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简介 FT<H]Nf HgYc@P*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。 DL
%S(l mMV2h|W 模型 DgC3>
yL ]NbX`' 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。 KlY,NSlQ 2]2{&b u Table 1. AZ眼睛模型的定义 ^GE^Q\&D& 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. :jBZK=3F> P8"6"}B;T 光源 5r^1CFO <V7SSm 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。 t'dHCp} mXQl; NY.}uZ 图1. 光源和提示信息使用 S@9w'upd 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。 KbXbT @bc[
eas 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。 Sjw2 j#Q 8mk}nex 图2. 字母F光源的设定方法光 S&5Q~}{, L[CU 图3. 字母F在视网膜上位置点列图 |sA4:Aq 视网膜的散射 N-XVRuv K5 5} Wi 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。 ub[""M? @YEw^J~ "kcpA#uD| 图4. 视网膜朗伯散射设定 u+I3IdU3 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。 aUKh})B JX2mTQ B jH ~Ml2 图5. 视网膜重点采样规格设定 _Wm(/ +G_| 脚本 p.@0=) n33JTqX 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: x1 .3W j #S@UTJa
图6. 用户对话框的创建与编辑 3DxZ#/! 图7. 用户对话框编辑器 CWE Ejl 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。 f@wsSm 余下的脚本计算与屈光度有关的所有参数。 j5PaSk&o= C$$"{FfgU" 分析 ,:v.L}+Z 0$n8b/%. 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 cYZwWMzp 70'}f 图7. 字母F在视网膜上颜色分析 M,.b`1-w 脚本代码 "}S9`-Wd| B@ZqJw9J[ Option Explicit 'Remove this to enable non-dimensioned variables to be used. )$ ofl%+ 2q`)GCES~ Dim entity As T_ENTITY =nJOaXR0 Dim op As T_OPERATION B0-4ZT Dim mat As T_MODELMATERIAL o,*folL Dim A As Double 1bV 2 Dim pupilDiam As Double _ff=B Dim eID As Long hg%@ W Dim parID As Long 6Y;Y}E Dim count As Integer 4a(g<5wfI Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Z_iAn TT Dim tlens As Double, nlens As Double /Oq1q._9F Dim curv As Double, conic As Double *]{9K Dim ok As Long &,W_#l{ "\VW.S Sub Main F,'^se4& 1Pud,!\%q '用户输入对话框 LVPt*S= / Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ,H.(\p_N TextBox 220,21,40,21,.TextBox1 'default: 0 ]I{qp~^#n Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 1VhoJGH;C OKButton 40,91,90,21 Ck ~V5 CancelButton 190,91,90,21 uB5h9&57 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 .\z|Fr TextBox 220,49,40,21,.TextBox2 'default: 4 8gVxiFjo End Dialog ~[d=s Dim dlg As UserDialog pr0@sri@ h]J&A ok = Dialog (dlg) !A'`uf4u F<PWBs% If ok=0 Then 'cancel button was pressed p/\$P= Print "Execution cancelled." 6.
+[
z End dD/29b( End If c8k6(#\ jjS{q,bo 'Assign accommodation and pupil diameter & use defaults if field left empty m[g< K If dlg.TextBox1 = "" Then H j5WJ{p. A = 0 'Default accommodation gFWEodx,9 Else 9B!im\]O A = CDbl(dlg.TextBox1) >wg9YZ~8 End If ^D W# QrNL7{ If dlg.TextBox2 = "" Then &;6|nl9; pupilDiam = 4 'Default pupil diameter r85Xa'hh Else jV,(P$ 5; pupilDiam = CDbl(dlg.TextBox2) [a>JG8[,t End If <B]i80. /%ODJ1 M Print " " }#\;np Print "Accommodation = " & A & " Diopters" Q.pEUDq/ Print "Pupil Diameter = " & pupilDiam & " mm" P`Hd*xh".j Z30z<d,j ' Calculate new parameters with accommodation V7B=+(xK taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness [#hl}q(P# %#Wg^l
' Rant = 12.0 - 0.4*A 'Radius of anterior lens c-s`>m CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens Kc JP^ *f0.= ? Rpost = -5.224557 + 0.2*A 'Radius of posterior lens c:h.J4mv CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens E&iWtwkz (PsSE:r}+ tlens = 3.767 + 0.04*A 'Lens thickness RS||KA])J o-Q]Dk1W
nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction \pewbu5^ rB.=f[aX[ 'Adjust parameters to account for accommodation !\&7oAs=I h0QYoDvbC '************************************************************************* [5RFQ! 'Aqueous thickness (Position of Lens) &{%S0\K Y '************************************************************************* u'$yYzBE eID = FindFullName( "Geometry.Arizona Eye.Lens" ) TzevC$m;z GetCustomElement eID, entity 6PzN>+t^y :{wsd$Qlj parID = FindFullName( "Geometry.Arizona Eye" ) yNLa3mW 8aZey_Hw;+ ' Delete any shift(s) in z MUCJ/GF* count = 0 Z5*(W;; While GetOperationCount(eID)>count (Qx-KRH GetOperation eID, count, op 5|6z1{g8 If op.Type="ShiftZ" Then 86^ZYh DeleteOperation eID,count L6rs9su=7 count=count-1 Lilk8|?#W End If ^O$[Y9~*
count=count+1 ~P]HG;$?n Wend w}U5dM` o%4&1^ Vg 'Set new shift in ohc/.5Kl op.Type = "ShiftZ" wCq)w=, op.val1 = taq TN |{P op.parent = parID YA;8uMqh; AddOperation eID, op ?(,5eg Print "Set aqueous humor thickness = " & taq-0.55 $@u^Jt, ? j quSR= '************************************************************************* +}(B856+ 'Radius and conic constant of anterior lens 2W"cTm
'************************************************************************* q*RaX
4V eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) ,s yA() GetConic eID, entity, curv, conic ;8;~C" y1\^v_.^ SetConic eID, entity, 1/Rant, CCant cP#]n)< Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant pZ_FVID OuBMVn '************************************************************************* #o r7T^ 'Radius and conic constant of posterior lens 7u`}t83a '************************************************************************* '#4mDz~ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ,a]~hNR*X GetConic eID, entity, curv, conic G%p!os\> ,],JI|Rl8c SetConic eID, entity, 1/Rpost, CCpost u'~b<@wHB Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost @8<uAu% e\
l,gQP '************************************************************************* 4na4Jsq{ 'Lens thickness (Position of posterior lens surface) /qkIoF2 '************************************************************************* zy/tQGTr@ L1Cn parID = FindFullName( "Geometry.Arizona Eye.Lens" ) !{]v='
d"d)<f
' Delete any z-shift(s) XM@-Y&c$A count = 0 h-_0 A] While GetOperationCount(eID)>count aD/,c1 GetOperation eID, count, op MY<!\4/ If op.Type="ShiftZ" Then }'.Sn{OWf DeleteOperation eID,count -{:LxE count=count-1 cdtzf:#q End If h&k^l, count=count+1 4|Gs(^nU Wend 8{4D |o#O F{H0
% 'Set new z-shift c7nk~K[6 op.Type = "ShiftZ" fkv{\zN op.val1 = tlens Lq
$4.l[j op.parent = parID Znl>*e/| AddOperation eID, op u&d v[ Print "Set lens thickness = " & tlens DHumBnQ ^SSOh# '************************************************************************* Pl5NHVr 'Lens index of refraction KGE-RK '************************************************************************* L^al1T eID = FindMaterial( "Lens" ) v!RB(T3 GetModelMaterial eID, mat QWW7I.9r >/HU' mat.Nd = nlens 69I.*[ SetModelMaterial eID, mat ??%T Print "Set lens index of refraction = " & nlens <#x%A0 >yT@?!/Q>' '************************************************************************* >*i8RqU 'Pupil diameter f_P+qm '************************************************************************* cA*X$j6 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) %:;[M|. Hv7D+j8M 'Adjust pupil diameter (trimming volume inner hole) i!}nGJGg
O<d?'{ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ZNC?Ntw /
-qt} ' Adjust pupil location to just in front of the lens gZ >orZL' parID = FindFullName( "Geometry.Arizona Eye" ) M>H^<N}'A eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) L"du"- count = 0 aj'8;E+ While GetOperationCount(eID)>count &Cpxo9- GetOperation eID, count, op Q.E^9giC If op.Type="ShiftZ" Then j!_^5d#d DeleteOperation eID,count Rb}&c)4 count=count-1 :8|3V~%m End If nTy,Jml count=count+1 K8 4cE Wend 6M vRR op.Type = "ShiftZ" ;s
B:s9M op.val1 = taq-0.01 .L{+O6*c op.parent = parID E?h2e~ ,] AddOperation eID, op ,,#rv-* lGHu@(n< Print "Set pupil diameter = " & pupilDiam GKx,6E#JM y~ 4nF 'Update AZ Eye subassembly Description {*Wwu
f. eID = FindFullName( "Geometry.Arizona Eye" ) D&6Qk&> GetEntity eID, entity I;.E}k entity.Description = "Accommodation = " & A & "D" 6V6g{6W,/ SetEntity eID, entity ,~?A.
5 YGpp:8pen Update qkG;YGio Print "DONE!" #`)-$vUv^f X%1.mTU~K End Sub 7{6. / z?7ic0
如果屈光度是4,光瞳直径是4,则会输出如下数据: KPe.AK,8 BRzWZq%r3 Accommodation = 4 Diopters QT l._j@ Pupil Diameter = 4 mm Rpd/9x.)& Set aqueous humor thickness = 2.81 gw"l& |