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简介 [LS s|f :kucDQE({? 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。 Ev&aD u)l[*";S 模型 `>`{DEDx{5 5NMju!/ 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。 'WwD$e0= [V;Q#r&+ Table 1. AZ眼睛模型的定义 7gt%[r M 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. "-G&]YMl J#G\7'?{ 光源 r7v1q hy@e(k|S]U 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。 QB7^8O!< a<Ps6' 9tB:1n} 图1. 光源和提示信息使用 9bD ER 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。 kk
aS&r> I0sw/,J/Z 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。 `~LaiN. !r+SE 图2. 字母F光源的设定方法光 *w1R> s?&UFyYb, 图3. 字母F在视网膜上位置点列图 |exjrsmM* 视网膜的散射 BR0P :h -[7S. 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。 ~Yl%{1 Yd<q4VJR "C]_pWk 图4. 视网膜朗伯散射设定 S&~;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。 *l'5z)] {c=H#- A |A:+[35 图5. 视网膜重点采样规格设定 K<"Y4O#] 脚本 |z.Ov&d4)( 9jrlB0 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: !,;/JxfgVh ],Y+|uX-> 图6. 用户对话框的创建与编辑 vv`,H~M6 图7. 用户对话框编辑器 q6V\n:hKV 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。 ]q@W(\I 余下的脚本计算与屈光度有关的所有参数。 !*=+E%7 s#V:!
7 分析 YnX6U1/^ c +]5[6 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 *7!*kqg!u F0+@FS0 图7. 字母F在视网膜上颜色分析 2(NN QU@Uz 脚本代码 I$1~;!< <,(Ww Option Explicit 'Remove this to enable non-dimensioned variables to be used. WJw
%[_W 98t|G5 Dim entity As T_ENTITY AO^c=^ Dim op As T_OPERATION "z ;ky8 Dim mat As T_MODELMATERIAL Tg#%5~IX Dim A As Double =VDtZSa!$^ Dim pupilDiam As Double aZYs?b>Gm Dim eID As Long l|~SVk| Dim parID As Long |PW.CV0, Dim count As Integer di#:KW Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Ih5F\eM Dim tlens As Double, nlens As Double <}^l MBa Dim curv As Double, conic As Double YDo,9 Dim ok As Long 4Awl <!.Qn
Y Sub Main jRo4+8 e=EM07z '用户输入对话框 &io*pmUm6 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 hS:j$je TextBox 220,21,40,21,.TextBox1 'default: 0 he1W22 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 '5m`[S-IU OKButton 40,91,90,21 FQ6{NMz,h CancelButton 190,91,90,21 nV+]jQ~o Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 p+d?k"WN? TextBox 220,49,40,21,.TextBox2 'default: 4 ,[0rh%%j End Dialog )K^5+oC17 Dim dlg As UserDialog s9}V nNr X| X~|&j ok = Dialog (dlg) <MoKTP-< +b6kU{ If ok=0 Then 'cancel button was pressed 4?9cyv4H Print "Execution cancelled." :p,DAt} End 5qx$=6PT End If 5Rec~&v b py576GwA 'Assign accommodation and pupil diameter & use defaults if field left empty E0Jk=cq If dlg.TextBox1 = "" Then 2zN%Z!a#J A = 0 'Default accommodation >J
No2 Else !^<%RT9@| A = CDbl(dlg.TextBox1) "<I*ViZ End If h2]gA_T` 74q|FQ If dlg.TextBox2 = "" Then J`x!c9 zg7 pupilDiam = 4 'Default pupil diameter _f5n
t:- Else QnNddCiu= pupilDiam = CDbl(dlg.TextBox2) KF4}cM=.5 End If WF0[/Y $S _VR Print " " pJ 7="n Print "Accommodation = " & A & " Diopters" -{'WIGm Print "Pupil Diameter = " & pupilDiam & " mm" j9Y'HU5" {]CO;5: ' Calculate new parameters with accommodation b];? tP taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness T1Y_Jf*KJ woCFkO;'O Rant = 12.0 - 0.4*A 'Radius of anterior lens H]/!J] CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens P1f@?R&t+ 5L8 )w5
Rpost = -5.224557 + 0.2*A 'Radius of posterior lens A#P]|i CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens XKq}^M&gy &;O)Dw tlens = 3.767 + 0.04*A 'Lens thickness I>L@P`d #+,O nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction #XJ`/\E] IJt8*
cw 'Adjust parameters to account for accommodation nY[]k p@ 8bIwRVA2\ '************************************************************************* p:n.:GZ=y 'Aqueous thickness (Position of Lens) iCrLZ"$M '************************************************************************* %+,7=Wt- eID = FindFullName( "Geometry.Arizona Eye.Lens" ) Y +9OP GetCustomElement eID, entity dW8M^A& -h/KrB parID = FindFullName( "Geometry.Arizona Eye" ) rFPfTpS {v>orP? ' Delete any shift(s) in z hRvjiK\ count = 0 Yuo While GetOperationCount(eID)>count ADQ#qA,/ GetOperation eID, count, op Y$SwQ;wl If op.Type="ShiftZ" Then :UgCP ~Y DeleteOperation eID,count &:"[hU count=count-1 O$Z<R:vVA End If T8ftBIOi count=count+1 ]7ZY|fP2 Wend f\~OG#AaX ]VU a$$ 'Set new shift in 09psqXU@I op.Type = "ShiftZ" sC=fXCGW\p op.val1 = taq &CEZ+\bA op.parent = parID 17nONhh AddOperation eID, op mSu1/?PS Print "Set aqueous humor thickness = " & taq-0.55 lrXi*u] &>.
w* '************************************************************************* k5%:L2FO 'Radius and conic constant of anterior lens *75?%l '************************************************************************* qd7 86~ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 3:;2Av2(X. GetConic eID, entity, curv, conic >sL"HyY#H +%hA6n SetConic eID, entity, 1/Rant, CCant DfNX@gbo Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant .jfkOt?2 mz~aSbb| '************************************************************************* vQ/&iAyut 'Radius and conic constant of posterior lens -8]M
,,? '************************************************************************* `f9I#B
eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) @+3@Z?!SZ GetConic eID, entity, curv, conic LS=HX~5C )Bq~1M 2 SetConic eID, entity, 1/Rpost, CCpost I C6}s Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost `2M`;$~ 5 uNV\_'9>Y '************************************************************************* _k,/t10 'Lens thickness (Position of posterior lens surface) 3 oG5E"G '************************************************************************* l$_Yl&!q$ <opBOZ
d parID = FindFullName( "Geometry.Arizona Eye.Lens" ) g`}+K U _FET$$>z N ' Delete any z-shift(s) ;&N;6V"} count = 0 MU ;
L7^ While GetOperationCount(eID)>count `zjEs8`' GetOperation eID, count, op R0n#FL^E If op.Type="ShiftZ" Then BihXYux* DeleteOperation eID,count HW)4#nLhh count=count-1 %b
H1We End If [a&|c%h count=count+1 4EO,9#0 Wend 86s.qPB0 o0nKgq'w|x 'Set new z-shift ]&')#YO op.Type = "ShiftZ" eN/o}<(e op.val1 = tlens ~
cKmf] op.parent = parID 1?6;Oc^ AddOperation eID, op d8|bO#a%9 Print "Set lens thickness = " & tlens z4snH%q .."= '************************************************************************* , 8NY<sFh 'Lens index of refraction P+m{hn~% '************************************************************************* BnLM ;5
> eID = FindMaterial( "Lens" ) yX}riXe GetModelMaterial eID, mat 1Qi5t?{ cI9} YSk mat.Nd = nlens |G+6R-_ SetModelMaterial eID, mat e%(,)WlTaU Print "Set lens index of refraction = " & nlens M>pcG.6V V Q6&7@
c '************************************************************************* 3aL8 gE 'Pupil diameter Fu*~{n '************************************************************************* Ix;9D'^} eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 6n{`t/ jXBAo 'Adjust pupil diameter (trimming volume inner hole) #|\NG H5f>Q0jq
SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" kvzGI>H: %"2;i@ ' Adjust pupil location to just in front of the lens i )Hjmf3 parID = FindFullName( "Geometry.Arizona Eye" ) m"{D}(TA eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) JsfX&dX0 count = 0 8._
A[{.f While GetOperationCount(eID)>count GZ.Fq GetOperation eID, count, op kxJ! #%w If op.Type="ShiftZ" Then 9'tElpDJ6# DeleteOperation eID,count v-;j44sB count=count-1 pXfg{2 End If .^<4] count=count+1 k^
CFu Wend W0]W[b,:u$ op.Type = "ShiftZ" b< |