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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 \[^! ys  
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。 :Q@/F;Z?  
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模型 ,u)jZ7  
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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。 +8itP>  
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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. /S1/ZI  
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光源 Vp|?R65S*  
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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。 K5 BL4N  
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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。 `8RKpZv&  
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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。 @|Yn~PwKs  
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[attachment=67933]
图2. 字母F光源的设定方法光 f% )9!qeW  
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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 {+E]c:{  
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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,]m8%GHE  
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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。 .SER,],P  
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[attachment=67936]
图5. 视网膜重点采样规格设定
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脚本 6kdbbGO-  
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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： ~"SQwE|  
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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。 #fns3=/ H  
余下的脚本计算与屈光度有关的所有参数。 tO:JB&vO2  
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分析 % ym};7'&b  
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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。 H)7v$A,5%  
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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 L8Tm8)  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. .7g h2K  
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Dim entity As T_ENTITY :ZIa   
Dim op As T_OPERATION Ue >]uZ|  
Dim mat As T_MODELMATERIAL @=dv[P" jn  
Dim A As Double p8%qU>~+4  
Dim pupilDiam As Double Y'i yfnk  
Dim eID As Long 6{1=3.CL  
Dim parID As Long $KGMAg/H  
Dim count As Integer j_N<aX  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double I@/ G#3Zr  
Dim tlens As Double, nlens As Double C:5- h(#  
Dim curv As Double, conic As Double qfE0J;e   
Dim ok As Long iKJqMES  
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Sub Main 9AX}V6\+  
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    '用户输入对话框 xS/W}-dPv  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 Nyy&'\`!  
        TextBox 220,21,40,21,.TextBox1 'default: 0 U,EoCAm>  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 S1U0sP@o  
        OKButton 40,91,90,21 Nb&j?./  
        CancelButton 190,91,90,21 @`4T6eL5  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 S7f.^8  
        TextBox 220,49,40,21,.TextBox2 'default: 4 m.Zy$SDj(  
    End Dialog _90D4kGU  
    Dim dlg As UserDialog Y|fD)zG_  
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    ok = Dialog (dlg) lTMY|{9  
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    If ok=0 Then    'cancel button was pressed .s*N1 U?h  
        Print "Execution cancelled." j}ob7O&U'w  
        End WK`o3ayH-  
    End If fe/;U=te  
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    'Assign accommodation and pupil diameter & use defaults if field left empty -!1=S: S  
    If dlg.TextBox1 = "" Then )4=86>XJT  
        A = 0           'Default accommodation d/Q#Z  
    Else <}{<FXk[  
        A = CDbl(dlg.TextBox1) $kTm"I  
    End If j*?8w(!  
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    If dlg.TextBox2 = "" Then nD BWm`kN  
        pupilDiam = 4   'Default pupil diameter //2O#Fg{/  
    Else cj>UxU][eS  
        pupilDiam = CDbl(dlg.TextBox2) A,<5W }  
    End If ,^?g\&f(  
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    Print " " FprdP*/  
    Print "Accommodation = " & A & " Diopters" $C7a #?YF,  
    Print "Pupil Diameter = " & pupilDiam & " mm" ,6;n[p"h|r  
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    ' Calculate new parameters with accommodation _HHvL=  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 8)1q,[:M  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens AyO%,6p[  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens UF!qp  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens +s}&'V^  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 940:NOgm  
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    tlens = 3.767 + 0.04*A                  'Lens thickness P! +Gwm{  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 7?whxi Qs  
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    'Adjust parameters to account for accommodation $^iio@SW{  
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    '************************************************************************* ^\ x'4!W  
    'Aqueous thickness (Position of Lens) + kKanm[!v  
    '************************************************************************* GfELL `yz  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) S<i1t[E @W  
    GetCustomElement eID, entity uM`i!7}  
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    parID = FindFullName( "Geometry.Arizona Eye" ) t <` As6}  
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    ' Delete any shift(s) in z .gg0rTf=-  
    count = 0 C~pas~  
    While GetOperationCount(eID)>count !ddyJJ^a  
        GetOperation eID, count, op $.Tn\4z&  
        If op.Type="ShiftZ" Then O"'xAPQW  
            DeleteOperation eID,count H\Qk U`b  
            count=count-1 &'>m;W  
        End If @G2# Z  
        count=count+1 xZ`z+)  
    Wend 5bt>MoKxv  
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    'Set new shift in z+yq%O  
    op.Type = "ShiftZ" Qa_V  
    op.val1 = taq _!o8s%9be  
    op.parent = parID v](Y n) #  
    AddOperation eID, op vQ*[tp#qU  
    Print "Set aqueous humor thickness = " & taq-0.55 u$R5Q{H_  
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    '************************************************************************* Dq<la+VlO  
    'Radius and conic constant of anterior lens ]Kq<U%x$  
    '************************************************************************* )=Z;H"_  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 7zH2dqrj  
    GetConic eID, entity, curv, conic R)66qRf  
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    SetConic eID, entity, 1/Rant, CCant $"vz>SuB  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 3l<qcKKc  
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    '************************************************************************* c7r( &h  
    'Radius and conic constant of posterior lens jl P*RX  
    '************************************************************************* TMMKRC1<  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) q2E{o)9  
    GetConic eID, entity, curv, conic 44*#qLN  
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    SetConic eID, entity, 1/Rpost, CCpost  ,RR{Y-  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost HZAT_  
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    '************************************************************************* h,Hr0^?  
    'Lens thickness (Position of posterior lens surface) QWOPCoUet  
    '************************************************************************* H*N<7#  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) VF2,(f-*  
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    ' Delete any z-shift(s) 67rY+u%  
    count = 0 (O J/u)W^  
    While GetOperationCount(eID)>count nKGQU,C  
        GetOperation eID, count, op m .(ja  
        If op.Type="ShiftZ" Then tAN!LI+w  
            DeleteOperation eID,count eWDXV-xD  
            count=count-1 anW['!T9{s  
        End If J-<P~9m~I  
        count=count+1 ?sQg{1"Zr  
    Wend |/K| Vwa  
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    'Set new z-shift +1T>Ob;hk  
    op.Type = "ShiftZ" )(G<(eiD  
    op.val1 = tlens c)#7T<>*'  
    op.parent = parID z~h?"'  
    AddOperation eID, op #k9&OS?  
    Print "Set lens thickness = " & tlens  G06;x   
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    '************************************************************************* >;Hx<FKxP  
    'Lens index of refraction T@ESMPeU:X  
    '************************************************************************* YWn""8p;P  
    eID = FindMaterial( "Lens" ) 9R$$(zB 1;  
    GetModelMaterial eID, mat ~:JAWs$\V  
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    mat.Nd = nlens '|]}f}Go  
    SetModelMaterial eID, mat R8[VD iM6E  
    Print "Set lens index of refraction = " & nlens nX:E(9q7c  
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    '************************************************************************* T2rwK2  
    'Pupil diameter sd\}M{U  
    '************************************************************************* d"n>Q Tn\  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) |5(un#  
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    'Adjust pupil diameter (trimming volume inner hole) E&J<qTH9  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" SHYekX  
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    ' Adjust pupil location to just in front of the lens Y&bYaq  
    parID = FindFullName( "Geometry.Arizona Eye" ) B)7:*Kj  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 4e>f}u 5  
    count = 0 4OM ]8I!  
    While GetOperationCount(eID)>count (+v':KH3_  
        GetOperation eID, count, op :a Cf@:']  
        If op.Type="ShiftZ" Then e/Z{{FP%6  
            DeleteOperation eID,count iyCH)MA  
            count=count-1 s@~3L  
        End If " oxUKT  
        count=count+1 1^o})9  
    Wend 4}D&=0IZ  
    op.Type = "ShiftZ" Fb<'L5}i  
    op.val1 = taq-0.01 z}J~X%}e  
    op.parent = parID Mm8_EjMp  
    AddOperation eID, op #(qvhoi7lM  
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    Print "Set pupil diameter = " & pupilDiam ;PMPXN'z6  
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    'Update AZ Eye subassembly Description *8qRdI9  
    eID = FindFullName( "Geometry.Arizona Eye" ) axnVAh|}S  
    GetEntity eID, entity T#rUbi>""  
    entity.Description = "Accommodation = " & A & "D" ^Vth;!o  
    SetEntity eID, entity -U> )B  
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    Update MA tF,  
    Print "DONE!" =^M Q 4  
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End Sub -d!84_d9  
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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： 8B6(SQp%  
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Accommodation = 4 Diopters .vmCKZ  
Pupil Diameter = 4 mm Ld:-S,2  
Set aqueous humor thickness = 2.81 ;(E]mbV'=  
Set anterior lens radius = 10.4 and conic constant = -2.375869 'GW~~UhdW  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 #lFsgb  
Set lens thickness = 3.927 )sIzBC  
Set lens index of refraction = 1.42672 .gNJY7`b  
Set pupil diameter = 4 ;YokPiBy  
DONE! %[*_-%  
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（文章来源：讯技光电）
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