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简介 bk=;=K 8q6Le{G 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。 u^^jt(j .L1[Rv3 模型 h\Y~sm?!` lsj9^z7 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。 #"TYk@whWf 6nsb)7a Table 1. AZ眼睛模型的定义 b W/T}FND 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. =Xid"$ 9+<A7PM1T 光源 q2`mu4B (yuOY/~k/ 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。 L">jSZW[[ z.)*/HGJm !
,H6.IH;S 图1. 光源和提示信息使用 HL$7Ou 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 ~X<$l+5 -%>Tjo@Bn 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。 dikX_ Q>D K+L9cv4 |* 图2. 字母F光源的设定方法光 ,SdxIhL 7iv g3* 图3. 字母F在视网膜上位置点列图 w&es N$2 视网膜的散射 x+%> 2qgj" A4d3hF~ l` 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 Dh#5-Kf% ei1;@k/ 4~oRcO8!Y 图4. 视网膜朗伯散射设定 fh1-]$z`~ 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。 gwB0/$!4" C~.\2D`zy $5\sV4 8f 图5. 视网膜重点采样规格设定 (+zU!9}I1 脚本 f`-vnh^+ =\i%,YY 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: \oGU6h< 9]G~i`QQ 图6. 用户对话框的创建与编辑 [?,+DY 图7. 用户对话框编辑器 Y37qjV 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 B
'd@ms 余下的脚本计算与屈光度有关的所有参数。 4pcIH5)z (&V*~OR 分析 S @!z'$& T(cpU,Q 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 `@6y Wb:X QGErQ
+l 图7. 字母F在视网膜上颜色分析 1`Bhis9X8 脚本代码 ^
rO}'~( S&cN+r Option Explicit 'Remove this to enable non-dimensioned variables to be used. ] ONmWo77o [{`&a#Q Dim entity As T_ENTITY O_
$ zK Dim op As T_OPERATION w'xPKO$bzR Dim mat As T_MODELMATERIAL 4/S3hH Dim A As Double DI-CC[ Dim pupilDiam As Double HG5E,^1n Dim eID As Long g*4^HbVxt Dim parID As Long 81I9xqvSd~ Dim count As Integer \l5G Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double X6r<#n|l Dim tlens As Double, nlens As Double G-vkkNj%e Dim curv As Double, conic As Double g~=-
,j| Dim ok As Long j/ARTaO1]" aE:$ N#|Qa Sub Main (v}l#M7w 6HVX4Z#VH '用户输入对话框 ,K&L/* Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 v.,D,6qZ TextBox 220,21,40,21,.TextBox1 'default: 0 \vL{f;2J Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 &RHx8zScP OKButton 40,91,90,21 zE}ry!{ CancelButton 190,91,90,21 }^odUIj Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 9r8bSV3` TextBox 220,49,40,21,.TextBox2 'default: 4 6s!=de End Dialog A*]sN8 Dim dlg As UserDialog ojIGfQV `'bu8JK ok = Dialog (dlg) <hgfgk7< o6:]Hvqjr If ok=0 Then 'cancel button was pressed "p>kiNu Print "Execution cancelled." uF
D End hb)83mH} End If rZRTQ h}oV)z6 'Assign accommodation and pupil diameter & use defaults if field left empty iE
,"YCK If dlg.TextBox1 = "" Then 99~-TiU A = 0 'Default accommodation ,v9*|>4 Else g- INhzMu A = CDbl(dlg.TextBox1) qUQP.4Z9 5 End If 6\QsK96_ +' .o If dlg.TextBox2 = "" Then eFQz G+/ pupilDiam = 4 'Default pupil diameter wu}Zu Else AC?a:{./ pupilDiam = CDbl(dlg.TextBox2) j#H&~f End If Y)AHM0;g *44E'Dxv Print " " [F,s=,S'M Print "Accommodation = " & A & " Diopters" E@Yq2FBpnn Print "Pupil Diameter = " & pupilDiam & " mm" 'f7s*VKG &?9~e>.OS ' Calculate new parameters with accommodation EPEn"{;U taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness `2G%&R,k"D ?y~"\iP Rant = 12.0 - 0.4*A 'Radius of anterior lens f Q2U| CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens &w^:nVgl 0(A&m , Rpost = -5.224557 + 0.2*A 'Radius of posterior lens nc#} \ CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens pE G!j ~ _=I&zUF tlens = 3.767 + 0.04*A 'Lens thickness xl(R|D)) z{U^j:A nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction S$GWY^5}{ <$`
^ 'Adjust parameters to account for accommodation /jn0Xh
};>~P%u32 '************************************************************************* ~8lB#NuN 'Aqueous thickness (Position of Lens) t8 ~isuiK '************************************************************************* hx}X=7w eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 0P4g6t}e GetCustomElement eID, entity 6eK7Jv\K h,i=Y+1 parID = FindFullName( "Geometry.Arizona Eye" ) lMjeq.5nP o-<.8Z}>at ' Delete any shift(s) in z gt(!I^LHYc count = 0
A4TW`g_zm While GetOperationCount(eID)>count >ZnnGX6$( GetOperation eID, count, op #sf1,k5' If op.Type="ShiftZ" Then BIjkW.uf DeleteOperation eID,count FBA th
!E count=count-1 "Q1oSpF End If /+?eSgM/ count=count+1 GrM`\MIO Wend S@WT;Q2Z p{O@ts: 'Set new shift in Ap<j;s4` op.Type = "ShiftZ" *V@t]d$=# op.val1 = taq %Lfy!]Ru op.parent = parID @`rC2-V AddOperation eID, op mFuHZ)iQG Print "Set aqueous humor thickness = " & taq-0.55 ?;
tz |k/;1.b!9( '************************************************************************* -N1X=4/fg 'Radius and conic constant of anterior lens ,y[w`Q\ '************************************************************************* O
_^Y*! eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) eOUEhpE GetConic eID, entity, curv, conic qfgw^2aUa >u?a#5R:m SetConic eID, entity, 1/Rant, CCant U%aDkC+M Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant j
k/-7/r V`"Cd?R0Z '************************************************************************* i$XT Qr0K= 'Radius and conic constant of posterior lens b'(Hwc\ t '************************************************************************* `s_k+ g eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) c/-PEsk_TP GetConic eID, entity, curv, conic 1,pPLc( qGECw# SetConic eID, entity, 1/Rpost, CCpost 6=jL2cqx Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost Lz`_&&6 B3&ETi5NTU '************************************************************************* (iu IeJ^Z 'Lens thickness (Position of posterior lens surface) ,TQ;DxB}=E '************************************************************************* A=BT2j'l) -;&-b >b
parID = FindFullName( "Geometry.Arizona Eye.Lens" ) }_9yemP x UTlM ' Delete any z-shift(s) VI8/@A1Gv count = 0 .;%`I While GetOperationCount(eID)>count E5t
/-4 GetOperation eID, count, op *30T$_PiX| If op.Type="ShiftZ" Then 2%~+c|TH.) DeleteOperation eID,count wRe2sjM count=count-1 JYa3xeC; End If d+&w7/F count=count+1 (bGk=q=M Wend WTu1t] y6 gaoj 'Set new z-shift eZmwF@ op.Type = "ShiftZ" r.v.y[u op.val1 = tlens 3F{R$M} op.parent = parID >$;,1N $bd AddOperation eID, op 9]^NAlno Print "Set lens thickness = " & tlens D]+@pKb X ="]q|Z '************************************************************************* v)LSH;< 'Lens index of refraction Q`z2SYz> '************************************************************************* ~f?brQ? eID = FindMaterial( "Lens" ) <l$ vnq GetModelMaterial eID, mat w,;ox2 5ih5=qX mat.Nd = nlens QTjnXg?Ri SetModelMaterial eID, mat 9Q&]5|x Print "Set lens index of refraction = " & nlens /Ca
M(^W K,@} 'N '************************************************************************* \};
4rm}V 'Pupil diameter ;H"OZRQ '************************************************************************* \N)!]jq eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 9oj0X>| 1 DfVSG1g 'Adjust pupil diameter (trimming volume inner hole) ]t_ Wl1*| fs8C ^Ik>~ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" Fuo.8 }C5Fvy6uz ' Adjust pupil location to just in front of the lens fTd":F parID = FindFullName( "Geometry.Arizona Eye" ) HK`r9frn eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Kj#h9e count = 0 Eg$Er*)h8 While GetOperationCount(eID)>count /D;cm GetOperation eID, count, op %Wt F\p If op.Type="ShiftZ" Then `i6q\-12n DeleteOperation eID,count #QiNSS count=count-1 &IkHP/ End If \d
QRQL{LL count=count+1 )?k~E=&o |