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简介 2\{/|\ J|xXo 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。 1N),k5I ;R
>>,&g 模型 e[k\VYj[ Cdl"TZ< 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。 4=q4_ \_T !T`g\za/ Table 1. AZ眼睛模型的定义 em'3 8L|( 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. #p"F$@N Tx?s?DwC 光源 tQj=m_ f$ /C.E 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。 $I`,nN v*excl~ 2;:]Q.g 图1. 光源和提示信息使用 uYTyR;a 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。 G]l/L\{ iMVQt1/ 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。 s,J\nbj0h lN.&46
e 图2. 字母F光源的设定方法光 %.[AZ> QdZHIgh`i 图3. 字母F在视网膜上位置点列图 pC4uar 视网膜的散射 #~*v*F~3 -XECYwTh 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。 [Qk j} l7ES*==&@0 E#w2'(t 图4. 视网膜朗伯散射设定 %Y`)ZKh
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。 ,vi6<C\ ;rJ#>7K Pw|/PfG 图5. 视网膜重点采样规格设定 a6T!)g 脚本 C1HNcfa7 ~O;?;@ 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: \XY2s&" g[2[
zIB= 图6. 用户对话框的创建与编辑 C/"Wh=h6 图7. 用户对话框编辑器 I~
SFY>s 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。 Y0'~u+KS`5 余下的脚本计算与屈光度有关的所有参数。 b4^a
zY 1
xr mmK 分析 pv|D{39Hs ZCuh^ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 iaJN~m\
M P`hg*"<V 图7. 字母F在视网膜上颜色分析 My9fbT 脚本代码 ;hDIoSz D>#Jh>4 Option Explicit 'Remove this to enable non-dimensioned variables to be used. kJXy) i#lO{ ] Dim entity As T_ENTITY %]DJ-7 xE Dim op As T_OPERATION +DT)7koA Dim mat As T_MODELMATERIAL Qa16x<Xlm Dim A As Double vP<8,XG Dim pupilDiam As Double h1_KZ[X Dim eID As Long wCr+/"t Dim parID As Long e3&.RrA Dim count As Integer $/i;UUd Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double ~f2-%~ Dim tlens As Double, nlens As Double vw
q Y;7 Dim curv As Double, conic As Double 6v-2(Y Dim ok As Long .=b)Ae c LTY(6we- Sub Main ?6^KY+ 5`C o2(*5*b!@e '用户输入对话框 F[|aDj@q e Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 CI?M2\<g TextBox 220,21,40,21,.TextBox1 'default: 0 wmS:*U2sc Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 q(@hYp#O"3 OKButton 40,91,90,21 5E|/n( CancelButton 190,91,90,21 Z"<tEOs/En Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Oz,/y3_ TextBox 220,49,40,21,.TextBox2 'default: 4 UD r@ End Dialog Q_R&+@ju Dim dlg As UserDialog *j=
whdw%J n47v5.Wn ok = Dialog (dlg) +l$BUX \xaK?_hv If ok=0 Then 'cancel button was pressed ddjaM/.E Print "Execution cancelled." VJ(#FA2 End Z4Qq#iHZR End If ('p~h-9Vi AUAJMS!m 'Assign accommodation and pupil diameter & use defaults if field left empty ~lLIq!!\ If dlg.TextBox1 = "" Then M>g\Y A = 0 'Default accommodation NvfQa6?; Else P\H$*6v( A = CDbl(dlg.TextBox1)
O%kX=6 End If |P]>[}mD p[%FH? If dlg.TextBox2 = "" Then f~? MNJ2 pupilDiam = 4 'Default pupil diameter 2^7VDqLc Else 4jl-? pupilDiam = CDbl(dlg.TextBox2) `H6kC$^Ofx End If E|d 8vt J;g+ Print " " qMe$Qr8 Print "Accommodation = " & A & " Diopters" p9)'nU'\t Print "Pupil Diameter = " & pupilDiam & " mm" W`-AN}C# <J QvuC ' Calculate new parameters with accommodation T/&4lJ^2l^ taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness v [ 4J0 <OEu 4,~: Rant = 12.0 - 0.4*A 'Radius of anterior lens @ zE>n CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens 0xM\+R~, AA
um1xl Rpost = -5.224557 + 0.2*A 'Radius of posterior lens bEE'50D CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens 2 -uL ,$96bF "# tlens = 3.767 + 0.04*A 'Lens thickness <x),HTJ +mN]VO*y nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 0ZXG{Gp9S IOsitMOX: 'Adjust parameters to account for accommodation =5jX#Dc5.+ >8nRP%r[5, '************************************************************************* bi bjFg 'Aqueous thickness (Position of Lens) t .&YD x '************************************************************************* Q!:J.J eID = FindFullName( "Geometry.Arizona Eye.Lens" ) gI
qYIt GetCustomElement eID, entity nDSmr G.,dP+i parID = FindFullName( "Geometry.Arizona Eye" ) z5v)~+"1 io$!z=W ' Delete any shift(s) in z a8Jn.! count = 0 S&% GB While GetOperationCount(eID)>count DUxj^,mf, GetOperation eID, count, op &C+pen)Z If op.Type="ShiftZ" Then LuB-9[^< DeleteOperation eID,count 7p(^I*| count=count-1 mpBSd+;Z End If gjJ?*N[ count=count+1 kckWBL Wend eEkFZx Yqy7__vm 'Set new shift in %+U.zd$ op.Type = "ShiftZ" ?A/+DRQ( op.val1 = taq ((TiBCF4 op.parent = parID HgP9evz,0 AddOperation eID, op 7c9-MP) Print "Set aqueous humor thickness = " & taq-0.55 S$Tc\/{ h+Dp<b '************************************************************************* ++Qg5FukR 'Radius and conic constant of anterior lens -gl7mO * '************************************************************************* W~J@v@..4 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) jiMI&cl GetConic eID, entity, curv, conic 18 pi3i[ y-gSal SetConic eID, entity, 1/Rant, CCant iw <2|]>l Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant mYf7?I~ %l!Gt"\xm '************************************************************************* ML!Zm[I9 'Radius and conic constant of posterior lens 4~8++b1/; '************************************************************************* pt&(c[ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) GpV"KVJJ/ GetConic eID, entity, curv, conic q[#2` #8G(r9 SetConic eID, entity, 1/Rpost, CCpost ~{hcJ:bI Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost r7r>1W%4 GU\}}j] '************************************************************************* 3zU!5tg 'Lens thickness (Position of posterior lens surface) <J4|FOz!= '************************************************************************* st"uD\L1p: xwr<ib: parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ?r"'JO.w S+G!o]&2 ' Delete any z-shift(s) y~CK&[H count = 0 *Y'@|xf* While GetOperationCount(eID)>count &R:$h*Wt| GetOperation eID, count, op #E%0 o If op.Type="ShiftZ" Then A`x_M!m DeleteOperation eID,count fX=o,=-f count=count-1 Sdl1k+u End If :|3n`, count=count+1 C=&7V Wend j]\3>. F3$@6J8<[z 'Set new z-shift ]5X=u(} op.Type = "ShiftZ" OTs vox|( op.val1 = tlens #%t&f"j2 op.parent = parID IKx]?0sS AddOperation eID, op aV?dy4o$ Print "Set lens thickness = " & tlens <<}t&qE%2% QZ!;` ?( '************************************************************************* !iBe/yb 'Lens index of refraction x#ub % t '************************************************************************* c+:LDc3!Gb eID = FindMaterial( "Lens" ) fG2hCP+ GetModelMaterial eID, mat t .*z)N Ffxf!zS mat.Nd = nlens =~M%zdIXv SetModelMaterial eID, mat 5}d"nx Print "Set lens index of refraction = " & nlens }!=}g|z#| :td#zM '************************************************************************* `NqX{26GV+ 'Pupil diameter \ 8v{9Yb '************************************************************************* 0J-] eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) /XtpGk_1) PMER~}^ 'Adjust pupil diameter (trimming volume inner hole) H4[];&]xr #w\Bc\ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" T=6fZ;7 P%`|Tu!B ' Adjust pupil location to just in front of the lens fx&b*OC parID = FindFullName( "Geometry.Arizona Eye" ) zs!}P eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) +DMD
g. count = 0 y5;l?v94 While GetOperationCount(eID)>count X=O}k& GetOperation eID, count, op Q>qx?
g If op.Type="ShiftZ" Then U40adP? a DeleteOperation eID,count zrD];DP count=count-1 r[>4b}4s End If )NG{iD{_] count=count+1 (#6E{@eq Wend m/W0vPM1 op.Type = "ShiftZ" Rv R,V op.val1 = taq-0.01 MRzrZZ%LQ op.parent = parID 9GdQ$^m AddOperation eID, op 9Yih%d,
;4DqtR"7Y Print "Set pupil diameter = " & pupilDiam "YLH]9"= Xq"@Z 'Update AZ Eye subassembly Description =Kdd+g! eID = FindFullName( "Geometry.Arizona Eye" ) A#&Q(g\YE GetEntity eID, entity tEEeek(! entity.Description = "Accommodation = " & A & "D" o(iv=(o SetEntity eID, entity |~Q`DdkX JN;92|x Update UO%VuC5B Print "DONE!" !Gwf"-TQ @R+bR<}] End Sub d0(GE4+/ y>+xdD0+ 如果屈光度是4,光瞳直径是4,则会输出如下数据: c-S_{~~ XI6LPA0% Accommodation = 4 Diopters @bu5{b+8 Pupil Diameter = 4 mm 9d ZE#l!Q Set aqueous humor thickness = 2.81 qucw%hJ r Set anterior lens radius = 10.4 and conic constant = -2.375869 =Rnx!E Set posterior lens radius = -4.424557 and conic constant = -3.081019 xgl~4 Set lens thickness = 3.927 "X/cG9Lw Set lens index of refraction = 1.42672 =\v./Q- Set pupil diameter = 4 ]KX _a1e DONE! "]BefvE
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