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简介 (0r3/t?DQ -UEZ#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。 z+wA
rPxc ]i)c{y 模型 ]=I@1B;_m '~<m~UXvD# 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#Y^>"|$. OA1uY83" Table 1. AZ眼睛模型的定义 yCR?UH; 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. O2E/jj m+R[#GE8# 光源 |Nn)m dJoaCf`w 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;Sb/ 3 F?*-4I- 8 &LQzwa 图1. 光源和提示信息使用 [< ?s?Ci 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。 ~O0 $Suv L|:`^M+^w 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 2DtM20<> ->-KCd1b 图2. 字母F光源的设定方法光 kQSy+q mt{nm[D!Xp 图3. 字母F在视网膜上位置点列图 oy=js - 视网膜的散射 =,=A,kI[; Y'S%O/$ 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。 ,t?B+$E ^z IW+: GqvpA#
i 图4. 视网膜朗伯散射设定 [)M%cyQ 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 2B[X,rL.pX XbKYiy :D6
ON"6 图5. 视网膜重点采样规格设定 _Xc8Yg }` 脚本 p!7FpxZY 2g-j.TM 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: KNvZm;Q6 Uw. `7b>B 图6. 用户对话框的创建与编辑 QUc= &5 % 图7. 用户对话框编辑器 i{NzV 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 /wEhVR`= 余下的脚本计算与屈光度有关的所有参数。 v5#jZ$<F D9=KXo^ 分析 *20jz< q460iL7yF} 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 x.!V^HQSN XK3tgaH 图7. 字母F在视网膜上颜色分析 Z,
Yb&b 脚本代码 4K#>f4(U`g 5h=}j Option Explicit 'Remove this to enable non-dimensioned variables to be used. vjGo;+K yy^q2P Dim entity As T_ENTITY kW Ml Dim op As T_OPERATION |&+o^ Dim mat As T_MODELMATERIAL DrUO- Dim A As Double &tLgG4pd Dim pupilDiam As Double d9fC<Tp Dim eID As Long I(L,8n5 Dim parID As Long {M4gF8(M Dim count As Integer mP~QWx![N Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double JxdDC^> 0 Dim tlens As Double, nlens As Double D&&9^t9S Dim curv As Double, conic As Double #4Rx]zW^% Dim ok As Long kzQ+j8.,U en4k/w_ Sub Main y1eWpPJa NqazpB* '用户输入对话框 u^+7hkk Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 58tARL Dr TextBox 220,21,40,21,.TextBox1 'default: 0 EPI4!3] Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 9iIhte. OKButton 40,91,90,21 h,u,^ r CancelButton 190,91,90,21 i/;\7n Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Db}j?ik/ TextBox 220,49,40,21,.TextBox2 'default: 4 Xv5wJlc!d End Dialog mW(W\'~_~ Dim dlg As UserDialog |PCm01NU! p?%y82E ok = Dialog (dlg) Olt?~} 8`B3;Zmm If ok=0 Then 'cancel button was pressed ?4#Li~q Print "Execution cancelled." B:yGS*.tu End hB]Np1(' End If @su^0 9n O'p9u@kc 'Assign accommodation and pupil diameter & use defaults if field left empty ios&n)W& If dlg.TextBox1 = "" Then $kdB |4C A = 0 'Default accommodation a8e6H30Sm Else ed{ -/l~j A = CDbl(dlg.TextBox1) r,8 [O End If T?CdZc. 4<w.8rR:A If dlg.TextBox2 = "" Then +<Nn~1 pupilDiam = 4 'Default pupil diameter zOAd~E Else
,h m\
pupilDiam = CDbl(dlg.TextBox2) ojm @t End If Ytp(aE: Wq D4YGN Print " " HTv2# Print "Accommodation = " & A & " Diopters" })H wh). Print "Pupil Diameter = " & pupilDiam & " mm" hohfE3rd Zgp4`)}: ' Calculate new parameters with accommodation GE:vp>>}` taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness !3c\NbU xf\ C|@i Rant = 12.0 - 0.4*A 'Radius of anterior lens }1L4"}L. CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens cN-?l7 x}wG:K Rpost = -5.224557 + 0.2*A 'Radius of posterior lens z3{G9Np CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens kr^P6}' B-Ll{k^ tlens = 3.767 + 0.04*A 'Lens thickness .O5Z8 p *2>&"B09` nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 7JD' ) WH#1zv 'Adjust parameters to account for accommodation 8?B!2 ihhDO mUto '************************************************************************* Hp|kQJ[L E 'Aqueous thickness (Position of Lens) g>E LGG|Q '************************************************************************* ^
glri$m eID = FindFullName( "Geometry.Arizona Eye.Lens" ) IEL%!RFG GetCustomElement eID, entity <6%?OJhp L Tm2G4+] parID = FindFullName( "Geometry.Arizona Eye" ) :;%2BSgFU p}}R-D&K ' Delete any shift(s) in z yM6pd U]i count = 0 UP$.+<vm While GetOperationCount(eID)>count D=A&+6B@- GetOperation eID, count, op h6L&\~pf If op.Type="ShiftZ" Then ;Zcswt8]u DeleteOperation eID,count 4@+`q * count=count-1 VD;01"#' End If kYE9M8s; count=count+1 (U DnsF Wend ;>%r9pz ~ 9!ngy*\x 'Set new shift in o"s)eh op.Type = "ShiftZ" Y,qI@n< op.val1 = taq j7Yu>cr op.parent = parID ]? c
B:} AddOperation eID, op ;}I:\P Print "Set aqueous humor thickness = " & taq-0.55 '&P%C" 5 ?.m bK '************************************************************************* +)AG* 'Radius and conic constant of anterior lens d(ZO6Nr Q '************************************************************************* 7(1|xYCx$ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) R+hU8 pu GetConic eID, entity, curv, conic udK%> #H&|*lr SetConic eID, entity, 1/Rant, CCant &C5_g$Ma.Z Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant pHGYQ;:L RT4x\&q '************************************************************************* A;q9rD,_
'Radius and conic constant of posterior lens mX"oW_EK '************************************************************************* +uF>2b6' eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) f#>,1,S GetConic eID, entity, curv, conic /$Ir5=B l ~"^7H?4e SetConic eID, entity, 1/Rpost, CCpost ?6!JCQJ< Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost *g "Nq+i@ 7DogM".}~Q '************************************************************************* (Bb5?fw 'Lens thickness (Position of posterior lens surface) ZoW?nxY '************************************************************************* a@K%06A;' E:_ZA parID = FindFullName( "Geometry.Arizona Eye.Lens" ) P-_6wfg,;> V;VHv=9`o ' Delete any z-shift(s) *uRBzO} count = 0 ]"As1" While GetOperationCount(eID)>count [-1^-bb GetOperation eID, count, op 4&lv6`G ` If op.Type="ShiftZ" Then q4h]o^ + DeleteOperation eID,count x
M/+L:_< count=count-1 /|m2WxK) End If {_"<1C count=count+1 .^33MWu6 Wend v|,1[i{ ah$b[\#C 'Set new z-shift .&iawz op.Type = "ShiftZ" \##zR_% op.val1 = tlens
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op.parent = parID |)DGkOtd AddOperation eID, op Mmj;-u Print "Set lens thickness = " & tlens \[i1JG .[KrlfI '************************************************************************* se2!N:|R!G 'Lens index of refraction tmYz R%i '************************************************************************* ;W
)Y
OT eID = FindMaterial( "Lens" ) np^N8$i:n GetModelMaterial eID, mat QD&`^(X1p ~8Fk(E_ mat.Nd = nlens qbN
=4 SetModelMaterial eID, mat j?\Qh Print "Set lens index of refraction = " & nlens ./Zk`-OBT F`W?II? '************************************************************************* Y=?3 js?O 'Pupil diameter Xf]d. : '************************************************************************* 9MJG;+B~ eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) zV37$Hb ;%9 |kU 'Adjust pupil diameter (trimming volume inner hole) 9wUkh}s r.&Vw|*> SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ? pmHFlx (_]~wi-, ' Adjust pupil location to just in front of the lens R$<&ie6UQ parID = FindFullName( "Geometry.Arizona Eye" ) OU_gdp eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) !sP{gi#= count = 0 &-6Gc;f8 While GetOperationCount(eID)>count 7M~K,E(7~ GetOperation eID, count, op 20 h, ^ If op.Type="ShiftZ" Then WIxy}3_to DeleteOperation eID,count %JBz5G count=count-1 ;7V%#- End If `5.'_3 count=count+1 _4So{~Gf1 Wend I-*S&SiXjI op.Type = "ShiftZ" %p=M; op.val1 = taq-0.01 pofie$ op.parent = parID n5NsmVW \x AddOperation eID, op xGg )Y# {rw|# Z>A Print "Set pupil diameter = " & pupilDiam j{A y\n ( azp):*f(" 'Update AZ Eye subassembly Description 'G4ICtHQ eID = FindFullName( "Geometry.Arizona Eye" ) X`>i&I] GetEntity eID, entity @o _}g !9= entity.Description = "Accommodation = " & A & "D" LckK\`mh SetEntity eID, entity }2.`N%[ osAd1<EIC Update G 4X|Bka Print "DONE!" nRS} }6Q Jhhb7uU+ End Sub 3yF,ak{Sl l<LI7Z]A 如果屈光度是4,光瞳直径是4,则会输出如下数据: <0&*9ZeD OKR
"4n: Accommodation = 4 Diopters $ @`V Pupil Diameter = 4 mm IueFx u Set aqueous humor thickness = 2.81 *zvx$yJ? Set anterior lens radius = 10.4 and conic constant = -2.375869 .}TZxla0Zr Set posterior lens radius = -4.424557 and conic constant = -3.081019 <uw9DU7G Set lens thickness = 3.927 m8hk:4Ae Set lens index of refraction = 1.42672 ?mxMk6w Set pupil diameter = 4 K`zdc`/ DONE! 9IfmW^0
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