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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 %H,s~IU  
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。 4z9lk^#"X  
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模型 =Vazxt@[  
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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。 c"pOi&  
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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. 4RYH^9;>K  
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光源 n;Q8Gg2U  
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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。 T#*H  
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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。 eF9GhwE=  
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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。 0\X<vrW  
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图2. 字母F光源的设定方法光 /F(n%8)Yq  
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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 7v)p\#-  
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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。 Y?3tf0t/  
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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。 GZNN2 '  
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图5. 视网膜重点采样规格设定
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脚本 V K 7  
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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： WKlyOK=}  
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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。 "wTCO1  
余下的脚本计算与屈光度有关的所有参数。 `Hlf.>b1  
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分析 J ~3m7  
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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。 L\:m)g,F.  
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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 '5De1K.\`  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. F}ATY!  
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Dim entity As T_ENTITY $["HC-n?.k  
Dim op As T_OPERATION \\#D!q*  
Dim mat As T_MODELMATERIAL *qy \%A  
Dim A As Double KGg S"d  
Dim pupilDiam As Double C9sU^ ]#F  
Dim eID As Long _#:7S sJ  
Dim parID As Long 4^l9d  
Dim count As Integer $S|+U}]C  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double a'?;;ZC-  
Dim tlens As Double, nlens As Double t~/:St  
Dim curv As Double, conic As Double !ZH "$m|  
Dim ok As Long 4A6Y \ZXI  
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Sub Main *YvtT (Gt  
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    '用户输入对话框 uH%b rbrU  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 LkS tU)  
        TextBox 220,21,40,21,.TextBox1 'default: 0 v7wyQx+Q  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Sl, DZ!  
        OKButton 40,91,90,21 @Xl(A]w%!  
        CancelButton 190,91,90,21 K6p\ >J  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 nLz;L r!  
        TextBox 220,49,40,21,.TextBox2 'default: 4 [,AFtg[  
    End Dialog \EVT*v=}/  
    Dim dlg As UserDialog /-[vC$B"  
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    ok = Dialog (dlg) SefhOh^,V  
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    If ok=0 Then    'cancel button was pressed E4892B:`  
        Print "Execution cancelled." } u;{38~  
        End 3Z9Yzv)A  
    End If C?gqX0[ q  
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    'Assign accommodation and pupil diameter & use defaults if field left empty M1-tRF  
    If dlg.TextBox1 = "" Then DPxx9lN_rx  
        A = 0           'Default accommodation ~ O#\$u  
    Else e72Fz#<q  
        A = CDbl(dlg.TextBox1) >ceC8"}J5M  
    End If zl :by?  
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    If dlg.TextBox2 = "" Then @u9L+*F  
        pupilDiam = 4   'Default pupil diameter ) Y)_T&O  
    Else 6)uBUM;i  
        pupilDiam = CDbl(dlg.TextBox2) L?N&kzA  
    End If `D[O\ VE  
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    Print " " B.5+!z&7  
    Print "Accommodation = " & A & " Diopters" N)g_LL>^  
    Print "Pupil Diameter = " & pupilDiam & " mm" B1 }-   
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    ' Calculate new parameters with accommodation uE')<fVX(  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness NgyEy n \  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens Q/]~`S  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens  (yP1}?  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens u>lt}0  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Eu(Qe ST\  
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    tlens = 3.767 + 0.04*A                  'Lens thickness )mm0PJF~q  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction q1:dcxR[  
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    'Adjust parameters to account for accommodation M@{?#MkS%  
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    '************************************************************************* =|E "  
    'Aqueous thickness (Position of Lens) 5eff3qrH{  
    '************************************************************************* ZEI)U, I.  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) cgrSd99.  
    GetCustomElement eID, entity .S 54:vs  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 0 (-4"u>?  
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    ' Delete any shift(s) in z xS1n,gTA  
    count = 0 &B(z**+9  
    While GetOperationCount(eID)>count NRtH?&7  
        GetOperation eID, count, op `YqtI/-w  
        If op.Type="ShiftZ" Then $f3IO#N  
            DeleteOperation eID,count 3XQa%|N(  
            count=count-1 V>QyiB  
        End If ?P0b/g  
        count=count+1 e1W9"&4>G{  
    Wend 3!p`5hJd  
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    'Set new shift in B.G6vx4yp  
    op.Type = "ShiftZ" -yqgs>R(d  
    op.val1 = taq aNu.4c/5  
    op.parent = parID gEk;Tj  
    AddOperation eID, op Bz }nP9  
    Print "Set aqueous humor thickness = " & taq-0.55 7!AyLw  
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    '************************************************************************* phu,&DS!  
    'Radius and conic constant of anterior lens O`y3H lc  
    '************************************************************************* j_g(6uZhz3  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) k)I4m.0a5  
    GetConic eID, entity, curv, conic e}?Q&Lci  
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    SetConic eID, entity, 1/Rant, CCant b+qd' ,.Z  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant y5eEEG6  
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    '************************************************************************* KuJ9bn{u!C  
    'Radius and conic constant of posterior lens {BJ>x:2  
    '************************************************************************* eX#.Zt]  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) `r SOt *<  
    GetConic eID, entity, curv, conic f9K7^qwkiz  
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    SetConic eID, entity, 1/Rpost, CCpost ?:$ q~[LY  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost o~XK*f=(  
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    '************************************************************************* phH@{mI  
    'Lens thickness (Position of posterior lens surface) aC}\`.Kb  
    '************************************************************************* -6DRX  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 'EIe5O p  
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    ' Delete any z-shift(s) q~> +x?30  
    count = 0 ]#G s6CsT|  
    While GetOperationCount(eID)>count qj~=qV0p  
        GetOperation eID, count, op op`9(=DJ]  
        If op.Type="ShiftZ" Then :8@)W<>%  
            DeleteOperation eID,count t)W=0iEd9  
            count=count-1 D@&xj_#\}  
        End If gra6&&^"  
        count=count+1 *xxk70Cb  
    Wend ~NIhS!  
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    'Set new z-shift EmT_T 3v  
    op.Type = "ShiftZ" K/*R}X  
    op.val1 = tlens -& (iU#W  
    op.parent = parID %/I:r7UR{  
    AddOperation eID, op EY"of[p  
    Print "Set lens thickness = " & tlens WOj}+?/3 R  
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    '************************************************************************* [j/|)cj  
    'Lens index of refraction hiVa\s  
    '************************************************************************* %mss{p!d6  
    eID = FindMaterial( "Lens" ) @H`jDaB 9  
    GetModelMaterial eID, mat K*5gb^Ul  
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    mat.Nd = nlens a&JY x  
    SetModelMaterial eID, mat 8gNTW7W/  
    Print "Set lens index of refraction = " & nlens _0$>LWO~  
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    '************************************************************************* gN<7(F  
    'Pupil diameter `WH$rx!  
    '************************************************************************* pv0|6X?J"  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) RTlC]`IGT  
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    'Adjust pupil diameter (trimming volume inner hole) # l9VTzi  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ?n{m2.H  
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    ' Adjust pupil location to just in front of the lens Ut2T:%m{  
    parID = FindFullName( "Geometry.Arizona Eye" ) 7HW:;2dL  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) (.=Y_g.  
    count = 0 v CsE|eMP  
    While GetOperationCount(eID)>count y2+f)Xp_.C  
        GetOperation eID, count, op 2fky z  
        If op.Type="ShiftZ" Then i45.2,  
            DeleteOperation eID,count ngZq]8 =o  
            count=count-1 f 4pIF"U9>  
        End If s/@uGC0>  
        count=count+1 ~/A2 :}Cp=  
    Wend %'WC7s  
    op.Type = "ShiftZ" 95IP_1}?  
    op.val1 = taq-0.01 1/mBp+D  
    op.parent = parID w!<e#Z]3b  
    AddOperation eID, op E8av/O VUd  
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    Print "Set pupil diameter = " & pupilDiam @$kO7k0{g  
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    'Update AZ Eye subassembly Description TI8\qIW  
    eID = FindFullName( "Geometry.Arizona Eye" ) ;5;>f)diS  
    GetEntity eID, entity &i3SB[|  
    entity.Description = "Accommodation = " & A & "D" |e!Y C iU  
    SetEntity eID, entity x7 e0&  
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    Update &iu]M=Y b  
    Print "DONE!" '2Zs15)V  
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End Sub 7l-MV n_8  
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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： ,? <;zq  
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Accommodation = 4 Diopters #QsJr_=  
Pupil Diameter = 4 mm 7R[7M%H  
Set aqueous humor thickness = 2.81 `vzMuL;  
Set anterior lens radius = 10.4 and conic constant = -2.375869 J#H,QYnf(L  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 bn|HvLQ"1  
Set lens thickness = 3.927 f%n ;Z}=  
Set lens index of refraction = 1.42672 f9UDH8X  
Set pupil diameter = 4 -}4CY\d6'  
DONE! Cm8h b  
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（文章来源：讯技光电）
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