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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 7S9Q{  
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。 TVFxEV7Fx  
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模型 X+XbIbUuL  
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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。 &,@wLy^ T  
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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. oM#S.f?  
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光源 YJ^TO\4WM  
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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。 |qsY0zx  
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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。 L #l|}u  
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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。 wY j~(P"  
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图2. 字母F光源的设定方法光 >xE{& ):  
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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 )ozN{&B6  
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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。 2=l !b/m  
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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。 +iPS=?S  
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图5. 视网膜重点采样规格设定
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脚本 jP";ll|c  
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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: ynN[N(m#  
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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。 Do|`wpR  
余下的脚本计算与屈光度有关的所有参数。 ngJES` 0d  
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分析 (Rk g  
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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。 \0pJ+@\T9  
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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 }r /L 9  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. hGF(E*  
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Dim entity As T_ENTITY * #;rp~  
Dim op As T_OPERATION YAZ=-@]`\  
Dim mat As T_MODELMATERIAL .{-8gAh  
Dim A As Double f(?`PD[  
Dim pupilDiam As Double GKPqBi[rO  
Dim eID As Long l(zkMR$b8  
Dim parID As Long MT#9x>  
Dim count As Integer r/L3j0  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double b\?#O}  
Dim tlens As Double, nlens As Double 6SsZK)X  
Dim curv As Double, conic As Double Pwz^{*u]  
Dim ok As Long 9#6ilF:F  
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Sub Main M)EUR0>8  
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    '用户输入对话框 ?#D@e5Wf  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 gpr];lgS  
        TextBox 220,21,40,21,.TextBox1 'default: 0 4Df TVO"h  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ,lA J{5\#  
        OKButton 40,91,90,21 4[.- a&!}  
        CancelButton 190,91,90,21 rf1nC$Sop  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 4 '9h^C&  
        TextBox 220,49,40,21,.TextBox2 'default: 4 1xq1te)  
    End Dialog r:Cad0xj;^  
    Dim dlg As UserDialog ,-DE;l^Q=  
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    ok = Dialog (dlg) _I|wp<R  
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    If ok=0 Then    'cancel button was pressed cX.v^9kuX  
        Print "Execution cancelled." ieS5*@^k  
        End J(/ eR,ak  
    End If B{1+0k  
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    'Assign accommodation and pupil diameter & use defaults if field left empty p7H*Ff`  
    If dlg.TextBox1 = "" Then web&M!-  
        A = 0           'Default accommodation S%xGXmZ  
    Else NK#Dq&W+&  
        A = CDbl(dlg.TextBox1) YBS]JCO  
    End If 1<5 9)RiO>  
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    If dlg.TextBox2 = "" Then <J H0 &  
        pupilDiam = 4   'Default pupil diameter vW)GUAF[  
    Else tg8VFH2q.z  
        pupilDiam = CDbl(dlg.TextBox2) XcfTE m  
    End If 4?yc/F=kI  
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    Print " " RXx +rdF0  
    Print "Accommodation = " & A & " Diopters" 5K6_#g4"  
    Print "Pupil Diameter = " & pupilDiam & " mm" U;V. +onv  
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    ' Calculate new parameters with accommodation At bqj?  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness q}\\p  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens v@t*iDa?7  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens !^"hYp`  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ] &G5/ ]f  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Fsq S)  
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    tlens = 3.767 + 0.04*A                  'Lens thickness .PAkW2\#  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Z(}x7jzW  
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    'Adjust parameters to account for accommodation o$-8V:)6d  
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    '************************************************************************* T:!sfhrZ~<  
    'Aqueous thickness (Position of Lens) 'Ux_X:,:;  
    '************************************************************************* s*8hN*A/,  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ka>RAr J  
    GetCustomElement eID, entity xwRnrWd^6  
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    parID = FindFullName( "Geometry.Arizona Eye" ) %MjPQ  
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    ' Delete any shift(s) in z D{l.WlA.  
    count = 0 } 1XLe  
    While GetOperationCount(eID)>count mJsYY,b8  
        GetOperation eID, count, op Bw#ubQJ8}  
        If op.Type="ShiftZ" Then _E30t( _.  
            DeleteOperation eID,count x1}q!)e  
            count=count-1 cLYc""=  
        End If Zgg7pL)#c  
        count=count+1 q!H 3JL  
    Wend 5AjK7[<L  
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    'Set new shift in C`jP8"-  
    op.Type = "ShiftZ" T*{zL  
    op.val1 = taq Asn0&Ys4  
    op.parent = parID 5PPy+36<~  
    AddOperation eID, op Fhsmpe~  
    Print "Set aqueous humor thickness = " & taq-0.55 gOWyV@  
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    '************************************************************************* e N-{  
    'Radius and conic constant of anterior lens P5d@-l%}  
    '************************************************************************* {&<}*4D  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) NuooA  
    GetConic eID, entity, curv, conic @LE?XlhD  
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    SetConic eID, entity, 1/Rant, CCant <eh(~  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant GVfu_z?  
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    '************************************************************************* Z*TW;h0ZQ3  
    'Radius and conic constant of posterior lens z67=v9+7  
    '************************************************************************* >C-_Zv<!T\  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) Gzir>'d2'V  
    GetConic eID, entity, curv, conic k,@J&   
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    SetConic eID, entity, 1/Rpost, CCpost ATzNV=2s  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost .3U[@*b(  
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    '*************************************************************************  g_>ZE  
    'Lens thickness (Position of posterior lens surface) !Q(xOc9>Ug  
    '************************************************************************* vl5n%m H>^  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) hKTg~y^  
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    ' Delete any z-shift(s) BH-[q9pf  
    count = 0 L@z !,r,  
    While GetOperationCount(eID)>count YEQW:r_h.S  
        GetOperation eID, count, op %)/f; T6  
        If op.Type="ShiftZ" Then XsOOkf\_  
            DeleteOperation eID,count )a^Yor)o"  
            count=count-1 S[a5k;8GL  
        End If |tg?b&QR  
        count=count+1 b66X])+4jE  
    Wend zkp Apj].  
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    'Set new z-shift AIm$in`P  
    op.Type = "ShiftZ" /SXz_ e  
    op.val1 = tlens ;ULC|7rL  
    op.parent = parID YF -w=Y6  
    AddOperation eID, op j&/.[?K  
    Print "Set lens thickness = " & tlens @ g75T`N  
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    '************************************************************************* $&8h=e~]-  
    'Lens index of refraction x ct U.)p  
    '************************************************************************* &Bn; Vi  
    eID = FindMaterial( "Lens" ) k,7+=.6  
    GetModelMaterial eID, mat r}\h\ {  
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    mat.Nd = nlens O^}v/}d  
    SetModelMaterial eID, mat Uxemlp%%*  
    Print "Set lens index of refraction = " & nlens -m160k3  
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    '************************************************************************* {% _j~  
    'Pupil diameter %EGr0R(  
    '************************************************************************* <KwK tgzs  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) grQnV' q  
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    'Adjust pupil diameter (trimming volume inner hole) jAK{<7v4U  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" =$8@JF'  
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    ' Adjust pupil location to just in front of the lens g`OOVaB  
    parID = FindFullName( "Geometry.Arizona Eye" ) {(OIu]:  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) bV`C;RPn  
    count = 0 sdf%  
    While GetOperationCount(eID)>count >C3NtGvy  
        GetOperation eID, count, op v1r_Z($  
        If op.Type="ShiftZ" Then T;4` wB8@  
            DeleteOperation eID,count f9,EWuQNS  
            count=count-1 cH;TnuX  
        End If ;:Z=%R$wJ  
        count=count+1 "PyWo  
    Wend d>, V  
    op.Type = "ShiftZ" 90T%T2K  
    op.val1 = taq-0.01 5w3ZUmjO  
    op.parent = parID ?{: D,{+  
    AddOperation eID, op `xUG|  
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    Print "Set pupil diameter = " & pupilDiam sc8DY!|OYN  
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    'Update AZ Eye subassembly Description xb>n&ym?  
    eID = FindFullName( "Geometry.Arizona Eye" ) ]iDJ*!I  
    GetEntity eID, entity 5_)@B]~nM  
    entity.Description = "Accommodation = " & A & "D" y?#9>S >:\  
    SetEntity eID, entity |= cCv_y  
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    Update -+}5ma  
    Print "DONE!" ZCQ< %f  
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End Sub 8PBU~mr  
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如果屈光度是4,光瞳直径是4,则会输出如下数据: C ]'g:93L  
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Accommodation = 4 Diopters nlzW.OLM  
Pupil Diameter = 4 mm mF'-Is  
Set aqueous humor thickness = 2.81 4TUtY:  
Set anterior lens radius = 10.4 and conic constant = -2.375869 SFn 3$ rh  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 tqf&N0*  
Set lens thickness = 3.927 .Z=Ce!  
Set lens index of refraction = 1.42672 YOV :  
Set pupil diameter = 4 rLJ[FqS  
DONE! $;Vc@mYGW;  
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(文章来源:讯技光电)
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