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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 (qXl=e8  
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。 O/2Jz  
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模型 -$m?ShDd  
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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"rlJC  
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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. [ O"8Tzr  
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光源 ]w[T_4 l  
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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。 y?s8UEC  
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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。 qEbzF#a-:  
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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。 Du2v,n5@  
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图2. 字母F光源的设定方法光 ~NtAr1  
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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 hMiuv_EO!  
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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。 M:Aik&  
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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。 )4P5i b  
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图5. 视网膜重点采样规格设定
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脚本 C8 b%r|^#  
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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： @GiR~bKZ  
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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。 KQ x<{-G6  
余下的脚本计算与屈光度有关的所有参数。 %Jpb&CEY  
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分析 z4nVsgQ$  
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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。 Y{8L ~U:  
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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 ^gdg0y!5~  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. 4D/mm(2d$  
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Dim entity As T_ENTITY B`4[@$  
Dim op As T_OPERATION 2,>q(M6,EA  
Dim mat As T_MODELMATERIAL R<!WW9IM  
Dim A As Double z^f-MgWG  
Dim pupilDiam As Double KcB  ?[  
Dim eID As Long n]B)\D+V^  
Dim parID As Long \4SFD 3$&  
Dim count As Integer '7F`qL\/#(  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double QsmG(1=  
Dim tlens As Double, nlens As Double i#jCf3%+ h  
Dim curv As Double, conic As Double y^C; ?B<  
Dim ok As Long b'N"?W^YQ  
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Sub Main N[}XLhbt  
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    '用户输入对话框 Oz9k.[j(  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 F|V co]"S1  
        TextBox 220,21,40,21,.TextBox1 'default: 0 r)mm8MI!Z  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 EMH?z2iGd  
        OKButton 40,91,90,21 aAko-,URC  
        CancelButton 190,91,90,21 l1o dkNf|  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 )^!-Aj\x  
        TextBox 220,49,40,21,.TextBox2 'default: 4 $gZ|=(y&r  
    End Dialog [,5clR=F  
    Dim dlg As UserDialog RWBmQg^]X  
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    ok = Dialog (dlg) 7$GP#V1r/  
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    If ok=0 Then    'cancel button was pressed ,ASY &J5)7  
        Print "Execution cancelled." }7$\F!R  
        End YA^9, q6u?  
    End If iA ZtV'VQ)  
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    'Assign accommodation and pupil diameter & use defaults if field left empty HIh oYSwB  
    If dlg.TextBox1 = "" Then v *:m|wl  
        A = 0           'Default accommodation McnP>n  
    Else *OF7 {^~&  
        A = CDbl(dlg.TextBox1) nbpN+a%  
    End If q#\eL~k  
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    If dlg.TextBox2 = "" Then ijhMJ?3  
        pupilDiam = 4   'Default pupil diameter ((dG<  
    Else Fr%KO)s2  
        pupilDiam = CDbl(dlg.TextBox2) $ ]81s`  
    End If m Xw1%w[*  
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    Print " " hG us!p"lw  
    Print "Accommodation = " & A & " Diopters" \iVYhl  
    Print "Pupil Diameter = " & pupilDiam & " mm" kLD)<D  
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    ' Calculate new parameters with accommodation <1jiU%!w  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 9J]LV'f7  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens */8\Z46z  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens d'-^ VxO0  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens qbAoab53  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Tf0#+6 1>  
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    tlens = 3.767 + 0.04*A                  'Lens thickness *smo{!0Gg  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Z=H f OC  
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    'Adjust parameters to account for accommodation OQsH,'  
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    '************************************************************************* H+0 *  
    'Aqueous thickness (Position of Lens) nEn2!)$  
    '************************************************************************* Lq&xlW j  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) QnGJ4F  
    GetCustomElement eID, entity tIvtiN6[|l  
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    parID = FindFullName( "Geometry.Arizona Eye" ) Q%>,5(_V]  
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    ' Delete any shift(s) in z @LmUCP~  
    count = 0 ^Ta"Uk'  
    While GetOperationCount(eID)>count Z2@&4_P  
        GetOperation eID, count, op BW*zj=N%  
        If op.Type="ShiftZ" Then >%[W2L\'  
            DeleteOperation eID,count 0!zWXKX  
            count=count-1 x-W0 h  
        End If ~p 1y+  
        count=count+1 (C:rH  
    Wend %q!nTG U~  
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    'Set new shift in 4@Qq5kpk*  
    op.Type = "ShiftZ" ~lL($rE  
    op.val1 = taq qy]-YJZ  
    op.parent = parID ](ninSX1w  
    AddOperation eID, op U9q*zP_jV  
    Print "Set aqueous humor thickness = " & taq-0.55 @GV^B'}*  
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    '************************************************************************* 8L@di  Y  
    'Radius and conic constant of anterior lens GQQ!3LwP\O  
    '************************************************************************* G@;aqe[dB  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) B?4\IXek  
    GetConic eID, entity, curv, conic 5SjS~ 9  
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    SetConic eID, entity, 1/Rant, CCant O| 2Q- @D  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant kDKpuA!  
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    '************************************************************************* i>~?XVU  
    'Radius and conic constant of posterior lens 6 qq7:  
    '************************************************************************* ibq@0CR  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" )  96BMJE'  
    GetConic eID, entity, curv, conic /IC' R"V a  
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    SetConic eID, entity, 1/Rpost, CCpost ev3x*}d0  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost #.@=xhK/  
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    '************************************************************************* oK>,MdB  
    'Lens thickness (Position of posterior lens surface) `4=b|N+b"  
    '************************************************************************* i~;8'>:|,M  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) =bDG|:+  
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    ' Delete any z-shift(s) >g[W@FhT'k  
    count = 0 X_qXH5^%  
    While GetOperationCount(eID)>count x6t;=  
        GetOperation eID, count, op W)#`4a^xj7  
        If op.Type="ShiftZ" Then  >4\xcL  
            DeleteOperation eID,count )=D&NO67Pq  
            count=count-1 5-OvPTY`M  
        End If  W 6~=?C  
        count=count+1 FMn&2fH  
    Wend 7'|PHQ?S  
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    'Set new z-shift cGp^;> ]M  
    op.Type = "ShiftZ" <-F"&LI{<  
    op.val1 = tlens _a&|,ajy >  
    op.parent = parID ;i9CQ0e ?  
    AddOperation eID, op #-;BU{3*  
    Print "Set lens thickness = " & tlens 9)">()8  
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    '************************************************************************* Pio^5jhB6  
    'Lens index of refraction AJT0)FCpR  
    '************************************************************************* z7q2+;L  
    eID = FindMaterial( "Lens" ) aM~fRra7  
    GetModelMaterial eID, mat 4i,SiFKB  
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    mat.Nd = nlens F(<8:`N;G  
    SetModelMaterial eID, mat  sD8S2  
    Print "Set lens index of refraction = " & nlens lIz_0rE  
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    '************************************************************************* g1~I*!p  
    'Pupil diameter !)O$Q}'\  
    '************************************************************************* {n]sRz  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" )  qR qy  
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    'Adjust pupil diameter (trimming volume inner hole) vgj^-  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ~t={ \,X\  
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    ' Adjust pupil location to just in front of the lens ?N*0 S'dY  
    parID = FindFullName( "Geometry.Arizona Eye" ) :2E1aVo4b  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) <+gl"lG  
    count = 0 [.X%:H+  
    While GetOperationCount(eID)>count ^d80\PXz  
        GetOperation eID, count, op ]ufW61W6Ci  
        If op.Type="ShiftZ" Then PQ}%}S7:  
            DeleteOperation eID,count /BM1AV{s6  
            count=count-1 @@IA35'tc  
        End If |L;psK  
        count=count+1 (:QQ7xc{}  
    Wend L]d@D0.Z  
    op.Type = "ShiftZ" f_ztnRw  
    op.val1 = taq-0.01 ,:4DN&<  
    op.parent = parID 8[)]3K x  
    AddOperation eID, op 6;cY!  
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    Print "Set pupil diameter = " & pupilDiam gvNZrp>e!  
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    'Update AZ Eye subassembly Description AwU c{h l<  
    eID = FindFullName( "Geometry.Arizona Eye" ) ^,lZ58 2  
    GetEntity eID, entity t i^v%+r1  
    entity.Description = "Accommodation = " & A & "D" _}OJPahw  
    SetEntity eID, entity ]<gCq/V#  
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    Update 9K':Fn2,  
    Print "DONE!" t3t0vWE<,  
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End Sub S9R]Zl7{-  
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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： *3O>J"  
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Accommodation = 4 Diopters JhCkkw  
Pupil Diameter = 4 mm &3Z. #*  
Set aqueous humor thickness = 2.81 Jh4&Qh|t  
Set anterior lens radius = 10.4 and conic constant = -2.375869 pP* ~ =?  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 ej%;%`C-  
Set lens thickness = 3.927 ] 5v4^mk  
Set lens index of refraction = 1.42672 <;cE/W}}  
Set pupil diameter = 4 7TkxvSL X  
DONE! R pI<]1  
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（文章来源：讯技光电）
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