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简介 y*}AX%8`e~ mr@_%U 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。 *4-r`k|@>/ r4 9UJE 模型 4Y`! bT` 2IKxh 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。 +xn&K"]:3 Jz=;mrW Table 1. AZ眼睛模型的定义 Y=5!QLV4 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. 3?.6K0L h~,x7]w6 光源 =ZCH1J5" tU9rCL:P 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。 ?nB helW^ P=f<#l"v dK:l&R 图1. 光源和提示信息使用 pZc9q8j3 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。 WA<H +F1]M2p] 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。 0\V\qAk eA~J4k_ 图2. 字母F光源的设定方法光 }UyzMy, &W&7bZ$; 图3. 字母F在视网膜上位置点列图 yfPCGCOW? 视网膜的散射 4aj[5fhb- 2v"wWap-+ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 r$b:1 C~ O4lxeiRgC F6RyOUma 图4. 视网膜朗伯散射设定 ~Y1"k]J 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。 tfi2y]{A wlm3~B\64 j)6@q@P/ 图5. 视网膜重点采样规格设定 Q.j-C}a 脚本 V_NjkyI wk-Mu\ 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: h-z%C6 ^AovkK(p 图6. 用户对话框的创建与编辑 ;yRwoTc)Y 图7. 用户对话框编辑器 $-C6pZN(X 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 (1j(*
?2 余下的脚本计算与屈光度有关的所有参数。 ;s}-X_O< d/0/$Bz}P 分析 pKOT Qf C! aX45eg 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 FiV^n6-F` qg_>`Bv"a 图7. 字母F在视网膜上颜色分析 uf{SxEa 脚本代码 Ig40#pA jD&}}:Dj Option Explicit 'Remove this to enable non-dimensioned variables to be used. Up]VU9z oN1!>S9m Dim entity As T_ENTITY "uV0Oj9: Dim op As T_OPERATION :vn0|7W4 Dim mat As T_MODELMATERIAL |YG)NO Dim A As Double w3>Y7vxiz` Dim pupilDiam As Double asm[-IB2u Dim eID As Long UiGUaB mF* Dim parID As Long htdn$kqG
Dim count As Integer -~rr<D\ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double sqq/b9 uL/ Dim tlens As Double, nlens As Double kMwIuy Dim curv As Double, conic As Double :kf3_?9rc Dim ok As Long &lXx0"-$ =$:4v`W0( Sub Main 4YU 1Kr4 F1Zk9%L%9$ '用户输入对话框 C%x(`S^/ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 dpc=yXg>"c TextBox 220,21,40,21,.TextBox1 'default: 0 ^>P@5gcoE( Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ByB0>G''. OKButton 40,91,90,21 ;X9MA=b CancelButton 190,91,90,21 oKMg7 3* Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 S`'uUvAA TextBox 220,49,40,21,.TextBox2 'default: 4 % @^VrhS End Dialog 6`$,-(J= Dim dlg As UserDialog Z3u""oM/ O*+w_fox ok = Dialog (dlg) I'6ed`|
K|Ij71 If ok=0 Then 'cancel button was pressed nvUkbmZG# Print "Execution cancelled." 8WLh]MD` End 34O+#0<y~ End If Qh1Kl_a?Lv RmCn&-i 'Assign accommodation and pupil diameter & use defaults if field left empty 7W>}7 If dlg.TextBox1 = "" Then ' /@!"IXz A = 0 'Default accommodation G`3vH, Else
=t>`<T|( A = CDbl(dlg.TextBox1) )}zA,FOA* End If $F
/p8AraK +kdU%Sm If dlg.TextBox2 = "" Then ,XF6Xsg2 pupilDiam = 4 'Default pupil diameter :67d>wb Else v#AO\zYKd pupilDiam = CDbl(dlg.TextBox2) #L1yL<' End If 5]2!Bb6> 5p>]zij> Print " " !&`7 Print "Accommodation = " & A & " Diopters" ogh2kht Print "Pupil Diameter = " & pupilDiam & " mm" \gPNHL* {&JurZ ' Calculate new parameters with accommodation ,y{fqa4 taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness @v:ILby4- D4x' Rant = 12.0 - 0.4*A 'Radius of anterior lens S)AE CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens N?u2,h- *b 7
^s,? Rpost = -5.224557 + 0.2*A 'Radius of posterior lens <?`e9o CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens S+\Mt+o f*R_\ tlens = 3.767 + 0.04*A 'Lens thickness ^!s}2GcS` |H|eH~.yg& nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction a1Y _0 \Jj'60L^ 'Adjust parameters to account for accommodation U:\oGa84A eB1eUK> '************************************************************************* I^C
]6D{ 'Aqueous thickness (Position of Lens) \2VZkVO9 '************************************************************************* !nD[hI8P eID = FindFullName( "Geometry.Arizona Eye.Lens" ) t)kr/Z*p\ GetCustomElement eID, entity EPUJa~4 6`PGV+3j parID = FindFullName( "Geometry.Arizona Eye" ) MrygEC 5 y`P7LC ' Delete any shift(s) in z fqp7a1qQl count = 0 vXWESy While GetOperationCount(eID)>count U=*q;$L# GetOperation eID, count, op (G b{ckzs If op.Type="ShiftZ" Then ^O\1v DeleteOperation eID,count l9Cy30O6 count=count-1 0i1?S6]d- End If W SeRV?+T count=count+1 b|pNc'u:Cn Wend &cv/q$W4 =GS_ G;Dz 'Set new shift in 7}HA_@[ op.Type = "ShiftZ" @RG3*3( op.val1 = taq jC }u>AB op.parent = parID WlJRKM2 AddOperation eID, op %li{VDb Print "Set aqueous humor thickness = " & taq-0.55 4xC6#:8 BqJrL/( '************************************************************************* (TK
cSVR 'Radius and conic constant of anterior lens ^rZ+H@p:6 '************************************************************************* P_}_D{G eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) \$++.%0 GetConic eID, entity, curv, conic \>CBam8d *h8XbBZH SetConic eID, entity, 1/Rant, CCant :zTj"P>"I Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ,DsT:8 &b:Zln.j '************************************************************************* m*WEge*$t 'Radius and conic constant of posterior lens <L[)P{jn?p '************************************************************************* 2FtEt+A+' eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) { l~T~3/i GetConic eID, entity, curv, conic '3,JL! [+2^n7R SetConic eID, entity, 1/Rpost, CCpost (>% Vj Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost p5 PON0dS p~y
4q4 '************************************************************************* uX!y,a/" 'Lens thickness (Position of posterior lens surface) IQ`aDo-V '************************************************************************* aQ3vG08L> wH5O>4LO parID = FindFullName( "Geometry.Arizona Eye.Lens" ) W;*vcbP 1;sAt;/W8 ' Delete any z-shift(s)
j7%%/%$o[ count = 0 IBHG1<3 While GetOperationCount(eID)>count t z>X'L GetOperation eID, count, op 'Z%aBCM If op.Type="ShiftZ" Then r/w@Dh]{_ DeleteOperation eID,count X%qR6mMfT7 count=count-1 %Y[/Ucdm End If lY8Qy2k| count=count+1 Hw3E S Wend jWjK -q@Y ziip*<a!_ 'Set new z-shift o=5uM op.Type = "ShiftZ" 2{qG op.val1 = tlens ]nGA1 S{ op.parent = parID Q^;\!$:M AddOperation eID, op f\_Q+!^ Print "Set lens thickness = " & tlens U/lra&P u+I3VK_) '************************************************************************* eJdQ7g[> 'Lens index of refraction ^OsUWhkV '************************************************************************* l"g%vS,;` eID = FindMaterial( "Lens" ) $G.|5sEk GetModelMaterial eID, mat 9%veUvY eesLTyD2_ mat.Nd = nlens yL,B\YCf8 SetModelMaterial eID, mat p5w g+K Print "Set lens index of refraction = " & nlens @Kb~!y@G En%o7^W++ '************************************************************************* FX%E7H 'Pupil diameter 3
+9|7=d '************************************************************************* a];i4lt(c eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) *38\&"s4_ X~b+LG/ 'Adjust pupil diameter (trimming volume inner hole) uU"s50m 7hE=+V8 SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" W u{nC AE~}^(G` ' Adjust pupil location to just in front of the lens ?Cl"jcQ* parID = FindFullName( "Geometry.Arizona Eye" ) msJn;(Pn eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) BE;iC.rW count = 0 wN.Jyb While GetOperationCount(eID)>count SpQ6A]M gm GetOperation eID, count, op J?DyTs3Z If op.Type="ShiftZ" Then )^3655mb DeleteOperation eID,count W{2y*yqY count=count-1 ZmF32Ir End If cE?J]5#^ count=count+1 Z0^do Wend 3_:k12%p op.Type = "ShiftZ" 81C?U5 op.val1 = taq-0.01 +[qy HTcG op.parent = parID QJ'C?hn AddOperation eID, op Cl=ExpX/O ;bmd<1 Print "Set pupil diameter = " & pupilDiam bBL"F!. 1Tkz! 'Update AZ Eye subassembly Description B 8,{jwB eID = FindFullName( "Geometry.Arizona Eye" ) )Qp?LECrt GetEntity eID, entity w=5qth7 entity.Description = "Accommodation = " & A & "D" wVX0!y6 SetEntity eID, entity h<q``hn> Gd 9B Update 1Zzw|@#>o Print "DONE!" s6IuM )x MR: {Ps&, End Sub dDn:^) ,@MPzpH 如果屈光度是4,光瞳直径是4,则会输出如下数据: sIe(;%[` U^I'X7`r Accommodation = 4 Diopters h[?28q$ Pupil Diameter = 4 mm XFYl[?`G Set aqueous humor thickness = 2.81 $cedO'] Set anterior lens radius = 10.4 and conic constant = -2.375869 S{06bLXU" Set posterior lens radius = -4.424557 and conic constant = -3.081019 1:8: yFV Set lens thickness = 3.927 HF:PF"|3 Set lens index of refraction = 1.42672 it@s(1EO# Set pupil diameter = 4 FB`HwE< DONE! f
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