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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 sOJ"~p  
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。 U7x}p^B9\N  
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模型 hr6f}2  
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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。 yx/:<^"-$  
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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. 1YnDho;~  
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光源 wRie{Vk  
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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。 7%w4?Nv3I  
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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。 89 (k<m  
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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。 $k!@e M/R  
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图2. 字母F光源的设定方法光 f4w|  
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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 Jge;/f!i  
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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。 3rR(>}:[V  
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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。 jJ?3z ,h  
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图5. 视网膜重点采样规格设定
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脚本 fYCAwS{  
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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： jliKMd<?  
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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。 Y@.:U*  
余下的脚本计算与屈光度有关的所有参数。 $!fz87-p>  
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分析 (cCB3n\20  
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 >)VrbPRuA  
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图7. 字母F在视网膜上颜色分析
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脚本代码 wPG3Ap8L  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. x&?35B i  
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Dim entity As T_ENTITY (oTx*GP>Y  
Dim op As T_OPERATION S*\`LBl"nX  
Dim mat As T_MODELMATERIAL i@g6%V=  
Dim A As Double cPtP?)38.  
Dim pupilDiam As Double `#l_`j=r$  
Dim eID As Long 5$O@+W!?@  
Dim parID As Long Z~P5SEg  
Dim count As Integer (2a~gQGD  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Zo&U3b{Dy  
Dim tlens As Double, nlens As Double CP={|]>+S  
Dim curv As Double, conic As Double 5SK.R;mn  
Dim ok As Long IXC: Q  
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Sub Main w1iQ#.4K_  
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    '用户输入对话框 >B3_P4pW9  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 sM-k,0z  
        TextBox 220,21,40,21,.TextBox1 'default: 0 wRWN]Vo  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 E7 7Au;TL  
        OKButton 40,91,90,21 *d)B4qG  
        CancelButton 190,91,90,21 wtRAq/  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 3:76x  
        TextBox 220,49,40,21,.TextBox2 'default: 4 DuCq16'0T  
    End Dialog ==Y^~ab;K  
    Dim dlg As UserDialog rVZk G,Q  
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    ok = Dialog (dlg) [Si`pPvl  
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    If ok=0 Then    'cancel button was pressed hL&z"_`  
        Print "Execution cancelled." U?.VY@  
        End `qUmOFl  
    End If HPu nNsA  
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    'Assign accommodation and pupil diameter & use defaults if field left empty zvSfW# *  
    If dlg.TextBox1 = "" Then Knn$<!>  
        A = 0           'Default accommodation 0naegy?,  
    Else mGoUF$9 k  
        A = CDbl(dlg.TextBox1) iao_w'tJ  
    End If 6&h,eQ!  
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    If dlg.TextBox2 = "" Then Xi$uK-AHpj  
        pupilDiam = 4   'Default pupil diameter m[%&K W(  
    Else nww,y  
        pupilDiam = CDbl(dlg.TextBox2) 7TlOF  
    End If a^|mF# z  
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    Print " " ])vM# f  
    Print "Accommodation = " & A & " Diopters" z!?xz  
    Print "Pupil Diameter = " & pupilDiam & " mm" [?_^Cy  
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    ' Calculate new parameters with accommodation @7.Ews5Mke  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 0riTav8  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens .y|*  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens yA =#Ji  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens l2z@t3{  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens }zj_Pp  
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    tlens = 3.767 + 0.04*A                  'Lens thickness arRb q!mO  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction #8rLB(  
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    'Adjust parameters to account for accommodation HZ )z^K?1  
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    '************************************************************************* 3Vs8"BFjz  
    'Aqueous thickness (Position of Lens) 1Sx2c  
    '************************************************************************* 9x23## s  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) |!,;IoZ  
    GetCustomElement eID, entity h b_"E, `F  
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    parID = FindFullName( "Geometry.Arizona Eye" ) =YOq0  
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    ' Delete any shift(s) in z }k~ih?E^s  
    count = 0 !%?O`+r  
    While GetOperationCount(eID)>count /R!:ll2  
        GetOperation eID, count, op ~5q1zr)E  
        If op.Type="ShiftZ" Then ot($aY,t  
            DeleteOperation eID,count <Y:{>=  
            count=count-1 wQEsq<  
        End If kc-=5l  
        count=count+1 #p*D.We  
    Wend -U.>K,M  
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    'Set new shift in x+EkL3{  
    op.Type = "ShiftZ" <A^sg?s<'  
    op.val1 = taq %|AebxB'o  
    op.parent = parID O`K2mt\%  
    AddOperation eID, op N:x--,2  
    Print "Set aqueous humor thickness = " & taq-0.55 J2adG+=  
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    '************************************************************************* %PM&`c98z7  
    'Radius and conic constant of anterior lens dhv?36uE  
    '************************************************************************* r2yJ{j&s  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) n+MWny  
    GetConic eID, entity, curv, conic Ql"kJ_F!br  
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    SetConic eID, entity, 1/Rant, CCant 2. '` mGu  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant g&z8t;@  
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    '************************************************************************* /s*.:cdH  
    'Radius and conic constant of posterior lens u}3D'h  
    '************************************************************************* ZP{<f~;  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) h?[|1.lJx(  
    GetConic eID, entity, curv, conic !6!Gx:  
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    SetConic eID, entity, 1/Rpost, CCpost 76H>ST@G|  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost f7YBhF  
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    '************************************************************************* Yw] 7@  
    'Lens thickness (Position of posterior lens surface) !7Eodq-0  
    '************************************************************************* 0FSNIPx  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 3ew4QPT'  
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    ' Delete any z-shift(s) qv& Bai[  
    count = 0 ZDg(D"  
    While GetOperationCount(eID)>count @A4$k dJ2  
        GetOperation eID, count, op &AN1xcx\  
        If op.Type="ShiftZ" Then Nv=78O1  
            DeleteOperation eID,count m _cRK}>  
            count=count-1 ^/_Yk.w  
        End If F~q(@.b  
        count=count+1 _%q~K (::  
    Wend k&2=-qgVR  
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    'Set new z-shift >H^#!eaqw  
    op.Type = "ShiftZ" |lt]9>|  
    op.val1 = tlens >`r3@|UY  
    op.parent = parID Z\?2"4H  
    AddOperation eID, op dgL>7X=7  
    Print "Set lens thickness = " & tlens 9w$m\nV  
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    '************************************************************************* W:,Wex^9n  
    'Lens index of refraction -Arsmo  
    '************************************************************************* h);^4cU  
    eID = FindMaterial( "Lens" ) t;BUZE_!0c  
    GetModelMaterial eID, mat 1rJ2}d\y  
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    mat.Nd = nlens L RVcf  
    SetModelMaterial eID, mat y(o)} m*0  
    Print "Set lens index of refraction = " & nlens GlnO8cAB  
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    '************************************************************************* |~r-VV(=  
    'Pupil diameter kk %32(By  
    '************************************************************************* ]I[~0PCSX  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) z%OKv[/N  
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    'Adjust pupil diameter (trimming volume inner hole) &W,jR|B  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" G@.MP| 2  
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    ' Adjust pupil location to just in front of the lens 6Q^~O*cw  
    parID = FindFullName( "Geometry.Arizona Eye" ) n:,mo}?X  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) t N{S;)q#X  
    count = 0 &}r"Z?f)  
    While GetOperationCount(eID)>count J0?kEr  
        GetOperation eID, count, op Ut;`6t  
        If op.Type="ShiftZ" Then Zz0e4C  
            DeleteOperation eID,count Y3Fj3NwS  
            count=count-1 |5bLV^mv]i  
        End If d'RvpoM  
        count=count+1 X` zWw_i  
    Wend <7M-?g:vj  
    op.Type = "ShiftZ" Snx!^4+MF  
    op.val1 = taq-0.01 EU$.{C_O(  
    op.parent = parID s_'&_>D  
    AddOperation eID, op gcU*rml  
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    Print "Set pupil diameter = " & pupilDiam Fl-\{vOn  
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    'Update AZ Eye subassembly Description 7;s#QqG`I  
    eID = FindFullName( "Geometry.Arizona Eye" ) `gX@b^  
    GetEntity eID, entity 0f^{Rp6  
    entity.Description = "Accommodation = " & A & "D" c+ oi8G  
    SetEntity eID, entity >?, Zn  
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    Update /ad9Q~nJ  
    Print "DONE!" =l/6-j^  
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End Sub J@s>Pe)  
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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： ffZ~r%25{  
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Accommodation = 4 Diopters G0E5Y;YIN$  
Pupil Diameter = 4 mm vADiW~^Q^  
Set aqueous humor thickness = 2.81 c$O8Rhx  
Set anterior lens radius = 10.4 and conic constant = -2.375869 : ?>7Z6  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 '<R>cN"  
Set lens thickness = 3.927 \$ytmtf5  
Set lens index of refraction = 1.42672 e$# *t  
Set pupil diameter = 4 4:`D3  
DONE! ghk=` !yKw  
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（文章来源：讯技光电）
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