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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 Nm^q.)dO  
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。 mGY 74>/  
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模型 z1Ju;k( 8  
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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。 W%$p,^@S5  
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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. $u"K1Q 3  
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光源 i$NnHj|  
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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。 |6;.C1\,  
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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。 iFDQnt [t  
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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。 "xO`&a{  
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图2. 字母F光源的设定方法光 ca`=dwe>  
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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 T-x`ut7c  
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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。 `}=Fw0  
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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。 9\n}!{@i  
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图5. 视网膜重点采样规格设定
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脚本 G.N3R  
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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： fklM Yu4:n  
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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。 -^Lj~O  
余下的脚本计算与屈光度有关的所有参数。 -`gC?yff:  
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分析 IaJ(T>" +  
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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。 M6I1`Lpf  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 un\^Wmbw  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. VT9$&\)>O  
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Dim entity As T_ENTITY \\T I4A^#  
Dim op As T_OPERATION PNG'"7O  
Dim mat As T_MODELMATERIAL R5FjJ>JE  
Dim A As Double C6Mb(&  
Dim pupilDiam As Double 0$ (}\hMLt  
Dim eID As Long ?|L)!LYx  
Dim parID As Long jC@^/rMh  
Dim count As Integer b6i0_fOO  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double _]4cY%s  
Dim tlens As Double, nlens As Double FJ!>3V;}  
Dim curv As Double, conic As Double b 9?w _  
Dim ok As Long [ wROIvV  
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Sub Main (0][hdI~B  
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    '用户输入对话框 B%t^QbU#\  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 vKW%l  
        TextBox 220,21,40,21,.TextBox1 'default: 0 jv7zvp  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Vr^wesT\Hx  
        OKButton 40,91,90,21 f+1]#"9i|  
        CancelButton 190,91,90,21 {P]l{W@li  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 3Q#VD)  
        TextBox 220,49,40,21,.TextBox2 'default: 4 7~65@&P>  
    End Dialog wVPq1? 9  
    Dim dlg As UserDialog e^FS/=  
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    ok = Dialog (dlg) ,aN/``j=  
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    If ok=0 Then    'cancel button was pressed /yOd]N;$  
        Print "Execution cancelled." dfrq8n]  
        End -py.Y Z  
    End If 5p>a]gp  
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    'Assign accommodation and pupil diameter & use defaults if field left empty 6 Ym[^U  
    If dlg.TextBox1 = "" Then @M,_mX  
        A = 0           'Default accommodation 4j | vzyc  
    Else 1{~9:U Q  
        A = CDbl(dlg.TextBox1) 5P! ZJ3C  
    End If qmK!d<4  
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    If dlg.TextBox2 = "" Then V^0*S=N  
        pupilDiam = 4   'Default pupil diameter `KL`^UqR  
    Else p;p G@Vg  
        pupilDiam = CDbl(dlg.TextBox2) USbiI %   
    End If ^GbyAYEp  
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    Print " " a"v D+r7Ol  
    Print "Accommodation = " & A & " Diopters" $HH(8NoL  
    Print "Pupil Diameter = " & pupilDiam & " mm" &o8\ $A  
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    ' Calculate new parameters with accommodation WOwIJrP  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 7Ua Ll  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens x=H*"L=  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens c_" .+Fa  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens X{ Nif G  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens +zlaYHj  
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    tlens = 3.767 + 0.04*A                  'Lens thickness UA/3lH}  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction +28FB[W  
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    'Adjust parameters to account for accommodation 1 t#Tp$  
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    '************************************************************************* lP@9%L  
    'Aqueous thickness (Position of Lens) J>+Dv?Ni$  
    '************************************************************************* P#yS]F/  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) TX*P*-'  
    GetCustomElement eID, entity PGybX:L  
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    parID = FindFullName( "Geometry.Arizona Eye" ) F"bbU/5  
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    ' Delete any shift(s) in z c XY!b=9  
    count = 0 Z|~<B4#c  
    While GetOperationCount(eID)>count bFTWuM  
        GetOperation eID, count, op 51rM6 BT  
        If op.Type="ShiftZ" Then B0YY7od  
            DeleteOperation eID,count ]];7ozS)X  
            count=count-1 7lh%\  
        End If Z|j8:Ohz  
        count=count+1 3)T5}_  
    Wend c\R! z&y~  
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    'Set new shift in LN7;Yr  
    op.Type = "ShiftZ" nVYh1@yLy  
    op.val1 = taq T? =jKLPC  
    op.parent = parID FUHjY  
    AddOperation eID, op X/.|S57  
    Print "Set aqueous humor thickness = " & taq-0.55 mMa7Eyaf  
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    '************************************************************************* |D^[]*cEH  
    'Radius and conic constant of anterior lens fs`<x*}K  
    '************************************************************************* PCFm@S@Q  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) fCTjTlh  
    GetConic eID, entity, curv, conic &QE* V  
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    SetConic eID, entity, 1/Rant, CCant O'p7^"M  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant %i^%D  
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    '************************************************************************* l\(t~Q  
    'Radius and conic constant of posterior lens *rqih_j0  
    '************************************************************************* CqF< BE  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 1W-!f%  
    GetConic eID, entity, curv, conic .Oim7JQ8  
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    SetConic eID, entity, 1/Rpost, CCpost +]AE}UXZoh  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost inhb>zB  
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    '*************************************************************************  EGV@L#  
    'Lens thickness (Position of posterior lens surface) ~JBQjb]  
    '************************************************************************* %u!#f<"[  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) HM<V$ R  
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    ' Delete any z-shift(s) D'</eJ  
    count = 0 <iTaJa$0m  
    While GetOperationCount(eID)>count 8IVKS>  
        GetOperation eID, count, op 6v.*%E*P  
        If op.Type="ShiftZ" Then 7IFUsli]  
            DeleteOperation eID,count R (hq Ba/V  
            count=count-1 wCkkfTO  
        End If 0w\gxd~'  
        count=count+1 AJq'~fC;I  
    Wend 'av OQj]`K  
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    'Set new z-shift o fN|%g /  
    op.Type = "ShiftZ" 6KV&E8Gn  
    op.val1 = tlens 4cs`R+]o  
    op.parent = parID /TpM#hkq/2  
    AddOperation eID, op IU3OI:uq  
    Print "Set lens thickness = " & tlens r{Xh]U&>k  
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    '************************************************************************* 8)sqj=  
    'Lens index of refraction :JPI#zZun  
    '************************************************************************* S6K aw  
    eID = FindMaterial( "Lens" ) m,8A2;&,8  
    GetModelMaterial eID, mat Q%@l`V)Rs  
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    mat.Nd = nlens XD*$$`+#  
    SetModelMaterial eID, mat %*LdacjZ  
    Print "Set lens index of refraction = " & nlens VP|9Cm=Fg  
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    '************************************************************************* 6 )Oe]{-  
    'Pupil diameter Vrz<DB^-e  
    '************************************************************************* Ei}B9 &O  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) Ma_! 1Y  
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    'Adjust pupil diameter (trimming volume inner hole) BEu9gu  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Km-lWreTH  
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    ' Adjust pupil location to just in front of the lens -6Cxz./#yS  
    parID = FindFullName( "Geometry.Arizona Eye" ) 2,dG Rf  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) -O-_F6p'D  
    count = 0 #B>Hq~ vrC  
    While GetOperationCount(eID)>count v!40>[?|p  
        GetOperation eID, count, op O4( Z%YBe  
        If op.Type="ShiftZ" Then v%B^\S3)  
            DeleteOperation eID,count *bwLi h!}H  
            count=count-1 {Uu7@1@n  
        End If u9'4q<>&  
        count=count+1 2D&tDX<  
    Wend G+}|gG8  
    op.Type = "ShiftZ" fz,8 <  
    op.val1 = taq-0.01 Z+Z`J; ,  
    op.parent = parID 8`'_ckIgr  
    AddOperation eID, op QNn$`Qz.  
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    Print "Set pupil diameter = " & pupilDiam /ptIxe  
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    'Update AZ Eye subassembly Description llQDZ}T  
    eID = FindFullName( "Geometry.Arizona Eye" ) nwW `Q>+#U  
    GetEntity eID, entity ^d-`?zb  
    entity.Description = "Accommodation = " & A & "D" ?I7%@x!+S  
    SetEntity eID, entity qH"e: wgL  
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    Update c5^i5de  
    Print "DONE!" Vk8:;Hj  
     #jK{)%}mA  
End Sub ~(G]-__B<  
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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： c~z{/L  
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Accommodation = 4 Diopters N',]WZ}  
Pupil Diameter = 4 mm Rnun() plJ  
Set aqueous humor thickness = 2.81 S yX>zN!  
Set anterior lens radius = 10.4 and conic constant = -2.375869 5qB>Song  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 -KbT[]  
Set lens thickness = 3.927 LWf+H 4iZ}  
Set lens index of refraction = 1.42672 ,SS@]9A &  
Set pupil diameter = 4 =as]>?<  
DONE! N!r@M."  
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（文章来源：讯技光电）
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