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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 )|]*"yf:E  
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。 X=jD^"-  
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模型 K,bX<~e5  
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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。 V_4=0(  
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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. I 'ha=PeVn  
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光源 7a4Z~r27/  
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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。 x45F-w{  
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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。 RRpCWc Iv"  
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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*C$  
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[attachment=67933]
图2. 字母F光源的设定方法光 CE4Kc33OU|  
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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 (Kw%fJT  
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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。 T|--ZRYn  
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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。 4=njM`8Y'  
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图5. 视网膜重点采样规格设定
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脚本 yi<H }&  
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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： |-]'~ @~  
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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。 }gQnr;lv  
余下的脚本计算与屈光度有关的所有参数。 O}z-g&e.U  
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分析 rL/H{.@$`  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 xeRoif\4c  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 .bNG:y>  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. qKI)*o062  
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Dim entity As T_ENTITY C!|Yz=e  
Dim op As T_OPERATION g7v(g?  
Dim mat As T_MODELMATERIAL Yo}QW;,g  
Dim A As Double % 3<7HY]~  
Dim pupilDiam As Double }u;`k'J@  
Dim eID As Long p|w0 i[hc  
Dim parID As Long dTQW/kAHQ  
Dim count As Integer 3 5p) e c  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Lr*\LP6jx3  
Dim tlens As Double, nlens As Double ugs9>`fF&  
Dim curv As Double, conic As Double 4 udW 6U  
Dim ok As Long tPFj[Y~Iy  
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Sub Main d_Z?i#r0l  
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    '用户输入对话框 ` c"  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 a-NicjV#  
        TextBox 220,21,40,21,.TextBox1 'default: 0 Am"&ApK  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ~ L"?C  
        OKButton 40,91,90,21 5jsZJpk$  
        CancelButton 190,91,90,21 yXCHBz6&  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 R|]n;*y  
        TextBox 220,49,40,21,.TextBox2 'default: 4 wT+\:y  
    End Dialog 2~%^ y6lR  
    Dim dlg As UserDialog a" L9jrVrw  
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    ok = Dialog (dlg) [=^Wj`;  
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    If ok=0 Then    'cancel button was pressed BR:Mcc  
        Print "Execution cancelled." ;]W@W1)$  
        End =OFx4#6a  
    End If BCh|^Pk  
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    'Assign accommodation and pupil diameter & use defaults if field left empty HmbQL2  
    If dlg.TextBox1 = "" Then Dv~jVIXu  
        A = 0           'Default accommodation JgBC:t^\pV  
    Else -[[( Zx  
        A = CDbl(dlg.TextBox1) ]l, ,en5V  
    End If bP&1tE  
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    If dlg.TextBox2 = "" Then dd *p_4;  
        pupilDiam = 4   'Default pupil diameter xcH&B %;f  
    Else E[<*Al +N  
        pupilDiam = CDbl(dlg.TextBox2) WJN) <+d  
    End If dj{~!}  
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    Print " " E@4/<;eKK  
    Print "Accommodation = " & A & " Diopters" z#2n+hwE  
    Print "Pupil Diameter = " & pupilDiam & " mm" 9T0g%&  
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    ' Calculate new parameters with accommodation h=B= J  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 0e1-ZP CDj  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens R[OXYHu  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens <6X*k{  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens iU AY  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 8#/y`ul  
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    tlens = 3.767 + 0.04*A                  'Lens thickness  s;-AZr)  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction `@#rAW D  
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    'Adjust parameters to account for accommodation UqNUX?(  
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    '************************************************************************* uF<?y0t  
    'Aqueous thickness (Position of Lens) 4iss j$  
    '************************************************************************* o7@C$R_#  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) <T&v\DN  
    GetCustomElement eID, entity \>X!n2rLZe  
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    parID = FindFullName( "Geometry.Arizona Eye" ) <. *bJ  
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    ' Delete any shift(s) in z GxEShSGOE  
    count = 0 m=SI *V  
    While GetOperationCount(eID)>count opMnLor  
        GetOperation eID, count, op  :>U+HQll  
        If op.Type="ShiftZ" Then dFy GI?  
            DeleteOperation eID,count \`E^>6!]q  
            count=count-1 A0:rn\$l3  
        End If MzDosr3:  
        count=count+1 X0REC%  
    Wend 9Vo*AK'&U  
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    'Set new shift in eze%RjO}  
    op.Type = "ShiftZ" DTSf[zP/  
    op.val1 = taq {Wu[e,p  
    op.parent = parID [FLR&=.(  
    AddOperation eID, op e~d=e3mBp  
    Print "Set aqueous humor thickness = " & taq-0.55 is~2{:  
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    '************************************************************************* =E<H_cUS  
    'Radius and conic constant of anterior lens Eku  9u  
    '************************************************************************* 6|~^P!&  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 5n{d jP  
    GetConic eID, entity, curv, conic 2`TV(U@  
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    SetConic eID, entity, 1/Rant, CCant ?{e}ouKYX1  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant _{-[1-lN5_  
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    '************************************************************************* :mW< E  
    'Radius and conic constant of posterior lens m(*rMO>_  
    '************************************************************************* q=Vh"]0g  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) EO~L.E%W  
    GetConic eID, entity, curv, conic Gx6%Z$2n  
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    SetConic eID, entity, 1/Rpost, CCpost lo(C3o'  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost oeB'{bG  
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    '************************************************************************* WgqSw%:$H  
    'Lens thickness (Position of posterior lens surface) ');vc~C  
    '************************************************************************* _OyQ:>M6P  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) W\NC3]  
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    ' Delete any z-shift(s) >6HGh#0(p  
    count = 0 6(rN(C  
    While GetOperationCount(eID)>count YO$D-  
        GetOperation eID, count, op X;N?L%Pp  
        If op.Type="ShiftZ" Then }Sbk qd5  
            DeleteOperation eID,count d?T!)w  
            count=count-1 \yC/OLXq  
        End If &i(Ip'r  
        count=count+1 f!`? _  
    Wend *LU/3H|}  
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    'Set new z-shift #Pp:H/b  
    op.Type = "ShiftZ" b%%r`j,'JE  
    op.val1 = tlens 0hV#]`9`gN  
    op.parent = parID c|;n)as9(%  
    AddOperation eID, op 0B7G:X0  
    Print "Set lens thickness = " & tlens Z )M "`2Ur  
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    '************************************************************************* ^2nrA pF  
    'Lens index of refraction xdgAu  
    '************************************************************************* ^`'\eEa  
    eID = FindMaterial( "Lens" ) 8c+V$rH_  
    GetModelMaterial eID, mat }!oEjcX'  
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    mat.Nd = nlens A5TSbW']+5  
    SetModelMaterial eID, mat ]}XDDPbZ}  
    Print "Set lens index of refraction = " & nlens wW1VOj=6V"  
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    '************************************************************************* H3<tsK=:  
    'Pupil diameter z3K$gEve  
    '************************************************************************* ]s AuL!  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) Sb/?<$>  
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    'Adjust pupil diameter (trimming volume inner hole) uBx\xeI  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" N68$b#9Ry  
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    ' Adjust pupil location to just in front of the lens AX8~w(sv  
    parID = FindFullName( "Geometry.Arizona Eye" ) kt2_WW[  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) aC\f;&P >  
    count = 0 KtL?,zi  
    While GetOperationCount(eID)>count tr[}F7n9  
        GetOperation eID, count, op AAlc %d/9  
        If op.Type="ShiftZ" Then *v+l,z4n  
            DeleteOperation eID,count eV|N@  
            count=count-1 ^EX"fRwNi  
        End If ;rT'~?q  
        count=count+1 E(4c&  
    Wend .Rk8qRB  
    op.Type = "ShiftZ" /=m AVA  
    op.val1 = taq-0.01 z/ 1$G"  
    op.parent = parID uI7n{4W*x  
    AddOperation eID, op sip4,>,E  
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    Print "Set pupil diameter = " & pupilDiam _M%S  
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    'Update AZ Eye subassembly Description V2Vr7v=Y"  
    eID = FindFullName( "Geometry.Arizona Eye" ) KUUA>'=  
    GetEntity eID, entity CW &z?Bra  
    entity.Description = "Accommodation = " & A & "D" a.Z@Z!*  
    SetEntity eID, entity ls^Z"9P  
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    Update  @./h$]6  
    Print "DONE!" lLTqk\8g  
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End Sub 3Tl<ST\  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： T?pS2I~  
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Accommodation = 4 Diopters 2CzhaO  
Pupil Diameter = 4 mm W7qh1}_%  
Set aqueous humor thickness = 2.81 nnv|GnQST  
Set anterior lens radius = 10.4 and conic constant = -2.375869 &W@2n&U.q  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 q*&R&K;q  
Set lens thickness = 3.927 ]$@a.#}  
Set lens index of refraction = 1.42672 Food<(!.>  
Set pupil diameter = 4 :25LQf^nz  
DONE! EnM  
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（文章来源：讯技光电）
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