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简介 8\B]! 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。 m)Sdogt_ Dwuao`~Xm 模型 =dDr:Y<@* A#KfG1K> 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。 6&s"
"J)3 #d;/Me Table 1. AZ眼睛模型的定义 cPbAR' 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. QP:|D_k "1|\V.>>; 光源 %E*Q0/ tv'=xDCp 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 e+T[
GW\66$| z6x`O-\ 图1. 光源和提示信息使用 ;\(X;kQi 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。 <tT.m[q g L5 Q^cY]p 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。 +
[~)a4# ~Y 3X* 图2. 字母F光源的设定方法光 /wT<p GvI8W)d3,R 图3. 字母F在视网膜上位置点列图 45.Vr[FS. 视网膜的散射 Df5!z \dx v$~$_K 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<c&;* .)Zs:50l z=yE- I{ 图4. 视网膜朗伯散射设定 "X,*VQl: 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。 B!1Bg9D _bn
"c@s gAr=fq-| 图5. 视网膜重点采样规格设定 EFn[[<&><t 脚本 P"%f8C~r o1Nfn'!3/> 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: J>8kJCh9g %WlTx&jSgE 图6. 用户对话框的创建与编辑 `lA_knS 图7. 用户对话框编辑器 l!mx,O` 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。 _"[Ls?tRX 余下的脚本计算与屈光度有关的所有参数。 $Ts;o wDDNB1_E 分析 i "d&U7Q $8WWN} OC 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 #\Zr$?t|V DIw9ov>k 图7. 字母F在视网膜上颜色分析 _F},Wp:Oh 脚本代码 6u>]-K5 DM,)nh6' Option Explicit 'Remove this to enable non-dimensioned variables to be used. Y.kgJ #2 JFFluL=- Dim entity As T_ENTITY Zm*q V! Dim op As T_OPERATION V{UY_
e8W Dim mat As T_MODELMATERIAL 'P)c'uqd# Dim A As Double pp@O6 Dim pupilDiam As Double ksf6O$ Dim eID As Long `j8pgnY>5~ Dim parID As Long Ey=ymf.} Dim count As Integer IG&twJR Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Q^bYx (r5w Dim tlens As Double, nlens As Double -2'1KAk-W Dim curv As Double, conic As Double iDWM-Ytx Dim ok As Long $plqk^P %,(X R` Sub Main ow{J;vFy\ 0Wj,=9q '用户输入对话框 2Z>8ROv^X Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 _L+j6N.h1 TextBox 220,21,40,21,.TextBox1 'default: 0 zx5#eMD Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 (67byO{ OKButton 40,91,90,21 X;n09 L`CB CancelButton 190,91,90,21 +)LCYDRV7 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 09qfnQG TextBox 220,49,40,21,.TextBox2 'default: 4 BA[ uO3\4 End Dialog &\%\"Zh Dim dlg As UserDialog IhRdn1& 6-z(34&N ok = Dialog (dlg) )-0+O=v 0SQrz$y If ok=0 Then 'cancel button was pressed udXzsY9Ng Print "Execution cancelled." '{-Ic?F<P End <4n"LJ9 End If zz!jt
A e_"m\e#N 'Assign accommodation and pupil diameter & use defaults if field left empty QQHQ3\ If dlg.TextBox1 = "" Then 5|cRHM# A = 0 'Default accommodation _xmQGX!| Else sY4q$Fq A = CDbl(dlg.TextBox1) N<ux4tz End If ?GlXxx=eV r.lHlHl If dlg.TextBox2 = "" Then Xmi~fie pupilDiam = 4 'Default pupil diameter Zl>dBc% Else Np i)R) pupilDiam = CDbl(dlg.TextBox2) *nYg-) End If 3-&~jm~" zk"8mTg Print " " RL$%Vy0 Print "Accommodation = " & A & " Diopters" D(OJr5Gg Print "Pupil Diameter = " & pupilDiam & " mm" ~>N63I6 I\x9xJ4x ' Calculate new parameters with accommodation ,`02fMOLc taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness +xvn n ALV(fv$cD Rant = 12.0 - 0.4*A 'Radius of anterior lens 3H0B+F2XQ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens no W]E}nN T:@7EL Rpost = -5.224557 + 0.2*A 'Radius of posterior lens QM*
T?PR CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens "}wO<O6[ ,<Z,- 0S tlens = 3.767 + 0.04*A 'Lens thickness M9""(`U hO&_VCk nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction CmV &+C$V% G |[{\ 'Adjust parameters to account for accommodation ]Vmo> )$1>6C\ '************************************************************************* &q@brX<,= 'Aqueous thickness (Position of Lens) k}p8"'O '************************************************************************* IxS%V31 eID = FindFullName( "Geometry.Arizona Eye.Lens" ) H%X F~tF: GetCustomElement eID, entity Fe4>G8uuwn i/skU9 parID = FindFullName( "Geometry.Arizona Eye" ) Ix}6%2\ 1]eRragm" ' Delete any shift(s) in z N'WC!K.e count = 0 vg5_@7 While GetOperationCount(eID)>count RgA"`p7{ GetOperation eID, count, op [61*/=gWe If op.Type="ShiftZ" Then "TJ*mN.i{} DeleteOperation eID,count g&85L$
count=count-1 ~D>pu%F End If bc4 V& count=count+1 KbtV> Wend W7
dSx as|w} $ 'Set new shift in D[ #V op.Type = "ShiftZ" M:{Aq&. op.val1 = taq ];4!0\M op.parent = parID |oke)w=gn AddOperation eID, op as!a!1 Print "Set aqueous humor thickness = " & taq-0.55 w3ni@'X8 KMz!4N '************************************************************************* BkGExz 'Radius and conic constant of anterior lens pm ,xGo2 '************************************************************************* #MlpOk*G eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) P3: t
4^ GetConic eID, entity, curv, conic y:}qoT_. XWnP(C9? SetConic eID, entity, 1/Rant, CCant (Jw_2pHxr" Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant |:&6eDlR 1*Pxndt& '************************************************************************* j&oRj6;Ha+ 'Radius and conic constant of posterior lens 4minzrKM\ '************************************************************************* Xs2 jR14` eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 0Zi+x#&d GetConic eID, entity, curv, conic T" W<l4i- t+iHsCG)> SetConic eID, entity, 1/Rpost, CCpost 1QG q;6\ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 5C9b*]-# =I546($ '************************************************************************* kuy?n-1g 'Lens thickness (Position of posterior lens surface) B(++*#T!^m '************************************************************************* ZQ_6I}i") T5."3i parID = FindFullName( "Geometry.Arizona Eye.Lens" ) L|T?,^ R-S<7Q3E0= ' Delete any z-shift(s) p8_^6wfg count = 0 0H}tb}4 While GetOperationCount(eID)>count z6C(?R GetOperation eID, count, op =+Fb\HvX{ If op.Type="ShiftZ" Then o+A1-&qhN DeleteOperation eID,count kFWwz^x count=count-1 $TXxhd 6 End If #BUq;5 count=count+1 *uhQP47B Wend 0X5cn 0L^ **Ioy+ 'Set new z-shift b4e~Z op.Type = "ShiftZ" ^w\22 Q op.val1 = tlens bGH#s {'5 op.parent = parID wW@e#: AddOperation eID, op UxTLr-db^ Print "Set lens thickness = " & tlens 7@fS2mu MO8}i?u=z '************************************************************************* BB/wL_=: 'Lens index of refraction 1@}F8&EZ '************************************************************************* hpF_@n
eID = FindMaterial( "Lens" ) h#hr'3bI1 GetModelMaterial eID, mat T+}|$/Tv mvEhP{w mat.Nd = nlens WMf /
S"= SetModelMaterial eID, mat S} m=|3%y Print "Set lens index of refraction = " & nlens tb+gCs'D J[ Gpd '************************************************************************* #:gd9os : 'Pupil diameter DWt|lO '************************************************************************* ltNCti{Q eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) JX=rL6Y@:; gT+g@\u[ 'Adjust pupil diameter (trimming volume inner hole) .n]"vpWm[ *OG<+#*\_? SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" V/ G1C^'/ Jw;~ $ ' Adjust pupil location to just in front of the lens sN[}B{+ parID = FindFullName( "Geometry.Arizona Eye" ) i<^X z eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) u?Ffqt9' count = 0 c| ^I} While GetOperationCount(eID)>count o72r `2 GetOperation eID, count, op %R c#/y If op.Type="ShiftZ" Then F}_b7|^ DeleteOperation eID,count o8g7wM]M count=count-1 \G gh 95y End If jq,M1 count=count+1 %} `` : Wend I@cw=_EQL op.Type = "ShiftZ" !/XNp QP op.val1 = taq-0.01 w.?4}'DK op.parent = parID }
{1IB AddOperation eID, op PEf yHf7` w \b+OW Print "Set pupil diameter = " & pupilDiam M}\h?s O+}py{ st 'Update AZ Eye subassembly Description F06o-xH= eID = FindFullName( "Geometry.Arizona Eye" ) d+q],\"R GetEntity eID, entity _re# b? entity.Description = "Accommodation = " & A & "D" +F8{4^w1 SetEntity eID, entity oP`l)` BPO5=]W 7 Update Tx;a2:6\[ Print "DONE!" b)d;eS fN&\8SPE End Sub E!9WZY %bi ie 如果屈光度是4,光瞳直径是4,则会输出如下数据: -l= 4{^pK %~!4DXrMk Accommodation = 4 Diopters fqgp{(`@> Pupil Diameter = 4 mm MGR:IOTa Set aqueous humor thickness = 2.81 >WSh)(Cg Set anterior lens radius = 10.4 and conic constant = -2.375869 ;qWu8\T+ Set posterior lens radius = -4.424557 and conic constant = -3.081019 ~[ufL25K Set lens thickness = 3.927 |R}=HsYey Set lens index of refraction = 1.42672 cpdESc9W Set pupil diameter = 4 pm6#azQ DONE! Tv=lr6t8 \Bo%2O%4 (文章来源:讯技光电)
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