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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 V|2[>\Cv  
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。 ~qE:Nz0@  
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模型 CSzu $Hnq  
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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。 p3IhK>  
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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. $L72%T  
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光源 Hr(%y&0  
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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。 $F@ ,,*  
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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。 [n$6 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。 fHgvh&FU  
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图2. 字母F光源的设定方法光 we33GMxHl`  
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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 gAK"ShOhG=  
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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。 (J.U{N v  
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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。 D1wONss  
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图5. 视网膜重点采样规格设定
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脚本 ]9}^}U1."  
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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： $AdBX}{  
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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。 Ed1y%mR>  
余下的脚本计算与屈光度有关的所有参数。 7DWGYvv[  
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分析 -7VQ {nC  
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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。 2k^'}7G%  
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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 $-paYQ4  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. bv}e[yH  
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Dim entity As T_ENTITY qTe@?j  
Dim op As T_OPERATION wotw nE  
Dim mat As T_MODELMATERIAL U.N?cKv  
Dim A As Double 0CK3jdZ+X  
Dim pupilDiam As Double # GzowI'  
Dim eID As Long 0@Z}.k30  
Dim parID As Long L.:8qY  
Dim count As Integer !1/F71l DX  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 'i4L.&  
Dim tlens As Double, nlens As Double -0P9|;h5  
Dim curv As Double, conic As Double v4F+^0?  
Dim ok As Long  upGLZ#  
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Sub Main gKtgW&PYm  
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    '用户输入对话框 mB"1QtD  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 t$rla _rbY  
        TextBox 220,21,40,21,.TextBox1 'default: 0 (QQkXlJ  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 T@a|*.V  
        OKButton 40,91,90,21 \;JZt[  
        CancelButton 190,91,90,21 S1U[{R?,  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ,( NN)Oj  
        TextBox 220,49,40,21,.TextBox2 'default: 4 q`UaJ_7  
    End Dialog KtHkLYOCG  
    Dim dlg As UserDialog aP#/%  
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    ok = Dialog (dlg) .aR9ulS  
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    If ok=0 Then    'cancel button was pressed ER0B{b  
        Print "Execution cancelled." W:K '2j  
        End A# Y:VavQ?  
    End If <,D*m+BWn  
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    'Assign accommodation and pupil diameter & use defaults if field left empty <,\U,jU _  
    If dlg.TextBox1 = "" Then "uFwsjz&B  
        A = 0           'Default accommodation t(jE9t|2e6  
    Else }b/P\1#z  
        A = CDbl(dlg.TextBox1) :aH5=@[!y  
    End If 4iss j$  
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    If dlg.TextBox2 = "" Then <T&v\DN  
        pupilDiam = 4   'Default pupil diameter B<0Kl.V  
    Else !s:e  
        pupilDiam = CDbl(dlg.TextBox2) Hz)i.AA 4  
    End If F~eY'~&H}  
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    Print " " KC)}M zt6_  
    Print "Accommodation = " & A & " Diopters" b`@J"E}  
    Print "Pupil Diameter = " & pupilDiam & " mm" <_#2+7Qs  
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    ' Calculate new parameters with accommodation 7Gy:T47T\@  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Ov ^##E  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens b'Km-'MtH  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens MdmN7>  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens V:vqt@  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens DTSf[zP/  
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    tlens = 3.767 + 0.04*A                  'Lens thickness fP\q?X@]E  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction 52zE -SY  
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    'Adjust parameters to account for accommodation &BRa5`  
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    '************************************************************************* )Yv=:+f  
    'Aqueous thickness (Position of Lens) ^3 9lUKL  
    '************************************************************************* cv G*p||  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) r$8'1s37`  
    GetCustomElement eID, entity *0to,$ n  
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    parID = FindFullName( "Geometry.Arizona Eye" ) om2N*W.gk  
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    ' Delete any shift(s) in z Q$v00z]f*  
    count = 0 ~f[ Y;  
    While GetOperationCount(eID)>count /R&h#;l  
        GetOperation eID, count, op ]Yw$A  
        If op.Type="ShiftZ" Then 5doi4b>]!  
            DeleteOperation eID,count -*z7`]5J  
            count=count-1 "r* `*1  
        End If oQObr  
        count=count+1 &K{8- t  
    Wend JWIY0iP  
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    'Set new shift in &lLfVa-l  
    op.Type = "ShiftZ" 8-B7_GoJ+B  
    op.val1 = taq 3%5a&b  
    op.parent = parID  ,w3-*z  
    AddOperation eID, op "~^0  
    Print "Set aqueous humor thickness = " & taq-0.55 YO$D-  
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    '************************************************************************* <r.QS[:h  
    'Radius and conic constant of anterior lens HE%/+mZN  
    '************************************************************************* WFh.oe8  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) sQac%.H;`U  
    GetConic eID, entity, curv, conic JE7m5k Ta  
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    SetConic eID, entity, 1/Rant, CCant .<F46?HS  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant #[bL9R5NC  
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    '************************************************************************* Cj<8r S4+  
    'Radius and conic constant of posterior lens {;u,04OVK  
    '************************************************************************* .8u@/f%pV  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) XFvl  
    GetConic eID, entity, curv, conic kuD$]A Q`&  
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    SetConic eID, entity, 1/Rpost, CCpost 9`*Eeb>  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost jD6HCIjd'  
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    '************************************************************************* &h I!mo  
    'Lens thickness (Position of posterior lens surface) ds9 'k.  
    '************************************************************************* G<n75!  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 45 sEhs[$  
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    ' Delete any z-shift(s) uC^)#Y\"  
    count = 0 =g9n =spAn  
    While GetOperationCount(eID)>count YWl#!"-  
        GetOperation eID, count, op i[IFD]Xy!j  
        If op.Type="ShiftZ" Then ( .cA'f?h  
            DeleteOperation eID,count 0Eb4wupo  
            count=count-1 $jg[6`L$  
        End If w\o6G7  
        count=count+1 $t):r@L  
    Wend B[GC@]HE  
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    'Set new z-shift XNWtX-[ ^@  
    op.Type = "ShiftZ" 6r<a  
    op.val1 = tlens Ne1Oz}  
    op.parent = parID PJC(:R(j  
    AddOperation eID, op ,%*UF6B M  
    Print "Set lens thickness = " & tlens &/]en|f"  
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    '************************************************************************* {x_.QWe5  
    'Lens index of refraction E(4c&  
    '************************************************************************* .Rk8qRB  
    eID = FindMaterial( "Lens" ) /=m AVA  
    GetModelMaterial eID, mat z/ 1$G"  
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    mat.Nd = nlens >,{s Fc  
    SetModelMaterial eID, mat hi1Ial\Y  
    Print "Set lens index of refraction = " & nlens U]sAYp^$  
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    '************************************************************************* hLLSmW (  
    'Pupil diameter [! $N Tt_  
    '************************************************************************* K>$f#^  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) uGMzU&+  
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    'Adjust pupil diameter (trimming volume inner hole) `|ie#L(:7/  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" `s CwgY+  
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    ' Adjust pupil location to just in front of the lens ~Kw#^.$3T  
    parID = FindFullName( "Geometry.Arizona Eye" ) S\).0goOW  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) U"k$qZ[  
    count = 0 P"_/P8  
    While GetOperationCount(eID)>count smf"F\W s  
        GetOperation eID, count, op V%oZT>T3  
        If op.Type="ShiftZ" Then p"ytt|H  
            DeleteOperation eID,count A9MM^j V8  
            count=count-1 k."p&  
        End If )@N d3Z  
        count=count+1 .xsfq*3e5  
    Wend G tI )O}  
    op.Type = "ShiftZ" e?]5q ez  
    op.val1 = taq-0.01 *U[yeE].  
    op.parent = parID  rL{R=0  
    AddOperation eID, op t5-O-AI[b{  
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    Print "Set pupil diameter = " & pupilDiam k7CKl;Fck  
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    'Update AZ Eye subassembly Description ' k,2*.A  
    eID = FindFullName( "Geometry.Arizona Eye" ) rm[C{Pn  
    GetEntity eID, entity nqyD>>  
    entity.Description = "Accommodation = " & A & "D"  'o-4'  
    SetEntity eID, entity ljKIxSvCFp  
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    Update JXB)'d0  
    Print "DONE!" =fcg4h5(  
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End Sub }D#: NlMp  
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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： e}UQN:1  
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Accommodation = 4 Diopters `6U!\D  
Pupil Diameter = 4 mm `L'g<VK;  
Set aqueous humor thickness = 2.81 3 _  
Set anterior lens radius = 10.4 and conic constant = -2.375869 3kn-tM  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 ]||b2[*  
Set lens thickness = 3.927 KNVu[P)rv  
Set lens index of refraction = 1.42672 IO\4dU)  
Set pupil diameter = 4 <u64)8'  
DONE! J usU5 e|  
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（文章来源：讯技光电）
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