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简介 <C\snB 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。 XW6>;:4k .bbl-a/
3 模型 `gq@LP"o ugg08 am! 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。 9)p VDS uX@RdkC Table 1. AZ眼睛模型的定义 %&bO+$H3 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. =iy%;>I` t?9F2rh 光源 =!_e(J tk4~ 8 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 oB8u[! ZK))91;v U7U-H\t7 图1. 光源和提示信息使用 U/E M(y 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 E1:{5F5/ 5haJPWG|' 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 ;5 cg<~t 79<{cexP 图2. 字母F光源的设定方法光 [QA@XBy6 Hep]jxp+ 图3. 字母F在视网膜上位置点列图 Ji SJi? 视网膜的散射 ,qJ/Jt$A O3#4B!J$E 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 A P><l@ q#Az\B: +\G/j ]3f 图4. 视网膜朗伯散射设定 M(o?I} 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 g$eb@0$ W:8_S%~d F!jYkDY 图5. 视网膜重点采样规格设定 |cL'4I>b9 脚本 TFWV(<
po+>83/!oq 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: TI: -Y@8 A7DEAT))4L 图6. 用户对话框的创建与编辑 zghUwW |K 图7. 用户对话框编辑器 h9c54Ux 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。 xN0n0 余下的脚本计算与屈光度有关的所有参数。 a6"Pe07t k'Fc:T8:~5 分析 hZ-No |XOD~Plo^ 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$:ZJ D1t@Y.vl 图7. 字母F在视网膜上颜色分析 ;
k{w@L.@ 脚本代码 ,tv
P"@d lN*O</L," Option Explicit 'Remove this to enable non-dimensioned variables to be used. s2)a8< =ZjF5,@ Dim entity As T_ENTITY `s(T(l Dim op As T_OPERATION P31}O2 Nh Dim mat As T_MODELMATERIAL DSad[>Uj], Dim A As Double ^il'Q_-{ Dim pupilDiam As Double x|n2,3% Dim eID As Long mR:G,XytxM Dim parID As Long ,TaaX I Dim count As Integer !VU[=~ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double UN[rW0* Dim tlens As Double, nlens As Double SU9qF73Y Dim curv As Double, conic As Double o:jLM7$= Dim ok As Long B ?96d'A :<f7;. Sub Main bIt%KG{PY6 `sOCJ|rc5 '用户输入对话框 f.cIh ZF Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 % \Nfj)9 TextBox 220,21,40,21,.TextBox1 'default: 0 E]V:@/(M' Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 7H~StdL/> OKButton 40,91,90,21 1a4
[w
CancelButton 190,91,90,21 j+NOT`& Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 T:IKyb TextBox 220,49,40,21,.TextBox2 'default: 4 IM),cOp= End Dialog B;?)
Dim dlg As UserDialog #jn6DL@[{ vQ"EI1=7Z ok = Dialog (dlg) H5uWI k/hE68<6i If ok=0 Then 'cancel button was pressed JPW+(n|g Print "Execution cancelled."
Y,z15i3j? End /H&: End If 0@z=0}0Z LM}0QL
m? 'Assign accommodation and pupil diameter & use defaults if field left empty nAv@^G2 If dlg.TextBox1 = "" Then *#{[9d A = 0 'Default accommodation .q#2 op Else YFgQ!\&59 A = CDbl(dlg.TextBox1) VXlTA>a } End If )]~'zOE_ VE1 B"s</ If dlg.TextBox2 = "" Then z%5i ^P pupilDiam = 4 'Default pupil diameter [4B.;MS( Else Wo&10S w pupilDiam = CDbl(dlg.TextBox2) N)G.^9 End If }
<; y,4f v[WbQ5AND Print " " +ou5cQ^ Print "Accommodation = " & A & " Diopters" MFO}E!9`q Print "Pupil Diameter = " & pupilDiam & " mm" a.QF`J4"' .n1]Yk;,1 ' Calculate new parameters with accommodation }3
NGMGu$ taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness l&cYN2T
b e#]=-^ Rant = 12.0 - 0.4*A 'Radius of anterior lens uSp=,2) CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens %cJ]Ds%V fXCx!3m Rpost = -5.224557 + 0.2*A 'Radius of posterior lens zB`)\ CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens zS*GYE(l^ 4SSq5Ve< tlens = 3.767 + 0.04*A 'Lens thickness rSDS9Vf( ]Ija,C!# nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction KY$6=/?U_ ;B>2oq 'Adjust parameters to account for accommodation +*-u_L\' jz(}P8 '************************************************************************* g(m3
& 'Aqueous thickness (Position of Lens) w.exLC '************************************************************************* P<yd eID = FindFullName( "Geometry.Arizona Eye.Lens" ) tAH,3Sz( / GetCustomElement eID, entity |mvy@hm :{<( )gfk parID = FindFullName( "Geometry.Arizona Eye" ) 4h wUH {:M5t1^UC ' Delete any shift(s) in z ?h4-D:!$L count = 0 Rg~ ~[6G> While GetOperationCount(eID)>count VKRj
1LXz GetOperation eID, count, op I;kKY
If op.Type="ShiftZ" Then k6-.XW DeleteOperation eID,count xgP/BK2" count=count-1 3#vhQ*xU End If RkP g&R;i count=count+1 7KU/ 1l9$9 Wend :FOMRrf7. uTY5.8 'Set new shift in .hW_P62\# op.Type = "ShiftZ" gf2<dEff op.val1 = taq DP`$gd op.parent = parID Xao
0cb.R AddOperation eID, op aLapb5VV Print "Set aqueous humor thickness = " & taq-0.55 I8
Ai_^P ':6!f '************************************************************************* Z'iXuI49 'Radius and conic constant of anterior lens >en,MT| '************************************************************************* WMfu5x7e4 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ;\yY* GetConic eID, entity, curv, conic Wi ]Mp7b HH/bBM! SetConic eID, entity, 1/Rant, CCant zTb!$8D"g Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant gd3~R+Kd S;[g0j '************************************************************************* F/;uN5{o 'Radius and conic constant of posterior lens {2?o: '************************************************************************* yZFm<_9> eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) D h y GetConic eID, entity, curv, conic . zf#S0y%( g}nlb.b]{m SetConic eID, entity, 1/Rpost, CCpost j]i:~9xKW Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost }Jkz0 JY~ _hlLM,p '************************************************************************* o#Q0J17i? 'Lens thickness (Position of posterior lens surface) L2:v#c()#) '************************************************************************* 3n-~+2l tM3eB= .* parID = FindFullName( "Geometry.Arizona Eye.Lens" ) N3 qtq9{ *k$&U3= ' Delete any z-shift(s) 2:0'fNXop count = 0 ??Zh$^No: While GetOperationCount(eID)>count +$R4'{9q GetOperation eID, count, op 6rlafISvO If op.Type="ShiftZ" Then >g8H DeleteOperation eID,count kd^CZ;O count=count-1 k fS44NV End If ab4(?-'- count=count+1 K~Lh'6 Wend lJHV c"*/ O^(ji8[l 'Set new z-shift 5*QNE! op.Type = "ShiftZ" Ul#||B .c{ op.val1 = tlens 2uw1R;zw op.parent = parID nRq@hk AddOperation eID, op !#P|2>>u Print "Set lens thickness = " & tlens 1"k"<{% F&?&8. '************************************************************************* .9X, )^D 'Lens index of refraction LlAMtw" '************************************************************************* .*+?] eID = FindMaterial( "Lens" ) wWV`k GetModelMaterial eID, mat QRbiO c\.Hs9T > mat.Nd = nlens *3 .+19Q SetModelMaterial eID, mat =ZdP0l+V=k Print "Set lens index of refraction = " & nlens \ci'Cbn\o f4F13n_0X '************************************************************************* D=*3Xd 'Pupil diameter rXR=fj= 2 '************************************************************************* {=n-S2% eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) m]t`;lr< UzZzt$Kw 'Adjust pupil diameter (trimming volume inner hole) &~`Ay4hq * N5cC#5`= SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" y"4Nw]kU CMk0(sztU_ ' Adjust pupil location to just in front of the lens Th&-n%r9K parID = FindFullName( "Geometry.Arizona Eye" ) .{,PC eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Bn>"lDf, count = 0 Lo"w,p`n@ While GetOperationCount(eID)>count Jv*[@
-.k GetOperation eID, count, op Fy(-.S1 If op.Type="ShiftZ" Then h>>KH*dQ DeleteOperation eID,count xb`,9.a7 count=count-1 |ymw])L End If 8}9B*m count=count+1 Ww8<f$ Wend QkMK\Up op.Type = "ShiftZ" Y`$dtg { op.val1 = taq-0.01 Z)=S. ) op.parent = parID JBY`Y]V3 AddOperation eID, op 3q +C8_: %6-5hBzZN Print "Set pupil diameter = " & pupilDiam IK#W80y Z4+S4cqnh 'Update AZ Eye subassembly Description 6:Eu[PE~w eID = FindFullName( "Geometry.Arizona Eye" ) p6=L}L GetEntity eID, entity ""LCyKu entity.Description = "Accommodation = " & A & "D" U;%I"
p`Z/ SetEntity eID, entity D|zlC,J, rof&O Update 3=r#=u5z Print "DONE!" WO=X*One GTvp)^h End Sub SRL`! ci]IH]x 如果屈光度是4,光瞳直径是4,则会输出如下数据: v]`}T/n +C`h*%BW Accommodation = 4 Diopters 6]`XW0{C Pupil Diameter = 4 mm -Ucj|9+(a
Set aqueous humor thickness = 2.81 uK_ Q l\d Set anterior lens radius = 10.4 and conic constant = -2.375869 e+Qq a4 Set posterior lens radius = -4.424557 and conic constant = -3.081019 vAeh#V~# Set lens thickness = 3.927 cT8b$P5w Set lens index of refraction = 1.42672 iR
k.t=B Set pupil diameter = 4 w.tQ)x1h DONE! 3I|&}+Z6 )`Zj:^bz9 (文章来源:讯技光电)
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