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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 v-SX PL]_^  
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。 cC>Svf[CzK  
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模型 }IZw6KiN  
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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。 \v6lcAL-  
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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. R|'W#"{@  
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光源 ;@Fb>l BhX  
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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。 pqb`g@  
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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。 "OK[uug  
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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。 R3U|{vgl  
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图2. 字母F光源的设定方法光 &^DVSVqs^  
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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 $-Ex g*i  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 c`p '5qz  
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[attachment=67935]
图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 A]'jsv!+  
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图5. 视网膜重点采样规格设定
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脚本 q)Nw$dW<  
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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： DE/SIy?  
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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。 [bP^RY:  
余下的脚本计算与屈光度有关的所有参数。 +llb{~ZN  
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分析 ERIMz ,  
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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。 +sjzT[ Dn  
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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 {FI*oO1A~  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. #8"oqqYi  
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Dim entity As T_ENTITY =FhP$r*  
Dim op As T_OPERATION aMhVO(+FW  
Dim mat As T_MODELMATERIAL 0t^FM<7G  
Dim A As Double {<gv1Yht  
Dim pupilDiam As Double A8vd@0  
Dim eID As Long 4BCe;Q^6  
Dim parID As Long iLuC_.'u=  
Dim count As Integer 2.niB>  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ?#=xx.cF  
Dim tlens As Double, nlens As Double Uc {m##!  
Dim curv As Double, conic As Double 8CZfz!2  
Dim ok As Long Fb]+h)on  
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Sub Main 3PU_STSix  
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    '用户输入对话框 h>\C2Q  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 s<F*kLib  
        TextBox 220,21,40,21,.TextBox1 'default: 0 <z,)4z++  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 "Esl I  
        OKButton 40,91,90,21 #Z2 'Y[@.  
        CancelButton 190,91,90,21 ylZQwICk  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 A|r3c?q  
        TextBox 220,49,40,21,.TextBox2 'default: 4 w/nohZF6H  
    End Dialog 37zB X~  
    Dim dlg As UserDialog /_qq(,3  
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    ok = Dialog (dlg) M.mn9kw`  
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    If ok=0 Then    'cancel button was pressed 9hIKx:XCg  
        Print "Execution cancelled." kx;X:I(5&P  
        End Z\CvaX  
    End If M<w.q|P  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ]64}Xob87_  
    If dlg.TextBox1 = "" Then 34u[#O{2  
        A = 0           'Default accommodation V'XEz;Ze  
    Else QLO;D)fC  
        A = CDbl(dlg.TextBox1) ,w#lUg p  
    End If cWkg.ri-x  
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    If dlg.TextBox2 = "" Then d,(y$V+  
        pupilDiam = 4   'Default pupil diameter -`k>(\Q< d  
    Else bu _ @>`S  
        pupilDiam = CDbl(dlg.TextBox2) R xITMt  
    End If N^rpPq  
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    Print " " hc|A:v)]  
    Print "Accommodation = " & A & " Diopters" @ar%`+_  
    Print "Pupil Diameter = " & pupilDiam & " mm" f1_;da  
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    ' Calculate new parameters with accommodation 7@;*e=v  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 8IlUbj  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 3<r7"/5  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens :.+w'SEn4M  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ZwMVFC-d  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens kS-BB[T  
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    tlens = 3.767 + 0.04*A                  'Lens thickness gFTU9k<  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction D", L.  
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    'Adjust parameters to account for accommodation 9!n:hhJM  
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    '************************************************************************* }+KM"+@$<  
    'Aqueous thickness (Position of Lens) 4@0aN6Os  
    '************************************************************************* |D)CAQn,  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) *LB-V%{|'  
    GetCustomElement eID, entity 1yE',9?  
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    parID = FindFullName( "Geometry.Arizona Eye" ) *U1*/Q.  
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    ' Delete any shift(s) in z fxcE1=a  
    count = 0 X <xM '  
    While GetOperationCount(eID)>count Y5GN7.  
        GetOperation eID, count, op 9Ad%~qciY  
        If op.Type="ShiftZ" Then 1 Gr^,Ry  
            DeleteOperation eID,count Eg`~mE+a  
            count=count-1 V4R s  
        End If R1LirZlzJ  
        count=count+1 IE\RP!  
    Wend `C>h]H(  
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    'Set new shift in LOkgeJuWv  
    op.Type = "ShiftZ" E^rBs2;9  
    op.val1 = taq QwhO /  
    op.parent = parID h/\v+xiF  
    AddOperation eID, op pA.orx  
    Print "Set aqueous humor thickness = " & taq-0.55 6Mc&=}bV  
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    '************************************************************************* 6h/!,j0:t_  
    'Radius and conic constant of anterior lens DL bP$&o  
    '************************************************************************* -I5]#%eX^  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) js"Yh  
    GetConic eID, entity, curv, conic }` 3-  
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    SetConic eID, entity, 1/Rant, CCant Bdh*[S\u@E  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 6E) T;R(@  
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    '************************************************************************* \/1~5mQ+  
    'Radius and conic constant of posterior lens qY-aR;  
    '************************************************************************* n/;{-  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) zKP[]S-  
    GetConic eID, entity, curv, conic eFs5 l  
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    SetConic eID, entity, 1/Rpost, CCpost i%133in  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ^iEf"r  
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    '************************************************************************* =&pR=vl  
    'Lens thickness (Position of posterior lens surface)  $Z &6  
    '************************************************************************* <IR@/b!,  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) *P *.'XM  
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    ' Delete any z-shift(s) AT t.}-  
    count = 0 D7pQWlN\  
    While GetOperationCount(eID)>count > U3>I^Y  
        GetOperation eID, count, op Lb$Uba-_  
        If op.Type="ShiftZ" Then *}:P  
            DeleteOperation eID,count z]g#2xD2  
            count=count-1 [uqr  
        End If 6 p;Pf9 f  
        count=count+1 7Z]?a  
    Wend \|X 1  
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    'Set new z-shift D`n<!"xg@$  
    op.Type = "ShiftZ" wa[J\lW  
    op.val1 = tlens 1Mq"f 7X8  
    op.parent = parID ;Uch  
    AddOperation eID, op ?z)2\D  
    Print "Set lens thickness = " & tlens q#Otp\f  
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    '************************************************************************* hK4ww"-  
    'Lens index of refraction 2 br>{^T  
    '************************************************************************* ZD50-w;  
    eID = FindMaterial( "Lens" ) J8FzQ2  
    GetModelMaterial eID, mat >*/ |t L  
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    mat.Nd = nlens )`k+Oyvi<  
    SetModelMaterial eID, mat T:Q+ Z }v+  
    Print "Set lens index of refraction = " & nlens q:vN3#=^qf  
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    '************************************************************************* LU*mR{B  
    'Pupil diameter $m>( kd1  
    '************************************************************************* X%!?\3S  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) U#Kw+slM  
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    'Adjust pupil diameter (trimming volume inner hole) tvJl-&'N  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" #@Tm5z  
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    ' Adjust pupil location to just in front of the lens (q 7;/n  
    parID = FindFullName( "Geometry.Arizona Eye" ) ]Gm&Kn >  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) iw(`7(*  
    count = 0 ZWFOC,)b  
    While GetOperationCount(eID)>count ^l(,'>Cn  
        GetOperation eID, count, op %,N-M]Jf  
        If op.Type="ShiftZ" Then V[44aN  
            DeleteOperation eID,count mV7_O//  
            count=count-1 U GOe(JB  
        End If UT_t]m  
        count=count+1 >SZuN"r8`  
    Wend $43CNnf3N  
    op.Type = "ShiftZ" ciH TnC  
    op.val1 = taq-0.01 K/(Z\lL  
    op.parent = parID MmfshnTN  
    AddOperation eID, op %AgCE"!  
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    Print "Set pupil diameter = " & pupilDiam y(Pv1=e  
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    'Update AZ Eye subassembly Description zS\m8[+]  
    eID = FindFullName( "Geometry.Arizona Eye" ) 0,LUi*10  
    GetEntity eID, entity E&vCzQ  
    entity.Description = "Accommodation = " & A & "D" iQh:y:Jo1&  
    SetEntity eID, entity 6>d 3*   
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    Update FP6Jf I8  
    Print "DONE!" IgF#f%|Q  
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End Sub ||Wg'$3  
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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： 2Q/V D,yU  
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Accommodation = 4 Diopters ~bjT,i  
Pupil Diameter = 4 mm t1l4mdp  
Set aqueous humor thickness = 2.81 # b= *hi`E  
Set anterior lens radius = 10.4 and conic constant = -2.375869 1rmN)  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 mc6W"  
Set lens thickness = 3.927 M w+4atO4[  
Set lens index of refraction = 1.42672 Sj'.)nz>  
Set pupil diameter = 4 oA ]F`N=  
DONE! YH[HJ#:7r  
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（文章来源：讯技光电）
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