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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 z|<oxF.  
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。 5{a( +'  
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模型 9vTQ^*b m  
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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。 ZX;k*OrW  
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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. Mh|`XO.5I  
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光源 rsv!mY,Em  
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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。 @,&m`qzd+  
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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。 j*u9+.   
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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。 =.oWguzu  
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图2. 字母F光源的设定方法光 Q $0%~`t  
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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 ebe@.ZVSi  
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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。 x2sOEkcQ  
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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。 @%nUfG7TQ  
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图5. 视网膜重点采样规格设定
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脚本 '?gI cWM  
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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： Ju7C?)x  
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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。 )v{41sM+  
余下的脚本计算与屈光度有关的所有参数。 + 4g%?5'  
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分析 <`_OpNxqW  
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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。 Fg\| e%  
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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 HL}~W}!j  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. d3G{0PX  
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Dim entity As T_ENTITY -0o6*?[Z  
Dim op As T_OPERATION W}2 &Pax  
Dim mat As T_MODELMATERIAL fk7Cf"[w  
Dim A As Double LL[#b2CKa  
Dim pupilDiam As Double "]s|D@^4#b  
Dim eID As Long RvSq KW8  
Dim parID As Long Y-3[KHD  
Dim count As Integer $jed{N7Y  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double QS [B  
Dim tlens As Double, nlens As Double + lB+|yJ+  
Dim curv As Double, conic As Double J&"?m.~@  
Dim ok As Long )=E~CpKV  
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Sub Main CxA\yG3L&  
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    '用户输入对话框 aDl, K;GL  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ( OyY_`  
        TextBox 220,21,40,21,.TextBox1 'default: 0 +8)]m<  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 HCx%_9xlm  
        OKButton 40,91,90,21 .5!sOOs$P  
        CancelButton 190,91,90,21 ,M@m4bx  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 |pH* CCA  
        TextBox 220,49,40,21,.TextBox2 'default: 4 qbU1qF/  
    End Dialog [|[sYo  
    Dim dlg As UserDialog (' Ko#3b  
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    ok = Dialog (dlg) ?z@v3(b[  
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    If ok=0 Then    'cancel button was pressed zyZok*s  
        Print "Execution cancelled." (~7m"?  
        End @4_rxu&  
    End If " _:iK]  
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    'Assign accommodation and pupil diameter & use defaults if field left empty DN"S,  
    If dlg.TextBox1 = "" Then  ^%5~ ;  
        A = 0           'Default accommodation 6MQs \J6.  
    Else f3zfRhkIk  
        A = CDbl(dlg.TextBox1) jom} _  
    End If Ig02M_  
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    If dlg.TextBox2 = "" Then GX7 eRqz>  
        pupilDiam = 4   'Default pupil diameter c?.r"5#  
    Else  :Hzz{'  
        pupilDiam = CDbl(dlg.TextBox2) @.Z[M  
    End If Z6IJo%s  
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    Print " " f@! fW&  
    Print "Accommodation = " & A & " Diopters" hJw |@V  
    Print "Pupil Diameter = " & pupilDiam & " mm" Y ]~ HAv '  
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    ' Calculate new parameters with accommodation vo(g0Au)  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness M<{5pH(K  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens smfG, TI  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens `1fJ:b/M  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens 1V|< A  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens &'5@azU  
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    tlens = 3.767 + 0.04*A                  'Lens thickness @<D'-mMt  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction ? G$Om  
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    'Adjust parameters to account for accommodation 'Q:i&dTg  
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    '************************************************************************* 3>-[B`dD(  
    'Aqueous thickness (Position of Lens) !,cQ'*<W8-  
    '************************************************************************* gYTyH.  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) @-'/__cgt  
    GetCustomElement eID, entity P0%N Q1bn  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 2d-TU_JqX  
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    ' Delete any shift(s) in z K&=1Ap  
    count = 0 |d,F-9iw  
    While GetOperationCount(eID)>count \%sPNw=e  
        GetOperation eID, count, op { 1+Cw?1d  
        If op.Type="ShiftZ" Then q';&SR#"`K  
            DeleteOperation eID,count $|4cJ#;^L  
            count=count-1 F(Lb8\to\M  
        End If Uc_jQ4e_  
        count=count+1 [J a)<!]<  
    Wend ]Nnxnp  
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    'Set new shift in UZzNVIXA%  
    op.Type = "ShiftZ" N]B)Fb  
    op.val1 = taq =nJ{$%L\x,  
    op.parent = parID =yl4zQmg$  
    AddOperation eID, op }x*7l`1  
    Print "Set aqueous humor thickness = " & taq-0.55 u?Fnln e4@  
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    '************************************************************************* 8';m)Jc  
    'Radius and conic constant of anterior lens # v{Y=$L  
    '************************************************************************* :lUX5j3  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 'S =sj}X  
    GetConic eID, entity, curv, conic 8O,? |c=>  
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    SetConic eID, entity, 1/Rant, CCant +"jl(5Q  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ?nQ_w0j  
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    '************************************************************************* j]r XoV>  
    'Radius and conic constant of posterior lens ?#d6i$  
    '************************************************************************* z8IPhE@  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) $j57LY|r  
    GetConic eID, entity, curv, conic }$l8d/_$[  
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    SetConic eID, entity, 1/Rpost, CCpost 1Fv8T'  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost *D2Nm9sl  
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    '************************************************************************* v2d<o[[C  
    'Lens thickness (Position of posterior lens surface) *P`v^&  
    '************************************************************************* vB^uxdt|m  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) $H'8 #:[d_  
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    ' Delete any z-shift(s) 2+z1h^)W  
    count = 0 tE@FvZC'=  
    While GetOperationCount(eID)>count cv2]*  
        GetOperation eID, count, op hR-K@fS%l'  
        If op.Type="ShiftZ" Then 2Zy_5>~  
            DeleteOperation eID,count UVrQV$g!  
            count=count-1 {V}qwm?  
        End If k}GjD2m  
        count=count+1 _g[-=y{Bb  
    Wend -;$nb~y  
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    'Set new z-shift r088aUO P  
    op.Type = "ShiftZ" 'TL2%T/)t  
    op.val1 = tlens G8eD7%{b:)  
    op.parent = parID -ey)J +?t  
    AddOperation eID, op >L gVj$Z  
    Print "Set lens thickness = " & tlens {Bh("wg$Lk  
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    '************************************************************************* P^pFqUL7#  
    'Lens index of refraction /t*YDWLg  
    '************************************************************************* &f-hG3/M  
    eID = FindMaterial( "Lens" ) iwU[6A  
    GetModelMaterial eID, mat w d/G|kNO  
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    mat.Nd = nlens  ;\qXbL7  
    SetModelMaterial eID, mat YGp)Oy}:  
    Print "Set lens index of refraction = " & nlens /4*WDiH  
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    '************************************************************************* oaK.kOo  
    'Pupil diameter FbAW_Am(  
    '************************************************************************* v8m`jxII64  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) dQD$K|aUp  
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    'Adjust pupil diameter (trimming volume inner hole) ='}#`',  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" %?9Ok  
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    ' Adjust pupil location to just in front of the lens &$=!dA  
    parID = FindFullName( "Geometry.Arizona Eye" ) H=p`T+  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 'N\&<dT>  
    count = 0 [}-3PpF  
    While GetOperationCount(eID)>count  Qqc]aVRF  
        GetOperation eID, count, op d]SYP  
        If op.Type="ShiftZ" Then _fn1)  
            DeleteOperation eID,count + BL{@,zr  
            count=count-1 eh(<m8I  
        End If $shp(T,q  
        count=count+1 )K;]y-Us[  
    Wend D//=m=  
    op.Type = "ShiftZ" FOH@OY  
    op.val1 = taq-0.01 Dz;HAyPj  
    op.parent = parID d(;4`kd*N  
    AddOperation eID, op M:n6BC>t"  
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    Print "Set pupil diameter = " & pupilDiam I4=Xb^Ux  
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    'Update AZ Eye subassembly Description $ 4m*kQ  
    eID = FindFullName( "Geometry.Arizona Eye" )  )h_8vO2  
    GetEntity eID, entity <+v{GF#R  
    entity.Description = "Accommodation = " & A & "D" z-r2!^q27  
    SetEntity eID, entity p?# pT}1  
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    Update HC*?DJ,  
    Print "DONE!" e,gyQjJR  
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End Sub ?X9U TOx  
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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： 8)j@aiF`  
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Accommodation = 4 Diopters FwG!>  
Pupil Diameter = 4 mm pQa:pX  
Set aqueous humor thickness = 2.81 `<frgXu64  
Set anterior lens radius = 10.4 and conic constant = -2.375869 Vzg=@A#  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 N|usFqCNk^  
Set lens thickness = 3.927 >IfV\ w32  
Set lens index of refraction = 1.42672 4aUiXyr*2  
Set pupil diameter = 4 G~,:2 o3  
DONE! 6'vbT~S!  
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（文章来源：讯技光电）
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