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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 ;{)@ghD  
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。 u+i/CE#w  
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模型 C&MqUj"]  
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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。 7*8nUq  
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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?` D\LZhf  
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光源 xVmUmftD  
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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。 'bqf?3W  
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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。 Z-r0 D  
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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。 j1C0LP8  
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图2. 字母F光源的设定方法光 5;%xqdD  
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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 D2mAyU -  
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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。 *h8XbBZH  
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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。 @!tmUme1c  
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图5. 视网膜重点采样规格设定
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脚本 FP cvkXQD  
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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： )FiU1E  
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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。 kUBHK"}K  
余下的脚本计算与屈光度有关的所有参数。 wH5O>4LO  
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分析 1;sAt;/W8  
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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。 2QD B'xs3  
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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 :)S4MoG  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. Y\2>y"8>$x  
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Dim entity As T_ENTITY 8U$UI  
Dim op As T_OPERATION >~r@*gml  
Dim mat As T_MODELMATERIAL W_lNvzag  
Dim A As Double %=>xzP(z  
Dim pupilDiam As Double z?g4^0e  
Dim eID As Long k3eN;3#&  
Dim parID As Long 2]KPW*V  
Dim count As Integer 3W00,f^9  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double >I ; #BE3  
Dim tlens As Double, nlens As Double 9Ei#t FMc  
Dim curv As Double, conic As Double MO+0]uh:  
Dim ok As Long .=<pU k 3G  
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Sub Main  D -EM  
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    '用户输入对话框 y 9mZQq  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 6 6;O3g'  
        TextBox 220,21,40,21,.TextBox1 'default: 0 M& L0n%,y5  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 `{[C4]Ew/  
        OKButton 40,91,90,21 -B! TA0=oJ  
        CancelButton 190,91,90,21 dXN&<Q,  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 $VNn`0^gF  
        TextBox 220,49,40,21,.TextBox2 'default: 4 'GT`% ck  
    End Dialog 2(xKE_|  
    Dim dlg As UserDialog IKj1{nZvDc  
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    ok = Dialog (dlg) 0{uX2h  
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    If ok=0 Then    'cancel button was pressed M#,+p8  
        Print "Execution cancelled." iIRigW  
        End "Vy\- ^  
    End If G*V 7*KC  
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    'Assign accommodation and pupil diameter & use defaults if field left empty <\NXCUqDpo  
    If dlg.TextBox1 = "" Then <<6#Uz.1  
        A = 0           'Default accommodation x$4'a~E  
    Else $9$NX/P  
        A = CDbl(dlg.TextBox1) S}yb~uc,  
    End If CKx}.<_  
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    If dlg.TextBox2 = "" Then 7qp|Msf},  
        pupilDiam = 4   'Default pupil diameter I<f M8t.Y>  
    Else z81!F'x;  
        pupilDiam = CDbl(dlg.TextBox2) ]>j_ Y ,  
    End If 53xq%  
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    Print " " NyNu1V$  
    Print "Accommodation = " & A & " Diopters" }x-8@9S~z  
    Print "Pupil Diameter = " & pupilDiam & " mm" 4(](' [M  
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    ' Calculate new parameters with accommodation 7?@v}%w  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness |'#NDFI>}  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens 3 Q;l*xu  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens Gd 9B  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens c7 -j  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens P@ u%{  
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    tlens = 3.767 + 0.04*A                  'Lens thickness /vKDlCH*  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction  su$juI{  
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    'Adjust parameters to account for accommodation pDT6>2t  
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    '************************************************************************* stScz#!  
    'Aqueous thickness (Position of Lens) ,\IZ/1  
    '************************************************************************* X88Zd M'  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) J.(_c ' r  
    GetCustomElement eID, entity W1z5|-T  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 7085&\9  
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    ' Delete any shift(s) in z * bK@A2`  
    count = 0 Q)/q h;R u  
    While GetOperationCount(eID)>count QO%K`}Q}  
        GetOperation eID, count, op >F v8 -  
        If op.Type="ShiftZ" Then 6fiJ' j@  
            DeleteOperation eID,count H?m2|.  
            count=count-1 |SmN.*&(9  
        End If 82<!b]^1  
        count=count+1 5s9~rm  
    Wend ub&1L_K  
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    'Set new shift in zc#`qa:0  
    op.Type = "ShiftZ" +gkB  
    op.val1 = taq DDEn63{  
    op.parent = parID Gu pKM%kM  
    AddOperation eID, op |qD<h  
    Print "Set aqueous humor thickness = " & taq-0.55 ?.H*!u+9>  
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    '************************************************************************* V& m\  
    'Radius and conic constant of anterior lens K;~dZ  
    '************************************************************************* $A ,=z  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ]z,?{S  
    GetConic eID, entity, curv, conic ,~!lNyL  
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    SetConic eID, entity, 1/Rant, CCant 3 V<8  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant x8^Dhpr6  
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    '************************************************************************* GUxhCoxb  
    'Radius and conic constant of posterior lens ROS0Q9X  
    '************************************************************************* NNT9\JRv_  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) z{ 8!3>:E  
    GetConic eID, entity, curv, conic Ni`qU(I'|  
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    SetConic eID, entity, 1/Rpost, CCpost b#F3,T__`Y  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ?$?Ni)Z  
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    '************************************************************************* Ez )Go6Q  
    'Lens thickness (Position of posterior lens surface) g!8-yri  
    '************************************************************************* $_ y"P  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) v{9eEk1  
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    ' Delete any z-shift(s) `c icjA@~  
    count = 0 C-(&zwj?!  
    While GetOperationCount(eID)>count jH8F^KJM[  
        GetOperation eID, count, op \%)p7PNY  
        If op.Type="ShiftZ" Then 8WvT0q>]  
            DeleteOperation eID,count !`u)&.t7  
            count=count-1 ,T]okN5uI  
        End If Vrnx# j-U  
        count=count+1 (b(iL\B$D=  
    Wend |Qm 7x[i  
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    'Set new z-shift b@7 ItzD  
    op.Type = "ShiftZ" 6|zA,-=  
    op.val1 = tlens _jtBU  
    op.parent = parID /+rHy7(\  
    AddOperation eID, op lHx$F ?  
    Print "Set lens thickness = " & tlens Nz m 7E]  
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    '************************************************************************* ,QK>e;:Be  
    'Lens index of refraction n7 S[ F3  
    '************************************************************************* P^ a$?  
    eID = FindMaterial( "Lens" ) rIXAn4,dTv  
    GetModelMaterial eID, mat WPPmh~:  
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    mat.Nd = nlens BM3nZ<%3  
    SetModelMaterial eID, mat sV-9 xh)i  
    Print "Set lens index of refraction = " & nlens )msqt!Ev  
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    '************************************************************************* !nTq"d%(W  
    'Pupil diameter O:1YG$uKa  
    '************************************************************************* o/Z?/alt4  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) c[4Z_5B  
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    'Adjust pupil diameter (trimming volume inner hole) ]86U -`p  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" IkD\YPL;  
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    ' Adjust pupil location to just in front of the lens +~7@K{6 q-  
    parID = FindFullName( "Geometry.Arizona Eye" ) r t f}4.  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) eOS#@6U=u  
    count = 0 !fZxK CsQ  
    While GetOperationCount(eID)>count =l {>-`:  
        GetOperation eID, count, op N O'-HKHj  
        If op.Type="ShiftZ" Then BwbvZfV|  
            DeleteOperation eID,count GR/ p%Y(  
            count=count-1 4/$]wK`  
        End If QH+Oi&xH  
        count=count+1 `/"TYR%  
    Wend F$d`Umqs;P  
    op.Type = "ShiftZ" }E*#VA0/nY  
    op.val1 = taq-0.01 Z x3m$.8  
    op.parent = parID kFeuKSa^d  
    AddOperation eID, op |06G)r&  
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    Print "Set pupil diameter = " & pupilDiam 1SQ&m H/  
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    'Update AZ Eye subassembly Description 7,Nd[ oL*7  
    eID = FindFullName( "Geometry.Arizona Eye" ) 41$7P[M;  
    GetEntity eID, entity \T>f+0=4  
    entity.Description = "Accommodation = " & A & "D" TTS }, `  
    SetEntity eID, entity ^ygN/a>rr  
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    Update e:&5Cvx  
    Print "DONE!" =Bl#CE)X  
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End Sub aabnlOVw  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： ^[!LU  
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Accommodation = 4 Diopters a>6!?:Rj  
Pupil Diameter = 4 mm qHklu2_%  
Set aqueous humor thickness = 2.81 !'MZeiLP  
Set anterior lens radius = 10.4 and conic constant = -2.375869 ]QRhTz  
Set posterior lens radius = -4.424557 and conic constant = -3.081019  ^~?VD  
Set lens thickness = 3.927 .pK_j~}P  
Set lens index of refraction = 1.42672 q8`JRmt)H  
Set pupil diameter = 4 0OP6VZ\  
DONE! 5_#wOz0u$  
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（文章来源：讯技光电）
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