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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 6O@J7P  
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。 @m?QR(LJ  
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模型 St<mDTi  
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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。 >I<r)w]  
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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. }@+NN ?P  
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光源 Lw'9  
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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。 j&UMjI9[  
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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。 a,Gxm!  
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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。 dDDGM:]  
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图2. 字母F光源的设定方法光 \*\R1_+  
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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 v_S4hz6w\  
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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。 3jogD  
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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。 UwY-7Mmo  
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图5. 视网膜重点采样规格设定
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脚本 NDO\B,7  
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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： ^O^:$nXhYy  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 +KEkmXZ  
余下的脚本计算与屈光度有关的所有参数。 fQnwy!-\  
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分析 !5}l&7:(MN  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 7:NmCpgL!  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 gLE7Edcp6V  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. r C[6lIP  
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Dim entity As T_ENTITY 9H]_4?aX  
Dim op As T_OPERATION aH_6s4+:  
Dim mat As T_MODELMATERIAL qIwV q!=  
Dim A As Double ~F, &GH  
Dim pupilDiam As Double .wrL3z_  
Dim eID As Long %ICglF R  
Dim parID As Long 3UUGblg`~  
Dim count As Integer {}>n{_  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double aaWJ* >rJ  
Dim tlens As Double, nlens As Double mV9A{h  
Dim curv As Double, conic As Double ps:f=6m2  
Dim ok As Long !wLg67X$ -  
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Sub Main 0m9ZQ O  
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    '用户输入对话框 fvo<(c#Y#  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 2 4\g bv<  
        TextBox 220,21,40,21,.TextBox1 'default: 0 P}3}ek1Ax  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 t@bt6J .{  
        OKButton 40,91,90,21 -dTLunv  
        CancelButton 190,91,90,21 9vGs;  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 3mt%!}S  
        TextBox 220,49,40,21,.TextBox2 'default: 4 pF=g||gS  
    End Dialog I12KT~z<r  
    Dim dlg As UserDialog ZX`J8lZP  
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    ok = Dialog (dlg) u~ F ;x Q  
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    If ok=0 Then    'cancel button was pressed s0LA^2U  
        Print "Execution cancelled." {6vEEU  
        End ,35&G"JK5  
    End If 5a8>g [2U  
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    'Assign accommodation and pupil diameter & use defaults if field left empty Sg*0[a3z  
    If dlg.TextBox1 = "" Then ('o&Q_  
        A = 0           'Default accommodation v1[_}N9f>H  
    Else %I4zQiJ%  
        A = CDbl(dlg.TextBox1) <ZPZk'53<f  
    End If J0<p4%Cf  
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    If dlg.TextBox2 = "" Then :pKG\A  
        pupilDiam = 4   'Default pupil diameter Bmr<O !  
    Else +GNWF% zN  
        pupilDiam = CDbl(dlg.TextBox2) )q?$p9  
    End If \%_ZV9cKF  
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    Print " " E)'8U  
    Print "Accommodation = " & A & " Diopters" sB*o)8  
    Print "Pupil Diameter = " & pupilDiam & " mm" I^0 t2[M  
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    ' Calculate new parameters with accommodation Etnb3<^[t  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness M23& <}Q8  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens CUhV$A#oo  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens z& 'f/w8  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens F,Fo}YQX  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 6&!l'[hU  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 03E3cp"  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ckwF|:e 7*  
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    'Adjust parameters to account for accommodation co]Gmg6p  
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    '************************************************************************* P>htQ  
    'Aqueous thickness (Position of Lens) G,DOBA  
    '************************************************************************* cF.mb*$K  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8W{~wg`  
    GetCustomElement eID, entity 5~xeO@%I  
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    parID = FindFullName( "Geometry.Arizona Eye" ) r@$B'CsLj  
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    ' Delete any shift(s) in z i[=C_+2  
    count = 0 GVObz?Z]SB  
    While GetOperationCount(eID)>count 8t``NZ[  
        GetOperation eID, count, op F$ {4X /9n  
        If op.Type="ShiftZ" Then G2@KI-  
            DeleteOperation eID,count zz3 r<?#5  
            count=count-1 TzY!D *%z  
        End If u9}!Gq  
        count=count+1  ^@q#$/z  
    Wend QN #)F  
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    'Set new shift in 2?1}ZXr  
    op.Type = "ShiftZ" \\iK'|5YG  
    op.val1 = taq OX)BP.h#  
    op.parent = parID ((9YG  
    AddOperation eID, op 51/sTx<Z}  
    Print "Set aqueous humor thickness = " & taq-0.55 J{H?xc o  
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    '************************************************************************* r /yHmEk&  
    'Radius and conic constant of anterior lens 8_awMVAy  
    '************************************************************************* |KaR n;BM  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) l'2H 4W_+  
    GetConic eID, entity, curv, conic R\ q):,  
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    SetConic eID, entity, 1/Rant, CCant ^6&_| f  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant W^|J/Y48  
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    '************************************************************************* G|V\^.f<  
    'Radius and conic constant of posterior lens s<#N]mp'   
    '************************************************************************* ,Z4^'1{D  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) r$?Vx_f`Q  
    GetConic eID, entity, curv, conic uf?b%:A  
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    SetConic eID, entity, 1/Rpost, CCpost w%I8CU_}.  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost #}j]XWy  
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    '************************************************************************* 2b~ HHVruX  
    'Lens thickness (Position of posterior lens surface) hqWbp*  
    '************************************************************************* omT(3)TP  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) fT x4vlI4  
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    ' Delete any z-shift(s) @oA0{&G{  
    count = 0 7>KQRLw  
    While GetOperationCount(eID)>count $&Ac5Zo%}  
        GetOperation eID, count, op ^Bn1;  
        If op.Type="ShiftZ" Then y* rY~U#3  
            DeleteOperation eID,count fYs?D+U;PF  
            count=count-1 >Ban?3{  
        End If e+x*psQ  
        count=count+1 YVJ+' A=|  
    Wend z2ds8-z  
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    'Set new z-shift [}@n*D$  
    op.Type = "ShiftZ" IF^[^^v+H  
    op.val1 = tlens q:Wq8  
    op.parent = parID "s> >V,  
    AddOperation eID, op M-vC>u3Y  
    Print "Set lens thickness = " & tlens <(Tiazg  
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    '************************************************************************* `fLfT'  
    'Lens index of refraction jB`7T^bU  
    '************************************************************************* ` -yhl3si  
    eID = FindMaterial( "Lens" ) ^b:Xo"q#H  
    GetModelMaterial eID, mat aDXpkG0E  
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    mat.Nd = nlens > Z]P]e  
    SetModelMaterial eID, mat ` v>/  
    Print "Set lens index of refraction = " & nlens ]|t9B/()i  
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    '************************************************************************* J/L)3y   
    'Pupil diameter \?r$&K]4  
    '************************************************************************* 3V"dG1?  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) f8R+7Ykx  
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    'Adjust pupil diameter (trimming volume inner hole) nhp)yW  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" R !jhwY$  
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    ' Adjust pupil location to just in front of the lens ys/`{:w8p  
    parID = FindFullName( "Geometry.Arizona Eye" )  )Kxs@F  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) RFhU#  
    count = 0 *m iONc  
    While GetOperationCount(eID)>count 8TUF w@H%  
        GetOperation eID, count, op  {`tHJ|8  
        If op.Type="ShiftZ" Then 5 Xk~,%-C  
            DeleteOperation eID,count LH bZjZ2  
            count=count-1 d$4WK)U  
        End If O.]_Ry\OXA  
        count=count+1 gQu\[e%mVo  
    Wend 8u4gx<;O  
    op.Type = "ShiftZ" vM5k4%D  
    op.val1 = taq-0.01 [kVpzpGr  
    op.parent = parID 58qaA\iw  
    AddOperation eID, op >3<&V{<K  
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    Print "Set pupil diameter = " & pupilDiam e6Wl7&@6  
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    'Update AZ Eye subassembly Description GH [ U!J  
    eID = FindFullName( "Geometry.Arizona Eye" ) `MN&(!&C*  
    GetEntity eID, entity Pw0{.W~r  
    entity.Description = "Accommodation = " & A & "D" <{3q{VW*  
    SetEntity eID, entity "K9vm^xP  
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    Update S~]8K8"sT  
    Print "DONE!" $_4oN(WSz  
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End Sub E|KLK4 ]  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： T3=-UYx]  
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Accommodation = 4 Diopters A}az m>  
Pupil Diameter = 4 mm R^n* o  
Set aqueous humor thickness = 2.81 v'mJ~tz  
Set anterior lens radius = 10.4 and conic constant = -2.375869 K * xM[vO  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 mBYS"[S(  
Set lens thickness = 3.927 DW'0j$;  
Set lens index of refraction = 1.42672 6$xo# }8  
Set pupil diameter = 4 EKeBTb  
DONE! S-H-tFy\\  
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（文章来源：讯技光电）
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