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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 DeGcS1_?  
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。 >kG: MJj  
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模型 wQ~F%rQ$  
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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。  ~ A4_  
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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. t^(wbC  
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光源 4 X6_p(  
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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。 <#No t1R  
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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。 i")ucrf  
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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。 G| .5.FK^  
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图2. 字母F光源的设定方法光 8@d,TjJDo  
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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 9{XC9 \~  
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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。  ylBjuD+  
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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。 $(ei<cAV  
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图5. 视网膜重点采样规格设定
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脚本  v{ *#  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： V j"B/@  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 GV(@(bI*  
余下的脚本计算与屈光度有关的所有参数。 9#ZR0t.cY  
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分析 )TV{n#n  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 F)^:WWVc#  
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图7. 字母F在视网膜上颜色分析
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脚本代码 V [KFZSA  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. +-+%6O<C  
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Dim entity As T_ENTITY y:+4-1  
Dim op As T_OPERATION P<{N)H 2r  
Dim mat As T_MODELMATERIAL tp3]?@0  
Dim A As Double "~^ #{q  
Dim pupilDiam As Double j`pX2S  
Dim eID As Long 1Xj>kE:  
Dim parID As Long K|g+W t^tQ  
Dim count As Integer U jrML  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double sGs_w:Hn  
Dim tlens As Double, nlens As Double M h5>@-fEE  
Dim curv As Double, conic As Double 380M &Guh  
Dim ok As Long eJ O+MurO  
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Sub Main c1L0#L/F6"  
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    '用户输入对话框 qH1&tW$  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 8C(@a[V  
        TextBox 220,21,40,21,.TextBox1 'default: 0 pwG"_|h  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 hxQx$  
        OKButton 40,91,90,21 a-<&(jV  
        CancelButton 190,91,90,21 WfF~\DlrD  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 TowRY=#jiS  
        TextBox 220,49,40,21,.TextBox2 'default: 4 1L\\](^ 3  
    End Dialog [c_o.`S_\  
    Dim dlg As UserDialog (^4V]N&  
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    ok = Dialog (dlg) aS,M=uqqK  
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    If ok=0 Then    'cancel button was pressed wW?/`>@  
        Print "Execution cancelled." >wOqV!0<  
        End DcL;7IT  
    End If ~ M!s0jT  
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    'Assign accommodation and pupil diameter & use defaults if field left empty |}Wm,J  
    If dlg.TextBox1 = "" Then "cVJqW  
        A = 0           'Default accommodation ;H;c Sn5uL  
    Else CV )v6f  
        A = CDbl(dlg.TextBox1) XV|u!'Ey  
    End If a(BEm_l3  
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    If dlg.TextBox2 = "" Then g4-UBDtYt  
        pupilDiam = 4   'Default pupil diameter [x\?._>  
    Else y (w&6:  
        pupilDiam = CDbl(dlg.TextBox2) Hk8pKpn3  
    End If ?\7$63gBH  
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    Print " " 1x8zub B  
    Print "Accommodation = " & A & " Diopters" ta'{S=^j  
    Print "Pupil Diameter = " & pupilDiam & " mm" -mur` tC  
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    ' Calculate new parameters with accommodation ;Or]x?-  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Svun RUE-f  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 44p?x8(z*  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens C@#KZ`c)  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens n |e=7?H8  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Y_SB3 $])  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 7)Y0D@wg  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction lc qpwSk  
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    'Adjust parameters to account for accommodation x $@Gp  
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    '************************************************************************* de<T5/  
    'Aqueous thickness (Position of Lens) ,u&K(Z%  
    '************************************************************************* zZ*\v  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) t<DZW#  
    GetCustomElement eID, entity |h6u%t2AY  
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    parID = FindFullName( "Geometry.Arizona Eye" ) r-aCa/4y!  
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    ' Delete any shift(s) in z WPpS?  
    count = 0 7q;wj~  
    While GetOperationCount(eID)>count $[1J[eY*  
        GetOperation eID, count, op FIEA 'kUy  
        If op.Type="ShiftZ" Then @}+F4Xh,L  
            DeleteOperation eID,count 8uD%  
            count=count-1 &o]ic(74c?  
        End If qQ T ^d  
        count=count+1 Fd(o8z8Q  
    Wend (S)jV 0  
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    'Set new shift in )ld`2) 4  
    op.Type = "ShiftZ" ^2 }p%j >  
    op.val1 = taq }xG~ a=,  
    op.parent = parID W#sCvI@   
    AddOperation eID, op sb"h:i>O4  
    Print "Set aqueous humor thickness = " & taq-0.55 =f\BAi  
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    '************************************************************************* 59X'-fg,  
    'Radius and conic constant of anterior lens mDX UF~G[  
    '************************************************************************* H2oD0f|  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) .;,` bH0  
    GetConic eID, entity, curv, conic uJ9 hU`h  
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    SetConic eID, entity, 1/Rant, CCant tYST&5Kh~  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant `\Ye:$q  
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    '************************************************************************* }h=}!R'm   
    'Radius and conic constant of posterior lens [MI?  
    '************************************************************************* "Iu Pg=|#  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) e4<[|B!O  
    GetConic eID, entity, curv, conic ^W*3S[-`g  
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    SetConic eID, entity, 1/Rpost, CCpost B +<i=w  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 5q95.rw  
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    '************************************************************************* s.j6" Q[W  
    'Lens thickness (Position of posterior lens surface) ~;D5j) 9I  
    '************************************************************************* uz'MUT(68  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) rOA{8)jIa*  
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    ' Delete any z-shift(s) -kkp Ew\  
    count = 0 </-aG[Fi  
    While GetOperationCount(eID)>count B82SAV/O  
        GetOperation eID, count, op Q=n2frW(T  
        If op.Type="ShiftZ" Then "R % 3v.Z  
            DeleteOperation eID,count v FWg0 $,  
            count=count-1 K!jMW  
        End If lSK<LytB  
        count=count+1 (>M? iB  
    Wend eccJt  
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    'Set new z-shift o|bm=&f  
    op.Type = "ShiftZ" IEeh9:Km  
    op.val1 = tlens .F^372hH3  
    op.parent = parID ;JV(!8[  
    AddOperation eID, op c#<p44>U  
    Print "Set lens thickness = " & tlens .g8db d  
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    '************************************************************************* :V ZXI#([  
    'Lens index of refraction y\@INA^  
    '************************************************************************* #2*6esP  
    eID = FindMaterial( "Lens" ) l,@rB+u  
    GetModelMaterial eID, mat V8}jFib  
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    mat.Nd = nlens 2e| m3  
    SetModelMaterial eID, mat AEE&{ _[S  
    Print "Set lens index of refraction = " & nlens $c1xh.  
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    '************************************************************************* $ )orXe|  
    'Pupil diameter `g^bQ x  
    '************************************************************************* Pt\GVWi_t  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) b<\aJb{2  
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    'Adjust pupil diameter (trimming volume inner hole) FfpP<(4  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" R>y/Y<5=  
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    ' Adjust pupil location to just in front of the lens RZbiiMC>  
    parID = FindFullName( "Geometry.Arizona Eye" ) E:ti]$$  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) qj1Fj  
    count = 0 v0u, :eZ4  
    While GetOperationCount(eID)>count c$b~? Mx  
        GetOperation eID, count, op |h^]`= 3  
        If op.Type="ShiftZ" Then f <pJ_  
            DeleteOperation eID,count ]CGH )4Pe  
            count=count-1 :]uz0s`>  
        End If :)DvZxHE@  
        count=count+1 5\.w\  
    Wend /y[zOT6  
    op.Type = "ShiftZ" >bbvQb +j  
    op.val1 = taq-0.01 @ @"abhT  
    op.parent = parID ,lb >  
    AddOperation eID, op 't n-o  
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    Print "Set pupil diameter = " & pupilDiam 6~tj"34_  
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    'Update AZ Eye subassembly Description O\q-Ai  
    eID = FindFullName( "Geometry.Arizona Eye" ) 4`'V%)M  
    GetEntity eID, entity H{ I,m-  
    entity.Description = "Accommodation = " & A & "D" ?L+|b5RS  
    SetEntity eID, entity sj8lvIY5  
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    Update :b"&Rc&s.  
    Print "DONE!" ES ?6  
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End Sub 7_CX6:  
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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： Z}yd` 7  
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Accommodation = 4 Diopters )(-aw,i K  
Pupil Diameter = 4 mm rbc7CPq_^  
Set aqueous humor thickness = 2.81 7Y6b<:4j  
Set anterior lens radius = 10.4 and conic constant = -2.375869 yII+#?D  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 ~*hCTqH vN  
Set lens thickness = 3.927 0 LQ%tn  
Set lens index of refraction = 1.42672 o(eh.  
Set pupil diameter = 4 rj/1AK  
DONE! 'H-hp   
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（文章来源：讯技光电）
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