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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 gb!@OZ c  
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。 >S?C {_g  
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模型 g]EQ2g_N1  
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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。 ~:P8g<w  
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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. oo$WD6eCR  
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光源 H{Y5YTg]  
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多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 Mip m&5R  
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图1. 光源和提示信息使用
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除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处，并增加了pre-propagation distance= -8。尽管光线在光瞳处创建，规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射，而不是在光瞳处入射。 dy8In%  
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在往下看是内置的脚本用来修改屈光度，使其为4（250mm），光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 4 _c:Vl  
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图2. 字母F光源的设定方法光 i 5 >J  
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图3. 字母F在视网膜上位置点列图
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视网膜的散射 &2<&X( )  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 ..Uw8u/  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 alb+R$s  
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图5. 视网膜重点采样规格设定
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脚本 xi1N? pP  
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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： fn?6%q,!ls  
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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。 jV|$? Rcl%  
余下的脚本计算与屈光度有关的所有参数。 NZ%~n:/V#  
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分析 K#6`LL m  
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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。 &\6`[# bT  
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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 #1qVFU  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. jN'fm  
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Dim entity As T_ENTITY $E9daUt8"J  
Dim op As T_OPERATION .' N O~  
Dim mat As T_MODELMATERIAL (-Ct!aW|  
Dim A As Double G4iLCcjY  
Dim pupilDiam As Double i6g[E 4nk  
Dim eID As Long 5S-o 2a  
Dim parID As Long pD}VB6=  
Dim count As Integer amk42  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double M5ySs\O4  
Dim tlens As Double, nlens As Double x}8T[  
Dim curv As Double, conic As Double Sfr\%Buv  
Dim ok As Long T>uWf#&pjs  
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Sub Main sh)) [V"8  
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    '用户输入对话框 UN .[,%<s  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 D-+)M8bt  
        TextBox 220,21,40,21,.TextBox1 'default: 0 CXP $bt}  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 M@2Qn-I  
        OKButton 40,91,90,21 5dNf$a0E  
        CancelButton 190,91,90,21 #u2&8-Gh  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 '*LN)E> d  
        TextBox 220,49,40,21,.TextBox2 'default: 4 cT=wJ  
    End Dialog lTOM/^L  
    Dim dlg As UserDialog 8hdAXWPn  
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    ok = Dialog (dlg) 6q uWO2x  
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    If ok=0 Then    'cancel button was pressed [|;Zxb:  
        Print "Execution cancelled." 3_eml\CY  
        End b\Xu1>  
    End If &F*QYz[  
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    'Assign accommodation and pupil diameter & use defaults if field left empty t>h i$NX{p  
    If dlg.TextBox1 = "" Then =&*QT&e  
        A = 0           'Default accommodation 0qd;'r<  
    Else .]ZuG  
        A = CDbl(dlg.TextBox1) )!*M 71  
    End If zf;[nz  
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    If dlg.TextBox2 = "" Then *I1W+W`G  
        pupilDiam = 4   'Default pupil diameter pA,EUh| H  
    Else [.Wt,zrE  
        pupilDiam = CDbl(dlg.TextBox2) *=0r>]  
    End If .s*EV!SE  
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    Print " " S{)n0/_  
    Print "Accommodation = " & A & " Diopters" [dF=1E>W_J  
    Print "Pupil Diameter = " & pupilDiam & " mm" NUnc"@  
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    ' Calculate new parameters with accommodation kRXg."b(  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness k42ur)pb  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens ;pyJ O_R[  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens Oi[9b  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens lgqL)^8A  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens <^'+ ]?  
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    tlens = 3.767 + 0.04*A                  'Lens thickness MH8%-UV  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction )"Br,uIv:/  
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    'Adjust parameters to account for accommodation /FV6lR!0^  
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    '************************************************************************* Yg,lJ!q  
    'Aqueous thickness (Position of Lens) ow$l!8  
    '************************************************************************* OmjT`,/  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) vMdhNOU  
    GetCustomElement eID, entity 2&K|~~  
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    parID = FindFullName( "Geometry.Arizona Eye" ) WCl;#=  
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    ' Delete any shift(s) in z L?C~ qS2g  
    count = 0 AG\ 852`1m  
    While GetOperationCount(eID)>count *]{I\rX  
        GetOperation eID, count, op PyxN_agf  
        If op.Type="ShiftZ" Then 0@x$Cp  
            DeleteOperation eID,count p}|wO&4h  
            count=count-1 4x?u5L 9o  
        End If {#M{~  
        count=count+1 rZQHB[^3  
    Wend )[X!/KR90  
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    'Set new shift in i{[H3p8  
    op.Type = "ShiftZ" -t'oW*kdL  
    op.val1 = taq K}3"KC  
    op.parent = parID J*&=J6  
    AddOperation eID, op UZ3Aq12U}a  
    Print "Set aqueous humor thickness = " & taq-0.55 j?hyN@ns  
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    '************************************************************************* "(&`muIc  
    'Radius and conic constant of anterior lens |/\1nWD  
    '************************************************************************* ~EkGG .  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 6@ ^`-N;  
    GetConic eID, entity, curv, conic j =%-b]  
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    SetConic eID, entity, 1/Rant, CCant 8B+^vF   
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 3v+}YT{>b  
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    '************************************************************************* J,KTc'[  
    'Radius and conic constant of posterior lens G/44gKl  
    '*************************************************************************  pytfsVM  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) @Hdg-f>y]  
    GetConic eID, entity, curv, conic -"9)c^KVx  
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    SetConic eID, entity, 1/Rpost, CCpost B_jI!i{N%o  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost f|1FqL+T]  
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    '************************************************************************* QnLg P7Ft  
    'Lens thickness (Position of posterior lens surface) \1 D,Kx;Cb  
    '************************************************************************* _?LI0iIFx  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) P,=J"%a-  
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    ' Delete any z-shift(s) DI[^H  
    count = 0 J uKaRR~  
    While GetOperationCount(eID)>count 8Kkr1}!wd  
        GetOperation eID, count, op 5g7}A`  
        If op.Type="ShiftZ" Then 8@ g D03  
            DeleteOperation eID,count T7_rnEOO   
            count=count-1 oioN0EuDk  
        End If oD1=}  
        count=count+1 tO3B_zC  
    Wend 1 K',Vw_  
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    'Set new z-shift r T$g^  
    op.Type = "ShiftZ" vAxtN RS  
    op.val1 = tlens k rjd:*E  
    op.parent = parID a :AcCd)  
    AddOperation eID, op Ggjb86v\  
    Print "Set lens thickness = " & tlens fltc dA  
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    '************************************************************************* ?KW?] o  
    'Lens index of refraction hmk5 1  
    '************************************************************************* ,W;8!n0  
    eID = FindMaterial( "Lens" ) S@-X?Lu  
    GetModelMaterial eID, mat 'Q,<_ L"  
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    mat.Nd = nlens * OFT)S  
    SetModelMaterial eID, mat _fw'c*j  
    Print "Set lens index of refraction = " & nlens #2,L)E\G8e  
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    '************************************************************************* Y :BrAa[  
    'Pupil diameter l%/,Ef*3  
    '************************************************************************* ]xs\,}I%  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ?"Q6;np*  
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    'Adjust pupil diameter (trimming volume inner hole) >.>5%  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" vUA`V\  
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    ' Adjust pupil location to just in front of the lens kp"cHJNx  
    parID = FindFullName( "Geometry.Arizona Eye" ) /m:}rD  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) e@Y R/I8my  
    count = 0 !{\c`Z<#  
    While GetOperationCount(eID)>count "5bk82."  
        GetOperation eID, count, op Hq8.O/Y"=  
        If op.Type="ShiftZ" Then ZrBxEf$f  
            DeleteOperation eID,count #k, kpL<a  
            count=count-1 I`1=VC]^8  
        End If ](pD<FfS]'  
        count=count+1 )I_I?e  
    Wend #kEdf0  
    op.Type = "ShiftZ" lN" rhZ  
    op.val1 = taq-0.01 ,B><la87  
    op.parent = parID "zc!QHpSd  
    AddOperation eID, op "w1jr 6"  
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    Print "Set pupil diameter = " & pupilDiam /8R1$7  
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    'Update AZ Eye subassembly Description =?hlgQ  
    eID = FindFullName( "Geometry.Arizona Eye" ) 5E8P bV-l  
    GetEntity eID, entity ;2}Gqh)Yr  
    entity.Description = "Accommodation = " & A & "D" hz|$3*q  
    SetEntity eID, entity "G:>}cs%?  
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    Update #.RI9B  
    Print "DONE!"  'M{_S  
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End Sub 2UquN0  
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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： V{r@D!}  
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Accommodation = 4 Diopters {3>^nMv@e  
Pupil Diameter = 4 mm `JCC-\9T_  
Set aqueous humor thickness = 2.81 EUgs2Fsb3  
Set anterior lens radius = 10.4 and conic constant = -2.375869 KN=Orx7Gy  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 /~Iy1L#  
Set lens thickness = 3.927 7E'C o|  
Set lens index of refraction = 1.42672 d8>D=Ve  
Set pupil diameter = 4 bH&H\ Mx_k  
DONE! 5P4 >xv[  
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（文章来源：讯技光电）
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