  
        TextBox 220,21,40,21,.TextBox1 'default: 0 )Wm:Ilq  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 O%kX=6  
        OKButton 40,91,90,21 jkIgEF2d*  
        CancelButton 190,91,90,21 p[%FH?  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 f~? MNJ2  
        TextBox 220,49,40,21,.TextBox2 'default: 4 DPZG_{3D  
    End Dialog i/U HDqZ  
    Dim dlg As UserDialog }%9A+w}o  
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    ok = Dialog (dlg) FCEFg)c5=  
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    If ok=0 Then    'cancel button was pressed 7].FdjT.  
        Print "Execution cancelled." uD''0G\  
        End %<8lLRl  
    End If 3Ga! )  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 8?O6IDeW  
    If dlg.TextBox1 = "" Then !1}A\S  
        A = 0           'Default accommodation 0"L_0 t:  
    Else Rx 4 ;X  
        A = CDbl(dlg.TextBox1) FHS6Mk26  
    End If \Z^YaKj&  
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    If dlg.TextBox2 = "" Then /-l7GswF  
        pupilDiam = 4   'Default pupil diameter 0ZXG{Gp9S  
    Else IOsitMOX:  
        pupilDiam = CDbl(dlg.TextBox2) Hinz6k6!  
    End If G_~w0r#  
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    Print " " jR#g>MDKB  
    Print "Accommodation = " & A & " Diopters" {(#>%f+|C  
    Print "Pupil Diameter = " & pupilDiam & " mm" q(J3fjY)  
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    ' Calculate new parameters with accommodation c?{&=,u2  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness )q\|f_  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens &AI/;zru  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens 1#9Q1@'OS  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ^xO CT=V  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 9air" 4  
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    tlens = 3.767 + 0.04*A                  'Lens thickness | *Dklo9{  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 8-c1q*q)  
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    'Adjust parameters to account for accommodation JZP>`c21y]  
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    '************************************************************************* vl<W`)'  
    'Aqueous thickness (Position of Lens) 8C2s-%:  
    '************************************************************************* )Ab!R:4  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) $UAmUQg)}_  
    GetCustomElement eID, entity %SL'X`j  
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    parID = FindFullName( "Geometry.Arizona Eye" ) xZ} 1dq8  
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    ' Delete any shift(s) in z 4 e1=b,  
    count = 0 WhsTKy&E  
    While GetOperationCount(eID)>count y-gSal  
        GetOperation eID, count, op i w<2|]>l  
        If op.Type="ShiftZ" Then EM+#h'%-  
            DeleteOperation eID,count JB~79Lsdz  
            count=count-1 AXhV#nZt0  
        End If _Kg:jal  
        count=count+1 sXdNlR&  
    Wend A"8` 5qa  
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    'Set new shift in ~{hcJ:bI  
    op.Type = "ShiftZ" /pZ]:.A  
    op.val1 = taq r7r>1W%4  
    op.parent = parID <taN3  
    AddOperation eID, op 3zU!5t g  
    Print "Set aqueous humor thickness = " & taq-0.55 /(Se:jH$>  
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    '************************************************************************* /l-lkG5  
    'Radius and conic constant of anterior lens e#MEDjm/)g  
    '************************************************************************* 7{ zkqug  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) Ai&-W  
    GetConic eID, entity, curv, conic dHV3d'.P  
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    SetConic eID, entity, 1/Rant, CCant l(Dkmt>^  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 6vySOVMj  
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    '************************************************************************* !sA[A>  
    'Radius and conic constant of posterior lens ,*SoV~  
    '************************************************************************* kGsd3t!'  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) F3$@6J8<[z  
    GetConic eID, entity, curv, conic :uE:mY%R  
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    SetConic eID, entity, 1/Rpost, CCpost s*<\ mwB  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost [;3` Aw  
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    '************************************************************************* ;Ll/rJ:*  
    'Lens thickness (Position of posterior lens surface) jEwfa_Q%  
    '************************************************************************* WV]%llj^  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 4<b=;8  
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    ' Delete any z-shift(s) #flOaRl.  
    count = 0 /g}2QmvH  
    While GetOperationCount(eID)>count Gzxq] Mg  
        GetOperation eID, count, op bjvpYZC\5  
        If op.Type="ShiftZ" Then 7p'L(dq  
            DeleteOperation eID,count -F.A1{l[.  
            count=count-1 *GxOiv7"4W  
        End If Wy{xTLXk2  
        count=count+1 {kGcZf3h  
    Wend %a- *Ku  
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    'Set new z-shift gFR9!=,/V%  
    op.Type = "ShiftZ" j{00iA}  
    op.val1 = tlens /[Oo*}Dc=F  
    op.parent = parID $89hkUuTu^  
    AddOperation eID, op zs! }P  
    Print "Set lens thickness = " & tlens s ~'><ioh  
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    '************************************************************************* h/u>F$}c  
    'Lens index of refraction X2>qx^jT  
    '************************************************************************* T~B'- >O  
    eID = FindMaterial( "Lens" ) VJ1(|v{D4[  
    GetModelMaterial eID, mat KLqn`m`O;  
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    mat.Nd = nlens >iefEv\  
    SetModelMaterial eID, mat .kO!8Q-;%  
    Print "Set lens index of refraction = " & nlens ,})x1y  
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    '************************************************************************* ^6*LuXPv  
    'Pupil diameter cR.[4rG'  
    '************************************************************************* gY'w=(/`  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) oNV5su  
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    'Adjust pupil diameter (trimming volume inner hole) HF@K$RPK  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ? U~}uG^  
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    ' Adjust pupil location to just in front of the lens n^O Wz4  
    parID = FindFullName( "Geometry.Arizona Eye" ) uM3F[p%V^  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 1 o5DQ'~n  
    count = 0 CS[[TzC=5  
    While GetOperationCount(eID)>count 'M"JF;*r  
        GetOperation eID, count, op 7bBOV(/s  
        If op.Type="ShiftZ" Then _y~H#r9:  
            DeleteOperation eID,count joaf0  
            count=count-1 sDV*k4  
        End If B-63IN  
        count=count+1 ~_vzss3-C  
    Wend =Rnx!E  
    op.Type = "ShiftZ" xgl~4  
    op.val1 = taq-0.01 "X/cG9Lw  
    op.parent = parID CV <@Rgoa  
    AddOperation eID, op ,/ V'(\>  
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    Print "Set pupil diameter = " & pupilDiam 7ky$9+~  
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    'Update AZ Eye subassembly Description pPztUz/.  
    eID = FindFullName( "Geometry.Arizona Eye" ) *h ~Y=#`8*  
    GetEntity eID, entity .BLF7> M1  
    entity.Description = "Accommodation = " & A & "D" 9A]XuPAlh  
    SetEntity eID, entity )IIQ{SwQq  
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    Update # L\t)W  
    Print "DONE!" IT \Pj_  
     BV=L.*  
End Sub -BWkPq!  
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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： t(SSrM]  
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Accommodation = 4 Diopters C#]%  
Pupil Diameter = 4 mm ~;/\l=Xl  
Set aqueous humor thickness = 2.81 3HsjF5?W  
Set anterior lens radius = 10.4 and conic constant = -2.375869 phIEz3Fu/  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 Q>gU(  
Set lens thickness = 3.927 {Kp<T  
Set lens index of refraction = 1.42672 iR-MuDM  
Set pupil diameter = 4 /f!_dJ^  
DONE! H!dUQ  
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（文章来源：讯技光电）
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