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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 5=?P 6I_$G  
人眼光学模型可用来设计眼科用设备，光学系统注定了要与人眼一起使用。本文演示了这样一个模型：Arizona眼睛模型，在Jim Schwiegerling教授的书中有详细描述：《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源，并包括一个基于想要的屈光度来调整模型的内嵌脚本。 TQ(q [:>  
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模型 jF?0,g  
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模型的定义如表1种所示，由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度（A）来决定。 QGpj$ _b  
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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. .:?v;rYk{  
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光源 -9dZT  
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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。  :tZsSK  
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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。 j6l1<3j  
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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。  LgF?1?  
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图2. 字母F光源的设定方法光 AZ!/{1Az  
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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 8]#FvgX  
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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。 EGD{nE  
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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。 F$8:9eL,T  
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图5. 视网膜重点采样规格设定
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脚本 --]blP7  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： ]C^ #)7  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 &W>\Vl1  
余下的脚本计算与屈光度有关的所有参数。 HW[&q  
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分析 :?f+*  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 |r+ x/,2-  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 J;>;K6pW  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. V~PGmn[V  
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Dim entity As T_ENTITY YAXd   
Dim op As T_OPERATION {eU>E /SQ  
Dim mat As T_MODELMATERIAL h_ t`)]-  
Dim A As Double pq0Z<b;2  
Dim pupilDiam As Double >C,0}lj  
Dim eID As Long k:n{AoUc  
Dim parID As Long i?B<&'G  
Dim count As Integer -$!r+4|q  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double l8E))oz1T  
Dim tlens As Double, nlens As Double \2u7>fU!  
Dim curv As Double, conic As Double &</)k|.A6\  
Dim ok As Long ` u3kP  
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Sub Main X(Af`KOg[  
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    '用户输入对话框 f IV"U  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 !9gpuS[  
        TextBox 220,21,40,21,.TextBox1 'default: 0 +m JG:n  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 JRBz/ j  
        OKButton 40,91,90,21 yuC"V'  
        CancelButton 190,91,90,21 MNU7OX<  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Jb{g{a/  
        TextBox 220,49,40,21,.TextBox2 'default: 4 mqeW,89  
    End Dialog ~98q1HgS]D  
    Dim dlg As UserDialog z~Zm1tZs  
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    ok = Dialog (dlg) \u.5 _ g  
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    If ok=0 Then    'cancel button was pressed =_&,^h@'3e  
        Print "Execution cancelled." )[Rwc#PA;  
        End R[F`b  
    End If R;AcAJ;  
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    'Assign accommodation and pupil diameter & use defaults if field left empty %^W(sB$b  
    If dlg.TextBox1 = "" Then &T-:`(  
        A = 0           'Default accommodation ;xq;c\N  
    Else 0R unex[  
        A = CDbl(dlg.TextBox1) MuO(%.H  
    End If Qv,ORm h5  
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    If dlg.TextBox2 = "" Then }#Up:o]A!  
        pupilDiam = 4   'Default pupil diameter  l  
    Else ?b d&Av  
        pupilDiam = CDbl(dlg.TextBox2) GQ Flt_  
    End If 6jMc|he  
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    Print " " 3I'7+?@@l  
    Print "Accommodation = " & A & " Diopters" &: LE]w  
    Print "Pupil Diameter = " & pupilDiam & " mm" eOVln1a  
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    ' Calculate new parameters with accommodation r *N@%T  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 11S{XbU  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens XwIHIG}  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens \xOYa  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens O&CY9 2)Lk  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens WO69Wo\C  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 3-y2i/4}$  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction T*k{^=6"!  
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    'Adjust parameters to account for accommodation =585TR; V  
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    '************************************************************************* iMYJVB=  
    'Aqueous thickness (Position of Lens) ) fuAdG  
    '************************************************************************* z\k 6."e_&  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) }lkU3Pf1U  
    GetCustomElement eID, entity &mJm'Ks  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 4\U"e*  
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    ' Delete any shift(s) in z mst;q@  
    count = 0 )CH\]>-FO  
    While GetOperationCount(eID)>count pcQzvLk  
        GetOperation eID, count, op UZJs!#P  
        If op.Type="ShiftZ" Then mg3YKHNG  
            DeleteOperation eID,count 'cN3Vv k  
            count=count-1 fob.?ID-;  
        End If rb.:(d)T  
        count=count+1 fn//j7 j  
    Wend z9Y}[ pN  
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    'Set new shift in ){J,Z*&  
    op.Type = "ShiftZ" V[* <^%  
    op.val1 = taq LqQ&4I  
    op.parent = parID i1qmFvksl  
    AddOperation eID, op Y4Jaw2b  
    Print "Set aqueous humor thickness = " & taq-0.55 CTB qX  
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    '************************************************************************* s|Vbc@t  
    'Radius and conic constant of anterior lens E zU=q E  
    '************************************************************************* R"`<ZY6(Ou  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) -C* UB  
    GetConic eID, entity, curv, conic meD?<g4n~"  
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    SetConic eID, entity, 1/Rant, CCant k _Bz@^J  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant . P! pC  
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    '************************************************************************* J.,7d ,  
    'Radius and conic constant of posterior lens L# .vbf  
    '************************************************************************* d?GB#N|+g  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) V?C a[  
    GetConic eID, entity, curv, conic F`f8q\Fc  
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    SetConic eID, entity, 1/Rpost, CCpost vcp[$-$QGJ  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost IDt7KJ@hc  
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    '************************************************************************* D89 (u.h  
    'Lens thickness (Position of posterior lens surface) `Yo!sgPO\  
    '************************************************************************* @3Mp>u/  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) D0p>Q^w  
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    ' Delete any z-shift(s) WD'[|s\  
    count = 0 LeXkl=CC  
    While GetOperationCount(eID)>count tc<HA7vpt~  
        GetOperation eID, count, op =(as{,j  
        If op.Type="ShiftZ" Then 8|S}!P"  
            DeleteOperation eID,count "xMnD(p  
            count=count-1 8(GJz ~y  
        End If 5uvFCY./c  
        count=count+1 Cq%1j[  
    Wend 5m a(~5  
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    'Set new z-shift 2)R*d  
    op.Type = "ShiftZ" 05[k@f$n  
    op.val1 = tlens qa)Qf,`  
    op.parent = parID @]:GTrs  
    AddOperation eID, op e_t""h4D  
    Print "Set lens thickness = " & tlens {$qLMx';  
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    '************************************************************************* %D<>F&h  
    'Lens index of refraction N:e5=;6s  
    '************************************************************************* (Q][d+} /  
    eID = FindMaterial( "Lens" ) \m3ca-Y  
    GetModelMaterial eID, mat gK>aR ^*  
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    mat.Nd = nlens ]w9\q*S]  
    SetModelMaterial eID, mat U=\!`_f':  
    Print "Set lens index of refraction = " & nlens M@78.lPS  
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    '************************************************************************* CUZ ;<Pn  
    'Pupil diameter GMYfcZ/,K  
    '************************************************************************* nv2p&-e+  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 1usLCG>w{  
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    'Adjust pupil diameter (trimming volume inner hole) jun$C Y4  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder"  `\#J&N  
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    ' Adjust pupil location to just in front of the lens =?gDM[t^  
    parID = FindFullName( "Geometry.Arizona Eye" ) dhmZ3~cW>  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) YgW 50)q^  
    count = 0 e?)ic\K  
    While GetOperationCount(eID)>count ^+'\ u;\  
        GetOperation eID, count, op +*ZF52hy|  
        If op.Type="ShiftZ" Then |$a!Zx94^  
            DeleteOperation eID,count E)utrO R  
            count=count-1 {S5H H"  
        End If MWron_xg  
        count=count+1 "jMSF@lr  
    Wend ;ax%H @o  
    op.Type = "ShiftZ" `78)|a*R.  
    op.val1 = taq-0.01 7,&M6<~  
    op.parent = parID ! 4{T<s;q  
    AddOperation eID, op 3"y,Ut KGa  
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    Print "Set pupil diameter = " & pupilDiam N@r`+(_t  
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    'Update AZ Eye subassembly Description s\A4y "  
    eID = FindFullName( "Geometry.Arizona Eye" ) P\2UIAPa\b  
    GetEntity eID, entity T?V!%AqY:  
    entity.Description = "Accommodation = " & A & "D" Rt2<F-gY  
    SetEntity eID, entity 9L9+zs3 k  
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    Update '\I!RAZ  
    Print "DONE!" f15f)P  
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End Sub *wD| e K7  
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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： Y$&+2w,)H,  
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Accommodation = 4 Diopters 5x/LHsr=m  
Pupil Diameter = 4 mm 1&Ruz[F5  
Set aqueous humor thickness = 2.81 $PE{}`#g  
Set anterior lens radius = 10.4 and conic constant = -2.375869 "0]s|ys6<  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 $K}Y  
Set lens thickness = 3.927 a1yGgT a?D  
Set lens index of refraction = 1.42672 b!3Y<D*  
Set pupil diameter = 4 8-cCWo c  
DONE! +Ssu^ >D  
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（文章来源：讯技光电）
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