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简介 K j6@= g]PC6xr38 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。 nzl3<Ar 4=ZN4=(_[ 模型 N3&n"w _d S*(ns<L 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。 uE&2M>2 RsnFjfb' Table 1. AZ眼睛模型的定义 D)J'xG_<O 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. U>a~V"5,u FK,Jk04on 光源 3bR 6Y[ dk@iAL*v 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。 D*q:XO6b xj.)iegQ f4+}k GJN 图1. 光源和提示信息使用 1*]@1DJt 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。 V w5@)l*f .!Q?TSQ+{! 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。 `E5vO1Pl FSyeDC^@ 图2. 字母F光源的设定方法光 Wf9K+my v$EgVcK 图3. 字母F在视网膜上位置点列图 W4rh7e4 视网膜的散射 DTM
xfQdk 0r ilg 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 ziG]BZ RRJN@|" =d1i<iw?- 图4. 视网膜朗伯散射设定 ZN-5W|' O 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 =d1R9O (0QYX[(r~o 'H)l~L 图5. 视网膜重点采样规格设定
%( o[Hsl 脚本 a+p_47 xa q-nM]Gm 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: 4e9'yi =y1/V'2E 图6. 用户对话框的创建与编辑 Y)9]I6n7 图7. 用户对话框编辑器 `yWWX.` 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 5:
O,-b& 余下的脚本计算与屈光度有关的所有参数。
-TKQfd ^]1M8R, 分析 =]hPX ]x`I@vSf7R 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 zoO9N oUHW h2fTG 图7. 字母F在视网膜上颜色分析 uY*|bD`6& 脚本代码 N!#TK9 /b~|(g31" Option Explicit 'Remove this to enable non-dimensioned variables to be used. 9lCZi? 1F58 2 l Dim entity As T_ENTITY eXsFPM Dim op As T_OPERATION *<T,Fyc| Dim mat As T_MODELMATERIAL F/zbb Dim A As Double qaN%&K9F8 Dim pupilDiam As Double } l4d/I Dim eID As Long 4.0JgX Dim parID As Long >aV
Q Dim count As Integer @&E{
L Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double X4}Lg2ts Dim tlens As Double, nlens As Double OBJk\j+Wi Dim curv As Double, conic As Double LG3:V'| Dim ok As Long =_Y#uE$ \IG"Te Sub Main Dt p\T|) *C n `pfO '用户输入对话框 kqie|_y Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 pX/,s#dY> TextBox 220,21,40,21,.TextBox1 'default: 0 SUQk0 (M Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 *1fZcw'C. OKButton 40,91,90,21 qX?k]m CancelButton 190,91,90,21 v3{[rK} Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Z )f\^ TextBox 220,49,40,21,.TextBox2 'default: 4 fb||q-E End Dialog TWFi.w4pY Dim dlg As UserDialog V=|X=:fuih 4)=\5wJDg1 ok = Dialog (dlg) :6Oh ?y@ 7ZVW7%,zF If ok=0 Then 'cancel button was pressed =7WE Print "Execution cancelled." (`pd> End qf2;yRc& End If (1my9k5C nQW`X=Ku 'Assign accommodation and pupil diameter & use defaults if field left empty j*aYh^ If dlg.TextBox1 = "" Then A&~<qgBTp A = 0 'Default accommodation 7iJ=~po:o Else NFQR A = CDbl(dlg.TextBox1) \x_fP;ma=_ End If *l-(tp5 ve|`I=?2 If dlg.TextBox2 = "" Then yIdM2#`u pupilDiam = 4 'Default pupil diameter ihrl!A5 Else ix=H=U]Q{ pupilDiam = CDbl(dlg.TextBox2) I3ZbHb-)_, End If 4vk^= #n_uELE Print " " =<M7t*! Print "Accommodation = " & A & " Diopters" mjd9]HgN Print "Pupil Diameter = " & pupilDiam & " mm" -bHfo%"^TT K&WNtk3hT ' Calculate new parameters with accommodation q3s
+?& taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness m8|&z{ #iot.alNA Rant = 12.0 - 0.4*A 'Radius of anterior lens A%G
\
AT CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens *\i<+~I@l _\P9~w
` Rpost = -5.224557 + 0.2*A 'Radius of posterior lens p2UZqq2 CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens |H)WJ/` P|S'MS';: tlens = 3.767 + 0.04*A 'Lens thickness x>@+lV'O v<`1z?dch nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction /_rg*y* esM<. 'Adjust parameters to account for accommodation i*JbFukG /!*gH1s '************************************************************************* [We(0wF[` 'Aqueous thickness (Position of Lens) ;b""N, '************************************************************************* =m4_8)-8u eID = FindFullName( "Geometry.Arizona Eye.Lens" ) `2Buf8|a, GetCustomElement eID, entity N2"4dVV; @42!\1YT parID = FindFullName( "Geometry.Arizona Eye" ) QcQ:hHF %`c?cB ' Delete any shift(s) in z J@{yWgLg count = 0 q1nGj While GetOperationCount(eID)>count ,'CDKzY GetOperation eID, count, op bm{L6D E If op.Type="ShiftZ" Then {GS7J DeleteOperation eID,count uxq!kF'Ls count=count-1 =%:mZ@x' End If .>-`2B*/ count=count+1 a/.O,&3
Wend ms8PFu(f NC 0H5 'Set new shift in NC;4 op.Type = "ShiftZ" %NbhR( op.val1 = taq ^ftZ{uA op.parent = parID iz`u@QKc% AddOperation eID, op a$c7d~p$I Print "Set aqueous humor thickness = " & taq-0.55 i6[,m*q~2x LDL#*g '************************************************************************* ba?]eK 'Radius and conic constant of anterior lens m6bI<C3^5 '************************************************************************* 6 m5 \f eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) <!\J([NM8 GetConic eID, entity, curv, conic j.GpJDq c7jft|4S SetConic eID, entity, 1/Rant, CCant -v9V/LJ Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant '|e5 cW6z &Jj^)GBU '************************************************************************* x C'>W"pY 'Radius and conic constant of posterior lens {Ex0mw)T '************************************************************************* |52VHW8c eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) HFwT
GetConic eID, entity, curv, conic g eaeOERc AM}-dKei| SetConic eID, entity, 1/Rpost, CCpost |WeLmy%9 Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost Gb%PBg}HH @ :i>q$aF '************************************************************************* uU`zbh}]L. 'Lens thickness (Position of posterior lens surface) :L9\`&}FS '************************************************************************* u>(s.4]+ J#CF S G parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8zz-jkR d}b#"A ' Delete any z-shift(s) |pr~Ohz count = 0 +MOUO$;fGt While GetOperationCount(eID)>count 8oY0?|_Bx GetOperation eID, count, op tkWWR%c" If op.Type="ShiftZ" Then Y3[< DeleteOperation eID,count +D1;_DU count=count-1 MC3XGnT#5 End If !.iA^D//] count=count+1 mxjY-Kq Wend n$}c+1
94W9P't 'Set new z-shift SsafRK$ op.Type = "ShiftZ" p`{9kH1m e op.val1 = tlens kaUH#;c>_ op.parent = parID THK)G2
= AddOperation eID, op FFH-Kw, Print "Set lens thickness = " & tlens }?>30+42: e)\s0# '*************************************************************************
4MRHz{`wa 'Lens index of refraction %Q}#x '************************************************************************* eUqsvF}l! eID = FindMaterial( "Lens" ) z;'"c3qG8 GetModelMaterial eID, mat qX:54$t Oa7`Y`6 mat.Nd = nlens k$o6~u 2& SetModelMaterial eID, mat w0moC9#$? Print "Set lens index of refraction = " & nlens k`.-PU -CY?~WL& '************************************************************************* " I`<s < 'Pupil diameter vyqlP;K '************************************************************************* ImklM7A eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) )R{4"&&2 J_U1eSz<j 'Adjust pupil diameter (trimming volume inner hole) {Ca#{LeLk K*;=^PY SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 1NN99^q ^5u} ' Adjust pupil location to just in front of the lens _V6;`{$WK parID = FindFullName( "Geometry.Arizona Eye" ) ^b;.zhp8;N eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 62%.ddM4 count = 0 &hd+x5 While GetOperationCount(eID)>count 2#6yO`?uo GetOperation eID, count, op ;{BELv-4 If op.Type="ShiftZ" Then 4<Bj;1*4 DeleteOperation eID,count QS_"fsyN: count=count-1 ^N`ar9Db End If ZxbWgM5rm count=count+1 O,9KhX+ Wend wC <!,tB(8 op.Type = "ShiftZ" uGc}^a2 op.val1 = taq-0.01 SMqJMirR op.parent = parID kP6g0,\|a| AddOperation eID, op Jh M.P9 Gnj|y?' Print "Set pupil diameter = " & pupilDiam @(Ou;Uy
5 ah]E 'Update AZ Eye subassembly Description *"O7ml] eID = FindFullName( "Geometry.Arizona Eye" ) RjSVa.x GetEntity eID, entity |CY.Y, entity.Description = "Accommodation = " & A & "D" 5"^$3&) SetEntity eID, entity _hA p@?
M `dn|nI2 Update J L`n12$m Print "DONE!" hM/|k0YV h+CTi6-p End Sub LJfd{R1y+ y&-j NOKLM 如果屈光度是4,光瞳直径是4,则会输出如下数据: #s)6u?N /u*((AJ?Qv Accommodation = 4 Diopters O|?>rK Pupil Diameter = 4 mm 5Ee%!Pk Set aqueous humor thickness = 2.81 e6QUe.S Set anterior lens radius = 10.4 and conic constant = -2.375869 @lDoMm,m' Set posterior lens radius = -4.424557 and conic constant = -3.081019 P8).Qn Set lens thickness = 3.927 Ngi$y>{Sq Set lens index of refraction = 1.42672 DE^{8YX, Set pupil diameter = 4 3iR;(l} DONE! 6i(nyA
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