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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 S,ud pQ7  
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。 GT80k]e.  
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模型 k {vd1,HZ  
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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。 ]&B/rSC  
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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. $ %|b6Gr/&  
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光源 XMykUr e|  
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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。 H3pZfdh?w  
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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。 7/fJQM  
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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。 j|qdf3^f  
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[attachment=67933]
图2. 字母F光源的设定方法光 EP<{3f y  
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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 |Q@(<'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。 G(o6/  
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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。 }5z!FXB  
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图5. 视网膜重点采样规格设定
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脚本 iCGHcN^3  
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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： `#r/L@QI  
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[attachment=67937]
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。 .<YfnW5/K  
余下的脚本计算与屈光度有关的所有参数。 h Y *^rY'  
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分析 `r}a:w-  
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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。 vS:=%@c>ta  
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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 ycEp,V;[Z  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. ]n'.}"8Kn  
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Dim entity As T_ENTITY 9I#a{%A:  
Dim op As T_OPERATION ]C|xo.=?]  
Dim mat As T_MODELMATERIAL Lm0q/d2|\X  
Dim A As Double qjf4G[]!  
Dim pupilDiam As Double X)c0 y3hk  
Dim eID As Long b"w2 2%  
Dim parID As Long :g-vy9vb  
Dim count As Integer e;"%h%'  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double \ 9sJ`,T?  
Dim tlens As Double, nlens As Double *Ct ^jU7  
Dim curv As Double, conic As Double Q(Pc  
Dim ok As Long A9Pq}3U  
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Sub Main JiXN"s^mcb  
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    '用户输入对话框 iRv \:.aQ.  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 v|jwz.jM  
        TextBox 220,21,40,21,.TextBox1 'default: 0 u2U+uD@yA  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 I=YZ!*f/`  
        OKButton 40,91,90,21 8p/&_<mnW  
        CancelButton 190,91,90,21 i^4i]+  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ' (3|hh)Tl  
        TextBox 220,49,40,21,.TextBox2 'default: 4 4]%MrSjS  
    End Dialog fCv.$5  
    Dim dlg As UserDialog sE^= ]N  
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    ok = Dialog (dlg) G?:5L0g  
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    If ok=0 Then    'cancel button was pressed ag!q:6&  
        Print "Execution cancelled." |~Vq"6`  
        End f4|ir3oy  
    End If Bv6~!p  
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    'Assign accommodation and pupil diameter & use defaults if field left empty yoBR'$-=  
    If dlg.TextBox1 = "" Then VlxHZ  
        A = 0           'Default accommodation <sjz_::V8R  
    Else ;4`%?6%  
        A = CDbl(dlg.TextBox1) bHz H0v]:  
    End If Wr4Ob*2iD  
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    If dlg.TextBox2 = "" Then IBh?vh  
        pupilDiam = 4   'Default pupil diameter ksAu=X:  
    Else ] ; B`'Ia  
        pupilDiam = CDbl(dlg.TextBox2) #[~f 6s9D  
    End If j[fY.>yt&  
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    Print " " % +M,FgW  
    Print "Accommodation = " & A & " Diopters" :8lqo%5  
    Print "Pupil Diameter = " & pupilDiam & " mm" ;7mE%1X  
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    ' Calculate new parameters with accommodation ]%h|ox0  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Q\2~^w1V  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens e:n3@T,R  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens @dvb%A&Pur  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens cN]g^  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens M#SGZ~=1r  
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    tlens = 3.767 + 0.04*A                  'Lens thickness m Wh   
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction -1]8f  
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    'Adjust parameters to account for accommodation a]?o"{{+  
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    '************************************************************************* XchVsA  
    'Aqueous thickness (Position of Lens) "pQ) 5/e  
    '************************************************************************* g6;a2  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) `4t*H>:y  
    GetCustomElement eID, entity OUtMel_  
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    parID = FindFullName( "Geometry.Arizona Eye" ) tS3{y*yi  
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    ' Delete any shift(s) in z [xl+/F7  
    count = 0 |OO2>(Fj  
    While GetOperationCount(eID)>count h@D!/PS  
        GetOperation eID, count, op zd {\XW  
        If op.Type="ShiftZ" Then 4+B OS ~  
            DeleteOperation eID,count HH7Bg0=(  
            count=count-1 42.y.LtZ  
        End If HD8*>p.  
        count=count+1 Q=F4ZrNqD  
    Wend 4So ,m0v  
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    'Set new shift in n4DKLAl  
    op.Type = "ShiftZ" jmn<gJ2Of  
    op.val1 = taq o=I.i>c  
    op.parent = parID !2]'S=Y  
    AddOperation eID, op n_P2l<F~/x  
    Print "Set aqueous humor thickness = " & taq-0.55 Cg];UB}k  
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    '************************************************************************* =g$>]AE  
    'Radius and conic constant of anterior lens t@3y9U$  
    '************************************************************************* :lp V  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) '2xfU  
    GetConic eID, entity, curv, conic Kb*X2#;*  
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    SetConic eID, entity, 1/Rant, CCant ,];QzENw  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ?m:,hI  
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    '************************************************************************* U6LENY+Ja  
    'Radius and conic constant of posterior lens 0z`-fQfK  
    '************************************************************************* NrWgaPO)i  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) i5Dq'wp  
    GetConic eID, entity, curv, conic 9"b  =W@  
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    SetConic eID, entity, 1/Rpost, CCpost mD go@ f  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost [IPXU9& Q  
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    '************************************************************************* Xx e07J~  
    'Lens thickness (Position of posterior lens surface) R9)"%SO<y  
    '************************************************************************* i 3i  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Z:Y_{YAD  
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    ' Delete any z-shift(s) @Avve8S  
    count = 0 +$ 0wBU  
    While GetOperationCount(eID)>count ]T1\gv1~  
        GetOperation eID, count, op o ^Ro 54i  
        If op.Type="ShiftZ" Then %v, a3^Qu  
            DeleteOperation eID,count wlw`%z-B2  
            count=count-1 V~"-\@  
        End If USJk *  
        count=count+1 R 9b0D>Lxt  
    Wend ^H~g7&f9?N  
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    'Set new z-shift =.ReM_.  
    op.Type = "ShiftZ" pMLTXqL  
    op.val1 = tlens '0 J*9  
    op.parent = parID a?8boN(  
    AddOperation eID, op ANq3r(  
    Print "Set lens thickness = " & tlens ['Y"6[1  
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    '************************************************************************* /#g P#Z%  
    'Lens index of refraction MWJ}  
    '************************************************************************* (e _l1O?  
    eID = FindMaterial( "Lens" ) u Xo?  
    GetModelMaterial eID, mat 't3&,:Y  
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    mat.Nd = nlens 7,"y!\  
    SetModelMaterial eID, mat A#8J6xcSrL  
    Print "Set lens index of refraction = " & nlens |}isSCt  
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    '************************************************************************* \"1%>O*  
    'Pupil diameter T$*#q('1"}  
    '************************************************************************* @!p0<&R@x  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) \%|%C  
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    'Adjust pupil diameter (trimming volume inner hole) DLD5>  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" j] J-#J  
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    ' Adjust pupil location to just in front of the lens 2U@:.S'K  
    parID = FindFullName( "Geometry.Arizona Eye" ) UT_kw}1o  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) __|Y59J%  
    count = 0 dheobD  
    While GetOperationCount(eID)>count iCtS<"@Yx  
        GetOperation eID, count, op rr]-$]Q  
        If op.Type="ShiftZ" Then _f"KB=A_x  
            DeleteOperation eID,count d9q`IZqee  
            count=count-1 *=X61`0  
        End If sQBKzvFO3  
        count=count+1 ;e0-FF+  
    Wend D-LQQ{!D5  
    op.Type = "ShiftZ" `APeS=< &  
    op.val1 = taq-0.01 QzS=oiL  
    op.parent = parID z-_$P)[c  
    AddOperation eID, op <RuLIu  
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    Print "Set pupil diameter = " & pupilDiam jM: |%o  
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    'Update AZ Eye subassembly Description Egmp8:nZl@  
    eID = FindFullName( "Geometry.Arizona Eye" ) +h@ZnFp3  
    GetEntity eID, entity /Xl(>^|&  
    entity.Description = "Accommodation = " & A & "D" Q'rgh+6  
    SetEntity eID, entity 8(g}/%1mt3  
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    Update mC} b>\  
    Print "DONE!" )zkr[;j~`  
     $bl<mG%#9  
End Sub Mh]4K" cs  
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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： $kccM& B  
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Accommodation = 4 Diopters U#:N/ts*(  
Pupil Diameter = 4 mm yVWt%o/  
Set aqueous humor thickness = 2.81 2TgS )  
Set anterior lens radius = 10.4 and conic constant = -2.375869 80K"u[  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 $}B&u)  
Set lens thickness = 3.927 SB,#y>Zv?  
Set lens index of refraction = 1.42672 \%_sL#?  
Set pupil diameter = 4 kn+@)3W:*  
DONE! mYbu1542'n  
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（文章来源：讯技光电）
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