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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 Q`(h  
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。 l=ZX9<3  
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模型 4j-%I7  
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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。 _[u fH*  
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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. sWX\/Iyy2p  
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光源 )W$@phY(I  
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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。 oh^QW`#(  
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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。 q b7ur;  
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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。 ,L9ioYbp  
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图2. 字母F光源的设定方法光 Vh5Z'4N  
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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 / WJ+e  
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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。 #tQ__ V   
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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。 =@0/.oSD  
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图5. 视网膜重点采样规格设定
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脚本 /;a b"b  
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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： B0eKj=y;  
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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。 Z^SF $+UN  
余下的脚本计算与屈光度有关的所有参数。 23~KzC  
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分析 ;ZowC#j  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 ?wYvBFRn7"  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 :ZP`Y%dt'  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. 76rRF   
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Dim entity As T_ENTITY 2P4$^G[  
Dim op As T_OPERATION h,%b>JFo  
Dim mat As T_MODELMATERIAL /$,~|X;&  
Dim A As Double =%+o4\N,  
Dim pupilDiam As Double Xj("  
Dim eID As Long &$+nuUA  
Dim parID As Long i#W0  
Dim count As Integer Ua= w;h  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double i%eq!q  
Dim tlens As Double, nlens As Double |#_`aT"  
Dim curv As Double, conic As Double UOAL7  
Dim ok As Long ( 17=|s  
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Sub Main 8*t8F\U#  
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    '用户输入对话框 7 G<v<&  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 re;^,  
        TextBox 220,21,40,21,.TextBox1 'default: 0 $X%'je  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ui$JQ_P  
        OKButton 40,91,90,21 Az"(I>VfD  
        CancelButton 190,91,90,21 ,Kw]V %xOb  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 vsL)E:0  
        TextBox 220,49,40,21,.TextBox2 'default: 4 6 (@U+`  
    End Dialog 4OOH 3O  
    Dim dlg As UserDialog "U DV4<|^k  
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    ok = Dialog (dlg) , e6}p  
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    If ok=0 Then    'cancel button was pressed !?u{2 D  
        Print "Execution cancelled." mqFo`Ee  
        End l[D5JnWxt  
    End If {j{H@rHuy  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 'ixu+.ZL/  
    If dlg.TextBox1 = "" Then jR[3{ Reo  
        A = 0           'Default accommodation 6*]g~)7`Q~  
    Else sWc_,[b  
        A = CDbl(dlg.TextBox1) +>uiI4g  
    End If vm y?8E6+  
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    If dlg.TextBox2 = "" Then ~7}aW#  
        pupilDiam = 4   'Default pupil diameter WzwH;!  
    Else @ppT;9<d  
        pupilDiam = CDbl(dlg.TextBox2) 8:)W!tr  
    End If X/l{E4Ex  
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    Print " " Gec?  
    Print "Accommodation = " & A & " Diopters" `f~\d.*U  
    Print "Pupil Diameter = " & pupilDiam & " mm" )* \N[zm  
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    ' Calculate new parameters with accommodation MY]<^/Q  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness !iO%?nW;  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens qij<XNZU"&  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens th?w&;L  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens qlJzXq{|`  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens sOY+ X  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ^-&BGQM  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction `3CdW  
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    'Adjust parameters to account for accommodation Mt93YD-2+  
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    '************************************************************************* H>qw@JiO!  
    'Aqueous thickness (Position of Lens) 3iI 4yg  
    '************************************************************************* 3m#/1=@o  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) +[R,wsG  
    GetCustomElement eID, entity @3Lh/&  
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    parID = FindFullName( "Geometry.Arizona Eye" ) #BZ2%\  
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    ' Delete any shift(s) in z MN.h,^b  
    count = 0 hN5?u:  
    While GetOperationCount(eID)>count 1j!LK-  
        GetOperation eID, count, op Z?);^m|T  
        If op.Type="ShiftZ" Then ]"2;x  
            DeleteOperation eID,count k"z ~>  
            count=count-1 |g@n'^]  
        End If ZgzjRa++  
        count=count+1 iiw\  
    Wend *:+&Sx L  
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    'Set new shift in V8Fp1?E9S  
    op.Type = "ShiftZ" +~x'1*A_  
    op.val1 = taq `Q@w*ta)  
    op.parent = parID DT Cwf  
    AddOperation eID, op |}-bMQ|  
    Print "Set aqueous humor thickness = " & taq-0.55 $\w<.)"#  
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    '************************************************************************* <?&Y_  
    'Radius and conic constant of anterior lens 0{q>'dv  
    '************************************************************************* )9]DJ!]&Q"  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) WCdl 25L#  
    GetConic eID, entity, curv, conic ILU7Yhk  
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    SetConic eID, entity, 1/Rant, CCant j TyR+#Wn  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ev'` K=n8  
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    '************************************************************************* wqnHaWd*  
    'Radius and conic constant of posterior lens xk:=.Qqh  
    '************************************************************************* d:X@zUR*)  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) i!a. 6Gq  
    GetConic eID, entity, curv, conic )-s9CWJv  
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    SetConic eID, entity, 1/Rpost, CCpost x@)G@'vV|  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost sP'U9l  
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    '************************************************************************* #hZ`r5GvTj  
    'Lens thickness (Position of posterior lens surface) 9zL(PkC%\  
    '************************************************************************* Ov-Y.+L:  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) =] +owl2  
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    ' Delete any z-shift(s) B4Fuvi  
    count = 0 CiNOGSlDj  
    While GetOperationCount(eID)>count F%tV^$%  
        GetOperation eID, count, op TFAd  
        If op.Type="ShiftZ" Then GyZpdp!  
            DeleteOperation eID,count yp!7^  
            count=count-1 Uk'bOp  
        End If DuMzK%  
        count=count+1 r6Qsh CA"  
    Wend _m.w5nJ  
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    'Set new z-shift _qO'(DKylC  
    op.Type = "ShiftZ" }WV}in0  
    op.val1 = tlens jl"su:y  
    op.parent = parID j2RdBoCt  
    AddOperation eID, op =o5|W'>`  
    Print "Set lens thickness = " & tlens a_3w/9L4r  
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    '************************************************************************* KDS} "/  
    'Lens index of refraction *6bO2LO"  
    '************************************************************************* Q@ Ze+IhK`  
    eID = FindMaterial( "Lens" ) %#<MCiaK  
    GetModelMaterial eID, mat $3 =S\jyfK  
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    mat.Nd = nlens o* ~aB_  
    SetModelMaterial eID, mat T'> MXFLh  
    Print "Set lens index of refraction = " & nlens 3oOr*N3R  
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    '************************************************************************* Lb,wn{  
    'Pupil diameter WS ^,@>A  
    '************************************************************************* p/U{*i ]t  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ;Rljx3!N  
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    'Adjust pupil diameter (trimming volume inner hole) Gsu?m  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" EeR}34  
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    ' Adjust pupil location to just in front of the lens hS1I ;*t  
    parID = FindFullName( "Geometry.Arizona Eye" ) ?2%;VKN4  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" )  tE#;$Ss  
    count = 0 kMx)G]  
    While GetOperationCount(eID)>count  i}_"  
        GetOperation eID, count, op z d6F}2*6  
        If op.Type="ShiftZ" Then .b? Aq^i8  
            DeleteOperation eID,count 7^7Jh&b)/  
            count=count-1 klR\7+lK  
        End If ~1&WR`U  
        count=count+1 9:P\)'y?  
    Wend :,ucJ|  
    op.Type = "ShiftZ" P1R5}i  
    op.val1 = taq-0.01 I^Dm 3yz  
    op.parent = parID oOHY+'V  
    AddOperation eID, op M-Ek(K3SRf  
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    Print "Set pupil diameter = " & pupilDiam u].7+{  
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    'Update AZ Eye subassembly Description |R2p^!m  
    eID = FindFullName( "Geometry.Arizona Eye" ) BwkY;Ur/AL  
    GetEntity eID, entity @^R l{p  
    entity.Description = "Accommodation = " & A & "D" #aQQd8   
    SetEntity eID, entity JW!.+ Q  
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    Update a^8PB|G  
    Print "DONE!" R nwFxFIQ  
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End Sub Re2&qxE  
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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： {a__/I>)  
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Accommodation = 4 Diopters `^] D;RfE  
Pupil Diameter = 4 mm Cv@)tb  
Set aqueous humor thickness = 2.81 HB{'MBs  
Set anterior lens radius = 10.4 and conic constant = -2.375869 bZ_TW9mq  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 %E5b }E#  
Set lens thickness = 3.927 K iEmvC  
Set lens index of refraction = 1.42672 9a @rsyX  
Set pupil diameter = 4 )Gm9x]SVl  
DONE! `U=Jbdc l3  
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（文章来源：讯技光电）
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