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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 :W.(S6O(  
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。 "W7K"=X  
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模型 l \!fj#  
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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。 CR`Q#Yi  
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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. j<99FW"@e  
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光源 bz2ztH9 n  
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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。 j@U]'5EVB  
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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。 $%CF8\0  
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在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 DJXmGt]  
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图2. 字母F光源的设定方法光 Yz/md1T$  
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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 GmeQ`;9,  
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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。 7$vYo _  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 F3v !AvA|  
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图5. 视网膜重点采样规格设定
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脚本 'RQ+g}|Ba!  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: \:# L)   
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 \}u Y'F  
余下的脚本计算与屈光度有关的所有参数。 "/*\1v9  
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分析 xjuN-  
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屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 }{K) 4M  
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图7. 字母F在视网膜上颜色分析
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脚本代码 {3>$[bT  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. P_dCR  
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Dim entity As T_ENTITY knu,"<  
Dim op As T_OPERATION 6"L cJ%o  
Dim mat As T_MODELMATERIAL =1FRFZI!j  
Dim A As Double b(eNmu  
Dim pupilDiam As Double {NmWQyEv  
Dim eID As Long U8s2|G;K  
Dim parID As Long ]}<}lI9  
Dim count As Integer 9N#_( uwt  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double $-OA'QwB]  
Dim tlens As Double, nlens As Double ~WeM TXF>y  
Dim curv As Double, conic As Double fy>{QC\  
Dim ok As Long . oF &Ff/[  
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Sub Main %~O,zs.2p  
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    '用户输入对话框 oA7tE u   
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 [`#CXq'  
        TextBox 220,21,40,21,.TextBox1 'default: 0 z\\[S@>pt  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 6y-@iJ*ld;  
        OKButton 40,91,90,21 !fV+z%:  
        CancelButton 190,91,90,21 7X`g,b!  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 <prk8jSWV  
        TextBox 220,49,40,21,.TextBox2 'default: 4 1*P~!2h  
    End Dialog 'Cb6Y#6  
    Dim dlg As UserDialog j nkR}wAA  
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    ok = Dialog (dlg) %^)fmu  
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    If ok=0 Then    'cancel button was pressed @+&LYy72  
        Print "Execution cancelled." .Yamc#A-  
        End /H[=5  
    End If AVsDt2A  
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    'Assign accommodation and pupil diameter & use defaults if field left empty e[{0)y>=  
    If dlg.TextBox1 = "" Then S*,17+6dV  
        A = 0           'Default accommodation gldAP:  
    Else po c`q5i+  
        A = CDbl(dlg.TextBox1) Z\(q@3C  
    End If f$o_e90mu  
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    If dlg.TextBox2 = "" Then P7[h-3+^  
        pupilDiam = 4   'Default pupil diameter #>a\>iKQ2q  
    Else W- $Z(Z XL  
        pupilDiam = CDbl(dlg.TextBox2) E'f{i:O "~  
    End If o3XvRj  
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    Print " " 7zl5yK N  
    Print "Accommodation = " & A & " Diopters" pN, u`[  
    Print "Pupil Diameter = " & pupilDiam & " mm" O0*p0J  
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    ' Calculate new parameters with accommodation ^L,K& Jd  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 9sM!`Lz{  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens N_LM/of|D  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens P7ao5NP  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens mn'A9er  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens `{8K.(])s!  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ]HbY  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ;'gWu  
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    'Adjust parameters to account for accommodation nF}vw |r>x  
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    '************************************************************************* b;L\EB  
    'Aqueous thickness (Position of Lens) mupT<_Y  
    '************************************************************************* xPdG*OcX!  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) `T1  
    GetCustomElement eID, entity V~qNyOtA]  
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    parID = FindFullName( "Geometry.Arizona Eye" ) gZVc 5u<  
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    ' Delete any shift(s) in z [=C6U_vU  
    count = 0 g/4[N{Xf  
    While GetOperationCount(eID)>count l#&8x  
        GetOperation eID, count, op I2XU(pYU  
        If op.Type="ShiftZ" Then z,RhYm  
            DeleteOperation eID,count &*o=I|pQ  
            count=count-1 y4yhF8E>;U  
        End If )',R[|<  
        count=count+1 fT|.@%"vc  
    Wend z>xmRs   
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    'Set new shift in cF*TotU_m  
    op.Type = "ShiftZ" `Uq#W+r,  
    op.val1 = taq `&qL(66  
    op.parent = parID #x@$ lc=k3  
    AddOperation eID, op UJUEYG  
    Print "Set aqueous humor thickness = " & taq-0.55 hy1oq7F(Q  
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    '************************************************************************* " > ypIR<  
    'Radius and conic constant of anterior lens g_E$=j92v  
    '************************************************************************* VD AaYDi  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) TT%M' 5&  
    GetConic eID, entity, curv, conic oE @a'*.\  
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    SetConic eID, entity, 1/Rant, CCant 3qgS&js 7  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant _1X!EH"  
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    '************************************************************************* {'flJ5]  
    'Radius and conic constant of posterior lens y<UK:^t31V  
    '************************************************************************* S E<FL/x1#  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) !"AvY y9  
    GetConic eID, entity, curv, conic E#34Wh2z  
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    SetConic eID, entity, 1/Rpost, CCpost lM`2sy  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost /A\8 mL8  
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    '************************************************************************* >fG3K`  
    'Lens thickness (Position of posterior lens surface) .N;=\C*  
    '************************************************************************* 4(n-_BS  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 5PCqYN(:B  
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    ' Delete any z-shift(s) ux-/>enc  
    count = 0 =HK!(C  
    While GetOperationCount(eID)>count yZ7&b&2nLn  
        GetOperation eID, count, op 1dY}\Sp  
        If op.Type="ShiftZ" Then Ep_HcX`  
            DeleteOperation eID,count UBKu /@[f@  
            count=count-1 QpH'PYy  
        End If },?kk1vIT{  
        count=count+1 8LJ8 }%*  
    Wend *tFHM &a  
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    'Set new z-shift .8g)av+  
    op.Type = "ShiftZ" of~4Q{f$6  
    op.val1 = tlens >h1}~jW+  
    op.parent = parID .~db4d]  
    AddOperation eID, op Y|m +dT6  
    Print "Set lens thickness = " & tlens lgAoJ[  
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    '************************************************************************* B4/>H|  
    'Lens index of refraction *"2+B&Y  
    '************************************************************************* Tb}4wLu  
    eID = FindMaterial( "Lens" ) >{ ]%F*p4  
    GetModelMaterial eID, mat ^#-l q)  
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    mat.Nd = nlens OO\+J  
    SetModelMaterial eID, mat S\EyCi+  
    Print "Set lens index of refraction = " & nlens GAzU?a{S  
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    '************************************************************************* )}R0Y=e  
    'Pupil diameter je-!4r,  
    '************************************************************************* S72+d%$  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) Y Uc+0  
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    'Adjust pupil diameter (trimming volume inner hole) "^[ 'y7i  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Po;W'7"Po`  
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    ' Adjust pupil location to just in front of the lens 2W(s(-hD  
    parID = FindFullName( "Geometry.Arizona Eye" ) _ye |Y  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) yzn%<H~  
    count = 0 w "F 9l  
    While GetOperationCount(eID)>count =?* !"&h  
        GetOperation eID, count, op s[*rzoA  
        If op.Type="ShiftZ" Then 0o4XUW   
            DeleteOperation eID,count 8rGgF]F  
            count=count-1 ~Cttzn]pR  
        End If *R,5h2;  
        count=count+1 +E+p"7  
    Wend 2s8a $3  
    op.Type = "ShiftZ" h4}84}5d  
    op.val1 = taq-0.01 'BxX0  
    op.parent = parID ]q[D>6_  
    AddOperation eID, op aK~8B_5k8  
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    Print "Set pupil diameter = " & pupilDiam ,ng Cv;s  
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    'Update AZ Eye subassembly Description gg/-k;@ Rf  
    eID = FindFullName( "Geometry.Arizona Eye" ) QL/(72K  
    GetEntity eID, entity bWS&Yk(  
    entity.Description = "Accommodation = " & A & "D"  A@('pA85  
    SetEntity eID, entity @4C% +-  
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    Update y<3-?}.aZ  
    Print "DONE!" =%O6:YM   
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End Sub aO[w/cGQ  
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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: >6-`}G+|  
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Accommodation = 4 Diopters Z\rwO>3  
Pupil Diameter = 4 mm Vp\,CuQ  
Set aqueous humor thickness = 2.81 C.P*#_R  
Set anterior lens radius = 10.4 and conic constant = -2.375869 QIEJ6`  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 Ne!lH@ql  
Set lens thickness = 3.927 4at?(B+  
Set lens index of refraction = 1.42672 Dy&i&5E.-l  
Set pupil diameter = 4 ]/6z; ~3U  
DONE! G*MUO#_iuh  
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(文章来源:讯技光电)
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