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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 d5O_~x f&  
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。 p^uX{!  
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模型 >PBP:s1f4>  
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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。 (+^z9p7/!  
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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. 6~@S,i1  
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光源 +4Uxq{.K  
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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。 2iJ)K rw  
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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。 (ndTEnpp  
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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。 [m9Iz!E  
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图2. 字母F光源的设定方法光 S);SfNh%CL  
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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 7i$)iNW  
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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。 X*^^W_LH.  
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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。 */7+pk(  
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图5. 视网膜重点采样规格设定
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脚本 3m#/1=@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： &O:IRR7p  
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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。 !)1gGXRY  
余下的脚本计算与屈光度有关的所有参数。 iW # |N^  
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分析 pr) `7VuKp  
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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。 |K(2_Wp  
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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 6Kbc:wlR  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. !*tV[0 i2  
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Dim entity As T_ENTITY x/B1\U I  
Dim op As T_OPERATION Oe/&Ryj=mm  
Dim mat As T_MODELMATERIAL `Nnaw+<]  
Dim A As Double e}u68|\EC  
Dim pupilDiam As Double S#^2k!(|G  
Dim eID As Long hn -!W;j  
Dim parID As Long b5@sG^  
Dim count As Integer 2 lc  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double NR6wNz&81  
Dim tlens As Double, nlens As Double QCD MRh n  
Dim curv As Double, conic As Double (qbL=R"  
Dim ok As Long XsXO S8  
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Sub Main Z"pCDW)  
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    '用户输入对话框 ]VkM)< +  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 J\@W+/#dF  
        TextBox 220,21,40,21,.TextBox1 'default: 0 4m:D8&D_M  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ms]r1x"  
        OKButton 40,91,90,21 b4R;#rm  
        CancelButton 190,91,90,21 d$H   
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 `B A'a" $  
        TextBox 220,49,40,21,.TextBox2 'default: 4 LJc"T)>$`  
    End Dialog JqmxS*_P  
    Dim dlg As UserDialog \x7^ly$_  
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    ok = Dialog (dlg) _u{z$;  
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    If ok=0 Then    'cancel button was pressed 1`Ig A0V`"  
        Print "Execution cancelled." lZr}F.7  
        End 4F`&W*x  
    End If V"Sa9P{y"  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ~z kzuh  
    If dlg.TextBox1 = "" Then 4aGVIQ  
        A = 0           'Default accommodation &Yklf?EZ>Q  
    Else )Ggv_mc h  
        A = CDbl(dlg.TextBox1) Vm*E^ v  
    End If KbSE=3  
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    If dlg.TextBox2 = "" Then {6tj$&\)  
        pupilDiam = 4   'Default pupil diameter ogvB{R  
    Else qI%X/'  
        pupilDiam = CDbl(dlg.TextBox2) PrKH{nyJk  
    End If =G9I7Y@  
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    Print " " Ntt*}|:QV<  
    Print "Accommodation = " & A & " Diopters" sx n{uRF  
    Print "Pupil Diameter = " & pupilDiam & " mm" 7C9_;81_Dt  
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    ' Calculate new parameters with accommodation x:6c@2  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness *N&~Uq^  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens h5Ee*D e  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens H:F'5Zt  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens lv>^P>S(O  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens Lb,wn{  
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    tlens = 3.767 + 0.04*A                  'Lens thickness p/U{*i ]t  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction B#G:aBCM  
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    'Adjust parameters to account for accommodation U0;pl2  
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    '************************************************************************* t$e'[;w  
    'Aqueous thickness (Position of Lens) c`@";+|r  
    '************************************************************************* _CMNmmp`e  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) bE;c&g  
    GetCustomElement eID, entity O.DO,]Uh  
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    parID = FindFullName( "Geometry.Arizona Eye" ) tv_&PIu]L  
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    ' Delete any shift(s) in z ,`bmue5  
    count = 0 `W:z#uNG]  
    While GetOperationCount(eID)>count E&N~ h|CL  
        GetOperation eID, count, op V}Ee1C  
        If op.Type="ShiftZ" Then N%F4ug@i   
            DeleteOperation eID,count X'88W-  
            count=count-1 x5|^p=  
        End If +s;>@j()V  
        count=count+1 $^_6,uBM[  
    Wend %Gl1Qi+Po_  
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    'Set new shift in PthgxB^  
    op.Type = "ShiftZ" S Rk%BJ? ~  
    op.val1 = taq ? G`6}NP  
    op.parent = parID K)9Rw2-AJ  
    AddOperation eID, op pMJm@f  
    Print "Set aqueous humor thickness = " & taq-0.55 u M\5GK  
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    '************************************************************************* "x vizvR  
    'Radius and conic constant of anterior lens UwxszEHC  
    '************************************************************************* { V) `6  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) $A`m8?bY  
    GetConic eID, entity, curv, conic Gj?$HFa  
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    SetConic eID, entity, 1/Rant, CCant _, E/HAX  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ,5x#o  
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    '************************************************************************* _RIlGs\.  
    'Radius and conic constant of posterior lens ps;dbY*s6  
    '************************************************************************* 8{i O#C  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) '#XT[\  
    GetConic eID, entity, curv, conic YS#*#!ZMn?  
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    SetConic eID, entity, 1/Rpost, CCpost @dUN3,}  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost d@ >i=l [  
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    '************************************************************************* 8ok=&Gq4  
    'Lens thickness (Position of posterior lens surface) x0b=r!Duu  
    '************************************************************************* 1+gFfKq  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) peF)U !`D  
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    ' Delete any z-shift(s) t>AOF\  
    count = 0 J&s$Wqf  
    While GetOperationCount(eID)>count op\$(7<d-  
        GetOperation eID, count, op %ioVNbrR7  
        If op.Type="ShiftZ" Then ? 3OfiGX?  
            DeleteOperation eID,count zPx R=0|  
            count=count-1 \+#EO%sN1%  
        End If _-lE$ O  
        count=count+1 P6O\\,B1A  
    Wend 641P)  
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    'Set new z-shift !:m.-TE  
    op.Type = "ShiftZ" !\<a2>4$T  
    op.val1 = tlens hPUAm6 b;  
    op.parent = parID p#{y9s4h  
    AddOperation eID, op BvsSrse  
    Print "Set lens thickness = " & tlens 'Y#'ozSQv  
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    '************************************************************************* E]rXp~AZm  
    'Lens index of refraction & W od  
    '************************************************************************* e b} P/  
    eID = FindMaterial( "Lens" ) lKw-C[  
    GetModelMaterial eID, mat jLVG=rOn  
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    mat.Nd = nlens y^,QM[&  
    SetModelMaterial eID, mat p<=Lh47 =  
    Print "Set lens index of refraction = " & nlens !8[T*'LJ-  
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    '************************************************************************* $TmEVC^ 0  
    'Pupil diameter X!qK[b@Z  
    '************************************************************************* 9-/q-,  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) DH yv^  
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    'Adjust pupil diameter (trimming volume inner hole) ,puoq {  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" L?j0t*do  
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    ' Adjust pupil location to just in front of the lens DPjs? M<  
    parID = FindFullName( "Geometry.Arizona Eye" ) XZ~kXE;B(  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) &F uPd}F  
    count = 0 +7}^Y}(  
    While GetOperationCount(eID)>count `z\hQ%1!F  
        GetOperation eID, count, op ["<Xh0_  
        If op.Type="ShiftZ" Then o 2 Nu@^+  
            DeleteOperation eID,count < j:\;mi;  
            count=count-1 }[;ZZm?  
        End If ea"X$<s>-  
        count=count+1 xeSch?}  
    Wend 'RV96lX<  
    op.Type = "ShiftZ" wn5OgXxG<  
    op.val1 = taq-0.01 U-9Aq  
    op.parent = parID Q?i_Nl/|  
    AddOperation eID, op nsR CDUCi  
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    Print "Set pupil diameter = " & pupilDiam (vO3vCYeQ  
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    'Update AZ Eye subassembly Description Kf:!tRE  
    eID = FindFullName( "Geometry.Arizona Eye" ) C '( Y  
    GetEntity eID, entity d\JaYizp  
    entity.Description = "Accommodation = " & A & "D" Q;$k?G=l  
    SetEntity eID, entity `!vqT 3p,  
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    Update P+o"]/7U  
    Print "DONE!" miaH,hm  
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End Sub \R<MQ# x  
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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： E2'Wzrovlo  
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Accommodation = 4 Diopters -xHR6  
Pupil Diameter = 4 mm [t?tLUg|6  
Set aqueous humor thickness = 2.81 o~~;I  
Set anterior lens radius = 10.4 and conic constant = -2.375869 R.rc h2  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 -`PziG l@<  
Set lens thickness = 3.927 ;#85 _/  
Set lens index of refraction = 1.42672 V1]GOmXz  
Set pupil diameter = 4 +c))fPuV  
DONE! lgaSIXDK  
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（文章来源：讯技光电）
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