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infotek 2020-12-09 09:18

Arizona眼睛模型

简介 bmC{d  
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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。 _t7aOH  
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模型 P= 26! b  
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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。 ][Cg8  
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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. ~ Q;qRx  
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光源 !uHVg(}  
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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`&"U[{  
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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。 Pu]Pp`SP  
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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。 [%6"UH r  
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图2. 字母F光源的设定方法光 p?sC</R  
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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 bu r0?q  
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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。 #ruL+- 8!<  
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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。 lxD~[e  
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图5. 视网膜重点采样规格设定
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脚本 -Fs<{^E3j  
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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: D j@7vM%_  
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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。 niJtgK:H^  
余下的脚本计算与屈光度有关的所有参数。 Bgj^n{9x  
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分析 C.;H?So(  
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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。 1$ C\ `  
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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 %oE3q>S$en  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. <C,lHt  
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Dim entity As T_ENTITY .a`(?pPr,  
Dim op As T_OPERATION 6Z3L=j  
Dim mat As T_MODELMATERIAL o& "nF+,  
Dim A As Double 8!(09gW'>  
Dim pupilDiam As Double -9z!fCu3  
Dim eID As Long _B5v&# h(.  
Dim parID As Long m<uBRI*I  
Dim count As Integer U0X? ~ 1  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double (7_}UT@w-  
Dim tlens As Double, nlens As Double &`IC 3O5  
Dim curv As Double, conic As Double }grel5lq  
Dim ok As Long )Cfk/OnRd  
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Sub Main zBTyRL l  
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    '用户输入对话框 m]#oZVngy  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 z->[:)c  
        TextBox 220,21,40,21,.TextBox1 'default: 0 5ps7)]  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ,4tuWO)"  
        OKButton 40,91,90,21 eQqx0+-0c  
        CancelButton 190,91,90,21 HSsG0&'-Y  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 V*1hoC#  
        TextBox 220,49,40,21,.TextBox2 'default: 4 "MNI_C#{  
    End Dialog nkn4VA?"  
    Dim dlg As UserDialog sw^4h`^'  
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    ok = Dialog (dlg) *kE<7  
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    If ok=0 Then    'cancel button was pressed [Y_CRxa\u  
        Print "Execution cancelled." -- chU5  
        End 6A9 r{'1  
    End If qPG>0 O  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ]n9gnE  
    If dlg.TextBox1 = "" Then o1zKns?  
        A = 0           'Default accommodation ]Ll<Z  
    Else &K.js  
        A = CDbl(dlg.TextBox1) -L&%,%  
    End If s7> a  
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    If dlg.TextBox2 = "" Then MGU%"7i'}  
        pupilDiam = 4   'Default pupil diameter o3OtG#g2  
    Else X&14;lu%p  
        pupilDiam = CDbl(dlg.TextBox2) GI _.[  
    End If $WS?/H0C  
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    Print " " p]E\!/  
    Print "Accommodation = " & A & " Diopters" jC}2>_#m(  
    Print "Pupil Diameter = " & pupilDiam & " mm" zD,K_HicI  
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    ' Calculate new parameters with accommodation WAqH*LB  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness mx3p/p  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens [.j&~\AG  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens _ ,~D]JYE  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens >#Ue`)d`aY  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens .Gq]Mrim9G  
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    tlens = 3.767 + 0.04*A                  'Lens thickness Rw!wfh_+  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction )N'rYS' 9  
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    'Adjust parameters to account for accommodation jH~VjE>  
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    '************************************************************************* wMvAm%}+  
    'Aqueous thickness (Position of Lens) V3v/h V:  
    '************************************************************************* DICS6VG}  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 'M!*Ge  
    GetCustomElement eID, entity '?)<e^  
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    parID = FindFullName( "Geometry.Arizona Eye" ) LzGSN  
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    ' Delete any shift(s) in z eB2a1<S&@  
    count = 0 _y5J]Yu`j  
    While GetOperationCount(eID)>count 1}ER+;If  
        GetOperation eID, count, op -ztgirU  
        If op.Type="ShiftZ" Then =GJ)4os  
            DeleteOperation eID,count YG K7b6  
            count=count-1 wGhy"1g#  
        End If 'gv ~M_  
        count=count+1 gEISnMH  
    Wend bSgdVP-  
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    'Set new shift in 'Hv=\p4$1  
    op.Type = "ShiftZ" N4rDe]JnPR  
    op.val1 = taq fq4[/%6,O  
    op.parent = parID 2qpUUo f  
    AddOperation eID, op ZWXA%u7V  
    Print "Set aqueous humor thickness = " & taq-0.55 iOXsj  
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    '************************************************************************* '1vm]+oM  
    'Radius and conic constant of anterior lens #fT<]j(  
    '************************************************************************* Gc*p%2c  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) Wi<g  
    GetConic eID, entity, curv, conic %@'[g]h k  
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    SetConic eID, entity, 1/Rant, CCant W'"p:Uh q  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant |] cFsB#G  
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    '************************************************************************* qW 2'?B3<  
    'Radius and conic constant of posterior lens OKV/=]GS  
    '************************************************************************* MHPh!  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 8Os: SC@Q  
    GetConic eID, entity, curv, conic Gy6PS{yY6t  
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    SetConic eID, entity, 1/Rpost, CCpost <*[D30<  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost >SHP,><H/  
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    '************************************************************************* *o6hDhg  
    'Lens thickness (Position of posterior lens surface) lQKq{WLFx.  
    '************************************************************************* .1YiNmW=  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 9CPr/q9'  
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    ' Delete any z-shift(s) ^,{ r[}  
    count = 0 1<F6{?,z  
    While GetOperationCount(eID)>count -jk-ve  
        GetOperation eID, count, op e N^6gub  
        If op.Type="ShiftZ" Then Ef\&3TcQ  
            DeleteOperation eID,count Rj!9pwvT  
            count=count-1 EYSBC",  
        End If f^|r*@o  
        count=count+1 Wxa</n8S[n  
    Wend ]S7>=S  
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    'Set new z-shift cceh`s=cU  
    op.Type = "ShiftZ" @&f~#Xe  
    op.val1 = tlens H8V@KB  
    op.parent = parID bj ,cU)t0  
    AddOperation eID, op RC~C}  
    Print "Set lens thickness = " & tlens  J;GYo|8  
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    '************************************************************************* &Y jUoe  
    'Lens index of refraction x:iLBYf  
    '************************************************************************* l?O%yf`s  
    eID = FindMaterial( "Lens" ) SYA0Hiw7P  
    GetModelMaterial eID, mat TpRI+*\  
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    mat.Nd = nlens "R^0eNv$  
    SetModelMaterial eID, mat UTVqoCHA  
    Print "Set lens index of refraction = " & nlens E_-g<Cw  
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    '************************************************************************* pM}n)Q!{3"  
    'Pupil diameter ,m[#<}xXA  
    '************************************************************************* >l^[73,]L  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ImsyyeY]  
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    'Adjust pupil diameter (trimming volume inner hole) =y0h\<[  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 6vf<lmN  
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    ' Adjust pupil location to just in front of the lens {r?+PQQ#  
    parID = FindFullName( "Geometry.Arizona Eye" ) 6r)B|~,OA  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) _Lgi5B%   
    count = 0 >!PCEw<i  
    While GetOperationCount(eID)>count o#hFK'&~  
        GetOperation eID, count, op jqQGn"!  
        If op.Type="ShiftZ" Then IHwoG(A~<  
            DeleteOperation eID,count .#LvvAeh  
            count=count-1 n!h952"  
        End If 4^7*R  
        count=count+1 ZY*_x)h+#7  
    Wend ;^ff35EE8  
    op.Type = "ShiftZ" rO]2we/B,4  
    op.val1 = taq-0.01 OjsMT]  
    op.parent = parID Lklb  
    AddOperation eID, op R= .UbY  
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    Print "Set pupil diameter = " & pupilDiam UV\&9>@L  
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    'Update AZ Eye subassembly Description XGAR8=tic  
    eID = FindFullName( "Geometry.Arizona Eye" ) >:|jds#  
    GetEntity eID, entity o,!W,sx_  
    entity.Description = "Accommodation = " & A & "D" x,Z:12H0  
    SetEntity eID, entity JfzfxfM  
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    Update ql7N\COoq  
    Print "DONE!" [ Q[ac 6f  
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End Sub :?:R5_Nd=  
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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: :.crES7<[X  
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Accommodation = 4 Diopters |`O210B@  
Pupil Diameter = 4 mm eKe[]/}e9  
Set aqueous humor thickness = 2.81 gH/(4h  
Set anterior lens radius = 10.4 and conic constant = -2.375869 U]"6KS   
Set posterior lens radius = -4.424557 and conic constant = -3.081019 h y"=)n(  
Set lens thickness = 3.927 * & : J  
Set lens index of refraction = 1.42672 (t"e#b(:  
Set pupil diameter = 4 G&@_,y|  
DONE! K<p)-q  
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