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xunjigd 2016-02-24 12:53

FRED运用:Arizona眼睛模型

简介 o=;.RYi  
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*I\FV  
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模型 <`-"K+e!J  
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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。 OEdp:dW|  
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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. V %Y.N4H  
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光源 PJO;[: .I  
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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。 "pMXTRb  
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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。 *DDfdn  
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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。 5>h2WL  
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图2. 字母F光源的设定方法光 cf0em!  
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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 9FPl  
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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。 0A5xG&  
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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。 Rg0\Ng4|G  
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图5. 视网膜重点采样规格设定
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脚本 nqiy)ZN#R  
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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: LoBKR c2t  
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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。 c{FvMV2em  
余下的脚本计算与屈光度有关的所有参数。 prIq9U|@  
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分析 v,g,c`BjK  
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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。 ^+,mxV'8!  
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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 'e{e>>03  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. f"k/j?e*  
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Dim entity As T_ENTITY Nm\I_wjX  
Dim op As T_OPERATION K;[V`)d'  
Dim mat As T_MODELMATERIAL 6 D!,vu  
Dim A As Double ,:=E+sS  
Dim pupilDiam As Double 9H.E15B  
Dim eID As Long y6:=2(]w<p  
Dim parID As Long %9Ulgs8=  
Dim count As Integer  kQX,MP(  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double {wA@5+[  
Dim tlens As Double, nlens As Double Fp@eb8Pl  
Dim curv As Double, conic As Double ce+\D'q[  
Dim ok As Long 1iF |t5>e  
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Sub Main xwK<f6H!y  
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    '用户输入对话框 yDy3;*lE  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 W e9C9)0  
        TextBox 220,21,40,21,.TextBox1 'default: 0 _NqEhf:8  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 9O}YtX2  
        OKButton 40,91,90,21 /l:3* u  
        CancelButton 190,91,90,21 +yCIA\i#t6  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 B;G|2um:$  
        TextBox 220,49,40,21,.TextBox2 'default: 4 QD"V=}'?  
    End Dialog fa<83<.D  
    Dim dlg As UserDialog OmKT}D~ 4  
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    ok = Dialog (dlg) %li'j|  
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    If ok=0 Then    'cancel button was pressed |q5\1}@:  
        Print "Execution cancelled." #C !8a  
        End <M+ZlF-`  
    End If _Vp9Y:mX2  
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    'Assign accommodation and pupil diameter & use defaults if field left empty }.` ycLW'  
    If dlg.TextBox1 = "" Then  /H!I90  
        A = 0           'Default accommodation K6|*-Wo.  
    Else 9LCV"xgX  
        A = CDbl(dlg.TextBox1) 5F <zW-;  
    End If 7b'XQ/rs  
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    If dlg.TextBox2 = "" Then JrCm >0g  
        pupilDiam = 4   'Default pupil diameter i ]F,Y;&|  
    Else ^>k[T.  
        pupilDiam = CDbl(dlg.TextBox2) 6ng . =  
    End If $?;aW^E  
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    Print " " cB?HMLbG>  
    Print "Accommodation = " & A & " Diopters" 2/>AmVM  
    Print "Pupil Diameter = " & pupilDiam & " mm" 4b6$Mj  
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    ' Calculate new parameters with accommodation vco:6Ab$  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness Fwho.R-.  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens {!6!z,  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens u49/LtB\  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens /r}t  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens 6,s@>8n  
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    tlens = 3.767 + 0.04*A                  'Lens thickness  l R;<6  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Isoqs(Oi  
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    'Adjust parameters to account for accommodation Mgf80r=  
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    '************************************************************************* 7{<t]wQq  
    'Aqueous thickness (Position of Lens) Y@#~8\_  
    '************************************************************************* BflF*-s ^  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) u4+)lvt  
    GetCustomElement eID, entity {WFYNEQ[  
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    parID = FindFullName( "Geometry.Arizona Eye" ) 0~n= |3*P  
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    ' Delete any shift(s) in z #M{}Grg  
    count = 0 f+L )x  
    While GetOperationCount(eID)>count jd(=? !_  
        GetOperation eID, count, op 6OIA>%{  
        If op.Type="ShiftZ" Then F"a,[i,[W  
            DeleteOperation eID,count ?^,GaZ^V  
            count=count-1 <8j n_6  
        End If Wq"pKI#x  
        count=count+1 Cn+TcdHX  
    Wend 51&wH  
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    'Set new shift in 63F0Za}h  
    op.Type = "ShiftZ" 2R|2yAh  
    op.val1 = taq HM ^rk  
    op.parent = parID &/a/V  
    AddOperation eID, op !~>u\h  
    Print "Set aqueous humor thickness = " & taq-0.55 pMs%`j#T  
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    '************************************************************************* .F%RW8=Q  
    'Radius and conic constant of anterior lens + Uj~zx@  
    '************************************************************************* .@1\26<  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 3MkF  
    GetConic eID, entity, curv, conic dR $@vDm  
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    SetConic eID, entity, 1/Rant, CCant p/SJt0  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 5r`g6@  
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    '************************************************************************* :5C9uW #  
    'Radius and conic constant of posterior lens 5 _] i==M  
    '************************************************************************* }bjTb!  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) t'R&$;z@b  
    GetConic eID, entity, curv, conic R},mq&f5  
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    SetConic eID, entity, 1/Rpost, CCpost INcJXlv  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ;QW)tv.y  
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    '************************************************************************* z[CCgs&vqe  
    'Lens thickness (Position of posterior lens surface) s}/YcUK  
    '************************************************************************* //| 9J(B]  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8 I,(\<Xv  
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    ' Delete any z-shift(s) %o*afd  
    count = 0 MhJq~G p  
    While GetOperationCount(eID)>count &eg]8kV  
        GetOperation eID, count, op BA L!6  
        If op.Type="ShiftZ" Then 7F.>M  
            DeleteOperation eID,count h:j-Xd$H+  
            count=count-1 q$U;\Mg)  
        End If 6t*=.b,N  
        count=count+1 fZXd<Fg+  
    Wend C.(<KV{b  
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    'Set new z-shift &S c0l/  
    op.Type = "ShiftZ" Y@;bA=Du}  
    op.val1 = tlens eN,m8A`/S  
    op.parent = parID RI-whA8+  
    AddOperation eID, op `^|mNh  
    Print "Set lens thickness = " & tlens zg|yW6l)9  
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    '************************************************************************* 574 b]  
    'Lens index of refraction */?L_\7  
    '************************************************************************* U3A>#EV  
    eID = FindMaterial( "Lens" ) n |.- :Zy  
    GetModelMaterial eID, mat i~k?k.t8  
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    mat.Nd = nlens @{XN}tWDOp  
    SetModelMaterial eID, mat -/7[_,  
    Print "Set lens index of refraction = " & nlens .hZ =8y9  
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    '************************************************************************* 5C{X$7u  
    'Pupil diameter PMkwY {.u  
    '************************************************************************* iY.~N#Q  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) aLq=%fsV)  
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    'Adjust pupil diameter (trimming volume inner hole) WV?iYX!  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Fv e,&~  
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    ' Adjust pupil location to just in front of the lens h7(twct  
    parID = FindFullName( "Geometry.Arizona Eye" ) !A!zG)Ue<  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ]P]lG-  
    count = 0 0#<_:E  
    While GetOperationCount(eID)>count j:U>V7Kn3~  
        GetOperation eID, count, op _VR4 |)1g  
        If op.Type="ShiftZ" Then (}] 74Lc  
            DeleteOperation eID,count Gs*ea'T)  
            count=count-1 ^k u~m5v  
        End If _%<7!|"  
        count=count+1 j>0S3P,  
    Wend w&C SE  
    op.Type = "ShiftZ" L{ .r8wSrI  
    op.val1 = taq-0.01 ~oSLWA9  
    op.parent = parID HQ2in_'  
    AddOperation eID, op MS,H12h  
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    Print "Set pupil diameter = " & pupilDiam V<ODt%  
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    'Update AZ Eye subassembly Description 9HP)@66  
    eID = FindFullName( "Geometry.Arizona Eye" ) 1Kwl_jf  
    GetEntity eID, entity zA( 2+e 7  
    entity.Description = "Accommodation = " & A & "D" zXVQLz5  
    SetEntity eID, entity w&f29#i;b  
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    Update [-Q"A 6!Zd  
    Print "DONE!" !.3 MtXr  
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End Sub x1A^QIuxO  
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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#*eo;o7  
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Accommodation = 4 Diopters h1)p{ 5}H  
Pupil Diameter = 4 mm i.K}(bo;b  
Set aqueous humor thickness = 2.81 EXb{/4  
Set anterior lens radius = 10.4 and conic constant = -2.375869 -pkeEuwv{  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 t}*teo[  
Set lens thickness = 3.927 8|yhe%-O  
Set lens index of refraction = 1.42672 KHF5Nt  
Set pupil diameter = 4 Hi.JL  
DONE! 9f BD.9A  
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(文章来源:讯技光电)
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