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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 o|zrD~&$  
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。 `@VM<av  
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模型 UE}8Rkt  
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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。 {[YqGv=fF  
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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. v#FJ+  
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光源 q\ \8b{~  
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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。 kxr6sO~  
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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。 Q2_WH)J 3  
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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。 -z>Z0viA  
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图2. 字母F光源的设定方法光 UY}9  
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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 z$I[kR%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。 q:EzKrE  
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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。 ,N))=/  
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图5. 视网膜重点采样规格设定
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脚本 "2vNkO##  
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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： $,z[XM&9)  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 ?C#F?N0  
余下的脚本计算与屈光度有关的所有参数。 N$ qNe'b  
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分析 \U<F\i  
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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。 \ eyQo>(  
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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 )=,9`+Zta  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. &Gy'AUz-  
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Dim entity As T_ENTITY x jP" 'yU  
Dim op As T_OPERATION 9`gGsC  
Dim mat As T_MODELMATERIAL 0%&fUz36E6  
Dim A As Double %xbz&'W,  
Dim pupilDiam As Double =?I1V#.  
Dim eID As Long KH@) +Rj  
Dim parID As Long yoA*\V  
Dim count As Integer &]"_pc/>m  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double qu#@F\gX  
Dim tlens As Double, nlens As Double F|n$0vQ*  
Dim curv As Double, conic As Double *~t$k56  
Dim ok As Long Z>MJ0J76]  
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Sub Main ]Xkc0E1  
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    '用户输入对话框 &:cTo(C'  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 vCU&yXGl  
        TextBox 220,21,40,21,.TextBox1 'default: 0 6_`eTL=G  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 1!v >I"]  
        OKButton 40,91,90,21 ]B[/sqf  
        CancelButton 190,91,90,21 ^&G O4u  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 wJ]$'c3  
        TextBox 220,49,40,21,.TextBox2 'default: 4 L[[H&#\  
    End Dialog ~i_ R%z:y  
    Dim dlg As UserDialog [(e`b  
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    ok = Dialog (dlg) -)->Jx:{  
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    If ok=0 Then    'cancel button was pressed o y%g{,V  
        Print "Execution cancelled." H @&"M%  
        End k}Clq;G  
    End If +IOKE\,Y  
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    'Assign accommodation and pupil diameter & use defaults if field left empty *i]Z=  
    If dlg.TextBox1 = "" Then :EldP,s#x%  
        A = 0           'Default accommodation WG[0$j  
    Else k f K"i  
        A = CDbl(dlg.TextBox1) 3Ns:O2|  
    End If lj}1'K@M  
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    If dlg.TextBox2 = "" Then ~pBxFA  
        pupilDiam = 4   'Default pupil diameter s7)# NT2  
    Else [Xo J7  
        pupilDiam = CDbl(dlg.TextBox2) 5A=xFj{  
    End If |sZ9 /G7  
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    Print " " HIp {< M3  
    Print "Accommodation = " & A & " Diopters" LM`tNZ1Fc!  
    Print "Pupil Diameter = " & pupilDiam & " mm" K v>#  
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    ' Calculate new parameters with accommodation #( Yb lY  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness ,vY I O  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 1p5q}">z  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ah@GSu;7  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens FU v)<rK  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens c$Nl-?W  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 0PX@E-n  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction f*H}eu3/j  
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    'Adjust parameters to account for accommodation sVl:EVv  
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    '************************************************************************* 1~iBzPU2  
    'Aqueous thickness (Position of Lens) BO cEL%+  
    '************************************************************************* 2!& ;ZcT,  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) `fE:5y  
    GetCustomElement eID, entity M(f*hOG{Y  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 2OOj8JS  
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    ' Delete any shift(s) in z JG+o~tQC  
    count = 0 [8g\pPQ  
    While GetOperationCount(eID)>count ZFw743G  
        GetOperation eID, count, op YO4ppL~xe  
        If op.Type="ShiftZ" Then KE1@z]  
            DeleteOperation eID,count 9 u89P  
            count=count-1 )$.9Wl Q  
        End If G!lykk]  
        count=count+1 7.'j~hJL  
    Wend ) W7H{#  
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    'Set new shift in o~N-x*   
    op.Type = "ShiftZ" F>{uB!!L4  
    op.val1 = taq |&*rSp2iH  
    op.parent = parID .:Xe*Q  
    AddOperation eID, op uPD_s[  
    Print "Set aqueous humor thickness = " & taq-0.55 VFp)`+8  
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    '************************************************************************* \FX3=WW  
    'Radius and conic constant of anterior lens \DdVMn  
    '************************************************************************* Ppn ZlGQ6  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ag4^y&  
    GetConic eID, entity, curv, conic 'n`$c{N<tM  
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    SetConic eID, entity, 1/Rant, CCant )u:8Pv  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant m/c~2?-;  
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    '************************************************************************* : .eS|  
    'Radius and conic constant of posterior lens D#(Pg  
    '************************************************************************* ,$*klod  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) #.K&]OV/88  
    GetConic eID, entity, curv, conic C8SNSeg  
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    SetConic eID, entity, 1/Rpost, CCpost c'4 \F9  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost J)~=b_'<  
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    '************************************************************************* RLr-xg$K-t  
    'Lens thickness (Position of posterior lens surface) r!=VV!XZ  
    '************************************************************************* _dY}86{  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) X*;p;N  
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    ' Delete any z-shift(s) [IW7]Fv<F  
    count = 0 ZuON@(  
    While GetOperationCount(eID)>count 7E]l=Z`x  
        GetOperation eID, count, op 5rhdm?Ls0  
        If op.Type="ShiftZ" Then L 3Iz]D3s  
            DeleteOperation eID,count ucO]&'hu:  
            count=count-1 =z dti'2{4  
        End If MYm6C;o$  
        count=count+1 vdM\scO:  
    Wend ~nlY8B(  
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    'Set new z-shift >l[N]CQ  
    op.Type = "ShiftZ" n[7zK'%Dxg  
    op.val1 = tlens z[Qv}pv  
    op.parent = parID ;bbEd'  
    AddOperation eID, op r-uIFhV^  
    Print "Set lens thickness = " & tlens mI18A#[ 3  
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    '************************************************************************* [!$>:_Vq/  
    'Lens index of refraction UJ&,9}L8  
    '************************************************************************* p5hP}Z4r  
    eID = FindMaterial( "Lens" ) 8t"DQ Y-R  
    GetModelMaterial eID, mat we? #)9Q<  
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    mat.Nd = nlens 2HNS|GHb&  
    SetModelMaterial eID, mat :zoX Xo  
    Print "Set lens index of refraction = " & nlens }9dgm[C[b  
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    '************************************************************************* C\[UAxZ3X  
    'Pupil diameter ' ga2C\)  
    '************************************************************************* S] a$w5ZP  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) bL%)k61G_v  
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    'Adjust pupil diameter (trimming volume inner hole) _Fjv.VQ,  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ^m9cEl^:nQ  
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    ' Adjust pupil location to just in front of the lens )}v2Z3:  
    parID = FindFullName( "Geometry.Arizona Eye" ) +d96Z^KUhv  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) VP&lWPA}\$  
    count = 0 /cn_|DwN5  
    While GetOperationCount(eID)>count ??;[`_h{bz  
        GetOperation eID, count, op Z5K,y19/~  
        If op.Type="ShiftZ" Then j.*}W4`Q_  
            DeleteOperation eID,count y.2 SHn0  
            count=count-1 8Sa<I .l  
        End If (@9-"W  
        count=count+1 j7zQ&ANF  
    Wend AnQRSB (  
    op.Type = "ShiftZ" .#}R$}e+  
    op.val1 = taq-0.01 'UKB pm/  
    op.parent = parID {s]eXc]K}  
    AddOperation eID, op t/ w>t! q  
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    Print "Set pupil diameter = " & pupilDiam g=wnly  
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    'Update AZ Eye subassembly Description l0f6Lxfz  
    eID = FindFullName( "Geometry.Arizona Eye" ) #kA+Yqy \)  
    GetEntity eID, entity Y`v&YcX;  
    entity.Description = "Accommodation = " & A & "D" 3ly|y{M",  
    SetEntity eID, entity ~}fpe>M:  
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    Update KAGq\7  
    Print "DONE!" <Z Ls+|1  
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End Sub OB:G5B`  
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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： U.\kAEJ  
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Accommodation = 4 Diopters *!r8HV/<  
Pupil Diameter = 4 mm xfilxd  
Set aqueous humor thickness = 2.81 tfO _b5g  
Set anterior lens radius = 10.4 and conic constant = -2.375869 :HC{6W`$  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 8oK30?  
Set lens thickness = 3.927 Y|",.~  
Set lens index of refraction = 1.42672 OWU]gh@r  
Set pupil diameter = 4 JkTL+obu  
DONE! 8@!SM  
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（文章来源：讯技光电）
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