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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 G[=;519  
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。 </b_Rar  
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模型 Gr'|nR8  
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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。 So= BcX-  
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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. @+a}O  
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光源 (C.aQ)|T  
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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。 `NNP}O2  
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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。 4y!GFhMh  
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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。 30<_`  
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图2. 字母F光源的设定方法光 ""m/?TZq'  
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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 ZZ/k7(8  
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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。 s#(7D3Pr#  
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[attachment=67935]
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。 9i D&y)$"  
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图5. 视网膜重点采样规格设定
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脚本 qE8Di\?  
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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： b`ksTO`}x  
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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。 V;Q@' <w  
余下的脚本计算与屈光度有关的所有参数。 m>?|*a,  
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分析 $`R=Q  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 na 0Zb  
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图7. 字母F在视网膜上颜色分析
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脚本代码 s>[Oe|`  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. R]RLy#j  
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Dim entity As T_ENTITY :XTxrYt28  
Dim op As T_OPERATION C%j@s|  
Dim mat As T_MODELMATERIAL i[w&!mn%  
Dim A As Double yo$A0Ti!w  
Dim pupilDiam As Double ywB0 D`s'  
Dim eID As Long |tz{Es<`B  
Dim parID As Long JvaHH!>d/  
Dim count As Integer RWoVN$i>  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double lQ"t#b+  
Dim tlens As Double, nlens As Double Z-M4J;J@}  
Dim curv As Double, conic As Double j 20m Z  
Dim ok As Long *Wcq'S  
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Sub Main )Y"t$Iw"  
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    '用户输入对话框 FI)0.p  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 '#~Sb8   
        TextBox 220,21,40,21,.TextBox1 'default: 0 V8b^{}nxt  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ~ H"-km"@  
        OKButton 40,91,90,21 Q5IN1 ^=HF  
        CancelButton 190,91,90,21 &(jt|?{  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Zm(}~C29  
        TextBox 220,49,40,21,.TextBox2 'default: 4 }:1qK67S  
    End Dialog Vg mYm~y'  
    Dim dlg As UserDialog 9WHarv2@  
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    ok = Dialog (dlg) o=F!&]+  
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    If ok=0 Then    'cancel button was pressed 6)FM83zk)K  
        Print "Execution cancelled." vkW;qt}yO  
        End z5sKV7&\[n  
    End If RER93:(  
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    'Assign accommodation and pupil diameter & use defaults if field left empty EJJ&`,q  
    If dlg.TextBox1 = "" Then zOJzQZ~  
        A = 0           'Default accommodation db3.X~Cn#s  
    Else 2%MS$Fto  
        A = CDbl(dlg.TextBox1) 3ZvQUH/{W  
    End If g%D.sc)69  
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    If dlg.TextBox2 = "" Then SL_JA  
        pupilDiam = 4   'Default pupil diameter "\M3||.!  
    Else =S\pI  
        pupilDiam = CDbl(dlg.TextBox2) Hq,N OP  
    End If ? :F Jc[J  
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    Print " " wB<cW>6  
    Print "Accommodation = " & A & " Diopters" 1z@ ncqe  
    Print "Pupil Diameter = " & pupilDiam & " mm" 59?$9}ob  
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    ' Calculate new parameters with accommodation lO}I>yo}\  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness RVpo,;:  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 3v)`` n@  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens Ihl]"76q/  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens &*~_ "WyU  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens /8P7L'Rb  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ETfoL.d$(  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction @X_)%Y-^O  
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    'Adjust parameters to account for accommodation ZPHatC  
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    '************************************************************************* }jg,[jw_"X  
    'Aqueous thickness (Position of Lens) Qaiqx"x3  
    '************************************************************************* /)r[}C0   
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) {65_k  
    GetCustomElement eID, entity !'=< uU-  
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    parID = FindFullName( "Geometry.Arizona Eye" ) ''.\DC~K  
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    ' Delete any shift(s) in z KoFWI_(b  
    count = 0 "}< baz  
    While GetOperationCount(eID)>count L0ZAF2O  
        GetOperation eID, count, op 85+w\KuEY  
        If op.Type="ShiftZ" Then #?bOAWAwLh  
            DeleteOperation eID,count r<"k /  
            count=count-1 .y#>mXm>  
        End If {.r9l  
        count=count+1 .L_ Hk  
    Wend VQpwHzh  
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    'Set new shift in .3xf!E*  
    op.Type = "ShiftZ" [ _&z+  
    op.val1 = taq Ia>~ph#]{`  
    op.parent = parID 4& 9V  
    AddOperation eID, op F>5)Clq  
    Print "Set aqueous humor thickness = " & taq-0.55 kyUG+M  
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    '************************************************************************* A)kdY!}  
    'Radius and conic constant of anterior lens Kp/l2?J"  
    '************************************************************************* =#vU$~a  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) smuQ1.b  
    GetConic eID, entity, curv, conic w-``kID  
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    SetConic eID, entity, 1/Rant, CCant vH]2t.\  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant (}CA?/  
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    '************************************************************************* 49 1 1  
    'Radius and conic constant of posterior lens <;NxmO<%\  
    '************************************************************************* kT&GsR/  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 2Vg+Aly4D  
    GetConic eID, entity, curv, conic Q_|Lv&  
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    SetConic eID, entity, 1/Rpost, CCpost ]DI%7kw'  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost  C0j`H(  
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    '************************************************************************* nsi&r  
    'Lens thickness (Position of posterior lens surface) %eE 6\f%g  
    '************************************************************************* r7  *'s  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) e:=+~F(f  
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    ' Delete any z-shift(s) NKRH>2,  
    count = 0 ImI, q:[67  
    While GetOperationCount(eID)>count vi0nJ -Xg  
        GetOperation eID, count, op hu-6V="^9  
        If op.Type="ShiftZ" Then U p: M[S  
            DeleteOperation eID,count Ba;tEF{X  
            count=count-1 ^1[u'DW4  
        End If Ert` ]s~  
        count=count+1 ~01Fp;L/  
    Wend w0fFm"A|W  
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    'Set new z-shift Tw9?U,]  
    op.Type = "ShiftZ" 5x' ^.$K >  
    op.val1 = tlens n7'X.=o7  
    op.parent = parID Bfr$&?j#  
    AddOperation eID, op etH]-S  
    Print "Set lens thickness = " & tlens "A&HNkRz  
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    '************************************************************************* %ZJ;>a#  
    'Lens index of refraction .T^e8  
    '************************************************************************* <qCfw>%2F  
    eID = FindMaterial( "Lens" ) &e1(|qax  
    GetModelMaterial eID, mat 0uf)6(f  
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    mat.Nd = nlens 1WLaJ%Fv  
    SetModelMaterial eID, mat N(L?F):fT  
    Print "Set lens index of refraction = " & nlens 33b 3v\N  
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    '************************************************************************* $rmfE  
    'Pupil diameter %8T"h  
    '************************************************************************* {~eVZVv  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) kY`L[1G$  
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    'Adjust pupil diameter (trimming volume inner hole) mEDi'!YE"  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" _9b;8%? Yf  
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    ' Adjust pupil location to just in front of the lens G,h=5y9_J  
    parID = FindFullName( "Geometry.Arizona Eye" ) ~> |o3&G{  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) S%k](\7!  
    count = 0 \>r<z46x  
    While GetOperationCount(eID)>count D]$X@2A  
        GetOperation eID, count, op =aE!y5  
        If op.Type="ShiftZ" Then hha^:,  
            DeleteOperation eID,count \Dr?}D  
            count=count-1 Kq2,J&Ca3  
        End If YVB\9{H?  
        count=count+1 MLn\ b0  
    Wend e-e*%  
    op.Type = "ShiftZ"  a 9f%p  
    op.val1 = taq-0.01 e`Vb.E)  
    op.parent = parID ![4<6/2gy  
    AddOperation eID, op WEFvJ0]  
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    Print "Set pupil diameter = " & pupilDiam E]j2%}6Z%  
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    'Update AZ Eye subassembly Description nA>kJSL'$  
    eID = FindFullName( "Geometry.Arizona Eye" ) gl~>MasV&  
    GetEntity eID, entity [agp06 $D?  
    entity.Description = "Accommodation = " & A & "D" CP!>V:w%9!  
    SetEntity eID, entity BX=YS)  
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    Update 1Ydym2  
    Print "DONE!" Y1Qg|U o  
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End Sub ?oO<PR}y  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： l2LUcI$ x  
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Accommodation = 4 Diopters fd} U l  
Pupil Diameter = 4 mm ?E:L6,a  
Set aqueous humor thickness = 2.81 @,{', =L6  
Set anterior lens radius = 10.4 and conic constant = -2.375869 m?Qr)F_M  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 L#^'9v}Hb  
Set lens thickness = 3.927 WYklS<B[  
Set lens index of refraction = 1.42672 {@8TGHKv  
Set pupil diameter = 4 ,3tcti~sZ  
DONE! ApxGrCu  
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（文章来源：讯技光电）
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