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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 <xS=#  
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。 7el<5chZ  
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模型 E1>/R  
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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。 7$b?m6fmK  
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Table 1. AZ眼睛模型的定义
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在FRED中使用0屈光度来创建的，光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. @Y' I,e  
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光源 f?0s &Xo  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 ~y\:iL//E  
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图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 x% XT2+  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 0U&d q#  
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图2. 字母F光源的设定方法光 P%GkcV  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 F2oJ]th.3  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 `Wf5  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 Wu{&;$  
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图5. 视网膜重点采样规格设定
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脚本 }GRMZh_8  
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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： w4OW4J#  
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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。 g3a/;wl  
余下的脚本计算与屈光度有关的所有参数。 !"(u_dFw  
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分析 BHiOQ0Fs  
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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。 4I.1D2 1jA  
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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 Sf5]=F-w  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. #O6 EP#B  
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Dim entity As T_ENTITY A5+5J_)*  
Dim op As T_OPERATION /d]~ly @uI  
Dim mat As T_MODELMATERIAL < %rh/r  
Dim A As Double p)z-W(  
Dim pupilDiam As Double zW)gC9_|m-  
Dim eID As Long a8NVLD>7}  
Dim parID As Long O"QHb|j  
Dim count As Integer *zSxG[s  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Okoo(dfM  
Dim tlens As Double, nlens As Double Ge~,[If+  
Dim curv As Double, conic As Double B<C&ay  
Dim ok As Long GMT or  
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Sub Main |=,83,a  
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    '用户输入对话框 (7 ijt  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 :B+Rg cqi  
        TextBox 220,21,40,21,.TextBox1 'default: 0 Rd vn)K  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 sr4jQo  
        OKButton 40,91,90,21 Zr9d&|$  
        CancelButton 190,91,90,21 $*i7?S@~-  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ,N0uR@GN  
        TextBox 220,49,40,21,.TextBox2 'default: 4 +0U#.|?  
    End Dialog qTS @D  
    Dim dlg As UserDialog km}MqBQl  
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    ok = Dialog (dlg) SLg+H  
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    If ok=0 Then    'cancel button was pressed OuNj:  
        Print "Execution cancelled." drs-mt8  
        End h$|3dz N  
    End If a0{[P$$  
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    'Assign accommodation and pupil diameter & use defaults if field left empty #_{0Ndp2  
    If dlg.TextBox1 = "" Then s`r-v/3l  
        A = 0           'Default accommodation 8Kk3_ y  
    Else lD-V9   
        A = CDbl(dlg.TextBox1) 7|K3WuLL  
    End If ~JAjr(G#o  
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    If dlg.TextBox2 = "" Then RP(a,D|  
        pupilDiam = 4   'Default pupil diameter :b <KX%g  
    Else u7n[f@Eg,%  
        pupilDiam = CDbl(dlg.TextBox2) T G_bje  
    End If 8H7O/n  
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    Print " " Rnzqw,q  
    Print "Accommodation = " & A & " Diopters" Q g$($   
    Print "Pupil Diameter = " & pupilDiam & " mm" )tScc*=8  
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    ' Calculate new parameters with accommodation 5Yn{?r\#F  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness ka!Bmv)  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens b~jIv:9T  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens :Jjw"}SfK#  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens is9}ePC7Xu  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens (*MNox?w  
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    tlens = 3.767 + 0.04*A                  'Lens thickness "Wo.8  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 6g}^Q?cpV#  
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    'Adjust parameters to account for accommodation <D~6v2$  
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    '************************************************************************* J6eJIKK  
    'Aqueous thickness (Position of Lens) )@!~8<_"  
    '************************************************************************* L{Q4=p,A  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) O%fUm0O d  
    GetCustomElement eID, entity l6V%"Lo/)  
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    parID = FindFullName( "Geometry.Arizona Eye" ) "\4]X"3<+  
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    ' Delete any shift(s) in z y!SF/i?Py  
    count = 0 kxygf9I!;  
    While GetOperationCount(eID)>count "Ys_ \  
        GetOperation eID, count, op =x=1uXQv5  
        If op.Type="ShiftZ" Then {5U1`>  
            DeleteOperation eID,count 4pLQ"&>}80  
            count=count-1 u/_Gq[Q,u  
        End If zwMQXI'k83  
        count=count+1 ;0;3BH A  
    Wend ==nYe { 2  
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    'Set new shift in C5>{Q:.`e'  
    op.Type = "ShiftZ" xR *5q1j  
    op.val1 = taq {An8/"bv}  
    op.parent = parID ^uC"dfH  
    AddOperation eID, op 4Y`! bT`  
    Print "Set aqueous humor thickness = " & taq-0.55 hK:#+hg,  
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    '************************************************************************* EW ~*@H  
    'Radius and conic constant of anterior lens :/>7$)+  
    '************************************************************************* GEhdk]<a7  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) )\um "l*\c  
    GetConic eID, entity, curv, conic w/qQ(]n8  
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    SetConic eID, entity, 1/Rant, CCant C]yvK}  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant n"XdHW0  
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    '************************************************************************* iSOD&J_  
    'Radius and conic constant of posterior lens _u#/u2<  
    '************************************************************************* Tf9&,!>V  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) PXOrOK  
    GetConic eID, entity, curv, conic h |s*i  
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    SetConic eID, entity, 1/Rpost, CCpost 5JQd)[Im  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 3Qqnw{*  
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    '************************************************************************* ' %bj9{(0  
    'Lens thickness (Position of posterior lens surface) d 8xk&za  
    '************************************************************************* UeMnc 5y  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) vs5 D:cZ}  
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    ' Delete any z-shift(s)  ~Y1"k]J  
    count = 0 5Z^$`$/.v#  
    While GetOperationCount(eID)>count #cw! &  
        GetOperation eID, count, op ;e&hM\p  
        If op.Type="ShiftZ" Then RA*_&Ll&!C  
            DeleteOperation eID,count 9`ri J4zl  
            count=count-1 I'KR'1z 9  
        End If Xulh.: N}  
        count=count+1 )v*v  
    Wend Wwn5LlJ^  
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    'Set new z-shift B ]|5?QP-  
    op.Type = "ShiftZ" [{6&.v  
    op.val1 = tlens PiIp<fJd$  
    op.parent = parID NTv#{7q  
    AddOperation eID, op -=-x>(pRW7  
    Print "Set lens thickness = " & tlens 6LSPPMM  
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    '************************************************************************* U92B+up-  
    'Lens index of refraction E'S<L|A/  
    '************************************************************************* !mw{T D  
    eID = FindMaterial( "Lens" ) m _t(rn~f6  
    GetModelMaterial eID, mat Pur"9jHa4  
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    mat.Nd = nlens }e&KO?x+  
    SetModelMaterial eID, mat 9`nP(~  
    Print "Set lens index of refraction = " & nlens K1m!S9d`x  
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    '************************************************************************* '^P*F9  
    'Pupil diameter &5kjjQ*HB  
    '************************************************************************* &(z8GYBr  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) t[H_6)  
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    'Adjust pupil diameter (trimming volume inner hole) hEdo,gF*  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" L<[,7V  
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    ' Adjust pupil location to just in front of the lens 9hz7drhR;\  
    parID = FindFullName( "Geometry.Arizona Eye" ) 0ER6cTo-t  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 2uI`$A:  
    count = 0 Sgjr4axu  
    While GetOperationCount(eID)>count h0y\,iWXb  
        GetOperation eID, count, op 9M-NItFos  
        If op.Type="ShiftZ" Then NO0[`jy(  
            DeleteOperation eID,count 37ri b  
            count=count-1 `9G$p|6  
        End If {ra Esb-X  
        count=count+1 h!JjN$  
    Wend Y/:Q|HnXQ  
    op.Type = "ShiftZ" _If@#WnoyA  
    op.val1 = taq-0.01 ]aL  [  
    op.parent = parID q)zu}m  
    AddOperation eID, op eBLHT  
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    Print "Set pupil diameter = " & pupilDiam YA8yMh*4D?  
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    'Update AZ Eye subassembly Description a3E*%G  
    eID = FindFullName( "Geometry.Arizona Eye" ) ;4O;74`Zh  
    GetEntity eID, entity Z "+rg9/p  
    entity.Description = "Accommodation = " & A & "D" `OF ;>u*:  
    SetEntity eID, entity {?h6*>-^Z  
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    Update TF ([yZO'  
    Print "DONE!" EC\rh](d 1  
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End Sub w~FO:/  
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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： &55uT;7] a  
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Accommodation = 4 Diopters ="[+6X  
Pupil Diameter = 4 mm jrMGc=KL  
Set aqueous humor thickness = 2.81 JY,l#?lM{  
Set anterior lens radius = 10.4 and conic constant = -2.375869 []]LyWk  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 >f9]Nj  
Set lens thickness = 3.927 G){1`gAhNJ  
Set lens index of refraction = 1.42672 \)6?u_(u  
Set pupil diameter = 4 5xn0U5U  
DONE! qz_TcU'  
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（文章来源：讯技光电）
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