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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 6Ahr_{  
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。 J@<!q  
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模型 ue9h   
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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。 WRM$DA  
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Table 1. AZ眼睛模型的定义
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在FRED中使用0屈光度来创建的，光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. M[z3 f  
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光源 %,;gP.dh7  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 [` 9^QEj  
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[attachment=67932]
图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 - 3]|[  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 HTN$ >QTI  
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图2. 字母F光源的设定方法光 P'F~\**5  
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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 e&ts\0  
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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。 p}BGw:=  
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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。 oX*b<d{\N  
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图5. 视网膜重点采样规格设定
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脚本 |G=FqAX H  
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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： I3An57YV].  
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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。 zQt1;bo  
余下的脚本计算与屈光度有关的所有参数。 jf8w7T  
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分析 G}q<{<+$  
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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。 2;h+;G  
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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 /wlFD,+8  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. ^} tuP  
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Dim entity As T_ENTITY {F/q{c~]  
Dim op As T_OPERATION xjE7DCmA  
Dim mat As T_MODELMATERIAL K,]woNxaw  
Dim A As Double <oQ6ZX  
Dim pupilDiam As Double wZ O@J|  
Dim eID As Long VH[l\I(h  
Dim parID As Long Z"]xdOre  
Dim count As Integer *iYMX[$  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double !L/tLHk+  
Dim tlens As Double, nlens As Double w~p4S+k&  
Dim curv As Double, conic As Double Z|}H^0~7S  
Dim ok As Long PQi }Evxa  
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Sub Main =^#0.  
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    '用户输入对话框 ps "9;4P  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 vWuyft*  
        TextBox 220,21,40,21,.TextBox1 'default: 0 !%X>rGkc  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 }&C dsCM>2  
        OKButton 40,91,90,21 3eJ\aVI>pE  
        CancelButton 190,91,90,21 KoFv0~8Q  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 M*v^N]>"G  
        TextBox 220,49,40,21,.TextBox2 'default: 4 }=TqJy1  
    End Dialog =?^-P{:\?  
    Dim dlg As UserDialog 6R L~iD;X  
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    ok = Dialog (dlg) Nz}|%.GP"  
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    If ok=0 Then    'cancel button was pressed I{Rz,D uAL  
        Print "Execution cancelled." 9OH.&g  
        End  GsI[N%  
    End If "--/v. Cs  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 2lF WW(  
    If dlg.TextBox1 = "" Then C"k2<IE  
        A = 0           'Default accommodation g^qz&;R]  
    Else `d.Gw+Un  
        A = CDbl(dlg.TextBox1) av"Dljc  
    End If u4@, *tT  
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    If dlg.TextBox2 = "" Then }F~f&<GX6  
        pupilDiam = 4   'Default pupil diameter /nwxuy  
    Else :{x!g6bK@  
        pupilDiam = CDbl(dlg.TextBox2) !,I7 ?O  
    End If xP XoJN  
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    Print " " }#1U D  
    Print "Accommodation = " & A & " Diopters" d~w}NK[(  
    Print "Pupil Diameter = " & pupilDiam & " mm" N|bPhssFw  
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    ' Calculate new parameters with accommodation Pv^(Q ]  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness *sjj"^'=  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens B>ms`|q=l  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens 8}Fw%;Cb  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens bXa %EMF  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 3csm`JVK  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ?ykVfO'  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 38Bnf  
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    'Adjust parameters to account for accommodation x8\E~6`,  
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    '************************************************************************* zv8aV2?D  
    'Aqueous thickness (Position of Lens) 45]Ym{]  
    '************************************************************************* !%SdTaC{T  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) aeN }hG  
    GetCustomElement eID, entity lCM6T;2ID  
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    parID = FindFullName( "Geometry.Arizona Eye" ) tI/mE[W  
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    ' Delete any shift(s) in z @9 n #vs  
    count = 0 <B|n<R<?  
    While GetOperationCount(eID)>count AAIyr703cQ  
        GetOperation eID, count, op }CB=c]p  
        If op.Type="ShiftZ" Then QO1A976o  
            DeleteOperation eID,count "Nk=g~|  
            count=count-1 /\IAr,w[  
        End If d A_S"Zc  
        count=count+1 X67C;H+  
    Wend @d8&3@{R^  
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    'Set new shift in Pn'QOVy  
    op.Type = "ShiftZ" .y/NudD  
    op.val1 = taq $@+p~)r(l  
    op.parent = parID y9l#;<b  
    AddOperation eID, op 7Va#{Y;Zy  
    Print "Set aqueous humor thickness = " & taq-0.55 N"q+UCRC  
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    '************************************************************************* *IMF4 x5M  
    'Radius and conic constant of anterior lens i_oro "%yL  
    '************************************************************************* qaCi)f!Dl  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) DK#65H'  
    GetConic eID, entity, curv, conic ZNL;8sI?>  
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    SetConic eID, entity, 1/Rant, CCant O+{pF.P#V  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ($ [r>)TG  
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    '************************************************************************* Cu)%s  
    'Radius and conic constant of posterior lens [9YlLL@  
    '************************************************************************* dw{#||  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 0`g}(}'L  
    GetConic eID, entity, curv, conic 34++Rr [G  
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    SetConic eID, entity, 1/Rpost, CCpost ,J`lr U0  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost LX(iuf+l  
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    '************************************************************************* V,|Bzcz  
    'Lens thickness (Position of posterior lens surface) `a/PIc"  
    '************************************************************************* kMJQeo79  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) MQbNWUi  
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    ' Delete any z-shift(s) Eezlx9b  
    count = 0 }LHT#{+ x  
    While GetOperationCount(eID)>count k^'d@1z;C  
        GetOperation eID, count, op <x>k3bD  
        If op.Type="ShiftZ" Then N18diP[C  
            DeleteOperation eID,count .JD4gF2N  
            count=count-1 3-_U-:2"  
        End If `DWi4y7  
        count=count+1 yuy+}]uB@  
    Wend **w*hd]  
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    'Set new z-shift {g:/ BFLr#  
    op.Type = "ShiftZ" @3expC  
    op.val1 = tlens ~H yyq-  
    op.parent = parID jV|$? Rcl%  
    AddOperation eID, op NZ%~n:/V#  
    Print "Set lens thickness = " & tlens G\,A> mT/P  
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    '************************************************************************* }G,SqpcG  
    'Lens index of refraction {Y@-*pL]  
    '************************************************************************* ^]sMy7X0IK  
    eID = FindMaterial( "Lens" ) kb}]sj  
    GetModelMaterial eID, mat _?(hWC"0  
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    mat.Nd = nlens _'v }=:X  
    SetModelMaterial eID, mat vElL.<..  
    Print "Set lens index of refraction = " & nlens &"H<+>`  
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    '************************************************************************* utm+\/  
    'Pupil diameter !+|N<`  
    '************************************************************************* G(|(y=ck  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) p$b= r+1f  
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    'Adjust pupil diameter (trimming volume inner hole) OL ]T+6X  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" |>/&EElD  
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    ' Adjust pupil location to just in front of the lens < jocfTBk  
    parID = FindFullName( "Geometry.Arizona Eye" ) m^oi4mV  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) <*(UvOQuX  
    count = 0 /YugQ.>| l  
    While GetOperationCount(eID)>count %6c*dy  
        GetOperation eID, count, op }2!5#/^~  
        If op.Type="ShiftZ" Then T.m)c%]^/  
            DeleteOperation eID,count 4k&O-70y4^  
            count=count-1 {+UNjKQC  
        End If k.%W8C<Pa  
        count=count+1 !K^Z5A_;  
    Wend <}Wy;!L  
    op.Type = "ShiftZ" fF-\TW  
    op.val1 = taq-0.01 }$k`[ivBx(  
    op.parent = parID 6q uWO2x  
    AddOperation eID, op 8,H5G`  
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    Print "Set pupil diameter = " & pupilDiam 3_eml\CY  
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    'Update AZ Eye subassembly Description `@.s!L(V  
    eID = FindFullName( "Geometry.Arizona Eye" ) *ZSp9g"Z  
    GetEntity eID, entity /%q9hI   
    entity.Description = "Accommodation = " & A & "D" !wb~A0m  
    SetEntity eID, entity ^(m6g&$(  
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    Update LX?r=_\  
    Print "DONE!" N5an9r&z(1  
     \A\yuJ=  
End Sub UE#Ni 5  
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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： IweK!,:>dN  
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Accommodation = 4 Diopters 't%%hw-m}  
Pupil Diameter = 4 mm -S3+ h$Y8  
Set aqueous humor thickness = 2.81 <%#y^_  
Set anterior lens radius = 10.4 and conic constant = -2.375869 &'ETx"  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 .s*EV!SE  
Set lens thickness = 3.927 >=W#z  
Set lens index of refraction = 1.42672 S{)n0/_  
Set pupil diameter = 4 [dF=1E>W_J  
DONE! 6p6Tse]  
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（文章来源：讯技光电）
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