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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 8_ tK4PwP  
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。 f^"N!f a  
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模型 '-"/ =j&d[  
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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。 0iwZT&O  
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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. ^]a#7/]o  
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光源 ?)1{)Erf8x  
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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。 OC<5E121>Y  
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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。 o)2W`i&  
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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。 x"{'&J[hx  
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图2. 字母F光源的设定方法光 rjPL+T_  
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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 `/ q|@B7  
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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。 cvfr)K[0  
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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。 S!3S4:]B^  
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图5. 视网膜重点采样规格设定
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脚本 P5#r,:zL  
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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: Z{|.1  
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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。 q&/Yg,p\  
余下的脚本计算与屈光度有关的所有参数。 \7l-@6 '7  
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分析 zOqn<Y@  
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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。 ghX|3lI\q  
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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 aP8H`^DFX>  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. ( |PAx (  
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Dim entity As T_ENTITY E gal4  
Dim op As T_OPERATION HaYE9/xS  
Dim mat As T_MODELMATERIAL 'C ~ y5j  
Dim A As Double ;+<&8.=,)  
Dim pupilDiam As Double A%D7bQ  
Dim eID As Long Z6_N$Z.A  
Dim parID As Long sM?MLB\Za  
Dim count As Integer _/s(7y!  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double i 4%xfN  
Dim tlens As Double, nlens As Double hvuIxqv!y  
Dim curv As Double, conic As Double @1 U&UH  
Dim ok As Long NyVnA  
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Sub Main P~G1EK|4  
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    '用户输入对话框 9f',7i  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 yI ld75S`  
        TextBox 220,21,40,21,.TextBox1 'default: 0 ;3kj2}  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 /u0' 6V  
        OKButton 40,91,90,21 tvu!< dxZ  
        CancelButton 190,91,90,21 |pmZ.r  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 +H9>A0JF  
        TextBox 220,49,40,21,.TextBox2 'default: 4 phn9:{TI  
    End Dialog -GqT7`:(H4  
    Dim dlg As UserDialog AjT%]9 V?  
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    ok = Dialog (dlg) VA9Gb 9  
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    If ok=0 Then    'cancel button was pressed )EL!D%<A  
        Print "Execution cancelled." qnoNT%xazo  
        End MH{GR)ng:9  
    End If zj/!In  
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    'Assign accommodation and pupil diameter & use defaults if field left empty VH(S=G5Yb  
    If dlg.TextBox1 = "" Then 8:#rA*Y  
        A = 0           'Default accommodation rN%F) q#  
    Else rDQ!zlg>l  
        A = CDbl(dlg.TextBox1) ,WG<hgg-U)  
    End If B?)@u|0  
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    If dlg.TextBox2 = "" Then m <w "T7  
        pupilDiam = 4   'Default pupil diameter `8I&7c  
    Else g=2Rqi5  
        pupilDiam = CDbl(dlg.TextBox2) +{/*z  
    End If sp ]zbX?  
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    Print " " ?@6/E<-Z$  
    Print "Accommodation = " & A & " Diopters" 0%Z]h?EYy|  
    Print "Pupil Diameter = " & pupilDiam & " mm" ' /$d0`3B>  
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    ' Calculate new parameters with accommodation <]T`3W9  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness [ e8x&{L-_  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens w 1Ec_y{  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens *JaqTI,e  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens N*`b%XGn3  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens TD9;kN1`  
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    tlens = 3.767 + 0.04*A                  'Lens thickness  (:";i&  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction #."Hh<C  
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    'Adjust parameters to account for accommodation  :Mcu  
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    '************************************************************************* p<&Xd}]"^W  
    'Aqueous thickness (Position of Lens) \/SQ,*O  
    '************************************************************************* }?@rO`:EF+  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) K3' niGT  
    GetCustomElement eID, entity tBm_YP[  
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    parID = FindFullName( "Geometry.Arizona Eye" ) Z{ u a=0  
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    ' Delete any shift(s) in z HoLv`JA  
    count = 0 JGFt0He]  
    While GetOperationCount(eID)>count 1t Jg#/?  
        GetOperation eID, count, op nD0}wiL{  
        If op.Type="ShiftZ" Then @_"9Dy Y%  
            DeleteOperation eID,count UDe |Sb  
            count=count-1 _kdL'x  
        End If DEw8*MN  
        count=count+1 `-\/$M9s=  
    Wend R@*O!bD  
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    'Set new shift in cDoo*  
    op.Type = "ShiftZ" if)Y9:{r^  
    op.val1 = taq A+&xMM2Wj  
    op.parent = parID 1N\D5g3  
    AddOperation eID, op ~+H" -+  
    Print "Set aqueous humor thickness = " & taq-0.55 .p ls!  
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    '************************************************************************* 6MG9a>=  
    'Radius and conic constant of anterior lens Pe_!?:vF  
    '************************************************************************* `$YP<CJeq  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) c.|l-zAeX  
    GetConic eID, entity, curv, conic 5PIZh<  
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    SetConic eID, entity, 1/Rant, CCant G|m1.=DJm  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ^Q{Bq  
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    '************************************************************************* kJAn4I.l  
    'Radius and conic constant of posterior lens X]y )ZF26  
    '************************************************************************* 9ktEm|F3  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) &(a(W22O  
    GetConic eID, entity, curv, conic QI!F6pGF  
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    SetConic eID, entity, 1/Rpost, CCpost #Ch;0UvFF  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost M('d-Q{B7L  
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    '************************************************************************* 5 #]4YI;  
    'Lens thickness (Position of posterior lens surface) #RMI&[M  
    '************************************************************************* / EMJSr  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) mF09U(ci  
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    ' Delete any z-shift(s) W0zbxJKjd  
    count = 0 d vOJW".  
    While GetOperationCount(eID)>count D\~e&0*  
        GetOperation eID, count, op _Hd{sd#xX1  
        If op.Type="ShiftZ" Then b}G24{  
            DeleteOperation eID,count Zw] ?.  
            count=count-1 %vO<9fE|1  
        End If FZH\Q~IUV  
        count=count+1 )2Hff.  
    Wend @ 2_<,;$  
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    'Set new z-shift gLL\F1|0x  
    op.Type = "ShiftZ" 'ZQWYr9R  
    op.val1 = tlens n^hocGH*  
    op.parent = parID tJ=di5&  
    AddOperation eID, op 6<5Jq\-h  
    Print "Set lens thickness = " & tlens E4D (,s  
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    '************************************************************************* d'l$$%zJ  
    'Lens index of refraction [rreFSy#@  
    '************************************************************************* y_}SK6{  
    eID = FindMaterial( "Lens" ) A%vsno!  
    GetModelMaterial eID, mat bO<0qM~  
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    mat.Nd = nlens 0m+8P$)C%  
    SetModelMaterial eID, mat `BnP[jF  
    Print "Set lens index of refraction = " & nlens cX At :m  
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    '************************************************************************* 2D([Z-<i  
    'Pupil diameter ~]8p_;\  
    '************************************************************************* Sd:.KRTu.  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) !Zbesp KZ  
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    'Adjust pupil diameter (trimming volume inner hole) ^GYq#q9Q  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Z,WW]Y,$  
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    ' Adjust pupil location to just in front of the lens nd+?O7~}(  
    parID = FindFullName( "Geometry.Arizona Eye" ) X^< >6|)  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ^p_u.P  
    count = 0 'H FKBp  
    While GetOperationCount(eID)>count &-GuKH(Y<  
        GetOperation eID, count, op $`vkw(;t)1  
        If op.Type="ShiftZ" Then P 4;{jG  
            DeleteOperation eID,count b Dg9P^<n  
            count=count-1 4w{-'M.B  
        End If XKq@]=\F  
        count=count+1 [[qwaI  
    Wend St>`p-  
    op.Type = "ShiftZ" W3LP ~  
    op.val1 = taq-0.01 v3JPE])/  
    op.parent = parID 6~W u`  
    AddOperation eID, op d.pp3D 9/  
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    Print "Set pupil diameter = " & pupilDiam m{&w{3pQk  
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    'Update AZ Eye subassembly Description jX|=n.#q  
    eID = FindFullName( "Geometry.Arizona Eye" ) g8yN% )[  
    GetEntity eID, entity +AK:(r  
    entity.Description = "Accommodation = " & A & "D" @8"18HEp#  
    SetEntity eID, entity Yg6I&#f7&  
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    Update )!C7bTv 4  
    Print "DONE!" g2'x#%ET  
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End Sub aqfL0Rg+`  
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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: +5*vABvCu  
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Accommodation = 4 Diopters |mj# 0  
Pupil Diameter = 4 mm ,U%=rfB~  
Set aqueous humor thickness = 2.81 e}Q>\t45  
Set anterior lens radius = 10.4 and conic constant = -2.375869 =hcPTU-QU  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 -SJSTO[/J  
Set lens thickness = 3.927 ~Oh=   
Set lens index of refraction = 1.42672 a`38db(z  
Set pupil diameter = 4 @xJCn}`Zj  
DONE! ?f@ 9nph  
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(文章来源:讯技光电)
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