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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 w>`h3;,2  
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。 lpM>}0v   
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模型 0U>t>&,"  
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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。 yFPaWW  
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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. 3/A!_Uc(  
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光源 mkj;PYa  
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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。 (<d&BV-"  
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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。 3<e(@W}n-M  
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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。 d'Ik@D]I  
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图2. 字母F光源的设定方法光 'XZI{q2i  
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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 bo~{<UT  
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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。 k *G!.  
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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。 %ojR?=ON  
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图5. 视网膜重点采样规格设定
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脚本 M<#)D  
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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：  xnRp/I  
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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。 YP$*;l  
余下的脚本计算与屈光度有关的所有参数。 ; $ ?jR c  
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分析 Q~b M  
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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"Z[s[  
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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 +GYI2  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. ~J. Fl[  
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Dim entity As T_ENTITY cyHak u+  
Dim op As T_OPERATION aaqd:N)  
Dim mat As T_MODELMATERIAL qm'C^ X?  
Dim A As Double 3w<j:\i  
Dim pupilDiam As Double  Z$#ZYD  
Dim eID As Long ^pQo`T6  
Dim parID As Long \@}$Wjsl  
Dim count As Integer z:i X]df  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Io4:$w  
Dim tlens As Double, nlens As Double rs 1*H  
Dim curv As Double, conic As Double PgG |7='  
Dim ok As Long T956L'.+G  
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Sub Main +U_-Lq )  
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    '用户输入对话框 z?t(+^  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 = @Nv:1:r  
        TextBox 220,21,40,21,.TextBox1 'default: 0 &TkbnDuYd~  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Lx:N!RDw  
        OKButton 40,91,90,21 q5\LdI2  
        CancelButton 190,91,90,21 4QKE{0NE  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 >NOYa3  
        TextBox 220,49,40,21,.TextBox2 'default: 4 CN$A-sjZ  
    End Dialog 'MdE}  
    Dim dlg As UserDialog }DUDA%U  
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    ok = Dialog (dlg) 't]EkH]BC  
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    If ok=0 Then    'cancel button was pressed oCdOC5  
        Print "Execution cancelled." M(h H#_ $  
        End =<'iLQb1  
    End If a] wcA  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ~oW8GQ  
    If dlg.TextBox1 = "" Then ^< /vbF  
        A = 0           'Default accommodation ^qus `6  
    Else h%w\O Z7  
        A = CDbl(dlg.TextBox1) ma-Y'  
    End If ,^IZ[D>u)  
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    If dlg.TextBox2 = "" Then /L|}Y242  
        pupilDiam = 4   'Default pupil diameter dYqDL<se/I  
    Else x&fCe{5  
        pupilDiam = CDbl(dlg.TextBox2) SQKY;p  
    End If U)/Ul>dY  
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    Print " " ;=9v mQA  
    Print "Accommodation = " & A & " Diopters" gAUQQ  
    Print "Pupil Diameter = " & pupilDiam & " mm" <K[Zl/7I  
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    ' Calculate new parameters with accommodation (Nlm4*{h  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 8Y0<lfG  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ty< tv|p  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens m',_k Y3  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens hYZ:" x  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens =+-.5M  
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    tlens = 3.767 + 0.04*A                  'Lens thickness iCSM1W3  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction v|RaB  
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    'Adjust parameters to account for accommodation )B&<Bk+  
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    '************************************************************************* z57papo  
    'Aqueous thickness (Position of Lens) ^$,kTU'=  
    '************************************************************************* i|,A1c"*  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8'xnhV  
    GetCustomElement eID, entity 4qz{ D"M  
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    parID = FindFullName( "Geometry.Arizona Eye" ) x-#9i  
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    ' Delete any shift(s) in z 5'-9?-S"  
    count = 0 ;F(01  
    While GetOperationCount(eID)>count x15tQb+  
        GetOperation eID, count, op Lpbn@y26<  
        If op.Type="ShiftZ" Then #:zPpMAl  
            DeleteOperation eID,count Ng39D#_)  
            count=count-1 [k=9 +0p  
        End If eC`f8=V  
        count=count+1 t RyGxqiG  
    Wend zPkPC}f(O  
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    'Set new shift in EF=D}"E6pO  
    op.Type = "ShiftZ" d lLk4a+  
    op.val1 = taq > ,Bu^] C  
    op.parent = parID 7%!KAtc  
    AddOperation eID, op Kcdd=2 [T  
    Print "Set aqueous humor thickness = " & taq-0.55 d1La7|43u  
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    '************************************************************************* wEc5{ b5M  
    'Radius and conic constant of anterior lens <0 idG  
    '************************************************************************* GWZXRUc  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ']Xx#U N  
    GetConic eID, entity, curv, conic MNmQ%R4jRN  
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    SetConic eID, entity, 1/Rant, CCant ,:4w$!;  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant E d/O\v@  
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    '************************************************************************* c]R![sa  
    'Radius and conic constant of posterior lens uPv?Hq  
    '************************************************************************* ^JDV4>S\  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) |+~2sbM  
    GetConic eID, entity, curv, conic 5o ^=~  
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    SetConic eID, entity, 1/Rpost, CCpost G ]By_  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost {$:13AnK   
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    '************************************************************************* =F[,-B~  
    'Lens thickness (Position of posterior lens surface) m8^2k2  
    '************************************************************************* %9Fg1LH42r  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) /iuNdh  
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    ' Delete any z-shift(s) @}!$NI8  
    count = 0 8HA=O ?Cg  
    While GetOperationCount(eID)>count h*Tiv^a  
        GetOperation eID, count, op cGp 6yf  
        If op.Type="ShiftZ" Then B8Zd#.6]  
            DeleteOperation eID,count BVp.A]  
            count=count-1 ;<<IXXKU  
        End If Li^!OHro.  
        count=count+1 K+OU~SED%F  
    Wend CWYJ<27v{  
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    'Set new z-shift !|c5@0Wr  
    op.Type = "ShiftZ" 8E%*o  
    op.val1 = tlens :/l   
    op.parent = parID io3'h:+9s  
    AddOperation eID, op +0 |0X {v  
    Print "Set lens thickness = " & tlens tb\pjLB][  
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    '************************************************************************* UQPE)G  
    'Lens index of refraction 6 74X)hB  
    '************************************************************************* !P3|T\|]+  
    eID = FindMaterial( "Lens" ) ,jcp"-5#j  
    GetModelMaterial eID, mat e'&{KD,-T  
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    mat.Nd = nlens '=* 5C{  
    SetModelMaterial eID, mat x&Rp m<4  
    Print "Set lens index of refraction = " & nlens  B4ze$#  
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    '************************************************************************* * ?fBmq[j  
    'Pupil diameter f BOG#-a}  
    '************************************************************************* yqI|BF`  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ^dD?riFAk  
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    'Adjust pupil diameter (trimming volume inner hole) >WX'oP(<  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Z Uv_u6aD  
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    ' Adjust pupil location to just in front of the lens Su#1yw>  
    parID = FindFullName( "Geometry.Arizona Eye" ) ek!N eu>  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) {!h[@f4  
    count = 0 heA\6W:u&  
    While GetOperationCount(eID)>count 6si-IJ  
        GetOperation eID, count, op g\'84:*J\  
        If op.Type="ShiftZ" Then 92Iv'(1ba  
            DeleteOperation eID,count (5&"Y?#o,  
            count=count-1 e?WR={  
        End If W:J00rsv=`  
        count=count+1 Z9I./s9  
    Wend Lp=B? H  
    op.Type = "ShiftZ" bxq`E!]  
    op.val1 = taq-0.01 xW~@V)OH  
    op.parent = parID .Oh$sma1  
    AddOperation eID, op ;7>--_?=  
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    Print "Set pupil diameter = " & pupilDiam N0C5FSH  
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    'Update AZ Eye subassembly Description jN0v<_PJED  
    eID = FindFullName( "Geometry.Arizona Eye" ) t:7jlD!d  
    GetEntity eID, entity lc7]=,qyF  
    entity.Description = "Accommodation = " & A & "D" [~wcHE  
    SetEntity eID, entity Ip x:k+J  
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    Update eSU8/9B  
    Print "DONE!" >2/zL.O  
     ?M2@[w8_  
End Sub qFk(UazN  
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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： o ++Hdvai  
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Accommodation = 4 Diopters jBbc$|O4SY  
Pupil Diameter = 4 mm _guY%2% yR  
Set aqueous humor thickness = 2.81 3Y8 V?* 1|  
Set anterior lens radius = 10.4 and conic constant = -2.375869 #Uu"olX7  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 ZlzFmNe60  
Set lens thickness = 3.927 ]\U'_G2]  
Set lens index of refraction = 1.42672 }f}&|Vap  
Set pupil diameter = 4 T9A5L"-6T  
DONE! kn.z8%^(  
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（文章来源：讯技光电）
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