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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 &{UqGD#1&  
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。 @&Bh!_TWc  
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模型 +@~WKa  
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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。 n,2   
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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. zRou~Kxi  
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光源 wjD<"p;P  
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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。 IWq#W(yM  
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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。 L!lmy&1  
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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。 \~"Ub"~I  
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[attachment=67933]
图2. 字母F光源的设定方法光 M/dgW` c  
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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 hlB\Xt  
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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。 q\]X1N  
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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。 w2'q9pB+  
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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 mXOI"B9Sq  
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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： [I3Nu8  
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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。  ;Pt8\X  
余下的脚本计算与屈光度有关的所有参数。 C| ~ A]wc=  
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分析 >&KH!:OX|  
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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。  3Iv^  
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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 "TZY)\{L  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. g"1V ]  
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Dim entity As T_ENTITY peO@ZKmM  
Dim op As T_OPERATION A}(]J!rc  
Dim mat As T_MODELMATERIAL $|-Lw!)D  
Dim A As Double *k62Qz3  
Dim pupilDiam As Double dX cbS<  
Dim eID As Long B[GC@]HE  
Dim parID As Long P'lnS&yA  
Dim count As Integer Wvf>5g)?  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double `}l%61n0  
Dim tlens As Double, nlens As Double $G9LaD#;M  
Dim curv As Double, conic As Double !q\=e@j-i  
Dim ok As Long W3tin3__  
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Sub Main 6I +0@,I  
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    '用户输入对话框 ly17FLJ].  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 .Rk8qRB  
        TextBox 220,21,40,21,.TextBox1 'default: 0 I]v2-rB&-  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 z/ 1$G"  
        OKButton 40,91,90,21 uI7n{4W*x  
        CancelButton 190,91,90,21 >,{s Fc  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 0w3c8s.  
        TextBox 220,49,40,21,.TextBox2 'default: 4 >0{}tRm-P&  
    End Dialog EVX3uC}{  
    Dim dlg As UserDialog W/!P1M n  
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    ok = Dialog (dlg) GpeW<% \P  
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    If ok=0 Then    'cancel button was pressed xR0T' @q  
        Print "Execution cancelled." = UH3.  
        End kWXLncE  
    End If eUA]OF @  
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    'Assign accommodation and pupil diameter & use defaults if field left empty >>P5 4|&  
    If dlg.TextBox1 = "" Then S\).0goOW  
        A = 0           'Default accommodation U"k$qZ[  
    Else lA5Dag'  
        A = CDbl(dlg.TextBox1) smf"F\W s  
    End If qgrJi +WZ  
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    If dlg.TextBox2 = "" Then O:wG/et  
        pupilDiam = 4   'Default pupil diameter k."p&  
    Else )@N d3Z  
        pupilDiam = CDbl(dlg.TextBox2) .xsfq*3e5  
    End If G tI )O}  
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    Print " " *U[yeE].  
    Print "Accommodation = " & A & " Diopters" @(,1}3s  
    Print "Pupil Diameter = " & pupilDiam & " mm" t5-O-AI[b{  
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    ' Calculate new parameters with accommodation 'I]XX==_  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness p\w<~ pN[  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens jz bq{#  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens I%3[aBz4  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens .G O0xnm  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens dz_S6o ]  
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    tlens = 3.767 + 0.04*A                  'Lens thickness wh8';LZ>R  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction MET9rT  
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    'Adjust parameters to account for accommodation w 9dkJo  
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    '************************************************************************* }UhYwJf89  
    'Aqueous thickness (Position of Lens) M13HD/~O  
    '*************************************************************************  /|0-O''  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) h aAY=:  
    GetCustomElement eID, entity ;g|Vt}a&4  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 928_e)V  
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    ' Delete any shift(s) in z m{/7)2.  
    count = 0 ^jL '*&l  
    While GetOperationCount(eID)>count %fj5 ;}E.  
        GetOperation eID, count, op %2\Hj0JQQ  
        If op.Type="ShiftZ" Then Og\k5.! ,  
            DeleteOperation eID,count r]3-}:vU  
            count=count-1 my?Ly(#  
        End If 6_j |@  
        count=count+1 _'=,c"  
    Wend y{ ur'**l  
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    'Set new shift in #EPC]jFk  
    op.Type = "ShiftZ" p `"k=tZ{  
    op.val1 = taq r_T)| ||v  
    op.parent = parID @-$8)?`q  
    AddOperation eID, op /LD3Bb)O  
    Print "Set aqueous humor thickness = " & taq-0.55 3!CUJs/W  
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    '************************************************************************* s2<!Zb4  
    'Radius and conic constant of anterior lens ]5ZXgz  
    '************************************************************************* '~[8>Q>  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) n7Ao.b%uk-  
    GetConic eID, entity, curv, conic 'cD?0ou`o  
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    SetConic eID, entity, 1/Rant, CCant QNNURf\[(  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant kKX' Y+  
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    '************************************************************************* Tgdy;?  
    'Radius and conic constant of posterior lens ={BD*= i  
    '************************************************************************* @62T:Vl  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) G3.aw  
    GetConic eID, entity, curv, conic x?h/e;  
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    SetConic eID, entity, 1/Rpost, CCpost hG1:E:}  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost *8}b&4O~  
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    '************************************************************************* zx.qN  
    'Lens thickness (Position of posterior lens surface) \[MAa:/  
    '************************************************************************* eADCT  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ?UXF z'  
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    ' Delete any z-shift(s) v] m/$X2  
    count = 0 {;yO3];Hqw  
    While GetOperationCount(eID)>count t>j_C{X1(  
        GetOperation eID, count, op +}:Z9AAMy  
        If op.Type="ShiftZ" Then 3c<aI =$^  
            DeleteOperation eID,count E>~R P^?Uz  
            count=count-1 ) c@gRb~  
        End If )jM%bUk,!  
        count=count+1 #ArrQeO 5_  
    Wend zoq;3a5cqB  
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    'Set new z-shift OH`a3E{e  
    op.Type = "ShiftZ" ;:;E|{e  
    op.val1 = tlens xGd60"w2  
    op.parent = parID "Y&I#&$b\  
    AddOperation eID, op {:X'9NEE  
    Print "Set lens thickness = " & tlens 1Bytu >2  
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    '************************************************************************* _4S^'FDo  
    'Lens index of refraction  o E+'@  
    '************************************************************************* mqSVd^  
    eID = FindMaterial( "Lens" ) xR+vu>f  
    GetModelMaterial eID, mat *$Q>Om]  
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    mat.Nd = nlens 0z8(9DlTc  
    SetModelMaterial eID, mat Eb3ZM#  
    Print "Set lens index of refraction = " & nlens WogUILB  
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    '************************************************************************* oF%m  
    'Pupil diameter o[C^z7WG0  
    '*************************************************************************  !:( +#  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ~D52b1f  
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    'Adjust pupil diameter (trimming volume inner hole) wkg4I.  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 3",gjXmBu  
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    ' Adjust pupil location to just in front of the lens +=tdgw/  
    parID = FindFullName( "Geometry.Arizona Eye" ) {oQs*`=l>  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) s:T%, xS  
    count = 0 UHl3/m7g  
    While GetOperationCount(eID)>count {lI}a8DP  
        GetOperation eID, count, op -#\T  
        If op.Type="ShiftZ" Then 4^7 v@3  
            DeleteOperation eID,count QV|6"4\  
            count=count-1 dX[I :,z*  
        End If V)$!WPL@  
        count=count+1 ETDWG_H |  
    Wend *xnZTj:  
    op.Type = "ShiftZ" ~ 'ZwD/!e  
    op.val1 = taq-0.01 =s\$i0A2  
    op.parent = parID ZFZ'&"+  
    AddOperation eID, op >S5J^c  
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    Print "Set pupil diameter = " & pupilDiam d4y#n=HnnV  
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    'Update AZ Eye subassembly Description 9*"  
    eID = FindFullName( "Geometry.Arizona Eye" ) !6/UwPs  
    GetEntity eID, entity /@Lk H$  
    entity.Description = "Accommodation = " & A & "D" ,np=m17  
    SetEntity eID, entity ;&d#)&O"e  
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    Update cy%M$O|hX5  
    Print "DONE!" {gD ED  
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End Sub f;E#CjlTL  
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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： e@3SF  
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Accommodation = 4 Diopters [RF,0>^b  
Pupil Diameter = 4 mm dL42)HP5  
Set aqueous humor thickness = 2.81 ,TBOEu."4  
Set anterior lens radius = 10.4 and conic constant = -2.375869 1]xmOx[mb  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 eMGJx"a  
Set lens thickness = 3.927 Ca-"3aQkc  
Set lens index of refraction = 1.42672 GcO2oq  
Set pupil diameter = 4 Bii'^^I;?  
DONE! [-(^>Y  
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（文章来源：讯技光电）
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