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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 ,f,+)C$  
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。 $qZ6i  
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模型 .:Wp9M  
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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。 @RuMo"js  
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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. hDUU_.q)D  
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光源 -:45Q{u/  
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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。 $w-@Oa*h9U  
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图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 S-Vxlku]  
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在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ~Cynw(  
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图2. 字母F光源的设定方法光 V7gL*,3>=  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 bi@'m?XwJ  
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在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 yn(bW\  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 +tg${3ti_  
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图5. 视网膜重点采样规格设定
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脚本 e(b$LUV  
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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: 8o $ ` '  
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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。 itiSZL,  
余下的脚本计算与屈光度有关的所有参数。 8+Gwv SDU  
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分析 [4dX[  
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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。 Q:y'G9b  
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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 l4iklg3  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. :+ 1Wmg  
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Dim entity As T_ENTITY 2!b##`UjA7  
Dim op As T_OPERATION C,LosAd  
Dim mat As T_MODELMATERIAL eC6wrpZO  
Dim A As Double H<?s[MH[  
Dim pupilDiam As Double +/M%%:>mY  
Dim eID As Long #@1(  
Dim parID As Long ,i;#e  
Dim count As Integer $2}%3{<j  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double #!#s7^%K&  
Dim tlens As Double, nlens As Double "*MF=VB1  
Dim curv As Double, conic As Double &Ll&A@yU  
Dim ok As Long #Oq.}x?i  
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Sub Main  H ="I=}  
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    '用户输入对话框 6'<[QoW];  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 d 792#Dc  
        TextBox 220,21,40,21,.TextBox1 'default: 0 )_4()#3  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 &rX#A@=  
        OKButton 40,91,90,21 8`]yp7ueS  
        CancelButton 190,91,90,21 vr2PCG[~  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 %p&y/^=0I  
        TextBox 220,49,40,21,.TextBox2 'default: 4 )DlKeiK  
    End Dialog :IfwhI)  
    Dim dlg As UserDialog P46Q3EE  
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    ok = Dialog (dlg) tp&|*M3  
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    If ok=0 Then    'cancel button was pressed |z:4T%ES  
        Print "Execution cancelled." L*vKIP<EMM  
        End _F|}=^Z`  
    End If `c-omNu  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 0!$y]Gr  
    If dlg.TextBox1 = "" Then Q[|*P ] w  
        A = 0           'Default accommodation (vchZn#  
    Else hv\Dz*XTs0  
        A = CDbl(dlg.TextBox1) fz2}M:u  
    End If #5'& |<  
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    If dlg.TextBox2 = "" Then 8~TKiR5  
        pupilDiam = 4   'Default pupil diameter @' ;.$  
    Else gxAy{ t  
        pupilDiam = CDbl(dlg.TextBox2) X:g#&e_  
    End If G|8>Q3D  
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    Print " " ~<s^HP2U{  
    Print "Accommodation = " & A & " Diopters" v7`{6Pf_$  
    Print "Pupil Diameter = " & pupilDiam & " mm" j|!t3}((  
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    ' Calculate new parameters with accommodation 8?YeaMIBB  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness BfVh\ lkH  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens BHZhdm@),  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens +"=ydF.9  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens w&Gc#-B  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens u*,>$(-u  
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    tlens = 3.767 + 0.04*A                  'Lens thickness / !MKijI  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction G43r85LO  
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    'Adjust parameters to account for accommodation 1<_/Qu>V  
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    '************************************************************************* K :~tZ  
    'Aqueous thickness (Position of Lens) BOq9\g`5s  
    '************************************************************************* (j??  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) rPGj+wL5-  
    GetCustomElement eID, entity a_?b <  
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    parID = FindFullName( "Geometry.Arizona Eye" ) SPt/$uYJ  
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    ' Delete any shift(s) in z e3~{l~ Rb  
    count = 0 gt02Csdt  
    While GetOperationCount(eID)>count i.`n^R;N  
        GetOperation eID, count, op 83gWA>Odh  
        If op.Type="ShiftZ" Then 3JBXGT0gJ  
            DeleteOperation eID,count ar}-~~h 5  
            count=count-1 =y)K er  
        End If N)R5#JX  
        count=count+1 n_9Ex&?e  
    Wend QKlsBq  
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    'Set new shift in `&OX|mL^w  
    op.Type = "ShiftZ" >$E;."a  
    op.val1 = taq [w|Klq5  
    op.parent = parID _ezRE"F5  
    AddOperation eID, op ~ &Ne P  
    Print "Set aqueous humor thickness = " & taq-0.55 _N^w5EBC]  
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    '************************************************************************* :Q ]"dbY^  
    'Radius and conic constant of anterior lens @p WN5VL  
    '************************************************************************* ljOY;WV3  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) fi%i 2Wy  
    GetConic eID, entity, curv, conic 5rdB>8W  
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    SetConic eID, entity, 1/Rant, CCant =r7!QXPH}  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant /w(g:e  
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    '************************************************************************* X~D[CwA|`  
    'Radius and conic constant of posterior lens |l+5E   
    '************************************************************************* U$& '>%#  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) e(|Z<6  
    GetConic eID, entity, curv, conic 83t/ \x,Q  
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    SetConic eID, entity, 1/Rpost, CCpost aK@ Y) Ju'  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost YI,t{Wy  
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    '************************************************************************* s_VcC_A  
    'Lens thickness (Position of posterior lens surface) AguE)I&m  
    '************************************************************************* Bps%>P~.  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) L-D4>+  
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    ' Delete any z-shift(s) >L2_k'uE+;  
    count = 0 d-+jb<C&  
    While GetOperationCount(eID)>count &s vg<UZ  
        GetOperation eID, count, op DR}I+<*%aD  
        If op.Type="ShiftZ" Then aXJ/"k #Tl  
            DeleteOperation eID,count n-" (~  
            count=count-1 *?HGi>]\ |  
        End If {>msE }L  
        count=count+1 fPUr O  
    Wend j7kX"nz  
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    'Set new z-shift 1Ng.Ukb  
    op.Type = "ShiftZ" cVL|kYVWT  
    op.val1 = tlens QDQ"Sc06  
    op.parent = parID {eaR,d~X  
    AddOperation eID, op f/#Id]B  
    Print "Set lens thickness = " & tlens \\KjiT'  
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    '************************************************************************* ZxwrlaA  
    'Lens index of refraction /#M1J:SV  
    '************************************************************************* D~ Y6%9  
    eID = FindMaterial( "Lens" ) :QGo -,6-  
    GetModelMaterial eID, mat +?o!"SJ  
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    mat.Nd = nlens ?0qD(cfx<  
    SetModelMaterial eID, mat [-_{3qq<e  
    Print "Set lens index of refraction = " & nlens EOrui:.B)  
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    '************************************************************************* |du%c`wl  
    'Pupil diameter \~E?;q!  
    '************************************************************************* nZ(]WPIN"  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) v7 *L3Ol  
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    'Adjust pupil diameter (trimming volume inner hole) '@.6Rd 8  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" {f #QZS!E  
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    ' Adjust pupil location to just in front of the lens ` 5Kg[nB:  
    parID = FindFullName( "Geometry.Arizona Eye" ) D:U6r^c  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) E.Xp\Dm71  
    count = 0 :C} I6v=  
    While GetOperationCount(eID)>count MOaI~xZ  
        GetOperation eID, count, op Za{O9Qc?D|  
        If op.Type="ShiftZ" Then ,Zn6T"[$  
            DeleteOperation eID,count vF$( Y/  
            count=count-1 Gg'!(]v  
        End If h8`On/Ur_8  
        count=count+1 rwLKY .J]  
    Wend 9m)$^U>oz  
    op.Type = "ShiftZ" ?K[Y"*y2  
    op.val1 = taq-0.01 A4,{ep'Z!  
    op.parent = parID ;^xM" {G8  
    AddOperation eID, op zK5&,/  
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    Print "Set pupil diameter = " & pupilDiam &Uam4'B6-  
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    'Update AZ Eye subassembly Description spfW)v/T!  
    eID = FindFullName( "Geometry.Arizona Eye" ) , yltt+ e  
    GetEntity eID, entity f X[xZGV,  
    entity.Description = "Accommodation = " & A & "D" :lB`K>)iB}  
    SetEntity eID, entity #("M4}~  
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    Update prj(  
    Print "DONE!" O] PM L`  
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End Sub (Ut8pa+yX  
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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,gT|4|B\g  
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Accommodation = 4 Diopters =l43RawAmu  
Pupil Diameter = 4 mm -n9&W  
Set aqueous humor thickness = 2.81 Ljm`KE\Q;t  
Set anterior lens radius = 10.4 and conic constant = -2.375869 F9j@KC(yg  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 xA Ez1  
Set lens thickness = 3.927 t,f ec>.  
Set lens index of refraction = 1.42672 ej-A =avd  
Set pupil diameter = 4 2/ 4zg  
DONE! Pjs=n7  
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(文章来源:讯技光电)
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