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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 &# @"^(} 6  
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。 3ep L'My$  
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模型 AI .2os*  
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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。 z=LO$,JW`  
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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. iz-O~T/^  
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光源 $-)y59w"  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 K$M,d - `b  
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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。 *oIKddZh  
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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。 87nsWBe  
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图2. 字母F光源的设定方法光 _[ `"E'  
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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 5gPAX $jH  
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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。 OZh+x`' #  
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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。 5{6ebq55"  
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图5. 视网膜重点采样规格设定
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脚本 g:c @  
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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： KBGJB`D*  
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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。 P.1iuZ "w  
余下的脚本计算与屈光度有关的所有参数。 c5rQkDW  
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分析 cWM|COXL+  
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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。 ^ihXM]1{G  
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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 o6K BJx  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. C12 7he  
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Dim entity As T_ENTITY Pjb9FCA'  
Dim op As T_OPERATION mLY*  
Dim mat As T_MODELMATERIAL 5\Y/so=  
Dim A As Double #CQ>d8&  
Dim pupilDiam As Double L kq>>?T=  
Dim eID As Long r IK|}5  
Dim parID As Long A#  M  
Dim count As Integer IfXLnD^||  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double f|^f^Hu:{  
Dim tlens As Double, nlens As Double hy)RV=X  
Dim curv As Double, conic As Double MM8)yCI  
Dim ok As Long P/PS(`  
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Sub Main _gGy(`  
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    '用户输入对话框 #EM'=Q%TO  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 86I*  
        TextBox 220,21,40,21,.TextBox1 'default: 0 1a!h&!$9  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Elq8WtS  
        OKButton 40,91,90,21 NR[mzJv  
        CancelButton 190,91,90,21 fIcv}Y  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 nz',Zm},  
        TextBox 220,49,40,21,.TextBox2 'default: 4 -?'CUm*Od  
    End Dialog '~cEdGD9H  
    Dim dlg As UserDialog IyuT=A~Ki  
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    ok = Dialog (dlg) .2P?1HpK  
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    If ok=0 Then    'cancel button was pressed 8dhY"&  
        Print "Execution cancelled." u@E M,o  
        End :qp"Ao{M  
    End If zef,*dQY   
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    'Assign accommodation and pupil diameter & use defaults if field left empty bH{aI:9Fb  
    If dlg.TextBox1 = "" Then $(R) =4  
        A = 0           'Default accommodation YeLOd  
    Else ]EnaZWyO]  
        A = CDbl(dlg.TextBox1) ;" *`  
    End If d/>,U7eS[+  
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    If dlg.TextBox2 = "" Then C(|5,P#5  
        pupilDiam = 4   'Default pupil diameter [BBKj)IK  
    Else YMTA`T(+  
        pupilDiam = CDbl(dlg.TextBox2) !f-o,RJ  
    End If v`BG1&/|  
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    Print " " ~,68S^nP)H  
    Print "Accommodation = " & A & " Diopters" ] <3?=$  
    Print "Pupil Diameter = " & pupilDiam & " mm" <WJ0St  
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    ' Calculate new parameters with accommodation 5]l7Z35  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness |S:!+[  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens \_AEuz3 F  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens |u r~s$8y-  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ~hslLUE  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens aSkx#mV  
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    tlens = 3.767 + 0.04*A                  'Lens thickness @) ZO$h  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction zWs*kTtA  
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    'Adjust parameters to account for accommodation 5f'g 3'  
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    '************************************************************************* Tj21YK.mk  
    'Aqueous thickness (Position of Lens) `XSc >  
    '************************************************************************* aXbNDj ][  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) M2E87w  
    GetCustomElement eID, entity (vAv^A*i}  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 3$N %iE6  
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    ' Delete any shift(s) in z .D,?u"fk|  
    count = 0 4Wla&yy  
    While GetOperationCount(eID)>count :-u-hO5*8  
        GetOperation eID, count, op A?Nn>xF9X  
        If op.Type="ShiftZ" Then m c\ C  
            DeleteOperation eID,count &#-|Yh/  
            count=count-1 >{ECyh;  
        End If dF{6>8D=5B  
        count=count+1 nR o=J5tY  
    Wend L7Qo-  
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    'Set new shift in mX@j  
    op.Type = "ShiftZ" xHv|ca.E  
    op.val1 = taq t}]9VD9  
    op.parent = parID ?-8y4 Ex  
    AddOperation eID, op :/@k5#DY  
    Print "Set aqueous humor thickness = " & taq-0.55 nY{i>Y  
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    '************************************************************************* { r6]MS#l1  
    'Radius and conic constant of anterior lens }c` ?0FQ  
    '************************************************************************* k;;nE o~6  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) X2 \E9hJg  
    GetConic eID, entity, curv, conic ;Ze"<U  
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    SetConic eID, entity, 1/Rant, CCant 4ef*9|^x#  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant yy1>r }L  
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    '************************************************************************* Z$!C=  
    'Radius and conic constant of posterior lens :v#k&Uh3y  
    '************************************************************************* ,'FD}yw4v  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) A#Xj]^-*  
    GetConic eID, entity, curv, conic H9%l?r5  
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    SetConic eID, entity, 1/Rpost, CCpost d@-wi%,^  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost gWFL  
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    '************************************************************************* TkA9tFi  
    'Lens thickness (Position of posterior lens surface) jEZ "  
    '*************************************************************************  Nm jzDN  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 9n_ eCb)H  
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    ' Delete any z-shift(s) [FB&4>V/  
    count = 0 7. %f01/i  
    While GetOperationCount(eID)>count !loO%3_)  
        GetOperation eID, count, op BApa^j\?  
        If op.Type="ShiftZ" Then %n jOX#.w  
            DeleteOperation eID,count F\JLbY{x]  
            count=count-1 #De(*&y2  
        End If pNuqT*  
        count=count+1 . /Y&\<  
    Wend zgK;4 22$m  
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    'Set new z-shift XHy ?  
    op.Type = "ShiftZ" 7 xUE,)?  
    op.val1 = tlens Im6U_JsNZh  
    op.parent = parID t{~@I  
    AddOperation eID, op z=B< `}@3  
    Print "Set lens thickness = " & tlens cu<y8 :U<  
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    '************************************************************************* {f-XyF1`  
    'Lens index of refraction .W$ sxVXB  
    '************************************************************************* U3/8A:$y  
    eID = FindMaterial( "Lens" ) /V#7=,,  
    GetModelMaterial eID, mat B7|c`7x(  
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    mat.Nd = nlens )&Mq,@  
    SetModelMaterial eID, mat O MvT;Vgg  
    Print "Set lens index of refraction = " & nlens LaclC]yLU  
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    '************************************************************************* 7x(v?  
    'Pupil diameter <}cZi4l'  
    '************************************************************************* hox< vr4  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) l77'Lne  
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    'Adjust pupil diameter (trimming volume inner hole) .+HcAx{/2  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" e+{BJN vz  
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    ' Adjust pupil location to just in front of the lens ~XKZXGw  
    parID = FindFullName( "Geometry.Arizona Eye" ) _-RyHgX  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) >9MS" t  
    count = 0 FllX za)  
    While GetOperationCount(eID)>count G1/Gq.<  
        GetOperation eID, count, op Hr&Ere8.4p  
        If op.Type="ShiftZ" Then o[oqPN3$Y  
            DeleteOperation eID,count ?aFZOc4   
            count=count-1 ($'V& x8T  
        End If ) P%4:P  
        count=count+1 {!r#f(?uT  
    Wend D7gHE  
    op.Type = "ShiftZ" 7 OWsHlU  
    op.val1 = taq-0.01 %{"dP%|w4}  
    op.parent = parID #Z0-8<\  
    AddOperation eID, op d>/Tu_ y  
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    Print "Set pupil diameter = " & pupilDiam G AEZY  
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    'Update AZ Eye subassembly Description *uU4^E(  
    eID = FindFullName( "Geometry.Arizona Eye" ) \447]<u  
    GetEntity eID, entity Zw24f1iY  
    entity.Description = "Accommodation = " & A & "D" SBL+e]P  
    SetEntity eID, entity _r5wF(Y?7  
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    Update ?;RD u[eD  
    Print "DONE!" In+^V([u+_  
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End Sub Z'ao[CG  
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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： 9 rS, ?  
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Accommodation = 4 Diopters UFf,+4q  
Pupil Diameter = 4 mm \HD-vINV;  
Set aqueous humor thickness = 2.81 Man^<T%F  
Set anterior lens radius = 10.4 and conic constant = -2.375869 ;j!UY.i  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 M}KZG'7  
Set lens thickness = 3.927 KC]tY9 FK  
Set lens index of refraction = 1.42672 'e85s%ru  
Set pupil diameter = 4 `@MPkC y1  
DONE! _Fxe|"<^  
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（文章来源：讯技光电）
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