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xunjigd 2016-02-24 12:53

FRED运用：Arizona眼睛模型

简介 '_f]qNy  
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。 pCE,l'Xa  
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模型 0gI^GJN%Y!  
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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。 *0K@^Db-  
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Table 1. AZ眼睛模型的定义
[attachment=67931]
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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. Qx B0I/ {  
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光源 %Km^_JM  
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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。 6`ZHFem  
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[attachment=67932]
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。 #s4v0auK  
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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。 w^_[(9 `  
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[attachment=67933]
图2. 字母F光源的设定方法光 4x`.nql  
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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 ?89K [D|  
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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。 NrHh(:  
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[attachment=67935]
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。 $.7Ov|  
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[attachment=67936]
图5. 视网膜重点采样规格设定
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脚本 #RJFJb/  
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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： 4 Qo(Wl  
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图6. 用户对话框的创建与编辑
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[attachment=67938]
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。 ._6|epJ#  
余下的脚本计算与屈光度有关的所有参数。 ?qdZ]M4e  
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分析 f vAF0 a  
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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。 =;) M+"  
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[attachment=67939]
图7. 字母F在视网膜上颜色分析
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脚本代码 <9BM%  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. I^CKq?V?:  
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Dim entity As T_ENTITY @CxXkR  
Dim op As T_OPERATION ]0 g$3  
Dim mat As T_MODELMATERIAL i uNBw]  
Dim A As Double Ah_T tj  
Dim pupilDiam As Double -F]0Py8(  
Dim eID As Long O%$XgEJ8p  
Dim parID As Long zv Dg1p  
Dim count As Integer wva| TZ  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double :~% zX*   
Dim tlens As Double, nlens As Double hj8S".A_  
Dim curv As Double, conic As Double voD0 u  
Dim ok As Long 4!I;U>b b  
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Sub Main bnm3 cR:h"  
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    '用户输入对话框 ';CL;A;  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 K4H U 9!  
        TextBox 220,21,40,21,.TextBox1 'default: 0 HxH.=M8S_  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 OLl?1  
        OKButton 40,91,90,21 #?V7kds]  
        CancelButton 190,91,90,21 G;'=#c ^  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 -f4>4@y  
        TextBox 220,49,40,21,.TextBox2 'default: 4 Xv5|j/<~p  
    End Dialog g4`)n`  
    Dim dlg As UserDialog )(aj  
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    ok = Dialog (dlg) $PNS`@B  
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    If ok=0 Then    'cancel button was pressed J[?7`6\M  
        Print "Execution cancelled." #Fl5]> |  
        End nJ ZQRRa:C  
    End If X-Q;4M-CJ  
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    'Assign accommodation and pupil diameter & use defaults if field left empty ,)CRozC\}K  
    If dlg.TextBox1 = "" Then z1WF@ Ej  
        A = 0           'Default accommodation Z,? T`[4B  
    Else -%h0`hOG{  
        A = CDbl(dlg.TextBox1) %"1*,g{  
    End If =>_k;x  
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    If dlg.TextBox2 = "" Then 6?CBa]QG  
        pupilDiam = 4   'Default pupil diameter 8%Wg;:DZx  
    Else pFUW7jE  
        pupilDiam = CDbl(dlg.TextBox2) $;ssW"7~Qn  
    End If 4Y=sTXbFt  
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    Print " " 3=SN;cn  
    Print "Accommodation = " & A & " Diopters" "]"!"#aMv  
    Print "Pupil Diameter = " & pupilDiam & " mm" N?7vcN+-t)  
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    ' Calculate new parameters with accommodation l5 FM>q  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness RgPY,\_9+  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens c<(LXf+61  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens 1e0O-aT#Q  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens 9Xr@ll  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens bc".R]  
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    tlens = 3.767 + 0.04*A                  'Lens thickness ~(|~Ze>  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction T.=du$  
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    'Adjust parameters to account for accommodation X1P_IB  
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    '************************************************************************* e^Ds|}{V  
    'Aqueous thickness (Position of Lens) {O"?_6',  
    '************************************************************************* A(xCW+h@)  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 0B4&!J  
    GetCustomElement eID, entity ^w+jPT-n  
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    parID = FindFullName( "Geometry.Arizona Eye" ) q0}?F  
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    ' Delete any shift(s) in z s 4Mi9h_  
    count = 0 " -Ie  
    While GetOperationCount(eID)>count ic"n*SZa  
        GetOperation eID, count, op 7jb{E+DrG  
        If op.Type="ShiftZ" Then h%hE$2  
            DeleteOperation eID,count lO+<T[  
            count=count-1 {GaQV-t  
        End If S[TJ{ L(  
        count=count+1 +UK".  
    Wend #&@qmps(T  
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    'Set new shift in ) OqQz7'  
    op.Type = "ShiftZ" x bG'![OX  
    op.val1 = taq pvz*(u  
    op.parent = parID .>(?c92  
    AddOperation eID, op O\5*p=v  
    Print "Set aqueous humor thickness = " & taq-0.55 "hRY+{m  
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    '************************************************************************* 3wS{@'  
    'Radius and conic constant of anterior lens A~vZ}?*M  
    '************************************************************************* MuQBn7F{c  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) dh7PpuN{  
    GetConic eID, entity, curv, conic CIM 9~:\  
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    SetConic eID, entity, 1/Rant, CCant !Q,A#N(  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant _{EO9s2FG  
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    '************************************************************************* ;w(]z  
    'Radius and conic constant of posterior lens oCLs"L-r{  
    '************************************************************************* =5P_xQx  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) AUloP?24  
    GetConic eID, entity, curv, conic CqXD z  
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    SetConic eID, entity, 1/Rpost, CCpost 23/!k}G"  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost \ B~9Ue!  
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    '************************************************************************* !b O8apn  
    'Lens thickness (Position of posterior lens surface) o W)M&$oS  
    '************************************************************************* h(,SAY_  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) n2bL-  
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    ' Delete any z-shift(s) DPfP)J:~  
    count = 0 Fj9/@pe1  
    While GetOperationCount(eID)>count eSynw$F2N  
        GetOperation eID, count, op 5Wj+ey^ ^w  
        If op.Type="ShiftZ" Then -aiQp@^/J  
            DeleteOperation eID,count H|='|k5Y.  
            count=count-1 j+3~  
        End If Sti)YCXH  
        count=count+1 ;Ef:mr"Nu  
    Wend PXGS5,  
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    'Set new z-shift >4a@rT/  
    op.Type = "ShiftZ" \s2hep  
    op.val1 = tlens D4yJ:ATO&  
    op.parent = parID [y y D-  
    AddOperation eID, op DBl.bgf  
    Print "Set lens thickness = " & tlens Xj^6ZJc  
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    '************************************************************************* #&.& Uu$  
    'Lens index of refraction M}4%LjD  
    '************************************************************************* j380=? 7  
    eID = FindMaterial( "Lens" ) >n@?F[Y  
    GetModelMaterial eID, mat ~UjFL~K}  
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    mat.Nd = nlens 'kc_OvVA  
    SetModelMaterial eID, mat eI?<*  
    Print "Set lens index of refraction = " & nlens X75>C<  
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    '************************************************************************* p ez^]I  
    'Pupil diameter =:a H2T*  
    '************************************************************************* 8NJ(l  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) U">D_ 8  
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    'Adjust pupil diameter (trimming volume inner hole) .+7GecYz  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" (veGztt  
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    ' Adjust pupil location to just in front of the lens CjM+%l0MW  
    parID = FindFullName( "Geometry.Arizona Eye" ) o)KF+[^  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) (yE?)s  
    count = 0 e#K =SV!H  
    While GetOperationCount(eID)>count hS&,Gm`^  
        GetOperation eID, count, op bD<[OerG  
        If op.Type="ShiftZ" Then fGJPZe  
            DeleteOperation eID,count nBL7LocvR  
            count=count-1 |")}p=   
        End If < vU<:S  
        count=count+1 IC+Z C   
    Wend %'j)~  
    op.Type = "ShiftZ" o)'T#uK  
    op.val1 = taq-0.01 K1Nhz'^=D  
    op.parent = parID |@={:gRJ{x  
    AddOperation eID, op ,+P!R0PNH  
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    Print "Set pupil diameter = " & pupilDiam )JE;#m0q  
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    'Update AZ Eye subassembly Description 3 q  
    eID = FindFullName( "Geometry.Arizona Eye" ) o:_}=1nh  
    GetEntity eID, entity `pzp(\lc  
    entity.Description = "Accommodation = " & A & "D" pt;E~_  
    SetEntity eID, entity Mjq1qEi"B  
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    Update |c,":R  
    Print "DONE!" ivC1=+  
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End Sub 8 s!0Z1Roc  
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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： r]?ZXe$;  
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Accommodation = 4 Diopters = ^:TW%O  
Pupil Diameter = 4 mm p*F&G=ZE  
Set aqueous humor thickness = 2.81 {bL6%._C  
Set anterior lens radius = 10.4 and conic constant = -2.375869 j]}A"8=1  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 _)Q) tOW  
Set lens thickness = 3.927 O^|dc=  
Set lens index of refraction = 1.42672 fM?HZKo  
Set pupil diameter = 4 U .hV1  
DONE! ]K0<DO9  
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（文章来源：讯技光电）
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