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简介 ]vyu! 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。 >y2;sJ4]D% qfO=_z ES 模型 GwOn&EpY! %TY;}V59 b 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。 2 kOFyD
r((2.,\Z Table 1. AZ眼睛模型的定义 6I$laHx? 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. +h64idM{U V)$y 光源 _f~(g1sE $`2rtF 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 +<G |Ru- -+'fn$ 19Cs
3B \4 图1. 光源和提示信息使用 S~dD ;R 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。 ){AtV&{$ x>>#<hOz[ 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。 6@7K\${ Quc,,#u 图2. 字母F光源的设定方法光 Z~g I ) b7
pD#v 图3. 字母F在视网膜上位置点列图 5E~?hWAv 视网膜的散射 dQ6n[$Q@N Qy)+YhE 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 (xp<@- xiu?BP?V ")/TbTVu 图4. 视网膜朗伯散射设定 E<[_L!2 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 *]ROUk@K= _RLx;Tn)L >^1|Mg/!> 图5. 视网膜重点采样规格设定 1g_(xwUp+ 脚本 O/X;(qYd
y$n7'W6 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: p!+7F\ ISQC{K']J 图6. 用户对话框的创建与编辑 H-?wEMi)*u 图7. 用户对话框编辑器 ]!u12^A{ 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。 hK!Z~
余下的脚本计算与屈光度有关的所有参数。 4?#0fK _(CuuP$`I 分析 2?",2x09 pK)*{fC$` 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 *WSH-*0 p*11aaIbp~ 图7. 字母F在视网膜上颜色分析 :NB,Dz+i 脚本代码 r52X}Y u/Os Option Explicit 'Remove this to enable non-dimensioned variables to be used. UbBo#(TZ) Hpo/CY/ Dim entity As T_ENTITY ]dXHjOpA Dim op As T_OPERATION omxBd#;F$ Dim mat As T_MODELMATERIAL A),nkw0X Dim A As Double 2<dl23 Dim pupilDiam As Double S(7_\8h Dim eID As Long -29Sw Dim parID As Long .YvE Dim count As Integer -Jo8jE~>V Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double jzuOs,:R Dim tlens As Double, nlens As Double CgLS2 Dim curv As Double, conic As Double V:M$-6jv Dim ok As Long #z|\AmZ\ 5z ebH Sub Main 3xhv~be sGNVZx '用户输入对话框 :!omog Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ; Q-f6)+& TextBox 220,21,40,21,.TextBox1 'default: 0 )P6n,\ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 o<`)cb } OKButton 40,91,90,21 HaP0;9q CancelButton 190,91,90,21 fV-vy]x.. Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 DRldRm/ TextBox 220,49,40,21,.TextBox2 'default: 4 RB5fn+FiZ End Dialog Evz;eobW/ Dim dlg As UserDialog 4<S*g u*W "K EB0U ok = Dialog (dlg) 'qTMY* fvajNP If ok=0 Then 'cancel button was pressed Oeo:V" Print "Execution cancelled." )"
H$1 End <1(:W[M End If Zk+J= Cwq} ILt95l 'Assign accommodation and pupil diameter & use defaults if field left empty
c#qOK If dlg.TextBox1 = "" Then x4SI TY A = 0 'Default accommodation *}9i@DP1, Else yVThbL_YJ A = CDbl(dlg.TextBox1) RjO9E.nm End If P) fv:a a8T<f/qW k If dlg.TextBox2 = "" Then '1)BZ!
pupilDiam = 4 'Default pupil diameter &"dT/5}6 Else
Bp3%*va pupilDiam = CDbl(dlg.TextBox2) *_<P%J End If ^(ks^<} !GkwbHr+p Print " " RUTlwTdv Print "Accommodation = " & A & " Diopters" G"CV
S@ Print "Pupil Diameter = " & pupilDiam & " mm" B;'Dh<J1 0\tk/<w2 ' Calculate new parameters with accommodation {mPaloA taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness P5;LM9W W~GbB:- Rant = 12.0 - 0.4*A 'Radius of anterior lens q #f
U* CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens p*10u@, V/Hjd`n)`i Rpost = -5.224557 + 0.2*A 'Radius of posterior lens ,jWMJ0X/N= CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens T ,,
Ao36 [@ ]f@Wd tlens = 3.767 + 0.04*A 'Lens thickness 73/kyu-0% D_GIj$%N[ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction qvz2u]IOw 7%Zl^c>q 'Adjust parameters to account for accommodation q!#e2Dx kBY54pl '************************************************************************* ScrE tN 'Aqueous thickness (Position of Lens) !Gu,X'#Ab '************************************************************************* V\zf yH\~ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) `"v5bk GetCustomElement eID, entity SCl$+9E v*%#Fp,g8 parID = FindFullName( "Geometry.Arizona Eye" ) %dTkw+J ~je#gVoUR ' Delete any shift(s) in z >=hOjV; count = 0 )SZt If While GetOperationCount(eID)>count i<|5~tm GetOperation eID, count, op QRj><TKi If op.Type="ShiftZ" Then ReOp,A/y DeleteOperation eID,count "}UJ~ j). count=count-1 \^iPU 27H End If 27*u^N*z@ count=count+1 *>!O2c Wend <@FOqi{o{ O=}4?Xv 'Set new shift in g(t"+
P op.Type = "ShiftZ" Zam.g>{] op.val1 = taq BP2-LG&\ op.parent = parID IM&2SSmYNH AddOperation eID, op E"5
zT1d Print "Set aqueous humor thickness = " & taq-0.55 U@+
@Mc &^e%gU8!\ '************************************************************************* gB@Xi* 'Radius and conic constant of anterior lens ~<Z;)e '************************************************************************* {S(d5o8 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 6k;__@B, GetConic eID, entity, curv, conic 6_/691 >*H>'O4 SetConic eID, entity, 1/Rant, CCant fk)ts,p? Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant I%^Ks$<" W R@=[G#TJ '************************************************************************* LtKiJ.j?A 'Radius and conic constant of posterior lens W
HO;;j '************************************************************************* {J q[N} eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) vlth\[ GetConic eID, entity, curv, conic DGr{x}Kq 3o%,8l, SetConic eID, entity, 1/Rpost, CCpost iph>"b$D Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost an^"_#8DA@ GHeJpS '************************************************************************* /*g3TbUs 'Lens thickness (Position of posterior lens surface) `O(ec '************************************************************************* O{a<f7 W / <WB%O parID = FindFullName( "Geometry.Arizona Eye.Lens" ) <b>@'\w9 8<M'~G%CEq ' Delete any z-shift(s) . $uvQpyh count = 0 LAeJz_9U While GetOperationCount(eID)>count AEx
I! GetOperation eID, count, op }$3eRu + If op.Type="ShiftZ" Then q}e"E
cr DeleteOperation eID,count aO('X3? count=count-1 BL<.u End If fv_}7t7 count=count+1 pkpD1c^ Wend V%'`nJ! !Uz{dFJf; 'Set new z-shift | 2BIAm] op.Type = "ShiftZ" W-q2|NK op.val1 = tlens
RvKP& op.parent = parID "l!WO`.zp= AddOperation eID, op .GUm3b Print "Set lens thickness = " & tlens BJ!b LQ y:(OZ%g '************************************************************************* l CHaRR7 'Lens index of refraction SA&0f&07i '************************************************************************* /e :V44 eID = FindMaterial( "Lens" ) A<l8CWv[ GetModelMaterial eID, mat Jm$.$B&I YO7Y1(` mat.Nd = nlens )z-)S SetModelMaterial eID, mat 0xrr9X< Print "Set lens index of refraction = " & nlens zbK=yOIOd k\$))<3 '************************************************************************* u- PAi5&n 'Pupil diameter R>SS\YC'X '************************************************************************* \Zz"%i eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) z+I'N4*^ t!QuM_i3 'Adjust pupil diameter (trimming volume inner hole) _O)xE9t#ru }&D~P>1 SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" C,7d O=UXe]D ' Adjust pupil location to just in front of the lens _@9[c9bO parID = FindFullName( "Geometry.Arizona Eye" ) WZO8|hY eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) `v3WJ>Q!N? count = 0 ifj%!* While GetOperationCount(eID)>count r!SMF]?SJ GetOperation eID, count, op iSu7K&X9q If op.Type="ShiftZ" Then x8k7y: DeleteOperation eID,count i'9aQi"G count=count-1 7S$Am84% End If xY9#ouF count=count+1 |N_tVE Wend 2g5i3C.q$ op.Type = "ShiftZ" |57u ; op.val1 = taq-0.01 +\g/KbV7 op.parent = parID 0Jz H dz AddOperation eID, op %@
UH,Ew Q ^X Print "Set pupil diameter = " & pupilDiam ap=m5h27 G2
A#&86J{ 'Update AZ Eye subassembly Description
0$)s? \ eID = FindFullName( "Geometry.Arizona Eye" ) FsQeyh> GetEntity eID, entity .j?`U[V%a entity.Description = "Accommodation = " & A & "D" 873$EiyXR SetEntity eID, entity O
]o7 nZZNx
Update !/]F.0 Print "DONE!" :T^!<W4 U-Ia$b-5! End Sub -^sW{s0Rc X[/>{rK 如果屈光度是4,光瞳直径是4,则会输出如下数据: rk$&sDc/3 3FRz&FS:j Accommodation = 4 Diopters "fK`F/ Pupil Diameter = 4 mm {gh41G;n Set aqueous humor thickness = 2.81 Z9X<W` Set anterior lens radius = 10.4 and conic constant = -2.375869 aT}Mn(F*? Set posterior lens radius = -4.424557 and conic constant = -3.081019 I5]=\k($ Set lens thickness = 3.927 ldp
x, Set lens index of refraction = 1.42672 S(NH# ^ Set pupil diameter = 4 +8qtFog$\g DONE! ^b|Z<oF yg({g
" (文章来源:讯技光电)
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