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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 c#-97"_8  
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。 x~Esu}x7  
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模型 q\Io6=39x  
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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。 :FgRe,D  
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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. E;Ftop  
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光源 2dlV'U_g  
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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。 'C8=d(mR=m  
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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。 w0`L)f5v  
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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。 Zkep7L   
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图2. 字母F光源的设定方法光 >Ezwl5b  
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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 }4ju2K  
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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。 lTd2~_  
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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。 MOeLphY  
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图5. 视网膜重点采样规格设定
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脚本 JX<W[P>M  
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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： R}26"+~  
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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。 vj$ 6  
余下的脚本计算与屈光度有关的所有参数。 oKJ7i,xT  
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分析 9 (.9l\h  
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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。 *g6o ;c  
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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 Xkm2C)  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. W+S; Do  
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Dim entity As T_ENTITY GK%ovK  
Dim op As T_OPERATION >D#}B1(!  
Dim mat As T_MODELMATERIAL nv{4 U}&P  
Dim A As Double 1 *CWHs  
Dim pupilDiam As Double 3) 0~:  
Dim eID As Long jdf@lb=5l  
Dim parID As Long ]*U')  
Dim count As Integer 4T E ?mh}  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 9?c^~77  
Dim tlens As Double, nlens As Double [![ (h %  
Dim curv As Double, conic As Double n"Vd"}sU.  
Dim ok As Long " ?,6{\y,  
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Sub Main 4,DsB'  
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    '用户输入对话框 L:Eb(z/D  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 y]9U FL"  
        TextBox 220,21,40,21,.TextBox1 'default: 0 e_-/p`9  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 mK4|=Q  
        OKButton 40,91,90,21 jtY~- @*  
        CancelButton 190,91,90,21 ;)a9Y?  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 "6QMa,)D  
        TextBox 220,49,40,21,.TextBox2 'default: 4 1z:N$O _v  
    End Dialog N|S xAg  
    Dim dlg As UserDialog Q>yt O'v1  
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    ok = Dialog (dlg) NvZ?e  
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    If ok=0 Then    'cancel button was pressed = h( n+y<  
        Print "Execution cancelled." -rlX<(pl)  
        End ?Fpl.t~  
    End If j}l8k@f  
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    'Assign accommodation and pupil diameter & use defaults if field left empty eMzCAO  
    If dlg.TextBox1 = "" Then N@)~j+Pz  
        A = 0           'Default accommodation o hlVc%a  
    Else R?s\0  
        A = CDbl(dlg.TextBox1) Bdepvc}[#  
    End If Am4(WXVQ  
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    If dlg.TextBox2 = "" Then FG:BRS<m~  
        pupilDiam = 4   'Default pupil diameter |lV9?#!  
    Else m)}MkC-  
        pupilDiam = CDbl(dlg.TextBox2) gw T,D.'Ut  
    End If !k9h6/ b6  
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    Print " " UULL:vqq  
    Print "Accommodation = " & A & " Diopters" s#ZH.z@J  
    Print "Pupil Diameter = " & pupilDiam & " mm" \S@6@ UGv  
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    ' Calculate new parameters with accommodation O]eJQ4XN<  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness a0\UL"z#+  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 1A-EP@# J  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ?UDO%`X  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens Uiw7Y\Im|  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens *`T &Dlt'8  
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    tlens = 3.767 + 0.04*A                  'Lens thickness Ya 4$7|(  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 5&= n  
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    'Adjust parameters to account for accommodation ,$$$_+m\  
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    '************************************************************************* B)8Hj).@B  
    'Aqueous thickness (Position of Lens) }* JMc+!9@  
    '************************************************************************* I3Xh[% -!  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 'U$VO q?!  
    GetCustomElement eID, entity *wcoDQ b;  
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    parID = FindFullName( "Geometry.Arizona Eye" ) \;gt&*$-  
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    ' Delete any shift(s) in z _\PoZ|G4y  
    count = 0 e}AJxBE  
    While GetOperationCount(eID)>count 5N<v'6&=  
        GetOperation eID, count, op rF3]AW(  
        If op.Type="ShiftZ" Then tta0sJ8 i  
            DeleteOperation eID,count Nn1^#kc  
            count=count-1 *Bsmn!_cB{  
        End If >Fk `h=Wd  
        count=count+1 @$Kq<P  
    Wend J5 ( D7rp#  
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    'Set new shift in iDc|9"|Tf3  
    op.Type = "ShiftZ" 1R9? [RE  
    op.val1 = taq ?^4sE-C6  
    op.parent = parID [:@?,?V\N  
    AddOperation eID, op } /3pC a  
    Print "Set aqueous humor thickness = " & taq-0.55 Q.dy $`\  
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    '************************************************************************* u@u.N2H.%  
    'Radius and conic constant of anterior lens W+C_=7_  
    '************************************************************************* v} ;qMceJ  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) [=3tAPpzK  
    GetConic eID, entity, curv, conic w*}yw"gP*0  
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    SetConic eID, entity, 1/Rant, CCant f<p4Pkv  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant bTp2)a^G  
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    '************************************************************************* x`vs-Y:P  
    'Radius and conic constant of posterior lens #(g+jb0E  
    '************************************************************************* bMOM`At>z  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) g~:(EO(w  
    GetConic eID, entity, curv, conic %kFELtx  
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    SetConic eID, entity, 1/Rpost, CCpost M 8j(1&(:  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost <`UG#6z8  
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    '************************************************************************* ^|i\d \  
    'Lens thickness (Position of posterior lens surface) _Ge^ -7  
    '************************************************************************* 3b\8907  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) "u8o?8+q~  
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    ' Delete any z-shift(s) 2*wO5v  
    count = 0 \(U"_NPp  
    While GetOperationCount(eID)>count 05VOUa*pb  
        GetOperation eID, count, op  `pd   
        If op.Type="ShiftZ" Then 7e{X$'  
            DeleteOperation eID,count ^~<Rzq!  
            count=count-1 [^}>AC*im  
        End If Bx : So6:  
        count=count+1 pkN:D+g S  
    Wend 6`baQ!xc.  
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    'Set new z-shift xD= qU  
    op.Type = "ShiftZ" X$|TN+Ub  
    op.val1 = tlens 0Q- Mxcj  
    op.parent = parID %*6oUb  
    AddOperation eID, op LLn{2,jfQ  
    Print "Set lens thickness = " & tlens ?}3PJVy?  
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    '************************************************************************* PUjoi@]  
    'Lens index of refraction ~d7Wjn$@  
    '************************************************************************* J6( RlHS;  
    eID = FindMaterial( "Lens" ) L+~YCat|$U  
    GetModelMaterial eID, mat 7?!Z+r  
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    mat.Nd = nlens -Mi}yi  
    SetModelMaterial eID, mat )y/DGSd  
    Print "Set lens index of refraction = " & nlens ]O7.ss/2  
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    '************************************************************************* gAr`hXO  
    'Pupil diameter &Ky u@Tt  
    '************************************************************************* $v'Y:  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) :m++ iR  
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    'Adjust pupil diameter (trimming volume inner hole) l'7Mw%6{  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" {NY~JFM  
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    ' Adjust pupil location to just in front of the lens /y9J)lx  
    parID = FindFullName( "Geometry.Arizona Eye" ) I)XOAf$6  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) WE.$at{*h  
    count = 0 m/<F 5R  
    While GetOperationCount(eID)>count u JQaHL!  
        GetOperation eID, count, op iJZ|[jEDV  
        If op.Type="ShiftZ" Then 5rfH;`  
            DeleteOperation eID,count ;naq-%'Sg  
            count=count-1 Wm$`ae   
        End If o4/I1Mq  
        count=count+1 #6N+5Yx_[  
    Wend {C/L5cZ]J  
    op.Type = "ShiftZ" i+)}aA  
    op.val1 = taq-0.01 [*9YIjn  
    op.parent = parID Gin_E&%g  
    AddOperation eID, op b'7z DZI]  
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    Print "Set pupil diameter = " & pupilDiam Q&Z4r9+Z  
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    'Update AZ Eye subassembly Description ~MhgAC  
    eID = FindFullName( "Geometry.Arizona Eye" ) vnC<*k4&v  
    GetEntity eID, entity #*Yi4Cn<  
    entity.Description = "Accommodation = " & A & "D" U/X|i /  
    SetEntity eID, entity M[YTk=IM#  
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    Update G`]v_`>  
    Print "DONE!" &o*s !u  
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End Sub (odR'#  
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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： v[{8G^Z}54  
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Accommodation = 4 Diopters Uvjdx(fY[a  
Pupil Diameter = 4 mm )-+\M_JK5  
Set aqueous humor thickness = 2.81 rU=b?D)n!w  
Set anterior lens radius = 10.4 and conic constant = -2.375869 9Fy\t{ks  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 .D8~)ZWN  
Set lens thickness = 3.927 I 1b  
Set lens index of refraction = 1.42672 3h9Sz8  
Set pupil diameter = 4 eyeNrk*2o  
DONE! m~)Fr8Wh6  
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（文章来源：讯技光电）
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