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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 OA!R5sOz"  
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。 F ZM2   
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模型 $+0=GN  
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模型的定义如表1种所示，由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度（A）来决定。 ?VUgwP_=  
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Table 1. AZ眼睛模型的定义
[attachment=67931]
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在FRED中使用0屈光度来创建的，光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. 7&=-a|k~  
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光源 v/]Qq  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 /rn"  
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[attachment=67932]
图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 =DGn,i9  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ]d[Rf$>vu0  
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[attachment=67933]
图2. 字母F光源的设定方法光 xX[?L9RGz  
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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 kA;xAb+U3  
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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。 sM #!Xl;  
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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。 Y')O>C0~  
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图5. 视网膜重点采样规格设定
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脚本 Uc_'3|e  
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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： DZ%g^DRZX  
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[attachment=67937]
图6. 用户对话框的创建与编辑
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[attachment=67938]
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。 I{`KKui<M  
余下的脚本计算与屈光度有关的所有参数。 >{phyByI  
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分析 73&]En  
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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。 X{5v?4wI  
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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 3~cS}N T  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. 3g?MEM~  
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Dim entity As T_ENTITY B, QC -Tn  
Dim op As T_OPERATION v< 65(I>  
Dim mat As T_MODELMATERIAL LFk5rv'sM0  
Dim A As Double ;J,,f1Vw  
Dim pupilDiam As Double d[s;a.  
Dim eID As Long <7vIh0  
Dim parID As Long ki[;ZmQq Y  
Dim count As Integer y8<lp+  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double x:f|3"\s  
Dim tlens As Double, nlens As Double 3Eb nZb  
Dim curv As Double, conic As Double 0C7thl{Dms  
Dim ok As Long *b$z6.  
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Sub Main UPfFT^=y  
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    '用户输入对话框 "-0pz\a  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 0Zc*YdH  
        TextBox 220,21,40,21,.TextBox1 'default: 0 N}8HK^n*  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 zPX=MfF  
        OKButton 40,91,90,21 V\iIvBpWg  
        CancelButton 190,91,90,21 m~= ]^e  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 G/LXUhuif  
        TextBox 220,49,40,21,.TextBox2 'default: 4 902!M65[rG  
    End Dialog D{,[\^c  
    Dim dlg As UserDialog _|^&eT-u  
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    ok = Dialog (dlg) o*O "\/pmF  
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    If ok=0 Then    'cancel button was pressed H3p4,Y}'#  
        Print "Execution cancelled." # `N6<nb  
        End gTmUK{y'  
    End If wzNt c)~i  
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    'Assign accommodation and pupil diameter & use defaults if field left empty zVc7q7E  
    If dlg.TextBox1 = "" Then g6[/F-3Qlf  
        A = 0           'Default accommodation I:uQB!  
    Else '-nuH;r  
        A = CDbl(dlg.TextBox1) %#S"~)  
    End If (!XYH@Mz<w  
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    If dlg.TextBox2 = "" Then ]AFM Y<mB  
        pupilDiam = 4   'Default pupil diameter p5twL  
    Else Qq;m"M/  
        pupilDiam = CDbl(dlg.TextBox2)  H3/Y  
    End If \Age9iz&  
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    Print " " {.' ,%)  
    Print "Accommodation = " & A & " Diopters" >'2w\Uk~:  
    Print "Pupil Diameter = " & pupilDiam & " mm" (IoPU+1b  
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    ' Calculate new parameters with accommodation f}9PEpa,Z  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness iS:PRa1  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens !"Oj$c -  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens /C,>  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens U!;aM*67  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens !q=Q~ea  
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    tlens = 3.767 + 0.04*A                  'Lens thickness v8'`gY  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction "zeJ4f  
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    'Adjust parameters to account for accommodation SqA+u/"j2  
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    '************************************************************************* ik1L  
    'Aqueous thickness (Position of Lens) >QZt)<[  
    '************************************************************************* X>@.-{6T  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) %<ptkZK#  
    GetCustomElement eID, entity } ^GV(]K  
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    parID = FindFullName( "Geometry.Arizona Eye" ) YP\4XI  
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    ' Delete any shift(s) in z !s[j1=y  
    count = 0 YCB 3  
    While GetOperationCount(eID)>count S] K6qY  
        GetOperation eID, count, op ;qVEI/  
        If op.Type="ShiftZ" Then IYM@(c@ld0  
            DeleteOperation eID,count &6|^~(P?  
            count=count-1 9a~BAH,j  
        End If (g )lv)4P  
        count=count+1 &h4Z|h[01  
    Wend Xv5Ev@T  
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    'Set new shift in 1:;&wf  
    op.Type = "ShiftZ" EhP&L?EL  
    op.val1 = taq t6L^ #\'  
    op.parent = parID xBI"{nGoN  
    AddOperation eID, op Ng;b!S  
    Print "Set aqueous humor thickness = " & taq-0.55 ukDH@/  
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    '************************************************************************* >gi{x|/  
    'Radius and conic constant of anterior lens C#?d=x  
    '************************************************************************* o%~K4 M".  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 4Tzu"y  
    GetConic eID, entity, curv, conic G`9F.T_Z^)  
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    SetConic eID, entity, 1/Rant, CCant a+a%}76N  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 'xrbg]b%  
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    '************************************************************************* ubCJZ"!  
    'Radius and conic constant of posterior lens TaHi+  
    '************************************************************************* tSXjp  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) f s"V'E2a  
    GetConic eID, entity, curv, conic 8JFkeU%yO  
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    SetConic eID, entity, 1/Rpost, CCpost wgR@M[]o;  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost K[|P6J   
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    '************************************************************************* g-V\ s&}  
    'Lens thickness (Position of posterior lens surface) x]J-q5  
    '************************************************************************* 8^"|-~#<  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) VX>t!JP p  
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    ' Delete any z-shift(s) \7tvNa,C  
    count = 0 ?>\]%$5o  
    While GetOperationCount(eID)>count . ;@) 5"  
        GetOperation eID, count, op +U/"F|M  
        If op.Type="ShiftZ" Then \utH*;J|x  
            DeleteOperation eID,count g$T_yT''  
            count=count-1 w>q_8V_K  
        End If 3^-)gK  
        count=count+1 O>F.Wf5g  
    Wend y`@4n.Q  
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    'Set new z-shift "N/K*  
    op.Type = "ShiftZ" ~ V- o{IA  
    op.val1 = tlens <C`eZ}Qqv  
    op.parent = parID ;WAu]C|  
    AddOperation eID, op x w83K  
    Print "Set lens thickness = " & tlens i\z0{;f|GX  
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    '************************************************************************* 5F+ f'~  
    'Lens index of refraction ?# c@Ag %  
    '************************************************************************* ,v5>sL  
    eID = FindMaterial( "Lens" ) :8L61d2(  
    GetModelMaterial eID, mat S_-mmzC(  
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    mat.Nd = nlens E|uXi)!.x  
    SetModelMaterial eID, mat u]-El}*[  
    Print "Set lens index of refraction = " & nlens Fl>j5[kLZ  
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    '************************************************************************* xENA:j?kF  
    'Pupil diameter k+G4<qw  
    '************************************************************************* zw9ULQ$#  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) knZd}?I*  
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    'Adjust pupil diameter (trimming volume inner hole) $/#)  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" (qONeLf%  
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    ' Adjust pupil location to just in front of the lens 4i&!V9@:  
    parID = FindFullName( "Geometry.Arizona Eye" ) I,?LZ_pK  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) P3FpU<OBwp  
    count = 0 "Ksd9,J\b  
    While GetOperationCount(eID)>count Yy~Dg  
        GetOperation eID, count, op s/^= WV  
        If op.Type="ShiftZ" Then 2qR@: ^  
            DeleteOperation eID,count g8@HAV^H  
            count=count-1 by ee-BU  
        End If ;.m[&h 0  
        count=count+1 ^o<Nz8  
    Wend }(O kl1  
    op.Type = "ShiftZ"  ]= D  
    op.val1 = taq-0.01 ATewdq[C  
    op.parent = parID au~gJW-  
    AddOperation eID, op jo:p*Q "F  
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    Print "Set pupil diameter = " & pupilDiam mM~Q!`Nf.  
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    'Update AZ Eye subassembly Description Raqr VC  
    eID = FindFullName( "Geometry.Arizona Eye" ) iU|C<A%Hh  
    GetEntity eID, entity ~%q e,  
    entity.Description = "Accommodation = " & A & "D" *g.,[a0  
    SetEntity eID, entity r2`?Ta  
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    Update Nq1RAM  
    Print "DONE!" w8zQDPVB%  
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End Sub ,FPgs0rrS  
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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： TQfY%GKg(  
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Accommodation = 4 Diopters |0Kt@ AJY  
Pupil Diameter = 4 mm R|yTUGY  
Set aqueous humor thickness = 2.81 nI` 1@ vB&  
Set anterior lens radius = 10.4 and conic constant = -2.375869 sbb{VV`I  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 3c"{Wu-}  
Set lens thickness = 3.927 DvKMb-*S  
Set lens index of refraction = 1.42672 ba.OjK@  
Set pupil diameter = 4 P=g+6-1  
DONE! $x<-PN  
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（文章来源：讯技光电）
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