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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 jt}Re,  
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。 ]ogifnwv  
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模型 k'iiRRM  
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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。 &>qUT]w  
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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. htB7 j(  
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光源 CA#g(SiZ  
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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。 {L;sF=d  
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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。 _&l8^MD  
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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。 Ke4oLF2  
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图2. 字母F光源的设定方法光 0$|VkMq(  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 SNqSp.>-U"  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 [R4# bl  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 br=e+]C Y)  
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图5. 视网膜重点采样规格设定
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脚本 o'lG9ePM|  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： zh) &6'S\  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 | +;ZC y  
余下的脚本计算与屈光度有关的所有参数。 21OfTV-+3  
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分析 -=lm`X<:  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 9SeGkwec?$  
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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 ),{3LIr  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. I0Do%  
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Dim entity As T_ENTITY "dCIg{j   
Dim op As T_OPERATION 4AhF E@  
Dim mat As T_MODELMATERIAL rv[BL.qV  
Dim A As Double <vl(a*4a  
Dim pupilDiam As Double ^:?z7m  
Dim eID As Long AkW,Fp1e  
Dim parID As Long *4~7p4 [  
Dim count As Integer 9y\nO)\Tv  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 05ZYOs}  
Dim tlens As Double, nlens As Double c+{XP&g8_J  
Dim curv As Double, conic As Double `_vPElQXZ#  
Dim ok As Long _3 [E$Lg  
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Sub Main 7eq.UyUxs  
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    '用户输入对话框 =x w:@(]{  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 g{DOQA  
        TextBox 220,21,40,21,.TextBox1 'default: 0 07^.Z[(pCt  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 T\wOGaCW  
        OKButton 40,91,90,21 4oF,;o+v\4  
        CancelButton 190,91,90,21 `*CoVx~fk  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 a?Om;-i2`S  
        TextBox 220,49,40,21,.TextBox2 'default: 4 QPVr:+\B{  
    End Dialog blz#M #  
    Dim dlg As UserDialog e77s?WxbK  
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    ok = Dialog (dlg) yzpa\[^  
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    If ok=0 Then    'cancel button was pressed VII`qbxT  
        Print "Execution cancelled." Q3lVx5G>4  
        End ~=wBF  
    End If XF{2'x_R  
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    'Assign accommodation and pupil diameter & use defaults if field left empty a w~a /T:  
    If dlg.TextBox1 = "" Then ,,XHw;{  
        A = 0           'Default accommodation <\:*cET3  
    Else dFeGibI{  
        A = CDbl(dlg.TextBox1) 0T3r#zQ  
    End If ^R\5'9K!  
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    If dlg.TextBox2 = "" Then \i~5H]?d  
        pupilDiam = 4   'Default pupil diameter *=z.H  *  
    Else Rpcnpo  
        pupilDiam = CDbl(dlg.TextBox2) $o\U q  
    End If 6O5E4=  
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    Print " " [\HAJA,  
    Print "Accommodation = " & A & " Diopters" C~iFFh6:  
    Print "Pupil Diameter = " & pupilDiam & " mm" bVRxGn @l  
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    ' Calculate new parameters with accommodation a(o[ bH.|;  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness /7*qa G  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens RmN\;G?}  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens Q6Zh%\+h(  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens Us9$,(3  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens =7P; /EV  
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    tlens = 3.767 + 0.04*A                  'Lens thickness 9]8M {L  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ;rta#pRn  
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    'Adjust parameters to account for accommodation #iGz&S3iN$  
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    '************************************************************************* ^?[^o\/@R  
    'Aqueous thickness (Position of Lens) X'bp?m  
    '************************************************************************* ]*;+ U6/?  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) : [vp.vw}/  
    GetCustomElement eID, entity PZA;10z  
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    parID = FindFullName( "Geometry.Arizona Eye" ) .J\U|r  
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    ' Delete any shift(s) in z ?t.?f`(|  
    count = 0 cfe[6N  
    While GetOperationCount(eID)>count FkE CY  
        GetOperation eID, count, op >|I3h5\M  
        If op.Type="ShiftZ" Then Y=rW.yK8  
            DeleteOperation eID,count CM's6qhQnn  
            count=count-1 J&:0ytG  
        End If m~NWY$oI9[  
        count=count+1 7erao-  
    Wend GrQAho  
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    'Set new shift in qaGIU`}:$A  
    op.Type = "ShiftZ" C1rCKKh  
    op.val1 = taq E 0pF; P5  
    op.parent = parID 0_y%Qj^e  
    AddOperation eID, op w)8@Tu:Q  
    Print "Set aqueous humor thickness = " & taq-0.55 $BBfsaJPT  
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    '************************************************************************* .y2<2eW  
    'Radius and conic constant of anterior lens >qUO_>  
    '************************************************************************* s* YFN#Wuc  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) >a-+7{};  
    GetConic eID, entity, curv, conic m<f{7]fi5  
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    SetConic eID, entity, 1/Rant, CCant =<_5gR  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant zXf+ieo  
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    '************************************************************************* m[7:p{  
    'Radius and conic constant of posterior lens X9gC2iSs]  
    '************************************************************************* |f}NO~CA  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) q(p0#Mk,E  
    GetConic eID, entity, curv, conic \+~4t  
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    SetConic eID, entity, 1/Rpost, CCpost aQmL=9  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost DVcu*UVw  
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    '************************************************************************* d,+n,;6Cf  
    'Lens thickness (Position of posterior lens surface) IP;@unBl  
    '************************************************************************* lqCn5|S]  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ^[Er%yr0  
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    ' Delete any z-shift(s) .XB] X  
    count = 0 k51s*U6=  
    While GetOperationCount(eID)>count XZ&v3ul  
        GetOperation eID, count, op ?W|IC8~d')  
        If op.Type="ShiftZ" Then bv4cw#5z$9  
            DeleteOperation eID,count mfN@tMp  
            count=count-1 *pD;AU  
        End If kZ.3\  
        count=count+1 Bw=[g&+o1@  
    Wend ` j<tI6[e  
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    'Set new z-shift ,;-*q}U  
    op.Type = "ShiftZ" y&Hh8|'mC  
    op.val1 = tlens YcV~S#b  
    op.parent = parID c6m,oS^  
    AddOperation eID, op .KsvRx  
    Print "Set lens thickness = " & tlens ,7g;r_qwA  
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    '************************************************************************* w1_Ux<RF  
    'Lens index of refraction R,bcE4WR"  
    '************************************************************************* tp^'W7E  
    eID = FindMaterial( "Lens" ) RHbp:Mlk  
    GetModelMaterial eID, mat \veL5  
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    mat.Nd = nlens W 8NA.  
    SetModelMaterial eID, mat (B-9M)  
    Print "Set lens index of refraction = " & nlens s- V$N  
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    '************************************************************************* +3>4 ?,^g  
    'Pupil diameter _64@zdL+  
    '************************************************************************* j2Y(Q/i  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) $IT9@}*{  
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    'Adjust pupil diameter (trimming volume inner hole) <6~;-ZQY  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" b]#d04]  
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    ' Adjust pupil location to just in front of the lens Y7)@(7G)\  
    parID = FindFullName( "Geometry.Arizona Eye" ) 8!6*|!,:?n  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) I}IW!K  
    count = 0 6S[D"Q94  
    While GetOperationCount(eID)>count Dg+d=I?  
        GetOperation eID, count, op W@dY:N}  
        If op.Type="ShiftZ" Then  Vb 9N~v  
            DeleteOperation eID,count Ds_ "m,  
            count=count-1 G9inNz*Cx  
        End If 34Khg  
        count=count+1 ~{G: ,|`  
    Wend ]Hy PJ  
    op.Type = "ShiftZ" E57{*C  
    op.val1 = taq-0.01 H;|:r[d!  
    op.parent = parID CZRo{2!?U  
    AddOperation eID, op WUS9zK  
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    Print "Set pupil diameter = " & pupilDiam qjzW9yV+  
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    'Update AZ Eye subassembly Description y?#J`o- O  
    eID = FindFullName( "Geometry.Arizona Eye" ) A i){,nh`0  
    GetEntity eID, entity 8G] m7Z  
    entity.Description = "Accommodation = " & A & "D" ]UT|BE4v  
    SetEntity eID, entity *yq]  
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    Update f\U&M,L\ '  
    Print "DONE!" bXwoJ2  
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End Sub A=d$ir K[  
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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： "IS^a jaq  
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Accommodation = 4 Diopters hUvuq,LH_  
Pupil Diameter = 4 mm EvQwGt1)P  
Set aqueous humor thickness = 2.81 ]~S+nl yd<  
Set anterior lens radius = 10.4 and conic constant = -2.375869 `{lAhZ5  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 IKzRM|/  
Set lens thickness = 3.927 D#Yx,`Ui  
Set lens index of refraction = 1.42672 EQ63VF  
Set pupil diameter = 4 35 5Sd;*  
DONE! F*JvpI[7n  
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（文章来源：讯技光电）
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