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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 nTSGcMI  
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。 S:] w@$  
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模型 >RxZ-.,a  
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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。 EX8:B.z`57  
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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. FXFQ@q*}v  
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光源 p/WEQ2   
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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^Z4  
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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。 VLtb16|  
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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。 A 20_a;V  
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图2. 字母F光源的设定方法光 lp?geav  
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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 z@VY s  
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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。 XLFJ?$)Tro  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 H5/%"1Q  
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图5. 视网膜重点采样规格设定
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脚本 &e[/F@\%  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： b#k$/A@  
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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。 Tb}`]Y`X  
余下的脚本计算与屈光度有关的所有参数。 61T"K  
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分析 4jis\W}%L3  
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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。 WABq6q!  
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图7. 字母F在视网膜上颜色分析
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脚本代码 RIl%p~  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. <+sv7"a  
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Dim entity As T_ENTITY u;~/B[  
Dim op As T_OPERATION 5@Ot@o  
Dim mat As T_MODELMATERIAL ^7TM.lE  
Dim A As Double y| @[?B  
Dim pupilDiam As Double wC<!,tB(8  
Dim eID As Long  uGc}^a2  
Dim parID As Long &bs/a] ?Z7  
Dim count As Integer 4\ H;A  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double eNu `\  
Dim tlens As Double, nlens As Double x1$fkNu  
Dim curv As Double, conic As Double qN}0$x>p  
Dim ok As Long 98Pt&C?-B  
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Sub Main uQ9P6w=Nt  
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    '用户输入对话框 XL g6?Nu  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 `EBo(^n}O  
        TextBox 220,21,40,21,.TextBox1 'default: 0 U $X"W'  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 M<~z=B#  
        OKButton 40,91,90,21 rMfp%DMA  
        CancelButton 190,91,90,21 7DKbuUK  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 5sFp+_``  
        TextBox 220,49,40,21,.TextBox2 'default: 4 l>7`D3  
    End Dialog "l n(EvW  
    Dim dlg As UserDialog +<|6y46  
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    ok = Dialog (dlg) EFqWnz  
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    If ok=0 Then    'cancel button was pressed @FdtM<X  
        Print "Execution cancelled." m+"?;;s  
        End 536H*HdN  
    End If :JxShF:M  
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    'Assign accommodation and pupil diameter & use defaults if field left empty iZwt,)(  
    If dlg.TextBox1 = "" Then EUu"H` E+  
        A = 0           'Default accommodation : JD% =w_  
    Else o[O-|XL_  
        A = CDbl(dlg.TextBox1)  l}5@6;}  
    End If \=XAl >}\  
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    If dlg.TextBox2 = "" Then r|{h7'  
        pupilDiam = 4   'Default pupil diameter g"FG7E&  
    Else ow>^(>^~  
        pupilDiam = CDbl(dlg.TextBox2) # ~} 26  
    End If S c_*L<$  
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    Print " " Jj8z~3XnJ  
    Print "Accommodation = " & A & " Diopters" .`)\GjDv  
    Print "Pupil Diameter = " & pupilDiam & " mm" &Op, ?\   
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    ' Calculate new parameters with accommodation 9.!6wd4mw  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness _b&Mrd  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens nws '%MK)  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ]Vln5U   
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens SWN i@  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens F@& R"-  
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    tlens = 3.767 + 0.04*A                  'Lens thickness dpDVEEs84  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction cuO(*%Is1  
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    'Adjust parameters to account for accommodation N/p9Ws  
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    '************************************************************************* m$ )yd~  
    'Aqueous thickness (Position of Lens) eB%KXPhMm  
    '************************************************************************* 8V`NQS$  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) j&6,%s-M`a  
    GetCustomElement eID, entity D^baXp8  
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    parID = FindFullName( "Geometry.Arizona Eye" ) puF'w:I (  
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    ' Delete any shift(s) in z : ^F+m QN  
    count = 0 GpMKOjVm|  
    While GetOperationCount(eID)>count ( v6tE[4  
        GetOperation eID, count, op x%pC.0%  
        If op.Type="ShiftZ" Then y>Zvose  
            DeleteOperation eID,count I= G%r/3  
            count=count-1 Dd-;;Y1C  
        End If :9Zu&t  
        count=count+1 h$F;=YS   
    Wend <H<5E'm  
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    'Set new shift in ZM K"3c9  
    op.Type = "ShiftZ" ([R}s/)$  
    op.val1 = taq (o~f6pNB,  
    op.parent = parID 1L]7*NJe  
    AddOperation eID, op !C * %,Ak  
    Print "Set aqueous humor thickness = " & taq-0.55 1t_$pDF}  
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    '************************************************************************* dIQ7u  
    'Radius and conic constant of anterior lens "nPmQ  
    '************************************************************************* *:J#[ET,  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) gcqcY  
    GetConic eID, entity, curv, conic #~3x^ 4Y  
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    SetConic eID, entity, 1/Rant, CCant M[}EVt~  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant T)&J}^j  
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    '************************************************************************* SlB,?R2  
    'Radius and conic constant of posterior lens Rp `JF}~o  
    '************************************************************************* h#'(i<5v  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) }YW0?-G.$  
    GetConic eID, entity, curv, conic )67_yHW  
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    SetConic eID, entity, 1/Rpost, CCpost kq6S`~J^R  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost D M(WYL{  
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    '************************************************************************* <h^'x7PkW5  
    'Lens thickness (Position of posterior lens surface) e48`cX\E  
    '************************************************************************* %;yDiQ!+  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) j}uFp|df<  
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    ' Delete any z-shift(s) T=35?   
    count = 0 &sR=N60n  
    While GetOperationCount(eID)>count "~Twx]Z  
        GetOperation eID, count, op m(>_C~rGN  
        If op.Type="ShiftZ" Then f ZL%H0&  
            DeleteOperation eID,count q$z#+2u  
            count=count-1 nv1'iSEeOl  
        End If 'bGL@H  
        count=count+1 g <^Y^~+E  
    Wend [/hS5TG|7  
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    'Set new z-shift "u5Hm ^H  
    op.Type = "ShiftZ" RmxgCe(2a  
    op.val1 = tlens }dw`[{cm  
    op.parent = parID ^ j;HYs_  
    AddOperation eID, op g66=3c9</6  
    Print "Set lens thickness = " & tlens $3S6{"  
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    '************************************************************************* [Av#Z)R  
    'Lens index of refraction vA@Kb3 ,  
    '************************************************************************* a]'sby  
    eID = FindMaterial( "Lens" ) TWYz\Hmw  
    GetModelMaterial eID, mat Kdh(vNB>  
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    mat.Nd = nlens @'L/]  
    SetModelMaterial eID, mat ?(Q" y\  
    Print "Set lens index of refraction = " & nlens 4v9zFJ<Z  
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    '************************************************************************* qH!}oPeU'  
    'Pupil diameter Qw4P{>|Y  
    '************************************************************************* *vv <@+gA  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) (oX|lPD<b  
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    'Adjust pupil diameter (trimming volume inner hole) @*q WV*$h  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" s (|T@g  
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    ' Adjust pupil location to just in front of the lens 7Ipt~K}  
    parID = FindFullName( "Geometry.Arizona Eye" ) au7%K5  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) (-*NRY3*  
    count = 0 Jfa=#`    
    While GetOperationCount(eID)>count Mf7Q+_!  
        GetOperation eID, count, op Y(GH/jw  
        If op.Type="ShiftZ" Then Pc >$[kT0  
            DeleteOperation eID,count (A O]f fBU  
            count=count-1 %])-+T  
        End If BM=`zGh"  
        count=count+1 8(3'YNC  
    Wend CN8GeZ-G  
    op.Type = "ShiftZ" qJ|ByZ.N+  
    op.val1 = taq-0.01 '<~rV  
    op.parent = parID /_y%b.f^  
    AddOperation eID, op &[,g `S0  
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    Print "Set pupil diameter = " & pupilDiam <_@ K4zV  
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    'Update AZ Eye subassembly Description 4 r#O._Z  
    eID = FindFullName( "Geometry.Arizona Eye" ) "Pi\I9M3  
    GetEntity eID, entity L>+g;GJ  
    entity.Description = "Accommodation = " & A & "D" / U1VE|T  
    SetEntity eID, entity B%gk[!d}8  
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    Update %HSS x+2oR  
    Print "DONE!" W"Hjn/xSS  
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End Sub !+Z"7e nj  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： hPr*<2mp  
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Accommodation = 4 Diopters f Z$<'(t  
Pupil Diameter = 4 mm QT{$2 7;  
Set aqueous humor thickness = 2.81 ;wND?:  
Set anterior lens radius = 10.4 and conic constant = -2.375869 #3u3WTk+  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 0CS^S1/[B`  
Set lens thickness = 3.927 #@H{Ypn`  
Set lens index of refraction = 1.42672 .O @bX)  
Set pupil diameter = 4 Fn$/ K  
DONE! NHA 2 i  
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（文章来源：讯技光电）
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