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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 ;/@?6T"  
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。 T3PX gL)o  
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模型 .OmQ'  
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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。 2)wAFO6u  
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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. CI,lkO|C  
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光源 u3]Uxy  
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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。 *(k%MTG  
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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。 oW^k7 #<e}  
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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。 <tFSF%vG=  
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图2. 字母F光源的设定方法光 %=V"CJ$|  
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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 u7HvdLql  
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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。 oEJaH  
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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。 m}98bw  
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图5. 视网膜重点采样规格设定
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脚本 P/ci/y_1  
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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： ~LbS~_\C=  
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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。 RU0i#suiz  
余下的脚本计算与屈光度有关的所有参数。 PWvSbn6  
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分析 s2%V4yy%  
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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。 h3kaD  
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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 !6H uFf  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used.  R:~(Z?  
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Dim entity As T_ENTITY p* RC  
Dim op As T_OPERATION y;nvR6)  
Dim mat As T_MODELMATERIAL Yt+h2ft!  
Dim A As Double o@9+mM"B)  
Dim pupilDiam As Double l-}KmZ]  
Dim eID As Long /v|Onq1Y4  
Dim parID As Long 6\4Z\82  
Dim count As Integer aG(hs J)  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double o'Wz*oY))\  
Dim tlens As Double, nlens As Double Stxp3\jEn  
Dim curv As Double, conic As Double =q+R   
Dim ok As Long BFWi(58q  
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Sub Main TQf L%JT  
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    '用户输入对话框 U\jb"  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 dv~pddOs  
        TextBox 220,21,40,21,.TextBox1 'default: 0 ;F5"}x  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 *%\mZ,s"  
        OKButton 40,91,90,21 2no$+4+z  
        CancelButton 190,91,90,21 "_< 9PM1t  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 pYo=oI  
        TextBox 220,49,40,21,.TextBox2 'default: 4 m`y9Cuk  
    End Dialog p|3b/plZ  
    Dim dlg As UserDialog h?Nek+1'  
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    ok = Dialog (dlg) T#EFXHPr  
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    If ok=0 Then    'cancel button was pressed M0L&~p_F  
        Print "Execution cancelled." ;+U<bqL6  
        End uSN"vpc4D  
    End If ,%[4j9#!_  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ?Ik4  
    If dlg.TextBox1 = "" Then ?Go!j?#a  
        A = 0           'Default accommodation KjYAdia:H  
    Else 1%~[rnQ  
        A = CDbl(dlg.TextBox1) 4^*,jS-9g}  
    End If &!L:"]=+  
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    If dlg.TextBox2 = "" Then 9b"MQ[B4#a  
        pupilDiam = 4   'Default pupil diameter 0[T,O,y  
    Else Eectxyr?;N  
        pupilDiam = CDbl(dlg.TextBox2) C ^w)|2o}  
    End If -*B`]  
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    Print " " 4)kG-[#  
    Print "Accommodation = " & A & " Diopters" jlqv2V7=/  
    Print "Pupil Diameter = " & pupilDiam & " mm" }Fa%%}  
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    ' Calculate new parameters with accommodation 5Bjgr  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness ,.tfWN%t\  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens `~# < &w  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ;H'gT+t<c  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens 2`?!+")  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens $}GTG'*.  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ,7_4 z]jK  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction [?k8}B)mHB  
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    'Adjust parameters to account for accommodation SaOYu &>  
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    '************************************************************************* 5!X1G8h)uy  
    'Aqueous thickness (Position of Lens) T/1gI9 X  
    '************************************************************************* %NHkDa!  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) fCWGAO2  
    GetCustomElement eID, entity "IQ/LbOqm_  
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    parID = FindFullName( "Geometry.Arizona Eye" ) uXjP`/R|  
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    ' Delete any shift(s) in z 2`G OJ,$  
    count = 0 &;&ho+qD  
    While GetOperationCount(eID)>count TZR)C P5  
        GetOperation eID, count, op -n80 &  
        If op.Type="ShiftZ" Then j|4C\~i  
            DeleteOperation eID,count b^0}}12  
            count=count-1 aj^wRzJ}zA  
        End If V[o`\|<  
        count=count+1 n+;6=1d7ZW  
    Wend Om;&_!i  
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    'Set new shift in TS2ZF{m  
    op.Type = "ShiftZ" EJ@p-}I!  
    op.val1 = taq h:Gu`+D>W  
    op.parent = parID ~\LCvcY"X  
    AddOperation eID, op j>-gO,v, y  
    Print "Set aqueous humor thickness = " & taq-0.55 anMF-x4/*q  
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    '************************************************************************* ",7Q   
    'Radius and conic constant of anterior lens R\@/U=iqR  
    '************************************************************************* &|3 $!S  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) }G4 z tiuG  
    GetConic eID, entity, curv, conic npJt3 Y_I  
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    SetConic eID, entity, 1/Rant, CCant FKNMtp[`  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ydRC1~f0  
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    '************************************************************************* ( +pLA"xq  
    'Radius and conic constant of posterior lens >Cw<BIF  
    '************************************************************************* S"wR%\NIp  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ?HF%(>M  
    GetConic eID, entity, curv, conic u/cg|]x&T  
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    SetConic eID, entity, 1/Rpost, CCpost S4=~`$eP  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost -gSUjP  
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    '************************************************************************* h 3]wL.V  
    'Lens thickness (Position of posterior lens surface) %?e& WLS  
    '************************************************************************* At7>V-f}  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ):i&`}SY  
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    ' Delete any z-shift(s) > ;/l)qk,  
    count = 0 GrUCZ<S  
    While GetOperationCount(eID)>count xx[9~z=d  
        GetOperation eID, count, op yE}}c{hSn  
        If op.Type="ShiftZ" Then nqInb:  
            DeleteOperation eID,count }ZYv~E'  
            count=count-1 #Q2Y&2`yGT  
        End If S30?VG9U0f  
        count=count+1 cSXwYZDx?  
    Wend n4}B r;%  
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    'Set new z-shift 0NS<?p~_S  
    op.Type = "ShiftZ" bbrXgQ`s+w  
    op.val1 = tlens -$\+' \  
    op.parent = parID NR`C(^}  
    AddOperation eID, op zuUW|r  
    Print "Set lens thickness = " & tlens W[Ls|<Q  
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    '************************************************************************* e" St_z(  
    'Lens index of refraction O^oWG&Y;v  
    '************************************************************************* ^s|6vd;PD=  
    eID = FindMaterial( "Lens" ) D9 g#F f6  
    GetModelMaterial eID, mat 0u;4%}pD  
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    mat.Nd = nlens i\,-oO  
    SetModelMaterial eID, mat N@t|7~  
    Print "Set lens index of refraction = " & nlens gIjh:_ Pz  
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    '************************************************************************* $<}$DH_Y  
    'Pupil diameter IZpP[hov  
    '************************************************************************* 7pe\M/kl  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) E*]bgD7V  
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    'Adjust pupil diameter (trimming volume inner hole) kqFP)!37  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 02 c':a=7  
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    ' Adjust pupil location to just in front of the lens SLa>7`<Q  
    parID = FindFullName( "Geometry.Arizona Eye" ) y*qVc E  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) D]zwl@sRX:  
    count = 0 h&KO<>  
    While GetOperationCount(eID)>count ;lE%M  
        GetOperation eID, count, op 1q7|OWFT  
        If op.Type="ShiftZ" Then [ CQ+p!QZ  
            DeleteOperation eID,count 'Gj3:-xqL  
            count=count-1 MN\HDKN  
        End If GPN]9  
        count=count+1 OCe!.`  
    Wend nLXlU*ES  
    op.Type = "ShiftZ" KVclhT<F  
    op.val1 = taq-0.01 fp`;U_-&0  
    op.parent = parID k>;`FFQU>  
    AddOperation eID, op F1*>y  
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    Print "Set pupil diameter = " & pupilDiam X% t1 T4  
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    'Update AZ Eye subassembly Description eA2@Nkw~)  
    eID = FindFullName( "Geometry.Arizona Eye" ) k\5c|Wq|g  
    GetEntity eID, entity rC5 p-B%  
    entity.Description = "Accommodation = " & A & "D" ! >FYK}c7  
    SetEntity eID, entity >*35C`^  
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    Update d; boIP`M;  
    Print "DONE!" TM%| '^)  
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End Sub ?9 <:QE;I>  
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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： (ZUHvvL  
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Accommodation = 4 Diopters gb[5&> (#  
Pupil Diameter = 4 mm oH97=>  
Set aqueous humor thickness = 2.81 3l rT3a3vV  
Set anterior lens radius = 10.4 and conic constant = -2.375869 glO^yZs  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 ~Y^+M*   
Set lens thickness = 3.927 "g5^_UP  
Set lens index of refraction = 1.42672 9+Np4i@  
Set pupil diameter = 4 fDv2JdiU  
DONE! @LF,O}[2J  
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（文章来源：讯技光电）
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