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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 MB]E[&Q!  
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。 ;UdM8+^/V]  
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模型 xT*'p&ap  
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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。 rOJ>lPs  
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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. yD9enYM  
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光源 V?mP7  
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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@.5   
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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。 ]kj^T?&n.  
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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。 P{Nvt/%  
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[attachment=67933]
图2. 字母F光源的设定方法光 8hGyh#  
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[attachment=67934]
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 &L6Ivpj-  
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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。 DB}Uzw|  
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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。 @-@Coy 4Tt  
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图5. 视网膜重点采样规格设定
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脚本 u>>|ZPe  
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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： !HTOE@  
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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。 d) -(C1f  
余下的脚本计算与屈光度有关的所有参数。 HUKrp*Hv  
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分析 "P! .5B  
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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。 8h] TI_  
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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 \8CCa(H  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. f3UCELJ  
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Dim entity As T_ENTITY EjP;P}_iK  
Dim op As T_OPERATION )fJ"Hq  
Dim mat As T_MODELMATERIAL ~WA@YjQ]  
Dim A As Double M=,pn+}y>  
Dim pupilDiam As Double MlV(XG>'  
Dim eID As Long QK_5gD`$a,  
Dim parID As Long C'#KTp4!1  
Dim count As Integer #:6-O  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double [ycX)iM  
Dim tlens As Double, nlens As Double yZlT#^$\  
Dim curv As Double, conic As Double @a8lF$<  
Dim ok As Long #A)V  
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Sub Main 4 \z@Evm  
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    '用户输入对话框 S,5ok0R  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 t<rIg1  
        TextBox 220,21,40,21,.TextBox1 'default: 0 ^4sfVpD2!  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 p]aEC+q  
        OKButton 40,91,90,21 o U=vl!\J  
        CancelButton 190,91,90,21 lY,^  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 (.-4Jn  
        TextBox 220,49,40,21,.TextBox2 'default: 4 /k'7j*t Z  
    End Dialog Zc7;&cz  
    Dim dlg As UserDialog l>6tEOXt  
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    ok = Dialog (dlg) <+QdBp'd;  
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    If ok=0 Then    'cancel button was pressed eB0exPz%  
        Print "Execution cancelled." ~b_DFj  
        End 7uR;S:WX  
    End If 56AC%_ g>  
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    'Assign accommodation and pupil diameter & use defaults if field left empty qvn.uujYS  
    If dlg.TextBox1 = "" Then ny-:%A  
        A = 0           'Default accommodation 0F[ f%2j  
    Else 0? {ADQz  
        A = CDbl(dlg.TextBox1) +bumWOQ'  
    End If b 3x|Dq.  
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    If dlg.TextBox2 = "" Then )Do 0  
        pupilDiam = 4   'Default pupil diameter /A{ Zf'DI  
    Else #E]K*mE'  
        pupilDiam = CDbl(dlg.TextBox2) &%OY"Y~bI!  
    End If &y!?R$?b  
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    Print " " REW[`MBQ  
    Print "Accommodation = " & A & " Diopters" `Gio 2gl9  
    Print "Pupil Diameter = " & pupilDiam & " mm" K<P d.:  
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    ' Calculate new parameters with accommodation 8c5YX  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness s%:fZ7y  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens C|ZPnm>f30  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens $a_y-lY  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens nCYkUDnZ  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens P%2v(  
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    tlens = 3.767 + 0.04*A                  'Lens thickness zu d_BOq{f  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction (=j;rfvP  
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    'Adjust parameters to account for accommodation Z"8lW+r *  
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    '************************************************************************* 9nR\7!_  
    'Aqueous thickness (Position of Lens) TUfj\d,  
    '************************************************************************* ZJ3g,dc  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) hTDK[4e  
    GetCustomElement eID, entity '|[!I!WB`  
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    parID = FindFullName( "Geometry.Arizona Eye" ) z:\9t[e4  
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    ' Delete any shift(s) in z n3iiW \  
    count = 0 =Dn <DV  
    While GetOperationCount(eID)>count `w!XO$"]Z  
        GetOperation eID, count, op G^.N$wcv  
        If op.Type="ShiftZ" Then D0Q9A]bD;  
            DeleteOperation eID,count $cSUB  
            count=count-1 ,iV%{*p]  
        End If ?~o`mg  
        count=count+1 4aHogheg  
    Wend *qzdt^[ xo  
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    'Set new shift in {;{U@Z  
    op.Type = "ShiftZ" VM$n|[C~  
    op.val1 = taq t'U=K>7  
    op.parent = parID kyHli~Nr"  
    AddOperation eID, op ji?Hw  
    Print "Set aqueous humor thickness = " & taq-0.55 oh{>nwH  
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    '************************************************************************* PK+sGV  
    'Radius and conic constant of anterior lens RBQ8+^  
    '************************************************************************* 6=f)3!=  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ?oYO !  
    GetConic eID, entity, curv, conic Sp\TaUzg  
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    SetConic eID, entity, 1/Rant, CCant 6l\5J6x  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant %5e|  
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    '************************************************************************* l|.}>SfL^u  
    'Radius and conic constant of posterior lens ^+yz}YFM  
    '************************************************************************* $9G& wH>{  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) "W(D0oy  
    GetConic eID, entity, curv, conic Em!- W5*s  
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    SetConic eID, entity, 1/Rpost, CCpost it}h8:^<  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost Wep^He\:  
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    '************************************************************************* MG=E 6:  
    'Lens thickness (Position of posterior lens surface) `jeATxWv  
    '************************************************************************* 'x%gJi#  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) T f3CyH!k  
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    ' Delete any z-shift(s) 3H,x4L5j  
    count = 0 Bc8&-eZ ,  
    While GetOperationCount(eID)>count 5|rBb[  
        GetOperation eID, count, op 5len} ){  
        If op.Type="ShiftZ" Then !Q>xVlPVu  
            DeleteOperation eID,count Z1,rN#p9  
            count=count-1 >J;TtNE:  
        End If ZS.=GjK  
        count=count+1 |" }rdOV)  
    Wend L-Q8iFW'  
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    'Set new z-shift tl_3 %$s  
    op.Type = "ShiftZ" 7{<v$g$  
    op.val1 = tlens <{W{ Y\_A>  
    op.parent = parID myj/93p}`b  
    AddOperation eID, op Sn[xI9}O  
    Print "Set lens thickness = " & tlens ;n't:yQW  
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    '************************************************************************* p<r^{y  
    'Lens index of refraction o<5`uV!f  
    '************************************************************************* .'`aX 7{\  
    eID = FindMaterial( "Lens" ) OkC.e')Vx  
    GetModelMaterial eID, mat r:sa|+  
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    mat.Nd = nlens B :%Vq2`  
    SetModelMaterial eID, mat \lg ^rfj  
    Print "Set lens index of refraction = " & nlens )Ra:s>  
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    '************************************************************************* P7w RX F{  
    'Pupil diameter P6_Hz!vE  
    '************************************************************************* frcX'M}%  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) Lyc6nP;F  
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    'Adjust pupil diameter (trimming volume inner hole) B=]j=\o  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" F`4W5~`  
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    ' Adjust pupil location to just in front of the lens p*PzfSLN  
    parID = FindFullName( "Geometry.Arizona Eye" ) KH,f'`  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) hr]+ 4!/  
    count = 0 lZAGoR;0Ra  
    While GetOperationCount(eID)>count ] !*K|?VL  
        GetOperation eID, count, op pT=^o  
        If op.Type="ShiftZ" Then ,<Cl^ ^a,  
            DeleteOperation eID,count >\K=)/W2  
            count=count-1 Y-})/zFc  
        End If 4AL,=C3  
        count=count+1 z9 0JZA  
    Wend J3y _JoS  
    op.Type = "ShiftZ" jvQ^Vh!mC  
    op.val1 = taq-0.01 _Yo)m |RaB  
    op.parent = parID koT3~FK  
    AddOperation eID, op n#}@| "J  
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    Print "Set pupil diameter = " & pupilDiam  B=*0  
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    'Update AZ Eye subassembly Description GDCp@%xW  
    eID = FindFullName( "Geometry.Arizona Eye" ) >h8m8J  
    GetEntity eID, entity W!HjO;  
    entity.Description = "Accommodation = " & A & "D" K^o$uUBe  
    SetEntity eID, entity <U$YJtEK  
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    Update >e;jGk?-  
    Print "DONE!" (_#E17U)_  
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End Sub lrc%GU):  
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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： a)W|gx6Y  
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Accommodation = 4 Diopters r3x;lICx-  
Pupil Diameter = 4 mm "tl{HM5u  
Set aqueous humor thickness = 2.81 ue3 ].:  
Set anterior lens radius = 10.4 and conic constant = -2.375869 T x Mh_  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 #qVvh3#g  
Set lens thickness = 3.927 ,62~u'hR5  
Set lens index of refraction = 1.42672 1VYH:uGuAU  
Set pupil diameter = 4 )7Hx <?P  
DONE! KPy)%i  
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（文章来源：讯技光电）
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