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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 `HU`=a&d  
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。 }CZ,WJz=  
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模型 tVQfR*=  
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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。 ~L Gkc t  
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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. hk4f)z  
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光源 5} |O  
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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。 ]YkF^Pf!v  
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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。 W+PAlsOC  
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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。 Pa 2HFy2  
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图2. 字母F光源的设定方法光 1Lwi?~!LI  
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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 ! e6;@*  
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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。 ,$5;  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 L5%~H?K(  
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图5. 视网膜重点采样规格设定
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脚本 T3Kq1 Rh  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： TveCy&  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 isHa4 D0  
余下的脚本计算与屈光度有关的所有参数。 +xRja(d6  
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分析 CZE5RzG  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 NFY,$  
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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 hU5[k/ q  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. ] =b?^'  
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Dim entity As T_ENTITY wQb")3dw  
Dim op As T_OPERATION nXK"BYe  
Dim mat As T_MODELMATERIAL eOy{]< l3  
Dim A As Double 8gJ"7,}-'  
Dim pupilDiam As Double IvetQ+  
Dim eID As Long &GwBxJ  
Dim parID As Long ?v#t{e0eQ  
Dim count As Integer _]1dm)%  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double n5 @H  
Dim tlens As Double, nlens As Double !40{1U&@a`  
Dim curv As Double, conic As Double 8U\;N  
Dim ok As Long -`]B4Nt6  
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Sub Main 0KnlomuH2  
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    '用户输入对话框 Mp?Ev.  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 /-E>5wU  
        TextBox 220,21,40,21,.TextBox1 'default: 0 "vH@b_>9|  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 go6Hb>  
        OKButton 40,91,90,21 (Z)  
        CancelButton 190,91,90,21 eL^,-3JA(]  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 .,l ?z  
        TextBox 220,49,40,21,.TextBox2 'default: 4 f!P.=Qo[=  
    End Dialog 8l>/ZZ.NXi  
    Dim dlg As UserDialog WXNJc  
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    ok = Dialog (dlg) !rb)Y;WQt  
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    If ok=0 Then    'cancel button was pressed gO<>L0,j  
        Print "Execution cancelled." "pdG%$  
        End S#!PDg  
    End If %whPTc0P  
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    'Assign accommodation and pupil diameter & use defaults if field left empty o&rejj#  
    If dlg.TextBox1 = "" Then V.'EP  
        A = 0           'Default accommodation 4&K~EX"^T  
    Else W3{k{~  
        A = CDbl(dlg.TextBox1) !K'kkn,h  
    End If &kXf)xc<~  
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    If dlg.TextBox2 = "" Then ~c! XQJ  
        pupilDiam = 4   'Default pupil diameter =B*,S#r  
    Else e_g7E+6  
        pupilDiam = CDbl(dlg.TextBox2) 0Vh|UJ'&7  
    End If W: cOzJ  
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    Print " " LEc%BQx  
    Print "Accommodation = " & A & " Diopters" cc.z C3Hs3  
    Print "Pupil Diameter = " & pupilDiam & " mm" VZb0x)w  
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    ' Calculate new parameters with accommodation d '4c?vC  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Th`IpxV  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ,S:g 5n>M  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens a5?Rj~h!<  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens |6"zIHvtc  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 4tCyd5u a8  
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    tlens = 3.767 + 0.04*A                  'Lens thickness e {N8|l  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Uj0DX >I  
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    'Adjust parameters to account for accommodation 5=., a5  
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    '************************************************************************* JdfjOlEb  
    'Aqueous thickness (Position of Lens) v#(wc +[  
    '************************************************************************* M!,$i  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) [j eZZB  
    GetCustomElement eID, entity )e4nKh],  
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    parID = FindFullName( "Geometry.Arizona Eye" ) bMxzJRrNg  
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    ' Delete any shift(s) in z BB|w-W=Kd  
    count = 0 :?U1^!$$1  
    While GetOperationCount(eID)>count o\g",O4-  
        GetOperation eID, count, op (4>k+ H  
        If op.Type="ShiftZ" Then 9%$4Ux*q  
            DeleteOperation eID,count %=]~5a9  
            count=count-1 1$q SbQ  
        End If ds4ERe /  
        count=count+1 S)n ~^q  
    Wend +K; X$kB  
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    'Set new shift in )4D |sN  
    op.Type = "ShiftZ" *t 3fbD  
    op.val1 = taq c9=;:E  
    op.parent = parID &`Z>zT}  
    AddOperation eID, op =sG  C  
    Print "Set aqueous humor thickness = " & taq-0.55 UCa(3p^V_  
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    '************************************************************************* U9SByqa1  
    'Radius and conic constant of anterior lens ES(b#BlrP/  
    '************************************************************************* V'mQ {[{R  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) t1 OnA#]/_  
    GetConic eID, entity, curv, conic #:v|/2   
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    SetConic eID, entity, 1/Rant, CCant va:5pvt2&  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant <omSK- T-  
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    '************************************************************************* (caxl^=  
    'Radius and conic constant of posterior lens GghZ".O  
    '************************************************************************* T5=3 jPQ  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ~N;kF.q&>&  
    GetConic eID, entity, curv, conic l7ZqkGG]  
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    SetConic eID, entity, 1/Rpost, CCpost gH,^XZe  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost f2`[skNj  
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    '************************************************************************* N41)?-7F  
    'Lens thickness (Position of posterior lens surface) &j<B22t!  
    '************************************************************************* ?R(fxx  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ;*BG{rkr  
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    ' Delete any z-shift(s) }G]6Rip 3  
    count = 0 `%ZM(9T  
    While GetOperationCount(eID)>count F *=>=  
        GetOperation eID, count, op `1=n H/E  
        If op.Type="ShiftZ" Then _s[ohMlh  
            DeleteOperation eID,count .D(H@3qA@  
            count=count-1 ^a0{"|Lq  
        End If o+*YX!]#L  
        count=count+1 2`9e20  
    Wend % r`hW \4{  
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    'Set new z-shift ,6=j'j1#a  
    op.Type = "ShiftZ"  _/;vsQB  
    op.val1 = tlens `aD~\O  
    op.parent = parID G|H+ ,B  
    AddOperation eID, op 7?9QlUO  
    Print "Set lens thickness = " & tlens -|bnvPmE  
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    '************************************************************************* A(V,qw8  
    'Lens index of refraction RP9#P&Qk  
    '************************************************************************* I<L  
    eID = FindMaterial( "Lens" ) _ I"}3*  
    GetModelMaterial eID, mat J&CA#Bg:w  
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    mat.Nd = nlens 2w_[c.  
    SetModelMaterial eID, mat R.@I}>  
    Print "Set lens index of refraction = " & nlens (HbA?Aja  
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    '************************************************************************* " R!,5HQF;  
    'Pupil diameter uH="l.u  
    '************************************************************************* cc- liY "  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) |L[/]@|  
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    'Adjust pupil diameter (trimming volume inner hole) a> qB k})  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" PvF3a `&r  
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    ' Adjust pupil location to just in front of the lens I!1|);li  
    parID = FindFullName( "Geometry.Arizona Eye" ) ]s_,;PGU  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 2T 3tKX  
    count = 0 G%ytp=N  
    While GetOperationCount(eID)>count S9RH&/^H  
        GetOperation eID, count, op xl2;DFiYt  
        If op.Type="ShiftZ" Then TS4Yzq,f  
            DeleteOperation eID,count \GYrP f$  
            count=count-1 xKl\:}Ytp  
        End If q>|&u  
        count=count+1 !-rG1VI_S*  
    Wend *Tc lc u  
    op.Type = "ShiftZ" $0 ]xeD0X  
    op.val1 = taq-0.01 |?A:[C#X  
    op.parent = parID D8X~qt/  
    AddOperation eID, op Rtpk_ND!  
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    Print "Set pupil diameter = " & pupilDiam ,/2&HZd  
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    'Update AZ Eye subassembly Description AS4mJ UU9  
    eID = FindFullName( "Geometry.Arizona Eye" ) {z#!3a  
    GetEntity eID, entity _cvA1Q"  
    entity.Description = "Accommodation = " & A & "D" @n,V2`"  
    SetEntity eID, entity "`Q &s  
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    Update %9vl  
    Print "DONE!" Jlp nR#@  
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End Sub VO JA}$  
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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： GHNw.<`l?  
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Accommodation = 4 Diopters s!<RWy+  
Pupil Diameter = 4 mm 9]C%2!Ur,  
Set aqueous humor thickness = 2.81 PH.g+u=v  
Set anterior lens radius = 10.4 and conic constant = -2.375869 S^s|/!>  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 |xawguJ  
Set lens thickness = 3.927 S5o,\wT  
Set lens index of refraction = 1.42672 uwl_TDc>%  
Set pupil diameter = 4 %lq[,6?>5  
DONE! 3 C{A  
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（文章来源：讯技光电）
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