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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 7)_0jp~2  
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。 'Fc&"(!||  
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模型 5>A3;P  
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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。 'R=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. -h.YQC`  
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光源 t1ZZru'r  
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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。 4-3B"  
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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。 *$l8H[  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ;[9cj&7C<  
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图2. 字母F光源的设定方法光 Rf%ver  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 y"9TS,lmK  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 4]dPhsey  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 5 !NPqka}.  
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图5. 视网膜重点采样规格设定
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脚本 3IJIeG>  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： G&n_vwZ%  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 j5/H#_ .  
余下的脚本计算与屈光度有关的所有参数。 _D+7w'8h  
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分析 wvh4AE5F|z  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 (8EZ,V:  
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图7. 字母F在视网膜上颜色分析
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脚本代码 W%$p,^@S5  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. R0=/ Th -  
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Dim entity As T_ENTITY <QJmdcG  
Dim op As T_OPERATION i$NnHj|  
Dim mat As T_MODELMATERIAL }3i@5ctQ  
Dim A As Double |6;.C1\,  
Dim pupilDiam As Double @rJ#Dr  
Dim eID As Long j1d=$'a "  
Dim parID As Long ( Rf)&KN  
Dim count As Integer zf S<X  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double BF@VgozW  
Dim tlens As Double, nlens As Double HR V/ A  
Dim curv As Double, conic As Double X F40;urm  
Dim ok As Long +22[ h@  
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Sub Main k&?QeXW  
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    '用户输入对话框 aY?}4Bx  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ;x7SY;0*  
        TextBox 220,21,40,21,.TextBox1 'default: 0 3NJH"amk  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 TfxKvol'  
        OKButton 40,91,90,21 +?L~fM69B  
        CancelButton 190,91,90,21 onmO>q*  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ?O3 G  
        TextBox 220,49,40,21,.TextBox2 'default: 4 AKWw36lm  
    End Dialog uL= \t=  
    Dim dlg As UserDialog u9&p/qMx2  
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    ok = Dialog (dlg) <l6CtK@  
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    If ok=0 Then    'cancel button was pressed U?rfE(!  
        Print "Execution cancelled." jQdfFR  
        End 8<G@s`*  
    End If :,u+[0-S  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ,L^L uw'7  
    If dlg.TextBox1 = "" Then Op0 #9W  
        A = 0           'Default accommodation M6I1`Lpf  
    Else Ga h e-%J  
        A = CDbl(dlg.TextBox1) C8jZcs#4  
    End If XR&*g1  
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    If dlg.TextBox2 = "" Then ruW6cvsvet  
        pupilDiam = 4   'Default pupil diameter I2Us!W>6-  
    Else p 2i5/Ly  
        pupilDiam = CDbl(dlg.TextBox2) 8[Qw8z5-  
    End If mB,7YZv  
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    Print " " J'7Oxjlg  
    Print "Accommodation = " & A & " Diopters" +`4|,K7'  
    Print "Pupil Diameter = " & pupilDiam & " mm" R'3i { 1  
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    ' Calculate new parameters with accommodation r({(;  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness GphG/C (  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens YnMph0\Y^  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens sM4wh_lO  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens #eaey+~  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens +:t1PV;l  
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    tlens = 3.767 + 0.04*A                  'Lens thickness v3/cNd3  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction (PNvv/A  
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    'Adjust parameters to account for accommodation $`Ou*  
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    '************************************************************************* s2$R2,  
    'Aqueous thickness (Position of Lens) g &za/F  
    '************************************************************************* Oo0$n]*;W  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) IKU -  
    GetCustomElement eID, entity  <O*q;&9  
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    parID = FindFullName( "Geometry.Arizona Eye" ) <ya3|ycnS  
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    ' Delete any shift(s) in z S38D cWIw  
    count = 0 %1 v)rg y  
    While GetOperationCount(eID)>count U/ZbE?it>  
        GetOperation eID, count, op &x;nP6mV  
        If op.Type="ShiftZ" Then h{! @^Q  
            DeleteOperation eID,count gC3{:MC-G  
            count=count-1 YcGqT2oLP  
        End If hsl8@=_ B  
        count=count+1 *yf+5q4t  
    Wend ^qDkSoqC"  
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    'Set new shift in $+mmqc8  
    op.Type = "ShiftZ" ctCfLlK  
    op.val1 = taq [$./'-I]  
    op.parent = parID _#L IG2d  
    AddOperation eID, op %0]&o, w{  
    Print "Set aqueous humor thickness = " & taq-0.55 *s!8BwiE  
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    '************************************************************************* 9xSAWKr,l  
    'Radius and conic constant of anterior lens X+*| nvq]  
    '************************************************************************* We9mkwK7C  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 2`lit@u&u  
    GetConic eID, entity, curv, conic RJWlG'i  
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    SetConic eID, entity, 1/Rant, CCant K.cNx  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant |e9}G,1  
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    '************************************************************************* 2D-*Z=5^  
    'Radius and conic constant of posterior lens 'rg$%M*(  
    '************************************************************************* qH-dT,`"{  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) )kkO:j  
    GetConic eID, entity, curv, conic B!Qdf8We  
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    SetConic eID, entity, 1/Rpost, CCpost UdY9*k  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost -_2= NA?t  
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    '************************************************************************* 8n'C@#{WV  
    'Lens thickness (Position of posterior lens surface) "+rX* ~  
    '************************************************************************* ^+P]_< 43  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ;bZ)q  
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    ' Delete any z-shift(s) hsl Js^  
    count = 0 p%G\5.GcJL  
    While GetOperationCount(eID)>count yEz2F3[ S  
        GetOperation eID, count, op GI~;2 `V  
        If op.Type="ShiftZ" Then v& ? Bqj  
            DeleteOperation eID,count ;%%=G;b9  
            count=count-1 KDY~9?}TM  
        End If 7?kvrIuY&  
        count=count+1 uxR_(~8  
    Wend a|fyo#L  
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    'Set new z-shift 3w0m:~KS6V  
    op.Type = "ShiftZ" Dm5UQe  
    op.val1 = tlens #!5GGe{I  
    op.parent = parID .AV--oA~  
    AddOperation eID, op u]oS91  
    Print "Set lens thickness = " & tlens Gud!(5'  
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    '************************************************************************* -nU_eDy  
    'Lens index of refraction l,d8% \  
    '************************************************************************* b|xz`wUH0$  
    eID = FindMaterial( "Lens" ) >`lf1x  
    GetModelMaterial eID, mat BgE]xm  
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    mat.Nd = nlens 0 ">#h  
    SetModelMaterial eID, mat $x 2t0@  
    Print "Set lens index of refraction = " & nlens F 6SIhf.;  
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    '************************************************************************* 5[;^Em)C  
    'Pupil diameter n'R 8nn6^  
    '************************************************************************* CwT52+Jb  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) nhy3E  
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    'Adjust pupil diameter (trimming volume inner hole) i1scoxX3\  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Qs4Jl;Y_  
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    ' Adjust pupil location to just in front of the lens zZA I"\;W  
    parID = FindFullName( "Geometry.Arizona Eye" ) iedoL0#  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Ot/Y?=j~  
    count = 0 $YW z~^f  
    While GetOperationCount(eID)>count *ZY{^f  
        GetOperation eID, count, op )~WxNn3rx  
        If op.Type="ShiftZ" Then L1aN"KGMF  
            DeleteOperation eID,count ZM5[ o m  
            count=count-1 )ll}hGS  
        End If 9@ ^/ON\O  
        count=count+1 !.F`8OD`u  
    Wend fEM8/bhq  
    op.Type = "ShiftZ" _:TD{EO$  
    op.val1 = taq-0.01 6g<JPc  
    op.parent = parID :yw0-]/DD  
    AddOperation eID, op &;,w})  
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    Print "Set pupil diameter = " & pupilDiam }G-qOt  
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    'Update AZ Eye subassembly Description =:#$_qR  
    eID = FindFullName( "Geometry.Arizona Eye" ) f9#B(4Tgi  
    GetEntity eID, entity :JPI#zZun  
    entity.Description = "Accommodation = " & A & "D" qA*QFQ'-  
    SetEntity eID, entity whvM^  
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    Update bu\,2t}B  
    Print "DONE!" ncu> @K$n  
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End Sub :y]l`Mo -  
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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： Mc{1Cdj  
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Accommodation = 4 Diopters A4'v Jk  
Pupil Diameter = 4 mm d~YDg{H  
Set aqueous humor thickness = 2.81 "j~=YW+l  
Set anterior lens radius = 10.4 and conic constant = -2.375869 .w&{2,a3  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 |QXW$  
Set lens thickness = 3.927 nfl6`)oW  
Set lens index of refraction = 1.42672 C[&L h_F\  
Set pupil diameter = 4 pcL02W|J  
DONE! _:=w6jCk  
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（文章来源：讯技光电）
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