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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 2|${2u`$&y  
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。 8`Tj*7Y=  
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模型 +9.GNu  
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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。 %<MI]D  
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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. "J 2v8c  
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光源 8(* ze+8  
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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。 SOluTFxUw  
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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。 zRB LkrC  
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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。 /&5:v%L  
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图2. 字母F光源的设定方法光 <WL] (-9I:  
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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=thaF.  
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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。 Kn}Y7B{  
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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。 ?_. SV g  
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图5. 视网膜重点采样规格设定
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脚本 B. #-@  
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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： srH.$Y;~  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 x6Q_+!mnk  
余下的脚本计算与屈光度有关的所有参数。 F/"lJ/I  
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分析 R[H#a v  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 )a$sx}  
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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 7+rroCr"  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. zvT8r(<n}  
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Dim entity As T_ENTITY % xBQX  
Dim op As T_OPERATION 4!Lj\.!$  
Dim mat As T_MODELMATERIAL  xC2y/ ?  
Dim A As Double ,N8SP 'R  
Dim pupilDiam As Double :*J!  
Dim eID As Long %%lJyLq'Vk  
Dim parID As Long ~_ko$(;A  
Dim count As Integer 4cDe'9 LA  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double isz-MP$:K5  
Dim tlens As Double, nlens As Double YyC$\HH6  
Dim curv As Double, conic As Double $Eo-58<q  
Dim ok As Long {Vf].l:kn  
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Sub Main J n'SGR  
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    '用户输入对话框 8/-hODoT_  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 D*ZswHT{y  
        TextBox 220,21,40,21,.TextBox1 'default: 0 H)5"<=]  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 8 LsJ}c  
        OKButton 40,91,90,21 _: !7M ^IU  
        CancelButton 190,91,90,21 Y5<W"[B!  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 l2kUa'O-  
        TextBox 220,49,40,21,.TextBox2 'default: 4 | zOwC9-6  
    End Dialog  x(A6RRh  
    Dim dlg As UserDialog LPkl16yZ  
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    ok = Dialog (dlg) [f=Y*=u9,  
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    If ok=0 Then    'cancel button was pressed I~,bZA  
        Print "Execution cancelled." 4 Z&KR<2Z  
        End <BK?@Xy  
    End If {6>$w/+~  
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    'Assign accommodation and pupil diameter & use defaults if field left empty S4 s#EDs  
    If dlg.TextBox1 = "" Then 18> v\Hi<  
        A = 0           'Default accommodation lO HW9Z  
    Else lDZ~  
        A = CDbl(dlg.TextBox1) (dHjf;  
    End If '>t'U?7w<  
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    If dlg.TextBox2 = "" Then RJdijj  
        pupilDiam = 4   'Default pupil diameter ~\ v"xV  
    Else x}#N?d  
        pupilDiam = CDbl(dlg.TextBox2) ?B<.d8i  
    End If 4TSkm`iR  
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    Print " " 1e I_F8I U  
    Print "Accommodation = " & A & " Diopters" @ 6H7  
    Print "Pupil Diameter = " & pupilDiam & " mm" LXf|n  
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    ' Calculate new parameters with accommodation %Hu.FS5'  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 7nZ3u _~  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 6+:;M b_S  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ]N:Wt2  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens 8( bK\-b  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens KIY9?B=+  
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    tlens = 3.767 + 0.04*A                  'Lens thickness /`j2%8^N  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ^,` L!3  
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    'Adjust parameters to account for accommodation fP llN8n  
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    '************************************************************************* Pav  
    'Aqueous thickness (Position of Lens) ulfs Z:  
    '************************************************************************* chM-YuN|  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) rVp^s/A^;  
    GetCustomElement eID, entity .p(r|5(b  
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    parID = FindFullName( "Geometry.Arizona Eye" ) nI8zT0o  
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    ' Delete any shift(s) in z \p!m/2  
    count = 0 yGH')TsjD  
    While GetOperationCount(eID)>count Is9.A_0h  
        GetOperation eID, count, op 8#HQ05q>  
        If op.Type="ShiftZ" Then !(y(6u#  
            DeleteOperation eID,count ovaX_d)cU  
            count=count-1 ,Bj]j -\Y  
        End If uxL3 8d]  
        count=count+1 /'^ BH A|h  
    Wend (Z8wMy&:  
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    'Set new shift in ::@JL  
    op.Type = "ShiftZ" #z}0]GJKj  
    op.val1 = taq ScRK1  
    op.parent = parID !04 ^E  
    AddOperation eID, op &"Fz)}  
    Print "Set aqueous humor thickness = " & taq-0.55 61*b|.sl'#  
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    '************************************************************************* m; PTO$--  
    'Radius and conic constant of anterior lens IG~Zxn1o  
    '************************************************************************* >E WK cocM  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ${`q!  
    GetConic eID, entity, curv, conic o%K1!'  
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    SetConic eID, entity, 1/Rant, CCant (A-Uo   
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant  1 K]  
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    '************************************************************************* \!k\%j 9  
    'Radius and conic constant of posterior lens l I2UpfkBP  
    '************************************************************************* lE3&8~2   
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) {fMo#`9=  
    GetConic eID, entity, curv, conic |WW'qg]Uu  
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    SetConic eID, entity, 1/Rpost, CCpost =q[ynZ8O\w  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost T;i+az{N:V  
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    '************************************************************************* y tTppmJF  
    'Lens thickness (Position of posterior lens surface) },#AlShZu  
    '************************************************************************* >uE<-klv  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) B&}lYo  
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    ' Delete any z-shift(s)  5e2yJ R  
    count = 0 h9 rrkV9  
    While GetOperationCount(eID)>count B'6(Ao=3/  
        GetOperation eID, count, op !0cb f&^:  
        If op.Type="ShiftZ" Then ~-~iCIaTb  
            DeleteOperation eID,count (>dL  
            count=count-1 $C8s  
        End If %@%~<U)W  
        count=count+1 ca%XA|_J  
    Wend ^;@!\Rc  
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    'Set new z-shift d/E0opv  
    op.Type = "ShiftZ" xP 3>8Y  
    op.val1 = tlens VGOdJ|2]Wr  
    op.parent = parID $-gRD|oY  
    AddOperation eID, op &pAmFe  
    Print "Set lens thickness = " & tlens 'JAe =K H  
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    '************************************************************************* >9[wjB2?}  
    'Lens index of refraction ^{-Z3Yxd  
    '************************************************************************* YwJ<0;:+hS  
    eID = FindMaterial( "Lens" ) 5=;'LWXCJ  
    GetModelMaterial eID, mat 5 gwEr170  
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    mat.Nd = nlens Sbj{)  
    SetModelMaterial eID, mat D \boF+^  
    Print "Set lens index of refraction = " & nlens 3.%jet1  
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    '************************************************************************* u)l[*";S  
    'Pupil diameter `>`{DEDx{5  
    '************************************************************************* g]._J  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 7Y^2JlZu=  
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    'Adjust pupil diameter (trimming volume inner hole) $oZV 54  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" x%RE3J-  
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    ' Adjust pupil location to just in front of the lens ;zi4W1  
    parID = FindFullName( "Geometry.Arizona Eye" ) fJn4'Q*U  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) z!^3%kJJ>  
    count = 0 SuA`F|7?P  
    While GetOperationCount(eID)>count `e5f69"  
        GetOperation eID, count, op ?gS~9jgcd  
        If op.Type="ShiftZ" Then OWmI$_L  
            DeleteOperation eID,count =7zvp,B  
            count=count-1 , ins/-3  
        End If s?&UFyYb,  
        count=count+1 )eBCO~HS  
    Wend BR0P :h  
    op.Type = "ShiftZ" >orDw3xC  
    op.val1 = taq-0.01 ~Yl%{1  
    op.parent = parID &P>a  
    AddOperation eID, op _({K6adb  
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    Print "Set pupil diameter = " & pupilDiam Mj:=$}rs^  
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    'Update AZ Eye subassembly Description A<cnIUW  
    eID = FindFullName( "Geometry.Arizona Eye" ) o&rNM5:  
    GetEntity eID, entity `wLMJ,@f.  
    entity.Description = "Accommodation = " & A & "D" 5~xv"S(E}  
    SetEntity eID, entity +p &$`(  
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    Update }I#,o!)Vd  
    Print "DONE!" vce1'aW  
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End Sub qF4pTQf  
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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： |FZIUS{]  
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Accommodation = 4 Diopters q=uJ^N  
Pupil Diameter = 4 mm ,F0bkNBG  
Set aqueous humor thickness = 2.81  c|~f[  
Set anterior lens radius = 10.4 and conic constant = -2.375869 {b26DKkQS  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 8,&QY%8pX  
Set lens thickness = 3.927 O:te;lQ K  
Set lens index of refraction = 1.42672 I i J%.U  
Set pupil diameter = 4 ;O * o  
DONE! 2ee((vO&  
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（文章来源：讯技光电）
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