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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 E' JVf%)  
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。 3,3{wGvHHW  
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模型 <MA!?7Z|  
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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。 L>xcgV7  
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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. 1K0 9iB  
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光源 kh^AH6{2  
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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。 UFouIS#L  
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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。 (U/6~r'.L  
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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。 Qn[4&nUD  
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图2. 字母F光源的设定方法光 `$G7Ia_ $]  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 @UkcvhH  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 E I)Pfx"0  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 qaG%PH}a  
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图5. 视网膜重点采样规格设定
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脚本 aNv6 "  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： &p=|z2 J  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 =QRLKo#_  
余下的脚本计算与屈光度有关的所有参数。 ,UH`l./3DX  
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分析 }P-9\*hlm  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 e_\4(4x  
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图7. 字母F在视网膜上颜色分析
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脚本代码 ]*sXISg1  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. pjIXZ=  
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Dim entity As T_ENTITY 6H.D `"cj  
Dim op As T_OPERATION i. `S0  
Dim mat As T_MODELMATERIAL D GOc!  
Dim A As Double fVb&=%e  
Dim pupilDiam As Double x4.-7%VV%  
Dim eID As Long A}H)ojG'v  
Dim parID As Long py P5^Qv  
Dim count As Integer \8{C$"F  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double c6E@+xU  
Dim tlens As Double, nlens As Double .~ZNlI {K  
Dim curv As Double, conic As Double -[0)n{AVvU  
Dim ok As Long k+JDbJ@  
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Sub Main M!!W>A@T[g  
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    '用户输入对话框 S-.!BQ@RMZ  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 5<,}^4wWZ  
        TextBox 220,21,40,21,.TextBox1 'default: 0 .OXvv _?<  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 C1)TEkc"C  
        OKButton 40,91,90,21 [M Z'i/  
        CancelButton 190,91,90,21 _d %H;<_  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Y;xVB" (  
        TextBox 220,49,40,21,.TextBox2 'default: 4 {xr4CDP  
    End Dialog &0Wv+2l @  
    Dim dlg As UserDialog WP2|0ib  
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    ok = Dialog (dlg) 2@uo2]o)  
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    If ok=0 Then    'cancel button was pressed z)]_(zZ^  
        Print "Execution cancelled." i7mT<w>?  
        End Vyu0OiGcR  
    End If N/qr}- 3z  
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    'Assign accommodation and pupil diameter & use defaults if field left empty g[q1P:I@W  
    If dlg.TextBox1 = "" Then D0lgKQ  
        A = 0           'Default accommodation 6$ 9n_AS  
    Else qyp"q{k0  
        A = CDbl(dlg.TextBox1) UT==x<  
    End If 0Evmq3,9  
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    If dlg.TextBox2 = "" Then eaYQyMv@  
        pupilDiam = 4   'Default pupil diameter [0Z r z+q  
    Else H2E!A2\m  
        pupilDiam = CDbl(dlg.TextBox2) &N[~+"  
    End If >m44U 9   
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    Print " " ~bdADVH  
    Print "Accommodation = " & A & " Diopters" a^,6[  
    Print "Pupil Diameter = " & pupilDiam & " mm" u6awcn  
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    ' Calculate new parameters with accommodation 0p*(<8D}  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness |L%F`K>Z:  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens M _Z*F!al<  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens bo0m/hVU  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens LXJ"ct  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens ^ :6v- Yx  
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    tlens = 3.767 + 0.04*A                  'Lens thickness Y \& 4`v'  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction )?K3nr  
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    'Adjust parameters to account for accommodation (`<l" @:_*  
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    '************************************************************************* *G.6\  
    'Aqueous thickness (Position of Lens) z"Gk K T  
    '************************************************************************* |9?67-  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) D?) "Z$  
    GetCustomElement eID, entity =zK7`5  
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    parID = FindFullName( "Geometry.Arizona Eye" ) iRPt0?$  
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    ' Delete any shift(s) in z &g\D-At  
    count = 0 `N_NzH  
    While GetOperationCount(eID)>count >(<OhS(  
        GetOperation eID, count, op f)({;,q  
        If op.Type="ShiftZ" Then p6A"_b^  
            DeleteOperation eID,count z5=&qo|f9l  
            count=count-1 _`+ !,kG[  
        End If c_yf=   
        count=count+1 R1! {,*Gy  
    Wend {I@@i8)]  
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    'Set new shift in :cnH@:  
    op.Type = "ShiftZ" ZcYxH|Gn  
    op.val1 = taq WW:@%cQ@  
    op.parent = parID q-KN{y/  
    AddOperation eID, op 3R !Mfz*  
    Print "Set aqueous humor thickness = " & taq-0.55 7;dV]N  
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    '************************************************************************* @-NdgM<  
    'Radius and conic constant of anterior lens #c5G"^)z  
    '************************************************************************* ^}ngb Dn  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) zF>| 9JU  
    GetConic eID, entity, curv, conic &\F`M|c  
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    SetConic eID, entity, 1/Rant, CCant CKNC"Y*X  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant :5L9tNr{_  
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    '************************************************************************* _SJ#k|vcq  
    'Radius and conic constant of posterior lens ?}D@{%O3T  
    '************************************************************************* Q$iYhR  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) [;7&E{,C  
    GetConic eID, entity, curv, conic 7i`@`0   
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    SetConic eID, entity, 1/Rpost, CCpost &y[Od{=  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 1 xm8w$%  
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    '************************************************************************* nr Jl>H  
    'Lens thickness (Position of posterior lens surface) <Qe30_<K  
    '************************************************************************* q~^Jd=cB\  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) AMp[f%X  
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    ' Delete any z-shift(s) ZZL.&Ho  
    count = 0 :EJ+#  
    While GetOperationCount(eID)>count R*`A',]:9  
        GetOperation eID, count, op @MWrUx  
        If op.Type="ShiftZ" Then Qr6[h!  
            DeleteOperation eID,count Smzy EMT  
            count=count-1 ; f:}gMK  
        End If Ms ;:+JI  
        count=count+1 {9q~bt  
    Wend @" UoQ_h%  
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    'Set new z-shift 1@JAY!yoo_  
    op.Type = "ShiftZ" 3K c  
    op.val1 = tlens 8  ;y N  
    op.parent = parID v}XMFC !  
    AddOperation eID, op -/*-e /+b  
    Print "Set lens thickness = " & tlens 7E*d>:5I  
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    '************************************************************************* ^ a#Vp  
    'Lens index of refraction y, @I6  
    '************************************************************************* PJA%aRP,:  
    eID = FindMaterial( "Lens" ) :8cp]v dW  
    GetModelMaterial eID, mat S 'S|k7Lp  
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    mat.Nd = nlens  w~wpm7  
    SetModelMaterial eID, mat {s&6C-  
    Print "Set lens index of refraction = " & nlens ]|ew!N$ar=  
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    '************************************************************************* Hy`Ee7>  
    'Pupil diameter f'` QW@U  
    '************************************************************************* } QVREj  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) FJDx80J  
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    'Adjust pupil diameter (trimming volume inner hole) $Zf hQ5bat  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ;WxE0Q:!~  
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    ' Adjust pupil location to just in front of the lens D|lp3\`%  
    parID = FindFullName( "Geometry.Arizona Eye" ) ejP273*ah  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 9aky+  
    count = 0 qOAK`{b  
    While GetOperationCount(eID)>count 5]D"y Ay81  
        GetOperation eID, count, op .G8+D%%.  
        If op.Type="ShiftZ" Then ?.Z4GWyXa  
            DeleteOperation eID,count N=R|s$,Oy9  
            count=count-1  0IO#h{t  
        End If !?!~8J~  
        count=count+1 jI:5[. Y  
    Wend &qKJN#NM@  
    op.Type = "ShiftZ" >Z@^R7_W  
    op.val1 = taq-0.01  ,U':=8  
    op.parent = parID WfYu-TK *  
    AddOperation eID, op S?TyC";!  
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    Print "Set pupil diameter = " & pupilDiam F*Lm=^:  
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    'Update AZ Eye subassembly Description ,?s3%<\2   
    eID = FindFullName( "Geometry.Arizona Eye" ) VA{2a7]  
    GetEntity eID, entity Tv2d?y  
    entity.Description = "Accommodation = " & A & "D" do0;"O0 (  
    SetEntity eID, entity $KDH"J  
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    Update GR6BpV7  
    Print "DONE!" $]O;D~  
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End Sub it?l! ~  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： B+W 4r9#  
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Accommodation = 4 Diopters rq=D[vX\N(  
Pupil Diameter = 4 mm mc37Y.  
Set aqueous humor thickness = 2.81 lU6?p")F1  
Set anterior lens radius = 10.4 and conic constant = -2.375869 Wc] L43u  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 T#&tf^;  
Set lens thickness = 3.927 hbfTv;=z  
Set lens index of refraction = 1.42672 N0`v;4gF$]  
Set pupil diameter = 4 Tp7*T8  
DONE! Y*oT (  
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（文章来源：讯技光电）
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