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简介 &Q-[; 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。 krQl^~@ 8
3z'# 模型 dWsT Jyx~ B`?N,N" 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。 5y1or X+]L-o6I2 Table 1. AZ眼睛模型的定义 d] b~)!VW 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. P &;y]
,)E 1fz*SIjG 光源 xoqiRtlY: (v|r'B9b 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。 UJee&4C-y |?OdV<5C , vY)n6 图1. 光源和提示信息使用 Vk MinE 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。 ^=eq .(> Wmz q 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。 q+YuVQ-fx E
S#rs=" 图2. 字母F光源的设定方法光 ZWf-X 6B7< 图3. 字母F在视网膜上位置点列图 L8K0^~Mk 视网膜的散射 [leW/2i C>*5=p|T 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。 'M~BE\ VK @$JwdL gKmX^A5< 图4. 视网膜朗伯散射设定 Z} c'Bm( 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。 2{Wo-B,wt~ xj0cgK|! cqeR<len 图5. 视网膜重点采样规格设定 E|pk. 脚本 \n[
392 T#\p%w9d 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: oS~}TR:} ao)Ck3] 图6. 用户对话框的创建与编辑 'Pf_5q 图7. 用户对话框编辑器 /nc~T3j 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。 RS'} nY} 余下的脚本计算与屈光度有关的所有参数。 |r5e{ q\a[S* 分析 o:_^gJ+| M(qxq(#{U 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`B[,* >Y}7[XK 图7. 字母F在视网膜上颜色分析 h2"9"*S1 脚本代码 W@l+ciZ_ 3DH.4@7P Option Explicit 'Remove this to enable non-dimensioned variables to be used. p?;-!TUv =K .r Dim entity As T_ENTITY {]=v]O|, Dim op As T_OPERATION $Z/klSEf Dim mat As T_MODELMATERIAL ,*7H|de7 Dim A As Double 2-~a
P Dim pupilDiam As Double lj)f4zu Dim eID As Long ^Z2kq2}a Dim parID As Long Yj)
e$f Dim count As Integer cFLd)mt/ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double !L77y^oV Dim tlens As Double, nlens As Double -PM)EGSk{ Dim curv As Double, conic As Double #Rc5c+/(
Dim ok As Long )%s +? )!cI|tovs Sub Main |=\91fP68` .8]Y- '用户输入对话框 X:Q$gO?[4 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 Y&s2C%jT TextBox 220,21,40,21,.TextBox1 'default: 0 6)ycmu;!$ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 U h.Sc:trA OKButton 40,91,90,21 ;+
G9- CancelButton 190,91,90,21 s;J\Kc?"| Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 z5 Bi=~=# TextBox 220,49,40,21,.TextBox2 'default: 4 }w@gj"\H End Dialog rR]-RX( Dim dlg As UserDialog k^^:;OR 6yI}1g ok = Dialog (dlg) X/Y#U\ 71O3O7 If ok=0 Then 'cancel button was pressed }kE87x' Print "Execution cancelled." =2,0Wo]$ End `@|w>8bMz{ End If kg3ppt 0 O~p7D 'Assign accommodation and pupil diameter & use defaults if field left empty )Pli}) If dlg.TextBox1 = "" Then &3Tx@XhO A = 0 'Default accommodation 8%[HYgd5) Else _UkmYZ/ A = CDbl(dlg.TextBox1) gLIT;BK End If Jf)3< ~G &!jq!u$( If dlg.TextBox2 = "" Then oEu>}JD pupilDiam = 4 'Default pupil diameter 1TjZ#yP%1 Else 2J<&rKCF pupilDiam = CDbl(dlg.TextBox2) Pdw#o^Iq^ End If ,GrB'N{8e $}R$t- Print " " ,)h)5o(? Print "Accommodation = " & A & " Diopters" }>&KUl Print "Pupil Diameter = " & pupilDiam & " mm" JDv-O&] cXN _*% ' Calculate new parameters with accommodation W&(f&{A taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness .
uR M{Bs =XT)J6z^" Rant = 12.0 - 0.4*A 'Radius of anterior lens xMI+5b8 CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens K)S;:MLG= ?} ( = Rpost = -5.224557 + 0.2*A 'Radius of posterior lens TJaeQqob CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens st/n"HQ e"Rm_t tlens = 3.767 + 0.04*A 'Lens thickness @u)
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Vd nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction F
Z!J Ftv8@l 'Adjust parameters to account for accommodation sG,+
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s '************************************************************************* rg5]&<Vq8 'Aqueous thickness (Position of Lens) )NT5yF,m '************************************************************************* ~|lIC !q eID = FindFullName( "Geometry.Arizona Eye.Lens" ) :eOR-}p' GetCustomElement eID, entity u@=?#a$$ (9$"#o parID = FindFullName( "Geometry.Arizona Eye" ) Ht[{ryTxu jtKn3m7 +p ' Delete any shift(s) in z lj2=._@R count = 0 ;/LD)$_ While GetOperationCount(eID)>count kWL.ewTiex GetOperation eID, count, op [s`
G^ If op.Type="ShiftZ" Then u3ZCT" ! DeleteOperation eID,count 7Kf}O6nE count=count-1 &ZJgQ-Pc(m End If Veji^-0E count=count+1 Zb''mf\ Wend
xh0 xSqDM eW8[I'v_& 'Set new shift in |n6Eg9 op.Type = "ShiftZ" bJ3(ckhq op.val1 = taq *t9eZ!_f? op.parent = parID &L4
q10-N AddOperation eID, op Zzj0\?Ul Print "Set aqueous humor thickness = " & taq-0.55 Tby,J
B^U ?m;;D'1j '************************************************************************* orIQ~pF# 'Radius and conic constant of anterior lens \u{8Bak0 '************************************************************************* qv+R:YYOq eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) .mxTfP=9 GetConic eID, entity, curv, conic F#V q#|_)> Cg!^S(U4 SetConic eID, entity, 1/Rant, CCant "uD=KlA Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant w1|Hy2D`0 TGV '************************************************************************* r;qzo. 'Radius and conic constant of posterior lens j+^L~, S '************************************************************************* 1BTIJ G w eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) &35|16z%@ GetConic eID, entity, curv, conic 8_we:
9A R+=a`0_S SetConic eID, entity, 1/Rpost, CCpost -50AX1h31: Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ;IZ?19Q OX hAha`R '************************************************************************* l]#!+@ 'Lens thickness (Position of posterior lens surface) ?m"|QS!!K '************************************************************************* 'Bq ZOZw wu~hqd parID = FindFullName( "Geometry.Arizona Eye.Lens" ) wH6u5*$p k%Vv?{g ' Delete any z-shift(s) raB+,Oi$G count = 0 3$p#;a:=n While GetOperationCount(eID)>count Vk}49O<K/ GetOperation eID, count, op ,x_Z JL If op.Type="ShiftZ" Then eD;6okdP DeleteOperation eID,count <$E6oZ count=count-1 ZX.TqvK/r End If BWq/TG=> count=count+1 8^yJqAXK Wend YD[H 1dG06<! 'Set new z-shift "pvZ,l>8f op.Type = "ShiftZ" S GcBmjP op.val1 = tlens Rp.W,)i op.parent = parID f_6`tq m% AddOperation eID, op ]]uHM}l Print "Set lens thickness = " & tlens [ygF0-3ND N:BL=}V '*************************************************************************
,=%nw]: 'Lens index of refraction 6Wf^0ok '************************************************************************* [aW = eID = FindMaterial( "Lens" ) QT!5l` GetModelMaterial eID, mat V[hK2rVH. 6m`{Z`c$ mat.Nd = nlens J !#Zi#8sF SetModelMaterial eID, mat Fi;VDK(V9 Print "Set lens index of refraction = " & nlens T] | d5E jX
*/piSq '************************************************************************* `~F5wh~ 'Pupil diameter Tj/GClD:% '************************************************************************* s:|M]. eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 3C^1frF PEXq:TA 'Adjust pupil diameter (trimming volume inner hole) _a'A~JY #}yTDBt SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" H7&xLYQ2 (H#M<N ' Adjust pupil location to just in front of the lens FxU'LN<;HY parID = FindFullName( "Geometry.Arizona Eye" ) *i%quMv eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) %FA@)?~ count = 0 6Z! y While GetOperationCount(eID)>count T0e<Slo~C GetOperation eID, count, op < |