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简介 C|pdv O nQdq^UB 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。 9mA{K 'AN>`\mR$ 模型 3k#~yaoI [sB 9gY( 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。 X 1
57$ -py@DzK Table 1. AZ眼睛模型的定义 AbZKYF
P 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. 9IX/wm" QQWadVQo 光源 }zhGS!fO ULMu19> 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。 KQB3m" 8Z(Mvq]f& :POj6j/ 图1. 光源和提示信息使用 <HbcNE~ 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。 |*}4 m'c `
,SiA-3* 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。 }Y;K~J |PC*=ykT3 图2. 字母F光源的设定方法光 |yx6X{$k xlQBe-Wg 图3. 字母F在视网膜上位置点列图 ;q*e=[_DF 视网膜的散射 (1#J% rqY`8Ry2M 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 l1f\=G?tmU Hy^N!rBxfO PYGRsrcFd# 图4. 视网膜朗伯散射设定 hEp(A8g)bQ 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 9I4K}R x QIq^/F0 {WYX~Mvvj 图5. 视网膜重点采样规格设定 V,%=AR5 脚本 ,^C--tgZJg H ' 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: >r !|sC g*_cPU0~m 图6. 用户对话框的创建与编辑 *{L)dW+: 图7. 用户对话框编辑器 s,]z[qB#$ 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。 \SBc; 余下的脚本计算与屈光度有关的所有参数。 INJEsz PpAu!2lt9 分析 MRdduPrM%$ 2.l:O2< 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 @0/+_2MH- z*a:L} $ 图7. 字母F在视网膜上颜色分析 _no*k?o* 脚本代码 'h,VR=e< h-`}L= Option Explicit 'Remove this to enable non-dimensioned variables to be used. c}2jmwq
]GW]dM Dim entity As T_ENTITY ivN&HAxI@ Dim op As T_OPERATION t:'Mh9h7u Dim mat As T_MODELMATERIAL C$XU%5qi Dim A As Double sM `DL Dim pupilDiam As Double ;EP:o%r Dim eID As Long u)+8S/ ) Dim parID As Long NgP&.39U Dim count As Integer 7_inJ$ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double A;]}m8(* Dim tlens As Double, nlens As Double vVFy*#I#_[ Dim curv As Double, conic As Double U_I5fK= Dim ok As Long |xdsl, 6\q]rfQ Sub Main K3#@SYj 6[ j.@[t '用户输入对话框 b?tB(if!I Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 %D\[* TextBox 220,21,40,21,.TextBox1 'default: 0 7%x[q} Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1
/} b03 OKButton 40,91,90,21 GLeK'0Q@ CancelButton 190,91,90,21 Bf ~vA4 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 r{L>
F]Tw TextBox 220,49,40,21,.TextBox2 'default: 4 U@uGNMKR End Dialog 0dE@c./R i Dim dlg As UserDialog S.-TOE C26>BU< ok = Dialog (dlg) -"'j7t: w"-Lc4t+ If ok=0 Then 'cancel button was pressed 'h|DO/X~L Print "Execution cancelled." 128EPK End KBx6NU?;PO End If ~j}cyHg g| I6'K!< 'Assign accommodation and pupil diameter & use defaults if field left empty [+n*~ If dlg.TextBox1 = "" Then keL&b/@ A = 0 'Default accommodation v$?+MNks Else mwHB(7YS, A = CDbl(dlg.TextBox1) jaII r06 End If PNgY>=Y K*LlW@ If dlg.TextBox2 = "" Then :LF? pupilDiam = 4 'Default pupil diameter Yg%I? Else 1ySk;;3 pupilDiam = CDbl(dlg.TextBox2) Vc&!OE End If ?PeJlpYzV 5q3JI Print " " E7j(QOf Print "Accommodation = " & A & " Diopters" [9evz}X Print "Pupil Diameter = " & pupilDiam & " mm" PUp6Q;AdQ B~MU^|v ' Calculate new parameters with accommodation 1"MhGNynB> taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness [1g8*j~L [=6]+V83M Rant = 12.0 - 0.4*A 'Radius of anterior lens Y!-M_v / CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens ;=)k<6 Dp,L/1GQ8 Rpost = -5.224557 + 0.2*A 'Radius of posterior lens #+ 0M2Sa CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens Lb:g4A" V_:1EBzz tlens = 3.767 + 0.04*A 'Lens thickness ,w<S|#W~+ Y,<{vLEC nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction ;DqWh0 k]F[>26k 'Adjust parameters to account for accommodation AVlhNIr BO~0ON0 '************************************************************************* I8hz(2jI 'Aqueous thickness (Position of Lens) q;T{|5/O '************************************************************************* <'y?KiphL eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 5d Eh7XL GetCustomElement eID, entity 2b}t,&bv? :%tU'w parID = FindFullName( "Geometry.Arizona Eye" ) deBY5| ,1~"eGl! ' Delete any shift(s) in z n4;.W#\ count = 0 =upeRY@u5 While GetOperationCount(eID)>count k9sh @ENy GetOperation eID, count, op kJ'[K!r If op.Type="ShiftZ" Then '\l" DeleteOperation eID,count >*~L28Fyn count=count-1 SD"FErJ End If ?8npG]L) count=count+1 dI.WK@W'o Wend jl4rbzse g1/:Q%R,
'Set new shift in &47i"% op.Type = "ShiftZ" 9vuyv*-}e op.val1 = taq fiK6@, op.parent = parID ,k +IPkN+ AddOperation eID, op hci6P>h<ia Print "Set aqueous humor thickness = " & taq-0.55 ?AK(| ~Z\8UsVN '************************************************************************* b z`+ k,* 'Radius and conic constant of anterior lens 7Haa;2
T' '************************************************************************* I:R[;TB?y eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) -]0OKE& GetConic eID, entity, curv, conic Ci@o|Y }tP 8bTn^!1 SetConic eID, entity, 1/Rant, CCant Uf:` Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant {f Py=,>Nb 'F+C4QAq '************************************************************************* x,=&JtKVc 'Radius and conic constant of posterior lens so,t '************************************************************************* F&!6jv eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ~8q)^vm>f? GetConic eID, entity, curv, conic %0S3V[4I !a{^=#qq&I SetConic eID, entity, 1/Rpost, CCpost tqz3zIQ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost ]J1dt N= LA!?H] '************************************************************************* [g7L&`f9 'Lens thickness (Position of posterior lens surface) ]~Rho_mq# '************************************************************************* pR*VdC _mY Km qMFB62 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) lEH65;Nh* S5gyr&dm ' Delete any z-shift(s) Xpr?Kgz count = 0 XQY#716) While GetOperationCount(eID)>count QmQ=q7 GetOperation eID, count, op A!od9W6 If op.Type="ShiftZ" Then ui<N[ DeleteOperation eID,count 8H%;WU9- count=count-1 p)KheLiZ End If D#_3^Kiawj count=count+1 D>`xzt '.6 Wend y*4=c_Z ux=w!y;} 'Set new z-shift !S$:*5=& op.Type = "ShiftZ" NxkGOAOE op.val1 = tlens bg!/%[ {M op.parent = parID ahJ`T*)HY AddOperation eID, op M,j U}yD3 Print "Set lens thickness = " & tlens prWk2_D;* w;%.2VJ '************************************************************************* 6|gCuT4 'Lens index of refraction )MtF23k)g '************************************************************************* 8EZ$g<} eID = FindMaterial( "Lens" ) x)
,eI'mf GetModelMaterial eID, mat 57'*w]4f G~F b mat.Nd = nlens Q7HRzA^- SetModelMaterial eID, mat `
)/vq-9 Print "Set lens index of refraction = " & nlens ~k"=4j9 B al`y '************************************************************************* aHV;N#Lx3 'Pupil diameter ?k+xSV '************************************************************************* >Rl" eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) Jz\%%C
qSM|hHDo) 'Adjust pupil diameter (trimming volume inner hole) -"R2 4R#chQ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 6]&OrS[ &u]8IEv}u ' Adjust pupil location to just in front of the lens S4Pxc
]! parID = FindFullName( "Geometry.Arizona Eye" ) Fe# 1 eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) h&M{]E9= count = 0 .8 2P(}h While GetOperationCount(eID)>count >f|||H}Snw GetOperation eID, count, op 034iK[ib" If op.Type="ShiftZ" Then ?1*cO:O DeleteOperation eID,count ^-TE([ bW count=count-1 /74QMx? End If ;(b9#b. count=count+1 M-$%Rzl_ Wend #%pI(,o= op.Type = "ShiftZ" J-[,KME_^ op.val1 = taq-0.01 kGH }[w op.parent = parID +=>,Pto< AddOperation eID, op 7z%L*z8V 5 )A1\ Print "Set pupil diameter = " & pupilDiam d8DV[{^ Ja|5 @ 'Update AZ Eye subassembly Description y|jl[pyg) eID = FindFullName( "Geometry.Arizona Eye" ) \q>bs|2 GetEntity eID, entity %h hfU6[ entity.Description = "Accommodation = " & A & "D" ;d@#XIS&-( SetEntity eID, entity ZFA`s
qT <]6SN Update %Si6]3-^@ Print "DONE!" Yc`o5Q\> 59 h]UX= End Sub Ozw.siD l94b^W}1)W 如果屈光度是4,光瞳直径是4,则会输出如下数据: S%$ }( $CRm3#+
~ Accommodation = 4 Diopters L,HhbTRca Pupil Diameter = 4 mm n|6Ic,:[ Set aqueous humor thickness = 2.81 7dN*lks Set anterior lens radius = 10.4 and conic constant = -2.375869 rbul8(1h Set posterior lens radius = -4.424557 and conic constant = -3.081019 mWv3!i;G<s Set lens thickness = 3.927 g6yB6vk Set lens index of refraction = 1.42672 ?Lx24*5% Set pupil diameter = 4 kF3k7,.8& DONE! # ncRb imVo<Je7z( _1!7V3|^ QQ:2987619807 .nO\kg oK
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