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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 "Z1&z-   
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。 P(gID  
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模型 M5bj |tQ4  
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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。 -X[8soz  
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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. "rlSK >`  
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光源 Ydd>A\v\;  
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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。 #K~j9DuR  
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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。 eX),B  
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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。 g|*eN{g]uE  
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图2. 字母F光源的设定方法光 K*i1! "w  
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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  ` :  
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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。 9Q5P7}%p  
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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。 2A;[Ek6{q  
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图5. 视网膜重点采样规格设定
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脚本 aI#n+PW  
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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： 7CN[Z9Y^}  
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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。 PvBbtC-9b  
余下的脚本计算与屈光度有关的所有参数。 w+(wvNmNEK  
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分析 MOeLphY  
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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。 ~"YNG?Rre  
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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 d*(\'6?  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. %4KJ&R (>[  
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Dim entity As T_ENTITY D;n%sRq(Z  
Dim op As T_OPERATION ">&:(<  
Dim mat As T_MODELMATERIAL 1@dx(_  
Dim A As Double ~ J{{n_G{  
Dim pupilDiam As Double ?a9k5@s  
Dim eID As Long XFe7qt;%  
Dim parID As Long )t=u(:u]  
Dim count As Integer L=FvLii.  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Y-{BY5E.  
Dim tlens As Double, nlens As Double "kg$s5o  
Dim curv As Double, conic As Double /8HO7E+5  
Dim ok As Long EZfa0jJD  
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Sub Main -ix1<e  
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    '用户输入对话框 v('d H"Y  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 o+Z9h1z%,  
        TextBox 220,21,40,21,.TextBox1 'default: 0 K! j*:{  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 K7VG\Ec  
        OKButton 40,91,90,21 l!` 0I] }  
        CancelButton 190,91,90,21 Y@Y(;C"SW  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 OFbg]{ub?  
        TextBox 220,49,40,21,.TextBox2 'default: 4 X5<.%@Z  
    End Dialog mnj A8@1  
    Dim dlg As UserDialog iCKwd9?)  
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    ok = Dialog (dlg) =lD]sk  
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    If ok=0 Then    'cancel button was pressed LS$82UB&  
        Print "Execution cancelled." uy:=V }p  
        End 5^/[]*  
    End If }O  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 0z#kV}wE  
    If dlg.TextBox1 = "" Then Af<>O$$6  
        A = 0           'Default accommodation 8E[`H  
    Else :n9^:srGZH  
        A = CDbl(dlg.TextBox1) ;P~S/j[ 8  
    End If Uroj%xN  
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    If dlg.TextBox2 = "" Then #Q7$I.O]  
        pupilDiam = 4   'Default pupil diameter sdD[`#  
    Else qQvb;jO  
        pupilDiam = CDbl(dlg.TextBox2) RY< b]|  
    End If D.`\ ^a  
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    Print " " 3>Snd9Q  
    Print "Accommodation = " & A & " Diopters" @~3c;9LkY  
    Print "Pupil Diameter = " & pupilDiam & " mm" &N0|tn  
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    ' Calculate new parameters with accommodation ,&G M\FTeb  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness W F<V2o{k  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens yFsXI0I[p  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens hM w`e  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens Z+(V \  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 7d)' y  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 1+($"$ZC&B  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Kf~+jYobO  
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    'Adjust parameters to account for accommodation AAgA]OD,  
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    '************************************************************************* Sw'?$j^3  
    'Aqueous thickness (Position of Lens) F2'cL@E3  
    '************************************************************************* Al}PJz\  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) F9w&!yW:  
    GetCustomElement eID, entity W^Y0>W~  
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    parID = FindFullName( "Geometry.Arizona Eye" ) f4}6$>)  
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    ' Delete any shift(s) in z k5(yf~!c  
    count = 0 ':4pH#E  
    While GetOperationCount(eID)>count @un }&URp  
        GetOperation eID, count, op &Sa~Wtm|*  
        If op.Type="ShiftZ" Then ts>}>}@vc  
            DeleteOperation eID,count 7:'>~>'  
            count=count-1 5&= n  
        End If [)n}!5fE  
        count=count+1 }4%)m  
    Wend ZRGZ'+hw  
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    'Set new shift in 8-YrmP2k  
    op.Type = "ShiftZ" @8yFM%  
    op.val1 = taq y:[]+  
    op.parent = parID >nEnX  
    AddOperation eID, op %tQ{Hf~  
    Print "Set aqueous humor thickness = " & taq-0.55 va2A@U  
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    '************************************************************************* E,yK` mPp^  
    'Radius and conic constant of anterior lens (OQ @!R&  
    '************************************************************************* Z"Ni Y  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) #)}bUNc'  
    GetConic eID, entity, curv, conic ] Nipo'N;  
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    SetConic eID, entity, 1/Rant, CCant BK SK@OV  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant |9$'?4F  
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    '************************************************************************* n ]}2O 4j  
    'Radius and conic constant of posterior lens \RyA}P5 S  
    '************************************************************************* ?Zp!AV  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) @6'E8NFl  
    GetConic eID, entity, curv, conic $OoN/^kv  
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    SetConic eID, entity, 1/Rpost, CCpost ;XQ lj?:  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ~(^*?(Z  
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    '************************************************************************* )0MshgM  
    'Lens thickness (Position of posterior lens surface) l{m~d!w`a  
    '************************************************************************* l0xFt ~l  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) <dPxy`_  
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    ' Delete any z-shift(s) yUwgRj  
    count = 0 Ltd?#HP  
    While GetOperationCount(eID)>count L#q9_-(#  
        GetOperation eID, count, op \[I .  
        If op.Type="ShiftZ" Then ?$4R <  
            DeleteOperation eID,count '?3z6%  
            count=count-1 05I39/T%  
        End If e`M]ZG rr  
        count=count+1 CVG>[~}(9'  
    Wend f.)F8!!  
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    'Set new z-shift T&"dBoUq>G  
    op.Type = "ShiftZ" *oX]=u&  
    op.val1 = tlens `R52{B#&/  
    op.parent = parID P`I G9  
    AddOperation eID, op Rue|<d1  
    Print "Set lens thickness = " & tlens 1za'u_  
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    '************************************************************************* ]N <]  
    'Lens index of refraction 1(7.V-(G  
    '************************************************************************* 'Mx K}9  
    eID = FindMaterial( "Lens" ) R:BBNzY}f  
    GetModelMaterial eID, mat KSB_%OI1  
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    mat.Nd = nlens rspoSPnY1  
    SetModelMaterial eID, mat 3_*Xk. .d  
    Print "Set lens index of refraction = " & nlens & Yf#O*  
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    '************************************************************************* :`u&TXsu  
    'Pupil diameter Ld3Bi2d|  
    '************************************************************************* ' raB  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) G1;'nwf}  
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    'Adjust pupil diameter (trimming volume inner hole) QJIItx4hE  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" @f5@0A\0  
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    ' Adjust pupil location to just in front of the lens KWh M  
    parID = FindFullName( "Geometry.Arizona Eye" ) {.3  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ,rB9esxic  
    count = 0 [[0bhmG)  
    While GetOperationCount(eID)>count k4F"UG-`  
        GetOperation eID, count, op xV>iL(?  
        If op.Type="ShiftZ" Then j #I:6yA3  
            DeleteOperation eID,count k#Ez  
            count=count-1 qM1)3.)[:  
        End If Jm (&G  
        count=count+1 &I}T<v{f  
    Wend Rw/JPC"  
    op.Type = "ShiftZ" f*T)*R_  
    op.val1 = taq-0.01 B=gsd0^]  
    op.parent = parID 42J';\)oP  
    AddOperation eID, op U.hERe ~X  
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    Print "Set pupil diameter = " & pupilDiam TI[UX16Tz1  
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    'Update AZ Eye subassembly Description j.;  
    eID = FindFullName( "Geometry.Arizona Eye" ) bQdSX8: !R  
    GetEntity eID, entity iIGI=EwZ  
    entity.Description = "Accommodation = " & A & "D" O\4+_y  
    SetEntity eID, entity (,Ja  
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    Update Jny)uo8  
    Print "DONE!" rW FcIh5  
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End Sub iF [?uF  
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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： s^g.42?u  
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Accommodation = 4 Diopters (aJP: ^  
Pupil Diameter = 4 mm Tf#2"(!  
Set aqueous humor thickness = 2.81 H}sS4[z  
Set anterior lens radius = 10.4 and conic constant = -2.375869 c/<Sa|'  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 /UpD$,T|^|  
Set lens thickness = 3.927 Hbjb7Y?[  
Set lens index of refraction = 1.42672 wc7mJxJxA  
Set pupil diameter = 4 QY~<~<d+G  
DONE! ?E+:]j_  
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（文章来源：讯技光电）
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