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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 4?;1cXXA  
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。 [/6IEt3}B  
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模型 S'lZ'H/  
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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。 0Kq\ oMn  
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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. % ?@PlQ  
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光源 UJ2Tj+  
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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。 y.HE3tH  
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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。 ^F/N-!}q  
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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。 =;4cDmZh  
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图2. 字母F光源的设定方法光 9m/v^  
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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 TkM8GK-3  
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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。 jA?A)YNQb  
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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。 oYG9i=lZ  
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图5. 视网膜重点采样规格设定
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脚本 +mIO*UQi  
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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： bH%k)  
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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。 N =FX3Z  
余下的脚本计算与屈光度有关的所有参数。 P-o/ax  
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分析 >4b:`L  
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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。 x1VBO.t=*  
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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 hd0d gc  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. SaceIV%(  
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Dim entity As T_ENTITY c5C 2xE}T  
Dim op As T_OPERATION jM]B\cvN  
Dim mat As T_MODELMATERIAL TwJiYXHw?  
Dim A As Double W5z<+8R  
Dim pupilDiam As Double <#/r.}.x  
Dim eID As Long \]uD"Jqv#  
Dim parID As Long K9O%SfshF  
Dim count As Integer .$&mWytw=  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double jGy%O3/  
Dim tlens As Double, nlens As Double Mm7;'Zbg  
Dim curv As Double, conic As Double :59fb"^$  
Dim ok As Long je LRS8];  
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Sub Main G%5bQ|O  
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    '用户输入对话框 9j<qi\SSI  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 qw?#~"Ca.  
        TextBox 220,21,40,21,.TextBox1 'default: 0 #@%DY*w]v  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ^F\RM4|,  
        OKButton 40,91,90,21 OD{()E?1B  
        CancelButton 190,91,90,21 T6mbGE*IeE  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 r'*x><m'  
        TextBox 220,49,40,21,.TextBox2 'default: 4 E/+H~YzO  
    End Dialog @ByD=  
    Dim dlg As UserDialog VS` tj  
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    ok = Dialog (dlg) 0APh=Alq  
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    If ok=0 Then    'cancel button was pressed n1!hfu7@s  
        Print "Execution cancelled." .kwz$b+h  
        End }OZut!_  
    End If m{#?fR=9  
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    'Assign accommodation and pupil diameter & use defaults if field left empty =f~8"j  
    If dlg.TextBox1 = "" Then ]cQYSN7!SY  
        A = 0           'Default accommodation AUk-[i  
    Else A$ 2AYQ  
        A = CDbl(dlg.TextBox1) xD.Uh}:J  
    End If =#=<%HPT  
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    If dlg.TextBox2 = "" Then X%X`o%AqC  
        pupilDiam = 4   'Default pupil diameter 1F|e/h%^  
    Else v;6O# ta'  
        pupilDiam = CDbl(dlg.TextBox2) Q' b@5o  
    End If FT'2 J  
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    Print " " xgp 6lO[  
    Print "Accommodation = " & A & " Diopters" vD-m FC)  
    Print "Pupil Diameter = " & pupilDiam & " mm" ccR#<Pb6q  
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    ' Calculate new parameters with accommodation Th.Mn}1%L  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 3bsuE^,.@  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ;15 j\{r  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens pZxuV(QP`  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ,vcg%~-  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens |7CFm  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 0%(.$c>:f  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction {D{' \]+  
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    'Adjust parameters to account for accommodation x& a<u@[wa  
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    '************************************************************************* HuI?kLfj\  
    'Aqueous thickness (Position of Lens) 1Zo"Xb  
    '************************************************************************* eo [eN.  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) Dve+ #H6N  
    GetCustomElement eID, entity '}5Yc,  
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    parID = FindFullName( "Geometry.Arizona Eye" ) [,a2A  
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    ' Delete any shift(s) in z H13kNhV9  
    count = 0 b # |  
    While GetOperationCount(eID)>count sx^0*h-Qq  
        GetOperation eID, count, op {t%Jc~p{  
        If op.Type="ShiftZ" Then K@<%Vc>L(  
            DeleteOperation eID,count CT0 ~  
            count=count-1 "3;b,<0  
        End If 9ao GptgN  
        count=count+1 1@Gmzh  
    Wend  o%SD\zk  
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    'Set new shift in UFl+|wf  
    op.Type = "ShiftZ" &;2@*#,  
    op.val1 = taq 'DdR2  
    op.parent = parID y[A%EMd  
    AddOperation eID, op =}K"@5J  
    Print "Set aqueous humor thickness = " & taq-0.55 Dt~ |)L+  
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    '************************************************************************* 1yd}F`{8UF  
    'Radius and conic constant of anterior lens E[a|.lnV  
    '************************************************************************* V`& O`  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) Z=.$mFE\  
    GetConic eID, entity, curv, conic mmvo >F"  
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    SetConic eID, entity, 1/Rant, CCant 7^FJ+gN8b  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant }UzRFIcv  
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    '************************************************************************* }!9KxwC(  
    'Radius and conic constant of posterior lens /v-:ca)7mI  
    '************************************************************************* ZW@%>_JR]  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) a+=.(g  
    GetConic eID, entity, curv, conic x_oiPu.V  
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    SetConic eID, entity, 1/Rpost, CCpost (iJ9ekB  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 7GDrH/yK  
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    '************************************************************************* $2/v8  
    'Lens thickness (Position of posterior lens surface) *-`-P  
    '************************************************************************* s ;2ih)[  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ?Rd{`5.D  
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    ' Delete any z-shift(s) hF^y4v|5  
    count = 0 '`sZo1x%f  
    While GetOperationCount(eID)>count T=,A pa  
        GetOperation eID, count, op LK:Jkjp^  
        If op.Type="ShiftZ" Then nm#,oX2C  
            DeleteOperation eID,count JU3to_Io  
            count=count-1 A +41JMH  
        End If B>UF dj]-  
        count=count+1 .I%`yhCW  
    Wend 4GqwY"ja  
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    'Set new z-shift *bSxobn  
    op.Type = "ShiftZ" #p7K2  
    op.val1 = tlens ?rxq//S2  
    op.parent = parID +)ba9bJ|  
    AddOperation eID, op k9m9IE"9=$  
    Print "Set lens thickness = " & tlens m <'&`B;  
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    '************************************************************************* f!Mx +ky  
    'Lens index of refraction v}sk %f  
    '************************************************************************* 952l1c!  
    eID = FindMaterial( "Lens" ) Sp/<%+2(  
    GetModelMaterial eID, mat RdqB^>X  
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    mat.Nd = nlens :r4o:@N'  
    SetModelMaterial eID, mat de_%#k1:L  
    Print "Set lens index of refraction = " & nlens iHKX#*  
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    '************************************************************************* *!^l ZpF  
    'Pupil diameter %:}o\ _w  
    '************************************************************************* ib-H jJ8  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ?egZkg=U  
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    'Adjust pupil diameter (trimming volume inner hole) b?K`DUju{0  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" xG WA5[YV  
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    ' Adjust pupil location to just in front of the lens u'; 9zk/$  
    parID = FindFullName( "Geometry.Arizona Eye" ) J%FF@.)k  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Ajm4q_  
    count = 0 F%IvgXt5  
    While GetOperationCount(eID)>count j;BlpRD}  
        GetOperation eID, count, op K05U>151  
        If op.Type="ShiftZ" Then gy Ey=@L  
            DeleteOperation eID,count 6aKfcvf &  
            count=count-1 B  
        End If ckYT69U  
        count=count+1 E NrcIZ  
    Wend mXs.@u/  
    op.Type = "ShiftZ" y96HTQ32  
    op.val1 = taq-0.01 ;EQ7kuJQ?  
    op.parent = parID #z+?t  
    AddOperation eID, op cH6++r  
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    Print "Set pupil diameter = " & pupilDiam E[cH/Rm  
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    'Update AZ Eye subassembly Description xqb*;TBh*  
    eID = FindFullName( "Geometry.Arizona Eye" ) > f'aW  
    GetEntity eID, entity c~+KrWbZ~  
    entity.Description = "Accommodation = " & A & "D" xp}M5|   
    SetEntity eID, entity =~>g--^U  
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    Update U$ 46=F|  
    Print "DONE!" @b!W8c 6  
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End Sub h[mJ=LIrg  
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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： oFGWI#]ts>  
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Accommodation = 4 Diopters oL~?^`cGZ  
Pupil Diameter = 4 mm L{rd',  
Set aqueous humor thickness = 2.81 S_TD o  
Set anterior lens radius = 10.4 and conic constant = -2.375869 0xY</S  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 z'7XGO'Lo  
Set lens thickness = 3.927 v[r 8-0c  
Set lens index of refraction = 1.42672 q ~^!Ck+#*  
Set pupil diameter = 4 FGzKx9I9  
DONE! s (K SN/  
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（文章来源：讯技光电）
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