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简介 {Mj- $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。 0i"2s}^+_ \crh`~?> 模型 Qn|8Ic` * "N">RjJ" 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。 ~3-"1E>Rgy @-L\c>rqT Table 1. AZ眼睛模型的定义 iITMBS`} 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. s FJ:09L| R|^bZf^ 光源 }D+ b`, vz#-uw,O: 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。 *DvX||`& ?(U;T!n =fH5r_n 图1. 光源和提示信息使用 +*xc4 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。 #?+[|RS| 6&5D4
V 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。 j^;P=L0= E|>-7k") 图2. 字母F光源的设定方法光 kN3 <l7 ~(^pGL3< 图3. 字母F在视网膜上位置点列图 <KK.f9^o( 视网膜的散射 }Xk_
xQVt{ WtKKdL 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。 "wcw`TsK ',!jYh}Uxk pH.&C 5kA 图4. 视网膜朗伯散射设定 9BpxbU+L; 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。 mA$86 X_ l53Q"ajG 94et ]u%7 图5. 视网膜重点采样规格设定 7.Z- 脚本 IiRQ-,t1 &;pM<h 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: z. X
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[B`4I 图6. 用户对话框的创建与编辑 ,?Ie!r$6 图7. 用户对话框编辑器 }apno|W& 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 (3$DUvx7 余下的脚本计算与屈光度有关的所有参数。 [&4+
<Nl' < qab\M0W 分析 i].E1},% V_, `?>O 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 K?[Vz[-Fc E3Y0@r 图7. 字母F在视网膜上颜色分析 -
AgD 脚本代码 BfCM\ij lwgwdB Option Explicit 'Remove this to enable non-dimensioned variables to be used. 9d^m 7}2 $M4Z_zle) Dim entity As T_ENTITY 9xj }<WM Dim op As T_OPERATION hu} vYA7ZH Dim mat As T_MODELMATERIAL 9B;WjXSe Dim A As Double [zm@hxym Dim pupilDiam As Double /n(0w` Dim eID As Long #:N#i Dim parID As Long L fcy#3! Dim count As Integer ,SNrcwv Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Zk lpnL*! Dim tlens As Double, nlens As Double *P9" 1K+ Dim curv As Double, conic As Double $0K@=7ms Dim ok As Long T[xIn+w {]8|\CcY? Sub Main P(Rl/eyRM RQ[/s
lg '用户输入对话框 P*?| E@;s` Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 vdvnwzp!l TextBox 220,21,40,21,.TextBox1 'default: 0 .%7Le|Fb" Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 L~)8Q(f OKButton 40,91,90,21 Cw(yp u CancelButton 190,91,90,21 YLTg(* Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 1$Q[%9 TextBox 220,49,40,21,.TextBox2 'default: 4 GTTEg{ End Dialog (B$>o.(JA Dim dlg As UserDialog :<B_V< T30fp ok = Dialog (dlg) ;92xSe"Ww jUNt4 If ok=0 Then 'cancel button was pressed %L]sQq, Print "Execution cancelled."
Hcg7u7M{ End "0Z/|& End If 6'N_bNW &v*4AZ[' 'Assign accommodation and pupil diameter & use defaults if field left empty 6lg]5d2CD If dlg.TextBox1 = "" Then _*?qOmf= A = 0 'Default accommodation 1hCU"|VH: Else
D8u`6/^ A = CDbl(dlg.TextBox1) UCmy$aW End If
ebJTrh <{ x=xo9wEg If dlg.TextBox2 = "" Then Rh)XYCM pupilDiam = 4 'Default pupil diameter @$^4Av- Else L5zCL0j` pupilDiam = CDbl(dlg.TextBox2) N0^SWA|S End If 4FZR }e\ J;>~PXB Print " " ^yc8is'` Print "Accommodation = " & A & " Diopters" PDw+Q Print "Pupil Diameter = " & pupilDiam & " mm" \xggIW.^0 psmDGSm,& ' Calculate new parameters with accommodation 6Y\TVRR taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness _+aR|AEC Kf[.@_TD<1 Rant = 12.0 - 0.4*A 'Radius of anterior lens v'?o#_La+ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens #"!ga)a%L d7r!<u&/ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens v@GhwL CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens +:ms`Sr> ?.F^Oi6
u tlens = 3.767 + 0.04*A 'Lens thickness $'5rS$]a/ Zqe$S
+u nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction u&S0 `i(b%$|^&Z 'Adjust parameters to account for accommodation vxk0@k_ 2bw), W '************************************************************************* p6BDhT(RS 'Aqueous thickness (Position of Lens) 0U*f"5F '************************************************************************* 8N"WKBj|_d eID = FindFullName( "Geometry.Arizona Eye.Lens" ) =8tK]lb GetCustomElement eID, entity <+q`Dk NrXIaN parID = FindFullName( "Geometry.Arizona Eye" ) \ILNx^$EL '&,p>aM ' Delete any shift(s) in z pL[3,.@WA count = 0 3 V ^5 4_ While GetOperationCount(eID)>count yl@Nyu GetOperation eID, count, op u8>aO>(bVg If op.Type="ShiftZ" Then y>E:]#F DeleteOperation eID,count n CX{tqy count=count-1 p9 ,[kb End If YRBJ(v"9 count=count+1 '-N5F Wend MS#*3Md&y u tkdL4G}' 'Set new shift in -eh .Tk op.Type = "ShiftZ" T*#M'H7LSQ op.val1 = taq %vZHHBylu op.parent = parID d(V4;8a0 AddOperation eID, op | Z7j
s" Print "Set aqueous humor thickness = " & taq-0.55 j[\:#/J U<sGj~"# '************************************************************************* &0bq3JGW 'Radius and conic constant of anterior lens J;wBS w%1 '************************************************************************* tw
zV-8\ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) YCb|eS^u GetConic eID, entity, curv, conic w[3a^ Btzes. SetConic eID, entity, 1/Rant, CCant ZD|F"v. Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant (*6 .-Xn z>,tP '************************************************************************* }s'=w]m 'Radius and conic constant of posterior lens C<T6l'S{? '************************************************************************* iQ2}*:Jc$ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) M"p%CbcI] GetConic eID, entity, curv, conic zx]r.V C:^
:^y SetConic eID, entity, 1/Rpost, CCpost V*2*5hx Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost [$d]U. k}nGgd6XD '************************************************************************* owA8hGF 'Lens thickness (Position of posterior lens surface) $vO<v<I'Gb '************************************************************************* }m^^6h /!t:MK; parID = FindFullName( "Geometry.Arizona Eye.Lens" ) [ypE[ M,ybj5:6 ' Delete any z-shift(s) 80g}<Lwc count = 0 > vXJ9\ While GetOperationCount(eID)>count "0 %fR" GetOperation eID, count, op 9yTDuhJ6 If op.Type="ShiftZ" Then |k]]dP|:' DeleteOperation eID,count :a2[d1 count=count-1 w;Fy/XQ End If HfH_jnR* count=count+1 ^q& Rl\ Wend PcZ<JJ16F$ bw/mF5AsW 'Set new z-shift \/SOpC op.Type = "ShiftZ" Yuf+d-% op.val1 = tlens 6+ptL-Zt< op.parent = parID e2V;6N AddOperation eID, op %1#|>^ Print "Set lens thickness = " & tlens vyWx{@ 37?X@@Z= '************************************************************************* NPO!J^^ 'Lens index of refraction `.pd %\ '************************************************************************* Tyaqa0 eID = FindMaterial( "Lens" ) bYem0hzOe GetModelMaterial eID, mat )
d'H&c3 u^]Gc p mat.Nd = nlens vNdX SetModelMaterial eID, mat =Xid"$ Print "Set lens index of refraction = " & nlens 9+<A7PM1T eS4t0`kP '************************************************************************* rbv 'Pupil diameter ~Hg*vCd ? '************************************************************************* :wRfk*Ly eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) )`Qr=DIsW 99'c\[fd' 'Adjust pupil diameter (trimming volume inner hole) Ywt9^M|z; doX`NbA SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" GeB-4img _*sd# ' Adjust pupil location to just in front of the lens yD!GgnW parID = FindFullName( "Geometry.Arizona Eye" ) vg X7B4 eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) W:w SM* count = 0 E;4d lL`* While GetOperationCount(eID)>count 6kR3[]:16v GetOperation eID, count, op \f Kn} ]kG If op.Type="ShiftZ" Then wpQp1){%Q DeleteOperation eID,count x+'Ea.^ count=count-1 4XiQ8"C End If 9|@5eN:N count=count+1 C~.\2D`zy Wend $5\sV4 8f op.Type = "ShiftZ" oL>o*/ op.val1 = taq-0.01 2p 7;v7)y op.parent = parID 7rGp^ AddOperation eID, op 4wEkxCWp/ 2t?>0)*m Print "Set pupil diameter = " & pupilDiam apM)$ :]8A;`G} 'Update AZ Eye subassembly Description *N{k#d/ eID = FindFullName( "Geometry.Arizona Eye" ) cL#zE GetEntity eID, entity QiVKaBS8 entity.Description = "Accommodation = " & A & "D" `8\"3S SetEntity eID, entity ) R5[aO UIIsgNca Update LKZ<\%
X Print "DONE!" kxA T wF6a*b@v End Sub KNP^k$=)3c *U8,Q]gS 如果屈光度是4,光瞳直径是4,则会输出如下数据: { VM^K1 +zo\#8*0MF Accommodation = 4 Diopters Gcxz$.( Pupil Diameter = 4 mm -Fop<q\b Set aqueous humor thickness = 2.81 W5Jb5 Set anterior lens radius = 10.4 and conic constant = -2.375869 $|!3ks Set posterior lens radius = -4.424557 and conic constant = -3.081019 6Rg>h Set lens thickness = 3.927 .K#'
Fec Set lens index of refraction = 1.42672 "18cD5-# Set pupil diameter = 4 CA$|3m9)NM DONE! EQHCw<e 2`FDY3n (文章来源:讯技光电)
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