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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 ~:z.Xu5m  
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。 Wm}c-GD  
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模型 t_3j_`  
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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。 PdcIHN  
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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. lhN@ ,q  
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光源 6ZQ |L=Ytp  
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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_'ERqQ  
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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。 03 @a G  
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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。 A>@#eyB  
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图2. 字母F光源的设定方法光 x o"GNFh!  
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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 T+0=Ou"N  
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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。 k)p` x"To  
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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。 w+br)  
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图5. 视网膜重点采样规格设定
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脚本 r6DLShP-Ur  
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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: sfM"!{7  
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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。 X{-4w([  
余下的脚本计算与屈光度有关的所有参数。 >ED;_L*_o  
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分析 #dauXUKH  
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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。 \]ib%,:YU  
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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 _Id'56N]J!  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. c#OxI*,+/  
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Dim entity As T_ENTITY @.t +  
Dim op As T_OPERATION :@L7RZ`_  
Dim mat As T_MODELMATERIAL 7+jxf[(XQ  
Dim A As Double {?qfH>oFA  
Dim pupilDiam As Double EmNVQ1w  
Dim eID As Long PucNu8   
Dim parID As Long x93@[B*%  
Dim count As Integer .n 9.y8C  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double P3oYk_oW  
Dim tlens As Double, nlens As Double PQHztS"  
Dim curv As Double, conic As Double GkAd"<B  
Dim ok As Long jD S?p)&  
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Sub Main ,1]UOQ>AP  
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    '用户输入对话框 d^v#x[1msZ  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 r:QLU]   
        TextBox 220,21,40,21,.TextBox1 'default: 0 A*h8 o9M  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 odP<S.  
        OKButton 40,91,90,21 M Kyj<@[  
        CancelButton 190,91,90,21 !wYN",R-  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ,ri&zbB  
        TextBox 220,49,40,21,.TextBox2 'default: 4 ?^&ih:"  
    End Dialog 6uRE9h|  
    Dim dlg As UserDialog W~ yb>+u  
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    ok = Dialog (dlg) a*M|_&MH*  
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    If ok=0 Then    'cancel button was pressed 7K"3[.  
        Print "Execution cancelled." ,:S#gN{U  
        End ` m 5\  
    End If ?eJ'$  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ?$pNduE  
    If dlg.TextBox1 = "" Then <&eJIz=  
        A = 0           'Default accommodation ~kc#"^s J  
    Else !'$*Z(  
        A = CDbl(dlg.TextBox1) =ejcP&-V/  
    End If H I9/  
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    If dlg.TextBox2 = "" Then iM .yen_vp  
        pupilDiam = 4   'Default pupil diameter U][E`[m#  
    Else { 4+/0\  
        pupilDiam = CDbl(dlg.TextBox2) [if(B\&  
    End If V9[_aP;  
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    Print " " 9SC1A-nF  
    Print "Accommodation = " & A & " Diopters" <$A,|m  
    Print "Pupil Diameter = " & pupilDiam & " mm" C|y^{4 |R  
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    ' Calculate new parameters with accommodation FBE|pG7  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness dv. 77q  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ~&:-c v  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens fw%p_Cm  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens p5]W2i.,  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens dV$[O`F* b  
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    tlens = 3.767 + 0.04*A                  'Lens thickness SU%O\ 4Ty  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ;(K/O?nrJ  
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    'Adjust parameters to account for accommodation PTHxvml  
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    '************************************************************************* %)V=)l.j  
    'Aqueous thickness (Position of Lens) 6$"IeBRO  
    '************************************************************************* wPU5L*/*i  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) qiOtbH=  
    GetCustomElement eID, entity gV)/lDEM5  
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    parID = FindFullName( "Geometry.Arizona Eye" ) b GSj?t9/  
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    ' Delete any shift(s) in z .*NPoW4Kv  
    count = 0 {GtX:v#  
    While GetOperationCount(eID)>count $2FU<w$5  
        GetOperation eID, count, op x|Uwk=;X|s  
        If op.Type="ShiftZ" Then Kmx4bp4  
            DeleteOperation eID,count ;)ay uS sQ  
            count=count-1 {X?Aj >l  
        End If /Ey%aA4v  
        count=count+1 shB3[W{}!)  
    Wend rk=/iD  
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    'Set new shift in Q'U!  
    op.Type = "ShiftZ" [( xPX  
    op.val1 = taq sssw(F  
    op.parent = parID XK~HfA?  
    AddOperation eID, op rFcz 0  
    Print "Set aqueous humor thickness = " & taq-0.55 t tr`  
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    '************************************************************************* P}'B~ ~9W  
    'Radius and conic constant of anterior lens (KO]>!t  
    '************************************************************************* 7OLHYt9  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) <uU<qO;6  
    GetConic eID, entity, curv, conic RH,x);J|  
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    SetConic eID, entity, 1/Rant, CCant K1YxF  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant q%d,E1  
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    '************************************************************************* ;Q3[} ]su  
    'Radius and conic constant of posterior lens !4v>|tq!  
    '************************************************************************* I_#5gq  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) =~s+<9c]  
    GetConic eID, entity, curv, conic r5[pT(XT]  
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    SetConic eID, entity, 1/Rpost, CCpost Lapeh>1T  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost F<h+d917  
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    '************************************************************************* Q~.t8g/  
    'Lens thickness (Position of posterior lens surface) |WUM=g7PC  
    '************************************************************************* lpPPI+|4N  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) _KloX{a  
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    ' Delete any z-shift(s) O\uIIuy  
    count = 0 "Plo[E  
    While GetOperationCount(eID)>count ZweAY.]e  
        GetOperation eID, count, op lA4-ZQ2Zp[  
        If op.Type="ShiftZ" Then >r X$E<B\  
            DeleteOperation eID,count h#Rza-?"\  
            count=count-1 VJ h]j (  
        End If pC,Z=+:  
        count=count+1 g/l:q&Q<  
    Wend An}RD73!w  
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    'Set new z-shift Tei2[siA5  
    op.Type = "ShiftZ" 34CcZEQQ  
    op.val1 = tlens vx7=I\1  
    op.parent = parID # B <%  
    AddOperation eID, op ;t9!< L  
    Print "Set lens thickness = " & tlens L[:A Ue  
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    '************************************************************************* L9^ M?.a  
    'Lens index of refraction U<F|A!Fg  
    '************************************************************************* !\VEUF,K?  
    eID = FindMaterial( "Lens" ) oM>UIDCY_v  
    GetModelMaterial eID, mat RIUJX{?  
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    mat.Nd = nlens Hr=|xw8.  
    SetModelMaterial eID, mat P9:5kiP H  
    Print "Set lens index of refraction = " & nlens G3y8M |:  
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    '************************************************************************* A#K<5%U{Mv  
    'Pupil diameter OpazWcMoo  
    '************************************************************************* ab9ecZ  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) &2.DZ),L  
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    'Adjust pupil diameter (trimming volume inner hole) z3 ^_C`(F  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" *@^@7`W  
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    ' Adjust pupil location to just in front of the lens /Q)I5sL@E  
    parID = FindFullName( "Geometry.Arizona Eye" ) "uL~D5!f  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) x'?p?u~[  
    count = 0 B R  
    While GetOperationCount(eID)>count C6F7,v62  
        GetOperation eID, count, op &N=vs  
        If op.Type="ShiftZ" Then _UZPQ[  
            DeleteOperation eID,count F#L1~\7  
            count=count-1 Tc"J(GWG  
        End If SmDNN^GR  
        count=count+1 0#=xUk#LP`  
    Wend R|$b\3  
    op.Type = "ShiftZ" }:0ru_F)(4  
    op.val1 = taq-0.01 vm;%713#1  
    op.parent = parID }=\?]9`  
    AddOperation eID, op ?+yM3As9_V  
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    Print "Set pupil diameter = " & pupilDiam 3O-vO=D  
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    'Update AZ Eye subassembly Description DOGGQ$0  
    eID = FindFullName( "Geometry.Arizona Eye" ) \6MM7x(U3  
    GetEntity eID, entity tw.GBR  
    entity.Description = "Accommodation = " & A & "D" SWhzcqp  
    SetEntity eID, entity Nr]Fh  
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    Update <[ 2?~s  
    Print "DONE!" MCEHv}W  
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End Sub _x""-X~OL  
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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: &b^~0Z  
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Accommodation = 4 Diopters ^ Lc\{,m  
Pupil Diameter = 4 mm KiI+ V;o  
Set aqueous humor thickness = 2.81 J;^PM:6  
Set anterior lens radius = 10.4 and conic constant = -2.375869 P%Vq#5  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 (p12=EB<  
Set lens thickness = 3.927 :] U\{;q2  
Set lens index of refraction = 1.42672  yZ[g2*1L  
Set pupil diameter = 4 iSoQ1#MP)2  
DONE! h/|p`MP\1  
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(文章来源:讯技光电)
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