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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 9M@,BXOt  
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。 ,j eC7-tX  
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模型 &cy<"y  
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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。 &,$N|$yK}|  
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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. eqqnR.0  
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光源 yER  
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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。 ]qiX"<s>~C  
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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。 9yj'->dL  
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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。 dAi.^! !  
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[attachment=67933]
图2. 字母F光源的设定方法光 {N@Pk[!  
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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 &@'+h* b  
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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。 S]Aaf-X_  
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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。 CaV)F3   
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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 ;&MnPFmq  
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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： d"thM  
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[attachment=67937]
图6. 用户对话框的创建与编辑
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[attachment=67938]
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。 :)%cL8Nz]$  
余下的脚本计算与屈光度有关的所有参数。 kR{$&cE^  
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分析 #It!D5A  
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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。 Ti>}To}B5  
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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 nI8zT0o  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. \p!m/2  
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Dim entity As T_ENTITY D[{"]=-  
Dim op As T_OPERATION $_gv(&ZT  
Dim mat As T_MODELMATERIAL =`l><  
Dim A As Double NWj4U3x  
Dim pupilDiam As Double SBY0L.  
Dim eID As Long y(=0  
Dim parID As Long ;Hb"SB  
Dim count As Integer zbfe=J4c  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double \\35} 9  
Dim tlens As Double, nlens As Double & d* bQv$  
Dim curv As Double, conic As Double S(0JBGC  
Dim ok As Long *p|->p6,u  
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Sub Main Hio+k^  
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    '用户输入对话框 #;UoZJ B  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 FA;B :O@:'  
        TextBox 220,21,40,21,.TextBox1 'default: 0 C#RueDa.  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 4v2JrC;  
        OKButton 40,91,90,21 'Y]<1M>.g  
        CancelButton 190,91,90,21 v+CW([zAx#  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 rw75(Lp{  
        TextBox 220,49,40,21,.TextBox2 'default: 4 ){w!< Lb  
    End Dialog _:JV-lM  
    Dim dlg As UserDialog ~eUv.I/  
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    ok = Dialog (dlg) 0UQ DB5u  
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    If ok=0 Then    'cancel button was pressed ?28)l 4 Ml  
        Print "Execution cancelled." FPEab69  
        End sR| /s3;  
    End If :)Da^V  
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    'Assign accommodation and pupil diameter & use defaults if field left empty E&Sr+D aPD  
    If dlg.TextBox1 = "" Then B0^:nYko  
        A = 0           'Default accommodation m3|l-[!OA"  
    Else HN<e)E38  
        A = CDbl(dlg.TextBox1) Kc+9n%sp  
    End If 8an_s%,AW  
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    If dlg.TextBox2 = "" Then D c]J3r  
        pupilDiam = 4   'Default pupil diameter 8'u,}b)  
    Else GD!!xt  
        pupilDiam = CDbl(dlg.TextBox2) d!"gb,ec  
    End If lT'V=,Y t  
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    Print " "  0 - u,AD  
    Print "Accommodation = " & A & " Diopters" D?"Q)kVuD  
    Print "Pupil Diameter = " & pupilDiam & " mm" w# ;t$qz}  
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    ' Calculate new parameters with accommodation lNv xt6@s  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness |2I p*  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens <O{G&  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens cN)noGkp  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ]K<7A!+@@p  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens tz2$j@!=  
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    tlens = 3.767 + 0.04*A                  'Lens thickness mQ\oR|  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction "p&4Sn3T2?  
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    'Adjust parameters to account for accommodation Y7`Dx'x  
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    '************************************************************************* [LSs|f  
    'Aqueous thickness (Position of Lens) ; $UB@)7%  
    '************************************************************************* {tnhP^C3>  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) Ky{C;7X  
    GetCustomElement eID, entity ] .c$(.  
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    parID = FindFullName( "Geometry.Arizona Eye" ) R#/0}+-M  
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    ' Delete any shift(s) in z 83Fmu/(  
    count = 0 7Y^2JlZu=  
    While GetOperationCount(eID)>count I5g!c|#y  
        GetOperation eID, count, op pwV{@h!  
        If op.Type="ShiftZ" Then i.+#a2   
            DeleteOperation eID,count x%RE3J-  
            count=count-1 Ft8ii|-  
        End If ;zi4W1  
        count=count+1 fJn4'Q*U  
    Wend i\\,Z L  
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    'Set new shift in I@q4D1g  
    op.Type = "ShiftZ" @oFuX.  
    op.val1 = taq OWmI$_L  
    op.parent = parID !r+SE  
    AddOperation eID, op <:~'s]`zf  
    Print "Set aqueous humor thickness = " & taq-0.55 _\AT_Zmy  
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    '************************************************************************* Il!#]  
    'Radius and conic constant of anterior lens 5Veybchy "  
    '************************************************************************* e'dZ2;X$zo  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) <Kq!)) J'  
    GetConic eID, entity, curv, conic  !:|D[1m  
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    SetConic eID, entity, 1/Rant, CCant y?V#LW[^E  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant m# I  
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    '************************************************************************* o&rNM5:  
    'Radius and conic constant of posterior lens `wLMJ,@f.  
    '************************************************************************* 5~xv"S(E}  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) +p &$`(  
    GetConic eID, entity, curv, conic t%30B^Ii%K  
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    SetConic eID, entity, 1/Rpost, CCpost vce1'aW  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost y3mJO[U0 a  
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    '************************************************************************* 3?yq*uE}  
    'Lens thickness (Position of posterior lens surface) = p$:vW  
    '************************************************************************* gz`P~7-w:  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) qISzn04  
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    ' Delete any z-shift(s) 8Sg :HU\  
    count = 0 N`!=z++G  
    While GetOperationCount(eID)>count #W=H)6  
        GetOperation eID, count, op Xq.G vZS`  
        If op.Type="ShiftZ" Then c"CF&vTp  
            DeleteOperation eID,count 4(}V$#^+  
            count=count-1 ;NrU|g/ksX  
        End If e{`DvfY21  
        count=count+1 W8s/"  
    Wend 7Dwf0Re`  
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    'Set new z-shift Ed&M  
    op.Type = "ShiftZ" ^[-3qi  
    op.val1 = tlens Z<6Fq*I  
    op.parent = parID #kL4Rm;  
    AddOperation eID, op i sV9nWo$  
    Print "Set lens thickness = " & tlens aT%6d@g  
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    '************************************************************************* $61*X f+*  
    'Lens index of refraction s4Y7x.-  
    '************************************************************************* 99..]  
    eID = FindMaterial( "Lens" ) >EIV`|b$h  
    GetModelMaterial eID, mat mRC6m K>  
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    mat.Nd = nlens pbb6?R,  
    SetModelMaterial eID, mat A;#GU`  
    Print "Set lens index of refraction = " & nlens 5K %  
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    '************************************************************************* #u6ZCv7u  
    'Pupil diameter .#$D\cwV  
    '************************************************************************* 9<S};I;  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ]NgEN  
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    'Adjust pupil diameter (trimming volume inner hole) 7Yd]#K{$  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" (xhV>hsA  
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    ' Adjust pupil location to just in front of the lens l:rT{l=8*  
    parID = FindFullName( "Geometry.Arizona Eye" ) 9a0ibN6m  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ^N_?&pgy  
    count = 0 !]z6?kUK  
    While GetOperationCount(eID)>count $mp'/]  
        GetOperation eID, count, op t|y`Bl2  
        If op.Type="ShiftZ" Then 8]-c4zK  
            DeleteOperation eID,count p6e9mSs  
            count=count-1 gXI8$W>  
        End If BSib/)p   
        count=count+1 bp?4)C*R  
    Wend -{'WIGm  
    op.Type = "ShiftZ" j9Y'HU5"  
    op.val1 = taq-0.01 W6[# q%o  
    op.parent = parID b#[7A  
    AddOperation eID, op 4Sxt<7[f  
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    Print "Set pupil diameter = " & pupilDiam 51lN,VVD  
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    'Update AZ Eye subassembly Description %1oG<s  
    eID = FindFullName( "Geometry.Arizona Eye" ) e+=P)Zp/  
    GetEntity eID, entity SYsbe 5j  
    entity.Description = "Accommodation = " & A & "D"  E\! <=  
    SetEntity eID, entity P<WCW3!JZ  
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    Update Y"&1jud4xl  
    Print "DONE!" Z#P:C":e  
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End Sub 4]$$ar)  
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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： bAa+MB#A  
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Accommodation = 4 Diopters "dO>P*k,  
Pupil Diameter = 4 mm :>'4@{'   
Set aqueous humor thickness = 2.81  ,m-/R  
Set anterior lens radius = 10.4 and conic constant = -2.375869 $rG~0  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 {KO +t7'Q  
Set lens thickness = 3.927 ') -Rv]xe  
Set lens index of refraction = 1.42672 <CnTiS#  
Set pupil diameter = 4 &7CAxU;i3  
DONE! (;o/2Q?  
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（文章来源：讯技光电）
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