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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 ;z7iUke0%  
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。 ]IkjZ=  
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模型 UeT"v?zP  
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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。 8DLMxG  
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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. z{^XU"yB  
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光源 s4}}MV3X  
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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。 (85F1"Jp  
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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。 -]PW\}w1  
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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。 2Sb~tTGz79  
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图2. 字母F光源的设定方法光 W~Mj6c~S"  
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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 "$:nz}  
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在散射文件中，有一个名为“Retina surface”的72%的反射型朗伯散射，它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射，改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 Ar=pzQ<Z{  
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图4. 视网膜朗伯散射设定
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注意在视网膜的表面有散射重点采样规格定义，在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳，半角度10度。 K=Fcy#, f  
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图5. 视网膜重点采样规格设定
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脚本 g >-iBxml  
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内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框，如下图所示： mKnkHGM  
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图6. 用户对话框的创建与编辑
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图7. 用户对话框编辑器
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如果“OK”按钮按下，将会核对对话框下面的代码行，如果点击取消则脚本终止。然后输入的参数赋予变量，如果此处是保留为空白，则使用默认值。因此，如果没有值输入并点击“OK”按钮，则脚本是以屈光度为0，光瞳直径为4mm来运行的。 FJ>| l#nO  
余下的脚本计算与屈光度有关的所有参数。 -\>Bphu,y  
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分析 jB?Tua$,s  
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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。 NY1olnI  
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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 p#J}@a  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. j t-ayLq  
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Dim entity As T_ENTITY ^i#q{@g  
Dim op As T_OPERATION u& :-&gva  
Dim mat As T_MODELMATERIAL [al$7R&  
Dim A As Double b^5rV5d  
Dim pupilDiam As Double gnB%/g[_  
Dim eID As Long )0RH"#, 2L  
Dim parID As Long v*l1"0$  
Dim count As Integer \nPa>2r  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double )>$xbo")k  
Dim tlens As Double, nlens As Double X )g <F  
Dim curv As Double, conic As Double (? YTQ8QR  
Dim ok As Long /[t]m,p$yq  
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Sub Main 0 Co_,"  
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    '用户输入对话框 #th^\pV  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 |ay W _5}  
        TextBox 220,21,40,21,.TextBox1 'default: 0 q}tLOVu1  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 nP4jOq*H  
        OKButton 40,91,90,21 8KT|ixs  
        CancelButton 190,91,90,21 Sep}{`u  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ;wgm 'jr  
        TextBox 220,49,40,21,.TextBox2 'default: 4 }N*6xr*X+  
    End Dialog z)yxz:E  
    Dim dlg As UserDialog ix$?/GlL  
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    ok = Dialog (dlg) nXk<DlTws  
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    If ok=0 Then    'cancel button was pressed Nx;U]O6A  
        Print "Execution cancelled." 4vW:xK  
        End  ]6W#P7  
    End If yo") G!BN  
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    'Assign accommodation and pupil diameter & use defaults if field left empty TR5"K{WDx  
    If dlg.TextBox1 = "" Then .& B_\*  
        A = 0           'Default accommodation Qp!r_a&  
    Else 70mQ{YNN  
        A = CDbl(dlg.TextBox1) RAR"9 N .  
    End If PDzVXLpC  
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    If dlg.TextBox2 = "" Then \zR{D}aS  
        pupilDiam = 4   'Default pupil diameter 6#K1LY5}  
    Else ke2'?,f  
        pupilDiam = CDbl(dlg.TextBox2) ,X)0+DNsq  
    End If (p-a;.Twj  
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    Print " " / \!hW-+]W  
    Print "Accommodation = " & A & " Diopters" k2" Z:\?z  
    Print "Pupil Diameter = " & pupilDiam & " mm" aYkm]w;C  
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    ' Calculate new parameters with accommodation }>6=(!  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness J}hi)k  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens >mgbs>  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens ;KWR/?ec  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens H"tS33  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens ,[D,G  
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    tlens = 3.767 + 0.04*A                  'Lens thickness s3W35S0Q3  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction LL7a 20  
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    'Adjust parameters to account for accommodation @c,}\"(  
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    '************************************************************************* cH.T6u_%  
    'Aqueous thickness (Position of Lens) &G@(f=  
    '************************************************************************* :G?"BL5vP  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) Hz`rw\\Xq  
    GetCustomElement eID, entity t7H2z}06=h  
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    parID = FindFullName( "Geometry.Arizona Eye" ) .[? E1we  
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    ' Delete any shift(s) in z p^Kp= z  
    count = 0 ) **k3u t4  
    While GetOperationCount(eID)>count HIcx "y  
        GetOperation eID, count, op >&f .^p  
        If op.Type="ShiftZ" Then \O/EY&  
            DeleteOperation eID,count ? }|;ai  
            count=count-1 .;u(uB;J6  
        End If hY7Q$B<  
        count=count+1 4d)w2t?H%  
    Wend WLV'@$<|(  
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    'Set new shift in VjS %!P  
    op.Type = "ShiftZ" h `d(?1  
    op.val1 = taq @tdX=\[~  
    op.parent = parID f#pT6  
    AddOperation eID, op e!URj\*  
    Print "Set aqueous humor thickness = " & taq-0.55 .7ESPr  
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    '************************************************************************* I1=YSi;A  
    'Radius and conic constant of anterior lens hun L V8z  
    '************************************************************************* c|x:]W'ij  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 4f ~CG r  
    GetConic eID, entity, curv, conic 6|r` k75.  
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    SetConic eID, entity, 1/Rant, CCant m=k(6  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ;TD<\1HJT=  
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    '************************************************************************* 6*Qn9Q%p-  
    'Radius and conic constant of posterior lens X&0m$x  
    '************************************************************************* (k"|k  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ELeR5xT  
    GetConic eID, entity, curv, conic #.?DsK_:@  
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    SetConic eID, entity, 1/Rpost, CCpost %?J\P@  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 1wmS?  
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    '************************************************************************* ]^Z7w`=%5  
    'Lens thickness (Position of posterior lens surface) KYD,eVQ  
    '************************************************************************* =L{lt9qQz  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) c Bb!7?6(  
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    ' Delete any z-shift(s) di]z  
    count = 0 q]=. Aik  
    While GetOperationCount(eID)>count 3Zs|arde2  
        GetOperation eID, count, op &NZN_%  
        If op.Type="ShiftZ" Then n=MdbY/k(  
            DeleteOperation eID,count /xJ,nwp7  
            count=count-1 :T" !6;  
        End If S;M'qwN  
        count=count+1 fu}NH \{  
    Wend &<R8'  
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    'Set new z-shift 1el?f>  
    op.Type = "ShiftZ" qEX2K^y'4"  
    op.val1 = tlens 73P=<3  
    op.parent = parID -`n>q^A7e  
    AddOperation eID, op $TU=^W)X  
    Print "Set lens thickness = " & tlens t }7hD  
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    '************************************************************************* 9xP{#Qa  
    'Lens index of refraction 5s8S;Pb]<  
    '************************************************************************* M(HU^?B{'  
    eID = FindMaterial( "Lens" ) /p~"?9b[ i  
    GetModelMaterial eID, mat ~` @dI  
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    mat.Nd = nlens ,w; ~R4x  
    SetModelMaterial eID, mat A@bWlwfl  
    Print "Set lens index of refraction = " & nlens i:Pg&474f  
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    '************************************************************************* I.r &;   
    'Pupil diameter w(8q qU+\  
    '************************************************************************* %E?:9. :NJ  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) >&TSz5Q  
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    'Adjust pupil diameter (trimming volume inner hole) h?j;*|o-  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 2hEB?ZAQZ  
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    ' Adjust pupil location to just in front of the lens ;@Ep?S @  
    parID = FindFullName( "Geometry.Arizona Eye" ) Wy@Z)z?  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) /D`M?nD7  
    count = 0 Ev0GAc1  
    While GetOperationCount(eID)>count $_k'!/5  
        GetOperation eID, count, op M$ep.<Z1|  
        If op.Type="ShiftZ" Then 7Ro7/PT (  
            DeleteOperation eID,count bW;0E%_  
            count=count-1 tBtJRi(  
        End If jV\M`=4IC  
        count=count+1 d8<Lk9H9R  
    Wend `]\4yTd  
    op.Type = "ShiftZ" ogs9obbZ!  
    op.val1 = taq-0.01 [6V'UI6  
    op.parent = parID WGN[`D"  
    AddOperation eID, op uEWWY t  
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    Print "Set pupil diameter = " & pupilDiam %\_I% yF  
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    'Update AZ Eye subassembly Description t!c8 c^HR  
    eID = FindFullName( "Geometry.Arizona Eye" ) JmrQDO_(  
    GetEntity eID, entity 4U<'3~RN  
    entity.Description = "Accommodation = " & A & "D" :>nk63V (  
    SetEntity eID, entity 5IW^^<kiu  
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    Update h#zx^F1  
    Print "DONE!" cx|[P6d  
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End Sub j$T2ff6  
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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： ^8.R 'Yq  
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Accommodation = 4 Diopters [ w  
Pupil Diameter = 4 mm }zRYT_:  
Set aqueous humor thickness = 2.81 $Bz|[=  
Set anterior lens radius = 10.4 and conic constant = -2.375869 Y((z9-`  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 BT 98WR"\  
Set lens thickness = 3.927 uQ&&? j  
Set lens index of refraction = 1.42672 _E)xR  
Set pupil diameter = 4 7$x@;%xd  
DONE! tH 5f;mY,  
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（文章来源：讯技光电）
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