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简介 ?3nR fKeT,U`W 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。 9{RB{<Se!
3L<wQ( 模型 1;C+$ G/b^|;41 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。 ~D<IB#C A0o-:n Fu Table 1. AZ眼睛模型的定义 [<2<Y 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. s%qF/70' !Y$h"<M 光源 iL7DRQ1 w$+&3t 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。 4 8:>NW `7[EKOJ3g ,=UK}*e" 图1. 光源和提示信息使用 gbI^2=YT' 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。 D>HOn^ tmv&U;0Z 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。 mtJ9nC N/Z2hn/m 图2. 字母F光源的设定方法光 :Pvzl1 \?Z{hmN 图3. 字母F在视网膜上位置点列图 ?j40}
B]]d 视网膜的散射 .LZwuJ^; 0O9Ni='Tn 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。 GR
+[UG -7*ET3NSI/ {t0)
q 图4. 视网膜朗伯散射设定 1M}5>V{ 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。 d@ i}-; ZX>AE3wk }@;ep&b* 图5. 视网膜重点采样规格设定 'JCZ]pZ 脚本 xC{qV, :ctu5{"UJ 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: U@HK+C"M| )we}6sE" 图6. 用户对话框的创建与编辑 Q?nN!eT 图7. 用户对话框编辑器 ->l%TCHP 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。 ePr&!Tz# 余下的脚本计算与屈光度有关的所有参数。 {l>yi N"" BCh" 分析 CS@FYO -&3hEv5 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 mzeY%A<0^ YpH&<$x: 图7. 字母F在视网膜上颜色分析 /JHc! D 脚本代码 X' d9[). "Q!(52_@J Option Explicit 'Remove this to enable non-dimensioned variables to be used. qyF{f8pzq :[O
8 Dim entity As T_ENTITY 6kNrYom Dim op As T_OPERATION S<VSn}vn Dim mat As T_MODELMATERIAL 3on7~*
Dim A As Double iH/6M Dim pupilDiam As Double `+o2DA)#( Dim eID As Long LS7, a| Dim parID As Long pm_`>3 Dim count As Integer `Gn50-@ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Ove<mFI\ Dim tlens As Double, nlens As Double g+pml*LJ Dim curv As Double, conic As Double (Dw,DY9 Dim ok As Long Y"~gw~7OD G&i!Hs Sub Main 8zRP(+&W qAn! Rk A '用户输入对话框 #~7ip\Uf[ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 0s/w,? TextBox 220,21,40,21,.TextBox1 'default: 0 >4#)r8;dx Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 *~t6(v? OKButton 40,91,90,21 OR%'K2C6S CancelButton 190,91,90,21 F<qz[,]|-j Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 t=Xv;=daB TextBox 220,49,40,21,.TextBox2 'default: 4 ~\Hc,5G End Dialog l:j4Ft 8 Dim dlg As UserDialog M_"L9^^>N VFRi1\G ok = Dialog (dlg) IFF92VD& q(`/Vo4g( If ok=0 Then 'cancel button was pressed P(+&OoY2 Print "Execution cancelled." 2w["aVr
= End 3~uW I%I` End If %p2Sh)@M XZ^^%*ew 'Assign accommodation and pupil diameter & use defaults if field left empty "uaMk}[ <! If dlg.TextBox1 = "" Then ]j`c]2EuP A = 0 'Default accommodation p-Kz-+A [ Else L<ue$' A = CDbl(dlg.TextBox1) wE? 'Cl End If GBRa.;Kk j!U-'zJ If dlg.TextBox2 = "" Then [co% :xJu pupilDiam = 4 'Default pupil diameter U56G. Else - `p4-J!Fy pupilDiam = CDbl(dlg.TextBox2) H@%GSE End If 0:9.;x9_ (oEC6F Print " " m 8aITd8 Print "Accommodation = " & A & " Diopters" 2QJ{a46} Print "Pupil Diameter = " & pupilDiam & " mm" v":x4!kdX 9s6U}a'c ' Calculate new parameters with accommodation Urr@a/7 taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness YVHm{A1b0 ?u "
4@ Rant = 12.0 - 0.4*A 'Radius of anterior lens 6YGubH7%_ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens 9}PhN<Gd %M7` Hwu Rpost = -5.224557 + 0.2*A 'Radius of posterior lens
TU:7Df CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens 8B\2Zfe u~WVGjoQ tlens = 3.767 + 0.04*A 'Lens thickness X voo= p<,*3huj nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction g^}8:,F_ mi,E- 'Adjust parameters to account for accommodation L"o>wYx q|!-0B@ '************************************************************************* xKuRh}^K 'Aqueous thickness (Position of Lens) ykV
5 '************************************************************************* Y]/%t{Y eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 6W]9$n\"? GetCustomElement eID, entity gcdlT7F)b- Wu[&Wv~ parID = FindFullName( "Geometry.Arizona Eye" ) =a@j= hc>HQrd ' Delete any shift(s) in z }:us:% count = 0 :h\Q;? While GetOperationCount(eID)>count H!5\v"]WB GetOperation eID, count, op w5A y)lz If op.Type="ShiftZ" Then 9~]~#Uj DeleteOperation eID,count YjxF}VI~< count=count-1 @+Si?8\ End If 4dO~C count=count+1 MvK !u Wend ]rWgSID VyzS^AHK 'Set new shift in "alyfyBu'M op.Type = "ShiftZ" '98VYCL op.val1 = taq A OISs4 op.parent = parID |iE50, AddOperation eID, op T
6)bD& Print "Set aqueous humor thickness = " & taq-0.55 1.D,W1s Tn*9lj4 '************************************************************************* iOU6V 'Radius and conic constant of anterior lens 1FlX'[vh '************************************************************************* 8ZM&(Lz7u eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) pEBM3r!X GetConic eID, entity, curv, conic E"qRw_
~t FbS|~Rp~ SetConic eID, entity, 1/Rant, CCant f&BY/ n, Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 9 7GV2]-M &O9 |#YUq '************************************************************************* 8$6Y{$&C 'Radius and conic constant of posterior lens o4m\~as)Y '************************************************************************* ^(vs.U^U< eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) OSs&r$ GetConic eID, entity, curv, conic }001K CG0
M SetConic eID, entity, 1/Rpost, CCpost g.BdlVB\ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost Si8pzd NidIVbT.A '************************************************************************* _F>CBG 'Lens thickness (Position of posterior lens surface) K@I
D/]PF '************************************************************************* "e.jZcN* p1Jh0o8 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) , w{e Fq|Ni$ ' Delete any z-shift(s) 9^oKtkoDZ count = 0 @ ;*Ksy@1O While GetOperationCount(eID)>count LAB=Vp1y3[ GetOperation eID, count, op #Y*X<L If op.Type="ShiftZ" Then {:6r;TB DeleteOperation eID,count 2oVSn" count=count-1 &J[:awQX End If 6 :b!F count=count+1 `uOT+B%R Wend 1S{D6#bE 5gYRwuf 'Set new z-shift L2\#w<d op.Type = "ShiftZ" `[f*Zv w op.val1 = tlens r[|Xy>Zj op.parent = parID A\4D79>x AddOperation eID, op
1eS&&J5 Print "Set lens thickness = " & tlens 3{'Ne}5%I >_[9t '************************************************************************* [k.t WA,& 'Lens index of refraction Q# ~Q=T'< '************************************************************************* mk.9OhYY eID = FindMaterial( "Lens" ) )
i;1*jK GetModelMaterial eID, mat u+Y\6~=+ q]T1dz? mat.Nd = nlens _Gn2o2T SetModelMaterial eID, mat Q-_N2W? Print "Set lens index of refraction = " & nlens QoI3>Oj= ^uKwB;@ '************************************************************************* $ `ov4W 'Pupil diameter C'9Cr}cZ. '************************************************************************* f.D?sH An eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 6n,i0W @5N]ZQ9 'Adjust pupil diameter (trimming volume inner hole) \y97W&AN 5eLtCsHz SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" LInz<bc<( ,]|#[ 8 ' Adjust pupil location to just in front of the lens Vc 1\i parID = FindFullName( "Geometry.Arizona Eye" ) %RTBV9LIXr eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) >" )Tf6zw& count = 0 3eb%OEMYk While GetOperationCount(eID)>count 95ZyP! GetOperation eID, count, op LhA*F[6$M If op.Type="ShiftZ" Then gZN8!#h}B DeleteOperation eID,count e%svrJ2 count=count-1 c/D+|X* End If c23oCfB> count=count+1 j_K4;k#r Wend ^]H5h ]U' op.Type = "ShiftZ" ). <-X^@ op.val1 = taq-0.01 ^X=arTE op.parent = parID B^1>PE AddOperation eID, op p)`{Sos `.E[}W Print "Set pupil diameter = " & pupilDiam BL0 {HV! t)~"4]{*}D 'Update AZ Eye subassembly Description Lf16j*}-Q eID = FindFullName( "Geometry.Arizona Eye" ) Zq^At+8+ GetEntity eID, entity *1uKr9 entity.Description = "Accommodation = " & A & "D" o)h_H; SetEntity eID, entity
CuFSeRe '.on)Zd. Update U_Vs.M.p Print "DONE!" C_(
*>!Z% / kE6@ End Sub }u\])I3 )Q=_0;#;k 如果屈光度是4,光瞳直径是4,则会输出如下数据: 6"wlg!k8 rA3$3GLQ- Accommodation = 4 Diopters YJ^]
u} Pupil Diameter = 4 mm gR&Q3jlIV Set aqueous humor thickness = 2.81 'H3^e} Set anterior lens radius = 10.4 and conic constant = -2.375869 3_ r*y9l Set posterior lens radius = -4.424557 and conic constant = -3.081019 34`'M+3 Set lens thickness = 3.927 {
d=^}-^ Set lens index of refraction = 1.42672 ^|/TC!v]M Set pupil diameter = 4 EMh7z7}Rr DONE! :G [|CPm-
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