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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 QH7 GEj]  
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。 47{5{/B-  
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模型 {gu3KV  
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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。 hRB?NM  
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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 bT{K|d-  
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光源 Gi@c`lRd1  
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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。 }{,Wha5\n  
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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。 3PLA*n+%  
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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。 PX23M|$!  
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图2. 字母F光源的设定方法光 Lq.2vfA>  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 @6R6.i5d  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 hz<TjWXv'  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 h|Qb:zEP,  
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图5. 视网膜重点采样规格设定
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脚本 >X iT[Ru  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： jRDvVV/-wr  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 Q]K$yo  
余下的脚本计算与屈光度有关的所有参数。 *6=9 8C4I  
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分析 :.a184ax  
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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。 SGy2&{\Z  
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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 SG0PQ  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. v7#|%  
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Dim entity As T_ENTITY cuy9QBB :  
Dim op As T_OPERATION tW-[.Y -M,  
Dim mat As T_MODELMATERIAL Tj<B;f!u  
Dim A As Double "VoufXM:  
Dim pupilDiam As Double *0V'rH)  
Dim eID As Long yFd94 2  
Dim parID As Long &U}8@;  
Dim count As Integer iG~&uEAJ  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double #QSSpsF@  
Dim tlens As Double, nlens As Double bt.3#aj  
Dim curv As Double, conic As Double Hmx.BBz  
Dim ok As Long kG}F/GN?  
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Sub Main OpIeo+^X*  
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    '用户输入对话框 VTyj<6Y  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 E GZiWBr  
        TextBox 220,21,40,21,.TextBox1 'default: 0 i`vy<Dvpz  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 w5/6+@}  
        OKButton 40,91,90,21 >@4AxV\  
        CancelButton 190,91,90,21 }?+tX<j  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 L?&&4%%  
        TextBox 220,49,40,21,.TextBox2 'default: 4 S}]B|Q  
    End Dialog ?q2Yk/P  
    Dim dlg As UserDialog +$2`"%nBG  
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    ok = Dialog (dlg) mDD96y  
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    If ok=0 Then    'cancel button was pressed ryA+Lli.  
        Print "Execution cancelled." %,ScGQE  
        End +bJ~S:[  
    End If _RZ"WA^[  
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    'Assign accommodation and pupil diameter & use defaults if field left empty %Lh+W<;  
    If dlg.TextBox1 = "" Then :7dc;WdM  
        A = 0           'Default accommodation ,]]IJ;:w  
    Else QF*cdc<  
        A = CDbl(dlg.TextBox1) )"6"g9A  
    End If Wyeb1  
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    If dlg.TextBox2 = "" Then 5tZ0zr  
        pupilDiam = 4   'Default pupil diameter ssoE,6kS  
    Else y"U)&1 c%  
        pupilDiam = CDbl(dlg.TextBox2) ZBN,%P!P0  
    End If sdyNJh7Jr  
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    Print " " `s Pk:cNz~  
    Print "Accommodation = " & A & " Diopters" 87eH~&<1  
    Print "Pupil Diameter = " & pupilDiam & " mm" k"/Rjd(;  
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    ' Calculate new parameters with accommodation K~S*<?  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Sl<1Rme=w  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens h.l.da1#  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens w1VYU>  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens b0@K ~O;g  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens uZ>q$ F  
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    tlens = 3.767 + 0.04*A                  'Lens thickness Km,o+9?1gF  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction `Lavjmfr2V  
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    'Adjust parameters to account for accommodation 8pftc)k  
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    '************************************************************************* n4}e!  
    'Aqueous thickness (Position of Lens) a) P r&9I  
    '************************************************************************* "zCT S  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) P4eH:0=#  
    GetCustomElement eID, entity W|uRQA`  
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    parID = FindFullName( "Geometry.Arizona Eye" ) c14d0x{  
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    ' Delete any shift(s) in z |_-w{2K  
    count = 0 F[!%,-*  
    While GetOperationCount(eID)>count tns8B  
        GetOperation eID, count, op k_zn>aR$F  
        If op.Type="ShiftZ" Then `YE= B{q  
            DeleteOperation eID,count ;FF+uK  
            count=count-1 $ Y^0l  
        End If [C<K~  
        count=count+1 ,R3TFVV!?  
    Wend 3 v.8  
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    'Set new shift in M+HhTW;I=  
    op.Type = "ShiftZ" ,9_O4O%  
    op.val1 = taq kS9;Tjcx  
    op.parent = parID 3/yt  
    AddOperation eID, op b09xf"D  
    Print "Set aqueous humor thickness = " & taq-0.55 4# ]g852  
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    '************************************************************************* llWY7u"  
    'Radius and conic constant of anterior lens g7*Uuh#  
    '************************************************************************* -38"S;M8  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ;Oqf{em];  
    GetConic eID, entity, curv, conic 'd&d"E[  
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    SetConic eID, entity, 1/Rant, CCant .s!0S-RkC  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant V@b7$z  
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    '************************************************************************* Ldv,(ZV,<  
    'Radius and conic constant of posterior lens =s]2?m  
    '************************************************************************* ^H1m8=  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) Nq8 3 6HL  
    GetConic eID, entity, curv, conic XBkaum4j  
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    SetConic eID, entity, 1/Rpost, CCpost kD%MFT4  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost eB1NM<V  
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    '************************************************************************* |uw48*t  
    'Lens thickness (Position of posterior lens surface) F --b,,  
    '************************************************************************* 5p S$rf  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) @fp@1n  
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    ' Delete any z-shift(s) oq!\100  
    count = 0 ]BjY UTNm  
    While GetOperationCount(eID)>count b$fmU"%&|  
        GetOperation eID, count, op YlGUd~$`"+  
        If op.Type="ShiftZ" Then L8f+uI   
            DeleteOperation eID,count 0Ui_Trlc  
            count=count-1 Us'JMZ~  
        End If <PuY"-`/Oc  
        count=count+1 &y=OZ !M  
    Wend etiUt~W  
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    'Set new z-shift lnyq%T[^  
    op.Type = "ShiftZ" d v[.u{#tP  
    op.val1 = tlens *GBV[D[G,  
    op.parent = parID O TlqJ  
    AddOperation eID, op :f39)g5>  
    Print "Set lens thickness = " & tlens ~/-SKGzo-  
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    '************************************************************************* SM RKEPwp&  
    'Lens index of refraction LTo!DUi`  
    '************************************************************************* eaDZ^Z Er  
    eID = FindMaterial( "Lens" ) % H"  
    GetModelMaterial eID, mat YtSYe%  
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    mat.Nd = nlens wzwv>@}  
    SetModelMaterial eID, mat Q5Nbu90  
    Print "Set lens index of refraction = " & nlens <ml?DXT  
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    '************************************************************************* V61oK  
    'Pupil diameter ;7?oJH;  
    '************************************************************************* Is3Y>oX  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 6wwbH}*=?  
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    'Adjust pupil diameter (trimming volume inner hole) *K$a;2WjzG  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" x,10o   
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    ' Adjust pupil location to just in front of the lens yGt [Qvx#  
    parID = FindFullName( "Geometry.Arizona Eye" ) +[uh);vD`G  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) zc;kNkV#1Y  
    count = 0 *v K~t|z  
    While GetOperationCount(eID)>count lV^:2I/  
        GetOperation eID, count, op 8\' tfHL  
        If op.Type="ShiftZ" Then vvxD}p=y  
            DeleteOperation eID,count *kK +Nvt8s  
            count=count-1 w/( T  
        End If L3wj vq^  
        count=count+1 8gE p5  
    Wend R0*P,~L;|  
    op.Type = "ShiftZ" C za }cF  
    op.val1 = taq-0.01 XBCHJj]k  
    op.parent = parID e\[q3J  
    AddOperation eID, op [j@i^B &  
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    Print "Set pupil diameter = " & pupilDiam tyW[i8)O}  
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    'Update AZ Eye subassembly Description 'h6G"=+  
    eID = FindFullName( "Geometry.Arizona Eye" ) UF5_be,D  
    GetEntity eID, entity TK' 5NM+4  
    entity.Description = "Accommodation = " & A & "D" sgK =eBE  
    SetEntity eID, entity FO_}9<s  
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    Update c)^A|{,G  
    Print "DONE!" 0Q7<;'m  
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End Sub 8w[O%  
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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： L{>rN`{  
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Accommodation = 4 Diopters PZV>A!7C8n  
Pupil Diameter = 4 mm j1{`}\e  
Set aqueous humor thickness = 2.81 ti9e(Jt!O  
Set anterior lens radius = 10.4 and conic constant = -2.375869 'G % ]/'_U  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 iN'T^+um=  
Set lens thickness = 3.927 C/N;4  
Set lens index of refraction = 1.42672 5TuwXz1v  
Set pupil diameter = 4 MYara;k  
DONE! y,&[OrCm^\  
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（文章来源：讯技光电）
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