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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 SXod r}  
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。 }#yRa Ip  
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模型 #Q$4EQB  
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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。 _Yh4[TT~/  
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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. `_v-Y`Z  
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光源 ;G},xDGO_m  
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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。 Zn9w1ev  
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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。 -k<.Q=]<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。 N?pD"re)6  
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图2. 字母F光源的设定方法光 T`WFY  
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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 @nZFw.  
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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。 %NAz(B  
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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。 WV&BZ:H  
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图5. 视网膜重点采样规格设定
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脚本 Nq9(O#}  
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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： @:c 1+  
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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。 Y.hrU*[J0  
余下的脚本计算与屈光度有关的所有参数。 | z('yy$  
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分析 gVI*`$  
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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。 ga,yFw  
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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 %ZQl.''ISa  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. -|3U0: 'm  
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Dim entity As T_ENTITY (Bmjz*%M  
Dim op As T_OPERATION O=-|b kO  
Dim mat As T_MODELMATERIAL (Hn,}(3S  
Dim A As Double iYnw?4Y  
Dim pupilDiam As Double I{RktO;1  
Dim eID As Long DvhK0L*Qr  
Dim parID As Long j$L<9(DoR  
Dim count As Integer ~q1s4^J  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double pw$I~3OFd  
Dim tlens As Double, nlens As Double 7C 4Njei"  
Dim curv As Double, conic As Double o+tY[UX  
Dim ok As Long CId`6W  
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Sub Main 4$|G$h  
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    '用户输入对话框 0<s)xaN>Y  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 3^fZUldf  
        TextBox 220,21,40,21,.TextBox1 'default: 0 2`Pk@,:_  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 K]7@%cS  
        OKButton 40,91,90,21 w6cPd'  
        CancelButton 190,91,90,21 ~\oJrRYR`  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 L?Lp``%bI7  
        TextBox 220,49,40,21,.TextBox2 'default: 4 s@ q54  
    End Dialog cdh1~'q/  
    Dim dlg As UserDialog i\<l&W  
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    ok = Dialog (dlg) :7`,dyIqT  
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    If ok=0 Then    'cancel button was pressed BHK_=2WYz  
        Print "Execution cancelled." d+IPa<N  
        End V,Gt5lL&/!  
    End If iD]!PaFD`  
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    'Assign accommodation and pupil diameter & use defaults if field left empty <<`."RY#0  
    If dlg.TextBox1 = "" Then '<Vvv^Er  
        A = 0           'Default accommodation #A))#sT'R  
    Else M9N|Ql  
        A = CDbl(dlg.TextBox1) 2+^#<Uok  
    End If $rlIJwqn  
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    If dlg.TextBox2 = "" Then \e=@h!p  
        pupilDiam = 4   'Default pupil diameter AX&1-U  
    Else F(w>lWs;  
        pupilDiam = CDbl(dlg.TextBox2) *".7O*jjV  
    End If +}1]8:>cq  
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    Print " " Y Jv{Z^;M  
    Print "Accommodation = " & A & " Diopters" dE^'URBiA  
    Print "Pupil Diameter = " & pupilDiam & " mm" lS,Hr3Lz  
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    ' Calculate new parameters with accommodation D!-zQ`^  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness =X1$K_cN  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens @&~BGh  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens I#mT#xs6  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens Z2`e*c-[E  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Z$pR_dazU  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ~f@;.  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction |[: `izW  
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    'Adjust parameters to account for accommodation VJNPs6  
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    '************************************************************************* %] Bb;0G  
    'Aqueous thickness (Position of Lens) A1Zu^_y'  
    '************************************************************************* *$s)p>  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) :2?'mKa7  
    GetCustomElement eID, entity Y6CadC  
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    parID = FindFullName( "Geometry.Arizona Eye" ) T"0a&.TLj  
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    ' Delete any shift(s) in z 16] O^R;r  
    count = 0 <oeHZD_ OR  
    While GetOperationCount(eID)>count )8vcg{b{d  
        GetOperation eID, count, op \/,SH?>4x  
        If op.Type="ShiftZ" Then 9sRP8Nj|  
            DeleteOperation eID,count 'LX=yL]I  
            count=count-1 <n#JOjHV  
        End If YZnrGkQ  
        count=count+1 wF&\@H  
    Wend aN7u j  
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    'Set new shift in $4L=Dg  
    op.Type = "ShiftZ" 't>Qj7vh0  
    op.val1 = taq ))MP]j9 T  
    op.parent = parID BkC(9[Ei  
    AddOperation eID, op (_W[~df4  
    Print "Set aqueous humor thickness = " & taq-0.55 ;DGWUK.U[H  
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    '************************************************************************* > Euput\  
    'Radius and conic constant of anterior lens J6Kf z~%  
    '************************************************************************* G3e%~  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 8pk5[=3Z  
    GetConic eID, entity, curv, conic V*/))n?  
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    SetConic eID, entity, 1/Rant, CCant JlH|=nIaj6  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant X~R qv5@-  
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    '************************************************************************* &"CS1P|  
    'Radius and conic constant of posterior lens F4PD3E_#  
    '************************************************************************* , <[os  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) nU`;MW/^w  
    GetConic eID, entity, curv, conic vi=yR  
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    SetConic eID, entity, 1/Rpost, CCpost q`\lvdl  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost |l ~ADEg  
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    '************************************************************************* kC#;j=K?  
    'Lens thickness (Position of posterior lens surface) BujWql  
    '************************************************************************* . XY'l  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) h&Sl8$jVp  
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    ' Delete any z-shift(s) : Z.mM5  
    count = 0 5<S1,u5  
    While GetOperationCount(eID)>count ES+&e/G"ds  
        GetOperation eID, count, op .3Ap+V8?  
        If op.Type="ShiftZ" Then !cq4+0{O;&  
            DeleteOperation eID,count a:8@:d1T K  
            count=count-1 I4)vJ0  
        End If HY42G#^  
        count=count+1 N7e^XUG   
    Wend y_nh~&  
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    'Set new z-shift WH/a#F  
    op.Type = "ShiftZ" Comu c  
    op.val1 = tlens y3xP~]n  
    op.parent = parID `ybZE+S.  
    AddOperation eID, op 68d@By  
    Print "Set lens thickness = " & tlens O-|3k$'\z  
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    '************************************************************************* [;b9'7j'  
    'Lens index of refraction ' ZB%McS  
    '************************************************************************* IEA[]eik>  
    eID = FindMaterial( "Lens" ) B[*i}k%i  
    GetModelMaterial eID, mat ,rN7X<s54  
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    mat.Nd = nlens %1lLUgf3G/  
    SetModelMaterial eID, mat ''(T3;^ +  
    Print "Set lens index of refraction = " & nlens >SzTZ3!E  
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    '************************************************************************* Oll\T GXP!  
    'Pupil diameter ;uJVY)7a  
    '************************************************************************* ^=@%@mR/[C  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) .=NK^  
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    'Adjust pupil diameter (trimming volume inner hole) }`eeItI+  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" %AJdtJ@0H  
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    ' Adjust pupil location to just in front of the lens eD/?$@y  
    parID = FindFullName( "Geometry.Arizona Eye" ) SQHV gj  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Zs4N0N{  
    count = 0 @B[V'|  
    While GetOperationCount(eID)>count ;m\(fW*ii  
        GetOperation eID, count, op ZE1#{u~[y  
        If op.Type="ShiftZ" Then ru U|  
            DeleteOperation eID,count |_A35"v  
            count=count-1 U@*z#T#"m  
        End If H<q:+  
        count=count+1 c1Hv^*Y  
    Wend AvwX 2?tc  
    op.Type = "ShiftZ" ](O!6_'d  
    op.val1 = taq-0.01 5-sxTp  
    op.parent = parID <vAg\Tv:S  
    AddOperation eID, op 4iw+3 Q|  
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    Print "Set pupil diameter = " & pupilDiam y@(U 6ZOyx  
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    'Update AZ Eye subassembly Description PeG8_X}u9  
    eID = FindFullName( "Geometry.Arizona Eye" ) Z$@Juv&>5^  
    GetEntity eID, entity `fL$t0 "  
    entity.Description = "Accommodation = " & A & "D" Y/4B*>kl  
    SetEntity eID, entity J"z8olV  
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    Update Aw5yvQ>]e  
    Print "DONE!" 7y60-6r  
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End Sub )UxF lp;\  
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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： P!-9cd1 C,  
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Accommodation = 4 Diopters -dza_{&+iZ  
Pupil Diameter = 4 mm *f,EDSN1@d  
Set aqueous humor thickness = 2.81 X2EC+<  
Set anterior lens radius = 10.4 and conic constant = -2.375869 GB{%4)%6  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 F &uU ,);  
Set lens thickness = 3.927 R[9[lQ'vR  
Set lens index of refraction = 1.42672 oEfKL`]B  
Set pupil diameter = 4 VbZZ=q=Kd  
DONE! gXF.e.uU  
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（文章来源：讯技光电）
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