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简介 M~Ttb29{ 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。 (la[KqqCO >slm$~rv 模型 q`NXJf=sc ~]C%/gEh 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。 A]0:8@k5 M<PIeKIEB Table 1. AZ眼睛模型的定义 Vr[czfROz' 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. /4\wn?f cTTW06^ 光源 j=?'4sF Kf tgOG
f 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。 PxS4,`#~ jnB~sbyA .xhK'}l[ 图1. 光源和提示信息使用 yS(}:'`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。 Sq\(pfvo 6z0@I* 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。 Vwk #qgnX =Z=o#46JY 图2. 字母F光源的设定方法光 XW{>-PBg: yXI >I 图3. 字母F在视网膜上位置点列图 lKWPTCU 视网膜的散射
HB+|WW t> YOr:sb 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。 ]?O2:X j>uj=B@ 7>XDNI 图4. 视网膜朗伯散射设定 ~lNsa".c 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。 css64WX^0c i)
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j~j jX 图5. 视网膜重点采样规格设定 yz8mP3"c:o 脚本 bXUy9-L ~/^5) g_ 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: G,Z^g|6 /~*_x=p: 图6. 用户对话框的创建与编辑 {7 TlN.( 图7. 用户对话框编辑器 76hOB@ 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。 bVP"(H] 余下的脚本计算与屈光度有关的所有参数。 n
-( |@NiW\O 分析 6T 8!xyi-+ Zo1,1O 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 I>L-1o|^ 0TpK#OlI|c 图7. 字母F在视网膜上颜色分析 AJ#Nenmj 脚本代码 {*{Ox[Nh{ @(r/dZc Option Explicit 'Remove this to enable non-dimensioned variables to be used. 6aM*:>C" )95f*wte Dim entity As T_ENTITY @gY)8xMbA Dim op As T_OPERATION PkI:*\R Dim mat As T_MODELMATERIAL dy_:-2S Dim A As Double MSf;ZB Dim pupilDiam As Double 8@so"d2e Dim eID As Long {s. = )0V Dim parID As Long H":oNpfb Dim count As Integer 2eMTxwt*S Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double J:V?EE,\- Dim tlens As Double, nlens As Double cnTaJ/o Dim curv As Double, conic As Double lNSLs"x^ Dim ok As Long ~69&6C1Ch *6q5S4 r Sub Main j?'GZ d"B Gea\,{E9xA '用户输入对话框 7uzkp&+: Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 SdD6 ~LS TextBox 220,21,40,21,.TextBox1 'default: 0 ,v"YqD+GC5 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 0_ 88V OKButton 40,91,90,21 Gz.|]:1 CancelButton 190,91,90,21 4?B\O`sy. Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 |\pbir TextBox 220,49,40,21,.TextBox2 'default: 4 %c4Hse#Y End Dialog 82l~G;.n3 Dim dlg As UserDialog Jv^h\~*jH Bz,?{o6s)Q ok = Dialog (dlg) d3xmtG {i h$2</J" If ok=0 Then 'cancel button was pressed zCk^B/j sM Print "Execution cancelled." %7|9sQ: End &Xf}8^T<V End If YPxM<Gfa8 .mR8q+I6 'Assign accommodation and pupil diameter & use defaults if field left empty {;2PL^i If dlg.TextBox1 = "" Then _bNzXF A = 0 'Default accommodation a|X a3E Else i{`:(F5* A = CDbl(dlg.TextBox1) wRVUu) End If !z>6Uf!{ *WuID2cOI If dlg.TextBox2 = "" Then
+U3DG$ pupilDiam = 4 'Default pupil diameter }~L.qG Else x7Yu I pupilDiam = CDbl(dlg.TextBox2) ,y#Kv|R End If > ;*b|Ik HAa;hb Print " " y gz6C Print "Accommodation = " & A & " Diopters" .6Pw|xu`Pw Print "Pupil Diameter = " & pupilDiam & " mm" vw9@v` k x<ZJb ' Calculate new parameters with accommodation 6^`1\
#f taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness #"G]ke1l$ p^w;kN Rant = 12.0 - 0.4*A 'Radius of anterior lens .:F%_dS D CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens 8A})V8 vQ
6^xvk] Rpost = -5.224557 + 0.2*A 'Radius of posterior lens r97pOs#5: CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens ) AvN\sC YpVD2.jy tlens = 3.767 + 0.04*A 'Lens thickness fumm<:<CLO 1n;0?MIZ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction J| w>a Tw-;7Ae 'Adjust parameters to account for accommodation GBPo8L"9 |Y,b?*UF '************************************************************************* .(cw>7e3D 'Aqueous thickness (Position of Lens) Li4zTR|U '************************************************************************* b0Ps5G\ u eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ,?^ p(w GetCustomElement eID, entity VAHh~Q6 ;e sBT2j~jhJ parID = FindFullName( "Geometry.Arizona Eye" ) yPb" V V Y7[) ' Delete any shift(s) in z \!.B+7t=I count = 0 R{SF(g3 While GetOperationCount(eID)>count 4O^xY
6m GetOperation eID, count, op !Wntd\w If op.Type="ShiftZ" Then gCB |DY DeleteOperation eID,count I;wp': count=count-1 A P?R"% End If 8p 'L#Q. count=count+1 286jI7 T Wend vApIHI?- .WZ^5>M- 'Set new shift in _-K2/6zy op.Type = "ShiftZ" TNe l/ op.val1 = taq )q8p k2 op.parent = parID 0ypNUG} AddOperation eID, op X^wt3<Kbf Print "Set aqueous humor thickness = " & taq-0.55 65JF`] }C"%p8=HM '************************************************************************* ];[}:f 'Radius and conic constant of anterior lens 7x|9n '************************************************************************* Ot_]3:`J~ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) E Nhl&J GetConic eID, entity, curv, conic vc;$-v$& N/"{.3{W SetConic eID, entity, 1/Rant, CCant l<58A7 Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant spH7 /5} ) j#`r/ '************************************************************************* k8&;lgO' 'Radius and conic constant of posterior lens gwuI-d^ '************************************************************************* $w`xvX eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) Tztu}t]N GetConic eID, entity, curv, conic U)]oO -P$PAg5"2 SetConic eID, entity, 1/Rpost, CCpost @<hb6bo,N Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost N2^=E1|_ 'T*&'RQr '************************************************************************* _7Ju 'Lens thickness (Position of posterior lens surface) /|6N*>l)y '************************************************************************* S6Q p_gm3Q parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 24 ' J XPXIg ' Delete any z-shift(s) r=
`Jn6@ count = 0 _Eo[7V{NY While GetOperationCount(eID)>count {T$9?`h~M GetOperation eID, count, op $f
<(NM6? If op.Type="ShiftZ" Then MS~(D.@ZS DeleteOperation eID,count RLjc&WhzXu count=count-1 iy.p n End If i+ ?^8# count=count+1 gV's=cQ Wend HmGWht6R F]O`3e=! 'Set new z-shift C2kPMB=Xo op.Type = "ShiftZ" t\dN DS op.val1 = tlens @Md/Q~> op.parent = parID w3ResQ AddOperation eID, op ~g]Vw4pv Print "Set lens thickness = " & tlens &-)N' VPJElRSH '************************************************************************* SwGx?U 'Lens index of refraction Woym/[i '************************************************************************* Q~
w|# eID = FindMaterial( "Lens" ) W' VslZG GetModelMaterial eID, mat -$ls(oot y'q$| mat.Nd = nlens W:2( .? SetModelMaterial eID, mat 6@5+m
0`u3 Print "Set lens index of refraction = " & nlens `Y$4 H,8L *Hn8)x}E '************************************************************************* L,/%f<wd 'Pupil diameter z43M]P< '************************************************************************* eu-*?]&Di eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) d7;um<%zn m+[Ux{$ 'Adjust pupil diameter (trimming volume inner hole) IFL*kB y dA8wL SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" lTgjq:mn ~qKY) "gG ' Adjust pupil location to just in front of the lens U?Zq6_M& parID = FindFullName( "Geometry.Arizona Eye" ) $7ZX]%<s eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) JX;G<lev count = 0 $Ds2>G4c While GetOperationCount(eID)>count j</: WRA`] GetOperation eID, count, op rq].UCj If op.Type="ShiftZ" Then 83_h J DeleteOperation eID,count Xl#ggub? count=count-1 zTSTEOP}%Y End If AQvudx)@" count=count+1 R
'zWYQ Wend 7Ovi{xd@ op.Type = "ShiftZ" \ Gvm9M op.val1 = taq-0.01 [RhO$c$[\ op.parent = parID LU%E:i| AddOperation eID, op Bj;'qB>3 ;N0XFjdR Print "Set pupil diameter = " & pupilDiam qo bc<- dUZ
,m9u 'Update AZ Eye subassembly Description $%#!bV eID = FindFullName( "Geometry.Arizona Eye" ) *^ZV8c} GetEntity eID, entity VY4yS*y entity.Description = "Accommodation = " & A & "D" ( Erc3Ac8 SetEntity eID, entity p_%Rt"! n Dxz~8 Update hRhe& ,v Print "DONE!" @I?=<Riu iqWQ!r^ End Sub `M8i92V\qY )3EY; 如果屈光度是4,光瞳直径是4,则会输出如下数据: w<(pl% !Wnb|=j Accommodation = 4 Diopters vA8nvoi Pupil Diameter = 4 mm OQJ6e:BGt Set aqueous humor thickness = 2.81 j A%u 5V Set anterior lens radius = 10.4 and conic constant = -2.375869 2c*GuF9(0 Set posterior lens radius = -4.424557 and conic constant = -3.081019 |@d\S[~ ^G Set lens thickness = 3.927 lt8|9"9< Set lens index of refraction = 1.42672 4|DWOQ': Set pupil diameter = 4 k5pN DONE! D'Q\za @\#td5' (文章来源:讯技光电)
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