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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 zg)-RCG  
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。 aH@GhI^@  
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模型 MBlh lMyI  
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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。 GI:J9TS  
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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. Qv~KGd9  
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光源 A}K2"lQ#>,  
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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。 1$1s 0yg  
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图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 7;]n+QRfm  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 O+ ].'  
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图2. 字母F光源的设定方法光 qyA%_;ReMY  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 jS_fwuM  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 fU?P__zU4  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 Ab| t E5%  
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图5. 视网膜重点采样规格设定
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脚本 fgzkc"ReK  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： /iz{NulOz*  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 -eZ$wn![  
余下的脚本计算与屈光度有关的所有参数。 |Z ), OW  
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分析 +>v3&[lGv  
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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。 "'# 18&N  
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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 QJeL&mf  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. MM+x}g.?  
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Dim entity As T_ENTITY +JDQ`Qk  
Dim op As T_OPERATION {>x6SVF  
Dim mat As T_MODELMATERIAL J(0E'o{ug  
Dim A As Double o8PK,!Pl  
Dim pupilDiam As Double 9FGe (t <  
Dim eID As Long >#9 f{  
Dim parID As Long H K]-QTEn  
Dim count As Integer CtEpS<*c  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ;7;=)/-  
Dim tlens As Double, nlens As Double \B72 # NR  
Dim curv As Double, conic As Double G)(vd0X1  
Dim ok As Long ~2HlAU))<&  
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Sub Main ( pDu  
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    '用户输入对话框 w)nFH)f  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 PG51+#  
        TextBox 220,21,40,21,.TextBox1 'default: 0 }fS`jq;  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 `f|Gw5R  
        OKButton 40,91,90,21 _S$ SL%;\  
        CancelButton 190,91,90,21 E4C yW  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 BXzn-S  
        TextBox 220,49,40,21,.TextBox2 'default: 4 4V6^@   
    End Dialog 2aDjt{7P  
    Dim dlg As UserDialog Lm!/ iseGv  
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    ok = Dialog (dlg) >e'Hz(~'/  
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    If ok=0 Then    'cancel button was pressed 3dl#:Si  
        Print "Execution cancelled." uG\ @e'pr  
        End oJ:\8>)9  
    End If XCN^>ToD  
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    'Assign accommodation and pupil diameter & use defaults if field left empty qk+RZ>T<o  
    If dlg.TextBox1 = "" Then .kl.awT  
        A = 0           'Default accommodation O ,9,= 2j  
    Else jmE\+yz  
        A = CDbl(dlg.TextBox1) EF8~rKO3  
    End If &E/0jxM1  
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    If dlg.TextBox2 = "" Then X2[d15!9  
        pupilDiam = 4   'Default pupil diameter @5=2+ M  
    Else 9%^IMUWA  
        pupilDiam = CDbl(dlg.TextBox2) +46m~" ]  
    End If 4#MPD  
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    Print " " *WQl#JAr  
    Print "Accommodation = " & A & " Diopters" 0etJ, _">  
    Print "Pupil Diameter = " & pupilDiam & " mm" q r<+@Q  
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    ' Calculate new parameters with accommodation 2[V9`r8*  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness "0V8i%a  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens LQo>wl  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens =[ +)T[  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens n>o0PtGxC  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens eoGGWW@[  
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    tlens = 3.767 + 0.04*A                  'Lens thickness &*\-4)Tf  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 6?(Z f  
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    'Adjust parameters to account for accommodation U4.- {.  
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    '************************************************************************* V."qxKsz  
    'Aqueous thickness (Position of Lens) c_N'S_)~7Q  
    '************************************************************************* l`b%imX  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) /ygC_,mx  
    GetCustomElement eID, entity &2Q0ii#Aa  
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    parID = FindFullName( "Geometry.Arizona Eye" ) \Um &  
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    ' Delete any shift(s) in z * ak"}s  
    count = 0 U 6`E\?d`  
    While GetOperationCount(eID)>count !]l!I9  
        GetOperation eID, count, op bpaS(nBy  
        If op.Type="ShiftZ" Then = a54  
            DeleteOperation eID,count W*!u_]K>  
            count=count-1 +wpQ$)\  
        End If %gbvX^E?  
        count=count+1 km=d'VvnI  
    Wend 2+'4m#@)  
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    'Set new shift in n B. u5  
    op.Type = "ShiftZ" g+zfa.wQ  
    op.val1 = taq FJC}xEMcN  
    op.parent = parID MVYf-'\^  
    AddOperation eID, op ;p] f5R^  
    Print "Set aqueous humor thickness = " & taq-0.55 IPxK$nI^  
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    '************************************************************************* 92pl#Igt  
    'Radius and conic constant of anterior lens i4g99Kvl  
    '************************************************************************* ,Srj38p  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) bi<?m^j  
    GetConic eID, entity, curv, conic 0'nY  
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    SetConic eID, entity, 1/Rant, CCant Uoqt  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant E==vk~cz  
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    '************************************************************************* Xt%>XP  
    'Radius and conic constant of posterior lens slRD /  
    '************************************************************************* lE 09Y  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) C0#"U f  
    GetConic eID, entity, curv, conic [ KT1.5M[  
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    SetConic eID, entity, 1/Rpost, CCpost &LM ^,xx}  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost nLjc.Z\Bl  
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    '************************************************************************* p(`?y:.3  
    'Lens thickness (Position of posterior lens surface) :,*{,^2q:  
    '************************************************************************* zZ})$Ny(  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) #->#mshd4  
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    ' Delete any z-shift(s) f83Tl~  
    count = 0 B 4my  
    While GetOperationCount(eID)>count u''~nSR3&  
        GetOperation eID, count, op 8Z1pQx-P2C  
        If op.Type="ShiftZ" Then $Eh8s(  
            DeleteOperation eID,count rZSX fgfr  
            count=count-1 ye^l~  
        End If ?=^ M(TA;  
        count=count+1 yw{;Qm2\7  
    Wend 8Ug`2xS<_  
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    'Set new z-shift 1~_&XNb&  
    op.Type = "ShiftZ" I6B4S"Q5<  
    op.val1 = tlens Rd|xw%R\mb  
    op.parent = parID g#b uy  
    AddOperation eID, op kIlK"=  
    Print "Set lens thickness = " & tlens [ta3sEPjs  
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    '************************************************************************* D/7hVwMw:  
    'Lens index of refraction {;[W'Lc  
    '************************************************************************* 2ij/!  
    eID = FindMaterial( "Lens" ) KfkE'_ F  
    GetModelMaterial eID, mat B6hd*f  
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    mat.Nd = nlens f:6%DT~a&C  
    SetModelMaterial eID, mat I'$}n$UvZ  
    Print "Set lens index of refraction = " & nlens '<v_YxEn  
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    '************************************************************************* fNllF,8}  
    'Pupil diameter M!nwcxB!  
    '************************************************************************* oPVyLD  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) e9e7_QG_-  
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    'Adjust pupil diameter (trimming volume inner hole) ^>H+#@R  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ;p U=>  
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    ' Adjust pupil location to just in front of the lens &GetRDr  
    parID = FindFullName( "Geometry.Arizona Eye" ) 057$b!A-a  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) LNR~F_64Q  
    count = 0 ""2g{!~r  
    While GetOperationCount(eID)>count `OP?[ f d  
        GetOperation eID, count, op X|3l*FL  
        If op.Type="ShiftZ" Then i9FtS7  
            DeleteOperation eID,count `4N{x.N  
            count=count-1  #Lq{_Y  
        End If x22:@Ot6  
        count=count+1 YKZk/m&H  
    Wend ])YGeY(V0+  
    op.Type = "ShiftZ" *gxo! F}  
    op.val1 = taq-0.01 i8Y$cac!  
    op.parent = parID buv*qPO  
    AddOperation eID, op iH#b"h{w  
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    Print "Set pupil diameter = " & pupilDiam ag \d4y6  
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    'Update AZ Eye subassembly Description 01P ~K|s  
    eID = FindFullName( "Geometry.Arizona Eye" ) ,*w  
    GetEntity eID, entity V&>\U?q:  
    entity.Description = "Accommodation = " & A & "D" ZJ7<!?6  
    SetEntity eID, entity kQY+D1  
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    Update cx(W{O"Jb  
    Print "DONE!" Q4&|^RLLG  
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End Sub ;N FTdP  
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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： %488"  
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Accommodation = 4 Diopters   ps*dO  
Pupil Diameter = 4 mm %%w/;o!c  
Set aqueous humor thickness = 2.81 j+>#.22+  
Set anterior lens radius = 10.4 and conic constant = -2.375869 (DW[#2\.  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 8sV_@<l<X  
Set lens thickness = 3.927 N%,!&\L  
Set lens index of refraction = 1.42672 v\UwL-4[  
Set pupil diameter = 4 { _]'EK/w  
DONE! Po: )b  
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（文章来源：讯技光电）
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