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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 &fy8,}  
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。 /sC[5G%  
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模型 <C`eZ}Qqv  
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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。 8}0y)aJ  
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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. U)%u`C0  
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光源 lR K ?%~  
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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。 [^=8k2  
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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。 v;qL? _:=c  
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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。 cWy0N  
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图2. 字母F光源的设定方法光 &J@ZF<Ib  
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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 W",jZ"7  
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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。 g\nL n#  
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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。 , ZW.P`  
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图5. 视网膜重点采样规格设定
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脚本 Jpnp'  
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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： TEyPlSGG  
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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。 F+^[8zK^  
余下的脚本计算与屈光度有关的所有参数。 $4) g uG)  
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分析 V0B4<TTAo~  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 SygsZv&LZ  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 hrxASAfg6  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. U.)eJ1a  
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Dim entity As T_ENTITY 3CL:VwoW  
Dim op As T_OPERATION 1fG@r%4  
Dim mat As T_MODELMATERIAL aa3YtNpP  
Dim A As Double 7cSvAX0Z.  
Dim pupilDiam As Double :P'5_YSi  
Dim eID As Long sA j$U^Gp  
Dim parID As Long BNLall  
Dim count As Integer z`6KX93  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double tjL#?j  
Dim tlens As Double, nlens As Double |0Kt@ AJY  
Dim curv As Double, conic As Double yrb%g~ELGn  
Dim ok As Long cZi&L p  
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Sub Main Jx,s.Z0@7,  
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    '用户输入对话框 }0*7bb  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 5PySCGv  
        TextBox 220,21,40,21,.TextBox1 'default: 0 !"">'}E1  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 R'_[RHFC  
        OKButton 40,91,90,21 J#^M   
        CancelButton 190,91,90,21 B W1O1zIh\  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 }?$Mh)  
        TextBox 220,49,40,21,.TextBox2 'default: 4 riQ?'!a7  
    End Dialog [:Y^0[2  
    Dim dlg As UserDialog Yi,um-%  
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    ok = Dialog (dlg) m{" zFD/  
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    If ok=0 Then    'cancel button was pressed }'JPA&h|  
        Print "Execution cancelled." ^Y!`wp2vn  
        End : DP{YL|x  
    End If 5 [*jfOz  
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    'Assign accommodation and pupil diameter & use defaults if field left empty Z$gY}Bz  
    If dlg.TextBox1 = "" Then WbF\=;$=7  
        A = 0           'Default accommodation nfR5W~%*:  
    Else MsiSC  
        A = CDbl(dlg.TextBox1) ^8*.r+7p  
    End If _;+&'=6.[  
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    If dlg.TextBox2 = "" Then 3H2'HO  
        pupilDiam = 4   'Default pupil diameter q9>w3 <  
    Else hHQt4 r'd  
        pupilDiam = CDbl(dlg.TextBox2) -8: @xG2  
    End If w\a#Bfcv  
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    Print " " t `oP;  
    Print "Accommodation = " & A & " Diopters" _,QUH"  
    Print "Pupil Diameter = " & pupilDiam & " mm" ^  +G> N  
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    ' Calculate new parameters with accommodation #k6T_ki  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 1U!CD-%(  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens U/;Vge8{  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens mv_-|N~  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens "@_f>3z  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens B("kE`  
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    tlens = 3.767 + 0.04*A                  'Lens thickness .T2I]d  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction MH-,+-Eq  
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    'Adjust parameters to account for accommodation CEiG jo^  
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    '************************************************************************* G4~J+5m k  
    'Aqueous thickness (Position of Lens) ^B7Aam  
    '************************************************************************* idQr^{  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) n/-I7Q!;u  
    GetCustomElement eID, entity i@6 kI C  
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    parID = FindFullName( "Geometry.Arizona Eye" ) Zv_<*uzKZ  
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    ' Delete any shift(s) in z tBt\&{=|D  
    count = 0 QGa"HG5NF  
    While GetOperationCount(eID)>count \4 DH&gZ[  
        GetOperation eID, count, op }j QwP3eY  
        If op.Type="ShiftZ" Then iD9GAe}x  
            DeleteOperation eID,count 3z#16*  
            count=count-1 >8c9-dTmf  
        End If U3>G9g>^B  
        count=count+1 3i<*,@CY  
    Wend zB4gnVhus|  
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    'Set new shift in FD8Hx\oF  
    op.Type = "ShiftZ" y_w4ei  
    op.val1 = taq cVU[>gkg_  
    op.parent = parID 8V@3T/}  
    AddOperation eID, op 7_LE2jpC,5  
    Print "Set aqueous humor thickness = " & taq-0.55 b=sc2 )3?  
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    '************************************************************************* gs'( px  
    'Radius and conic constant of anterior lens eG<32$I  
    '************************************************************************* KpWQ;3D2  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) BX?Si1c  
    GetConic eID, entity, curv, conic  I2b[  
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    SetConic eID, entity, 1/Rant, CCant 16AYB17  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant q~lmOT~E  
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    '************************************************************************* fz%urbJR  
    'Radius and conic constant of posterior lens hP #>`)aNY  
    '************************************************************************* +%0+  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) r'j*f"uAm  
    GetConic eID, entity, curv, conic ~FJd{$2x`  
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    SetConic eID, entity, 1/Rpost, CCpost XWk^$"  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost H}d&>!\}F  
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    '************************************************************************* (%".=x-  
    'Lens thickness (Position of posterior lens surface) [/I4Pe1Yj%  
    '************************************************************************* `5 bHZ  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Al! P=h  
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    ' Delete any z-shift(s) i=Y#kL~f  
    count = 0 Y?Xs Z  
    While GetOperationCount(eID)>count  RszqDm  
        GetOperation eID, count, op Y.ic=<0H  
        If op.Type="ShiftZ" Then jZ)1]Q2  
            DeleteOperation eID,count I~Ziq10  
            count=count-1 #=h~Lr'UH  
        End If z.FO6y6L  
        count=count+1 dQt]r  
    Wend rTQrlQ:@  
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    'Set new z-shift i0hF9M  
    op.Type = "ShiftZ" 1aKY+4/G  
    op.val1 = tlens .(D-vkz'  
    op.parent = parID JPRl/P$  
    AddOperation eID, op 26j ; RV  
    Print "Set lens thickness = " & tlens Go8 m  
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    '************************************************************************* 4~DoqT  
    'Lens index of refraction N,L$+wm  
    '************************************************************************* 7aS`S F  
    eID = FindMaterial( "Lens" ) =*fOej>G  
    GetModelMaterial eID, mat ftRf~5d2  
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    mat.Nd = nlens "??$yMW  
    SetModelMaterial eID, mat ~'n3],o?  
    Print "Set lens index of refraction = " & nlens ngE5$}UM  
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    '************************************************************************* h?jKq2`  
    'Pupil diameter XI@;;>D1=U  
    '************************************************************************* pxjb^GZ0  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ~m'PAC"Q$  
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    'Adjust pupil diameter (trimming volume inner hole) !;>j(xc  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" <;G.(CK@n  
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    ' Adjust pupil location to just in front of the lens ~"xc 3(h  
    parID = FindFullName( "Geometry.Arizona Eye" ) N$i!25F`  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) /SO 4O|b  
    count = 0 J sde+G,N  
    While GetOperationCount(eID)>count _XvSe]`f`  
        GetOperation eID, count, op %v5IR  
        If op.Type="ShiftZ" Then 7S|nn|\Kp  
            DeleteOperation eID,count yL{X}:;}  
            count=count-1  Em?bV(  
        End If VXX7Y? !  
        count=count+1 06X4mu{  
    Wend Gf*|f"O  
    op.Type = "ShiftZ" jOV,q%)^,:  
    op.val1 = taq-0.01 ;W 16Hr Z  
    op.parent = parID k /srT<  
    AddOperation eID, op [M?'N w/[S  
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    Print "Set pupil diameter = " & pupilDiam ROb2g|YXG  
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    'Update AZ Eye subassembly Description Qu]F<H*Y|  
    eID = FindFullName( "Geometry.Arizona Eye" ) d|I?%LX0p  
    GetEntity eID, entity uf q9+}  
    entity.Description = "Accommodation = " & A & "D" R<]f[  
    SetEntity eID, entity 2z#gn9Wb  
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    Update Qx<86aKkF  
    Print "DONE!" `,~8(rIM  
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End Sub L{&5Ets  
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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： m}`!FaB #  
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Accommodation = 4 Diopters BeFCt;  
Pupil Diameter = 4 mm 'qoDFR\v  
Set aqueous humor thickness = 2.81 I.'(n8*  
Set anterior lens radius = 10.4 and conic constant = -2.375869 _e4%<!1  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 s&.VU|=VQ@  
Set lens thickness = 3.927 'fo.1  
Set lens index of refraction = 1.42672 so=Ux2  
Set pupil diameter = 4 N./l\NtZ  
DONE! | 6/ # H*  
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（文章来源：讯技光电）
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