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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 yj$$k~@  
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。 18^#:=Z  
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模型 r` B(ucE  
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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。 QdIx@[+WOq  
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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. zq6)jHfq.  
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光源 {+~ JTrp  
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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。 MzFFWk  
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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。 M7[GwA[Z +  
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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。 ~6"=d  
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图2. 字母F光源的设定方法光 E^iShe  
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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 "S]G+/I|iw  
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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。 Gx7bV}&PN  
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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。 0HO'%'Ga*  
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图5. 视网膜重点采样规格设定
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脚本 i zYC0T9  
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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： =]r2;014  
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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/pMg#-  
余下的脚本计算与屈光度有关的所有参数。 gg/ts]$  
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分析 Q #X'.](1  
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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。 : ?}mu1  
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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 P5H_iH  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. bU/4KZ'-^  
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Dim entity As T_ENTITY !PA><F  
Dim op As T_OPERATION 1 0zw}1x  
Dim mat As T_MODELMATERIAL lUaJC'~p  
Dim A As Double -dWg1`;  
Dim pupilDiam As Double Qqi?DW1)-  
Dim eID As Long }$'XV.  
Dim parID As Long P:_bF>r ?  
Dim count As Integer hH9~.4+*`g  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double {+ Ibi{  
Dim tlens As Double, nlens As Double em95ccs'-  
Dim curv As Double, conic As Double t-5K dLB  
Dim ok As Long ?(U a+*b  
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Sub Main qDTdYf  
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    '用户输入对话框 uts>4r>+  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 : h(Z\D_  
        TextBox 220,21,40,21,.TextBox1 'default: 0 1l/t|M^I  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 mlCBstt{  
        OKButton 40,91,90,21 %Oo f/q  
        CancelButton 190,91,90,21 D^2lb"3  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 $hHV Ie]+  
        TextBox 220,49,40,21,.TextBox2 'default: 4 >gs_Bzy]  
    End Dialog &]Uo>Gb3!q  
    Dim dlg As UserDialog #?k</~s6M`  
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    ok = Dialog (dlg) Ozhn`9L+1!  
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    If ok=0 Then    'cancel button was pressed B;F ~6i  
        Print "Execution cancelled." AAs&P+;  
        End V%)Tu{L  
    End If .P`QCH;Ih  
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    'Assign accommodation and pupil diameter & use defaults if field left empty vBJxhK-  
    If dlg.TextBox1 = "" Then 0{uaSR  
        A = 0           'Default accommodation )#8g<]q  
    Else xkw=os  
        A = CDbl(dlg.TextBox1) r{t6Vv2J  
    End If -)B_o#2=2  
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    If dlg.TextBox2 = "" Then 4;W{#jk  
        pupilDiam = 4   'Default pupil diameter <5mv8'{L  
    Else  BdiV  
        pupilDiam = CDbl(dlg.TextBox2) K9.Gjw  
    End If MoQ\~/Z|  
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    Print " " 83I 5n&)  
    Print "Accommodation = " & A & " Diopters" SASLeGaV  
    Print "Pupil Diameter = " & pupilDiam & " mm" <&3aP}  
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    ' Calculate new parameters with accommodation VH~YwO!x  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness b1cVAfUP  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens <G|i5/|7  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens R|'W#"{@  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens ;@Fb>l BhX  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens M2w'cdHk  
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    tlens = 3.767 + 0.04*A                  'Lens thickness JKfJ%yy |  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction H8[A*uYL  
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    'Adjust parameters to account for accommodation b=xn(HE8|  
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    '************************************************************************* Osm))Ua(  
    'Aqueous thickness (Position of Lens) 3(\D.Z  
    '************************************************************************* rD4 umWi  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) IQ_s]b;z  
    GetCustomElement eID, entity Hnk&2bY  
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    parID = FindFullName( "Geometry.Arizona Eye" ) {QylNC9  
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    ' Delete any shift(s) in z fglfnx0{  
    count = 0 K)! ^NT  
    While GetOperationCount(eID)>count Xpn\TD<_I  
        GetOperation eID, count, op pvUV5^B(M  
        If op.Type="ShiftZ" Then bKGX> %-  
            DeleteOperation eID,count $C5*@`GM$  
            count=count-1 V`#2jDz  
        End If fV5$[CL1  
        count=count+1 (g/A uL  
    Wend .kg 3>*  
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    'Set new shift in YfB)TK\W9/  
    op.Type = "ShiftZ" $.,B2}'  
    op.val1 = taq tkcs6uy  
    op.parent = parID <>9!oOa  
    AddOperation eID, op ) c\Y!vS  
    Print "Set aqueous humor thickness = " & taq-0.55 J](NCD  
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    '************************************************************************* K_YOp1  
    'Radius and conic constant of anterior lens Zs=A<[  
    '************************************************************************* uf#h~;B  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) p? o[+L<  
    GetConic eID, entity, curv, conic \q1tT!]  
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    SetConic eID, entity, 1/Rant, CCant "4H@&:-(p  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant fxPg"R!1i  
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    '************************************************************************* ;[R6rVHe{  
    'Radius and conic constant of posterior lens `}#rcDK  
    '************************************************************************* i$<['DY  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 0LH6G[  
    GetConic eID, entity, curv, conic .cQO?UKK  
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    SetConic eID, entity, 1/Rpost, CCpost S\8v)|Pr  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ^ZQMRNP{r  
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    '************************************************************************* ~ W8X g)  
    'Lens thickness (Position of posterior lens surface) 8R3{YJ6@T  
    '************************************************************************* O;<wD h)Yt  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) d7vPZ_j^z  
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    ' Delete any z-shift(s) d2#NRqgQ  
    count = 0 s<F*kLib  
    While GetOperationCount(eID)>count <z,)4z++  
        GetOperation eID, count, op bp:`m>4<  
        If op.Type="ShiftZ" Then D/."0 #q  
            DeleteOperation eID,count M@.S Q@E  
            count=count-1 =eQB-Xe8Y  
        End If F&czD;F  
        count=count+1 0<\|D^m=&h  
    Wend OLb s~ >VA  
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    'Set new z-shift Ia#!T"]@W6  
    op.Type = "ShiftZ" 'l.tV7  
    op.val1 = tlens T[|#DMg$F  
    op.parent = parID apk,\L@sZ  
    AddOperation eID, op 5;0w({1l  
    Print "Set lens thickness = " & tlens C LaQE{  
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    '************************************************************************* #!R>`l(S  
    'Lens index of refraction B~Kx Up  
    '************************************************************************* cr!W5+r  
    eID = FindMaterial( "Lens" ) Qi`3$<W>  
    GetModelMaterial eID, mat /Pg)7Zn  
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    mat.Nd = nlens 5 qfvHQ ~M  
    SetModelMaterial eID, mat Z?'CS|u d  
    Print "Set lens index of refraction = " & nlens bN. G%1  
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    '************************************************************************* 5Z!$?J4Rl  
    'Pupil diameter 0#J~@1Gf  
    '************************************************************************* +QFKaS<sn  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) r V%6 8x9  
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    'Adjust pupil diameter (trimming volume inner hole) ~{Iw[,MJ  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" L K #A  
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    ' Adjust pupil location to just in front of the lens A?lL K&*  
    parID = FindFullName( "Geometry.Arizona Eye" ) |KYl'"5\  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) OCx'cSs-=  
    count = 0 $k\bP9  
    While GetOperationCount(eID)>count g9pKoi|\E  
        GetOperation eID, count, op F6q=W#~  
        If op.Type="ShiftZ" Then J=3{<Xl  
            DeleteOperation eID,count b\(f>g[  
            count=count-1 U7g`R@  
        End If k={D!4kKz  
        count=count+1 J -z.  
    Wend Mgw#4LU  
    op.Type = "ShiftZ" l7VO8p]y[R  
    op.val1 = taq-0.01 !.j{vvQ/  
    op.parent = parID u;q Q/Ftb  
    AddOperation eID, op #7 O7O~  
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    Print "Set pupil diameter = " & pupilDiam S5hc@^|0Z  
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    'Update AZ Eye subassembly Description ]"T157F  
    eID = FindFullName( "Geometry.Arizona Eye" ) fF0K].  
    GetEntity eID, entity !}*vM@)1  
    entity.Description = "Accommodation = " & A & "D" uBww  
    SetEntity eID, entity jv~#'=T'  
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    Update { }/  
    Print "DONE!" y ~  K8  
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End Sub $JOz7j(  
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如果屈光度是4，光瞳直径是4，则会输出如下数据： %DiQTg7V,  
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Accommodation = 4 Diopters 0e8  
Pupil Diameter = 4 mm _K9PA[m5 ~  
Set aqueous humor thickness = 2.81 i<Ms2^  
Set anterior lens radius = 10.4 and conic constant = -2.375869 oi0O4J%H  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 HHx:s2G  
Set lens thickness = 3.927 .$-;`&0cZ  
Set lens index of refraction = 1.42672 zRjbEL  
Set pupil diameter = 4 = cxO@Fu  
DONE! hD5@PeLh  
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（文章来源：讯技光电）
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