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infotek 2020-12-09 09:18

Arizona眼睛模型

简介 <<@$0RW  
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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。 x'+lNlv  
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模型 7y&Fb  
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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。 |k{?\(h;  
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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. n Uz 2~z  
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光源 1K"``EvNB  
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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。 n1a;vE{!  
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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。 nG1 mx/w  
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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。 Xl.h&x0? 8  
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图2. 字母F光源的设定方法光 $C##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 3o%JJIn&  
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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。 o) `zb?  
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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。 &kB[jz_[A  
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图5. 视网膜重点采样规格设定
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脚本 5H1SC8+B,  
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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: OY*BVJ^  
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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。 VZ &>zF  
余下的脚本计算与屈光度有关的所有参数。 2T<QG>;)j  
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分析 VHsuC$3W  
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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。 w6y?D<  
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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 !T@>Ld:  
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Option Explicit     'Remove this to enable non-dimensioned variables to be used. 8RbtI4  
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Dim entity As T_ENTITY >V;JI;[  
Dim op As T_OPERATION W1$B6+}Z0V  
Dim mat As T_MODELMATERIAL 1b+ B  
Dim A As Double yHLc lv  
Dim pupilDiam As Double k2sb#]-/}  
Dim eID As Long , d ?4"8_  
Dim parID As Long -iGt]mbJkP  
Dim count As Integer HdGAE1eU]}  
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double -q[T0^e S  
Dim tlens As Double, nlens As Double L;I .6<K.  
Dim curv As Double, conic As Double )p4o4 aM  
Dim ok As Long Hq8<g$  
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Sub Main &_HSrU  
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    '用户输入对话框 )5_GJm&R9  
    Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 zL5r8mD3  
        TextBox 220,21,40,21,.TextBox1 'default: 0 4JKB6~Y  
        Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 I >k3X~cG  
        OKButton 40,91,90,21 $]:I1I  
        CancelButton 190,91,90,21 ;Jr6  
        Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 {cnya*  
        TextBox 220,49,40,21,.TextBox2 'default: 4 Kg=TPNf"$  
    End Dialog Qzw~\KY:  
    Dim dlg As UserDialog *E+2E^B  
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    ok = Dialog (dlg) GeWB"(t  
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    If ok=0 Then    'cancel button was pressed FVMR9~&+  
        Print "Execution cancelled." P5* :r3>  
        End RQWVjF#  
    End If xY(+[T!OF  
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    'Assign accommodation and pupil diameter & use defaults if field left empty xcnHj1r-o'  
    If dlg.TextBox1 = "" Then \)eHf 7H  
        A = 0           'Default accommodation ji? 0;2Y  
    Else ,w; ~R4x  
        A = CDbl(dlg.TextBox1) iN8?~T}w  
    End If +"Ih'bb`j  
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    If dlg.TextBox2 = "" Then U8]L3&~  
        pupilDiam = 4   'Default pupil diameter w(8q qU+\  
    Else D QP#h5O  
        pupilDiam = CDbl(dlg.TextBox2) 7s; <5xc  
    End If m(q6Xe:Vc  
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    Print " " Wg[?i C*~  
    Print "Accommodation = " & A & " Diopters" BF<7.<,  
    Print "Pupil Diameter = " & pupilDiam & " mm" v]F q}I"  
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    ' Calculate new parameters with accommodation 0*L|r Jf  
    taq = 0.55 + 2.97 - 0.04*A              'Aqueous thickness 4A^hP![c#]  
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    Rant = 12.0 - 0.4*A                     'Radius of anterior lens MVg`6&oH  
    CCant = -7.518749 + 1.285720*A          'Conic constant of anterior lens EJjTf:  
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    Rpost = -5.224557 + 0.2*A               'Radius of posterior lens N#@xo)-H  
    CCpost = -1.353971 - 0.431762*A         'Conic constant of posterior lens \3n{%\_  
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    tlens = 3.767 + 0.04*A                  'Lens thickness %}%D8-d}G  
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    nlens = 1.42 + 0.00256*A - 0.00022*A^2  'Lens index of refraction Fe.Y4\xz  
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    'Adjust parameters to account for accommodation ?=jmyDXH!  
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    '************************************************************************* %\_I% yF  
    'Aqueous thickness (Position of Lens) *U.$=4Az  
    '************************************************************************* {.bLh 0  
    eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ,r{*o6  
    GetCustomElement eID, entity :>nk63V (  
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    parID = FindFullName( "Geometry.Arizona Eye" ) _t6siB_u  
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    ' Delete any shift(s) in z |.=Ee+HZ  
    count = 0 -?e~dLu  
    While GetOperationCount(eID)>count tirw{[X0n  
        GetOperation eID, count, op 2]eh[fRQ  
        If op.Type="ShiftZ" Then #I%< 1c%XA  
            DeleteOperation eID,count (6u<w#u  
            count=count-1 [ w  
        End If 7 tF1g=\  
        count=count+1 $^IuE0.  
    Wend -4,qAnuMx  
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    'Set new shift in lk \|EG  
    op.Type = "ShiftZ" 3 C=nC  
    op.val1 = taq V J){@  
    op.parent = parID 0MMY{@n  
    AddOperation eID, op 6'(5pt  
    Print "Set aqueous humor thickness = " & taq-0.55 + h`:qB  
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    '************************************************************************* TMKemci  
    'Radius and conic constant of anterior lens ]SBv3Q0D7  
    '************************************************************************* &w2.b:HF  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 1(w0* `  
    GetConic eID, entity, curv, conic P{(m:`N  
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    SetConic eID, entity, 1/Rant, CCant ~IE:i-Kz  
    Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant k :7UU4M 5  
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    '************************************************************************* '0H +2  
    'Radius and conic constant of posterior lens LN?T$H  
    '************************************************************************* ;Zj Qy,H%  
    eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) H\8i9RI  
    GetConic eID, entity, curv, conic uFSgjWJ#~  
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    SetConic eID, entity, 1/Rpost, CCpost GPP~*+n  
    Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost X-Xf6&Uz  
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    '************************************************************************* q5lRc=.b[  
    'Lens thickness (Position of posterior lens surface) 5tP0dQYd  
    '************************************************************************* 5y=X?hF~)  
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    parID = FindFullName( "Geometry.Arizona Eye.Lens" ) +;Cq>1x,  
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    ' Delete any z-shift(s) &^9f)xb  
    count = 0 o"Ef>5N  
    While GetOperationCount(eID)>count kG?tgO?*  
        GetOperation eID, count, op ,>{4*PM(  
        If op.Type="ShiftZ" Then 8C,?Ai<ro  
            DeleteOperation eID,count <6dD{{J]>p  
            count=count-1 KT?vs5jg$&  
        End If L4Nk+R;  
        count=count+1 ;a{ Dr  
    Wend &JfyXM[]  
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    'Set new z-shift HP]Xh~aP  
    op.Type = "ShiftZ" q n=6>wP  
    op.val1 = tlens nn#A-x}~;b  
    op.parent = parID ,e.y4 vnU  
    AddOperation eID, op N_C\L2  
    Print "Set lens thickness = " & tlens ]PUyX8'~  
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    '************************************************************************* =b`>ggw#  
    'Lens index of refraction ,Oxdqxu7  
    '************************************************************************* E_ mgYW*5  
    eID = FindMaterial( "Lens" ) XHN?pVZ7  
    GetModelMaterial eID, mat >#!n"i;  
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    mat.Nd = nlens Lb2Bu>  
    SetModelMaterial eID, mat <LBMth  
    Print "Set lens index of refraction = " & nlens '?3Hy|}  
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    '************************************************************************* ).v;~yE   
    'Pupil diameter 4`Fbl]Q   
    '************************************************************************* T+sO(;  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) P Cw.NJd$  
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    'Adjust pupil diameter (trimming volume inner hole) 5fVdtJk7  
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    SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" b?w4Nx#  
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    ' Adjust pupil location to just in front of the lens  4jG@ #  
    parID = FindFullName( "Geometry.Arizona Eye" ) D;Az>]>q  
    eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) )}paQmy#  
    count = 0 dZnq 96<:|  
    While GetOperationCount(eID)>count l8^^ O   
        GetOperation eID, count, op yGS._;#R  
        If op.Type="ShiftZ" Then zlSwKd(  
            DeleteOperation eID,count  #lJF$  
            count=count-1 Y ciZU  
        End If Bb-x1{t  
        count=count+1 P6IhpB59  
    Wend t`F%$q  
    op.Type = "ShiftZ" !3HMGzt  
    op.val1 = taq-0.01 3FNj~=N  
    op.parent = parID w7dG=a&  
    AddOperation eID, op #}k^g:l1  
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    Print "Set pupil diameter = " & pupilDiam @<alWBS  
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    'Update AZ Eye subassembly Description \UNw43EL  
    eID = FindFullName( "Geometry.Arizona Eye" ) (F_#LeJ|  
    GetEntity eID, entity > ]6Eb`v  
    entity.Description = "Accommodation = " & A & "D" E; RI.6y  
    SetEntity eID, entity 7&T1RB'>  
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    Update O"Xjv`j:  
    Print "DONE!" lHP[WO  
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End Sub 3!*J;Y  
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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: <Pf W  
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Accommodation = 4 Diopters /B1NcRS  
Pupil Diameter = 4 mm >L=l{F6 p  
Set aqueous humor thickness = 2.81 hg\$>W~ 2  
Set anterior lens radius = 10.4 and conic constant = -2.375869 tSQ>P -O  
Set posterior lens radius = -4.424557 and conic constant = -3.081019 _jnH!Mw  
Set lens thickness = 3.927 jUjQ{eT  
Set lens index of refraction = 1.42672 L TO1LAac  
Set pupil diameter = 4 [>6:xGSe9X  
DONE! 8[zP2L!-  
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