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简介 >#u9W'@| QOT|6)Yb 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。 j Wpm"C
\mp2LICQg 模型 ;W~H|M A,PF#G( 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。 HpCTQ\H C-2{<$2k Table 1. AZ眼睛模型的定义 ZovF]jf k 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. lf`" (:./ dbe\ YE 光源 S{d]0 5MX7V4ist 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 s:/Wz39SY3 NflwmMJ xR~9|H9a 图1. 光源和提示信息使用 QgF2f/;! 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 &x"hM b )(si/]\ 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 &s0_^5B0 I+GP`=\ 图2. 字母F光源的设定方法光 ;{j@ia 5K#<VU*: 图3. 字母F在视网膜上位置点列图 r"4&.&6 视网膜的散射 NG+%H1!$_ "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。 9O4\DRe5c #Fkn-/nL 'hNRIM1 图4. 视网膜朗伯散射设定 1sNZl& 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。 )u?^w GeFu_7u!| $?*XPzZ 图5. 视网膜重点采样规格设定 werTwe2Q 脚本 WF_24Mw ?{]"UnyVE* 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: /Z1>3=G by O*lMIWx 图6. 用户对话框的创建与编辑 VJbn/5+P 图7. 用户对话框编辑器 iezY+`x4 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。 H tx)MEZ 余下的脚本计算与屈光度有关的所有参数。 ~P,@">} .22}=z 分析 70F(`; Iy;bzHXs 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 dTVh{~/ gg?O0W{ 图7. 字母F在视网膜上颜色分析 4<btWbk5u* 脚本代码 rCsH
0:l8P j"Z9}F@ Option Explicit 'Remove this to enable non-dimensioned variables to be used. cnL@j_mb $_+.D`vx` Dim entity As T_ENTITY K)P].htw Dim op As T_OPERATION ,|^ lqY Dim mat As T_MODELMATERIAL q^Ui2 Dim A As Double NOQSL T= Dim pupilDiam As Double S{S.H?{F
Dim eID As Long k/m-jm_h Dim parID As Long S]<%^W' Dim count As Integer rPx:o}&< Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double |bX{MF Dim tlens As Double, nlens As Double ]]6 Dim curv As Double, conic As Double H|8i|vbi Dim ok As Long ^K?Mq1"Db "ZR^w5 Sub Main w9,w?%F OE(!^"5?[ '用户输入对话框 :^ J'_ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 J%1 2Ey@6 TextBox 220,21,40,21,.TextBox1 'default: 0 X8~gLdv8 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 G|LcTV OKButton 40,91,90,21 \w=*:Z CancelButton 190,91,90,21 [J6q(}f Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 s-e<&*D[ TextBox 220,49,40,21,.TextBox2 'default: 4 +`+r\*C5 End Dialog QN8.FiiD Dim dlg As UserDialog wh#x`Nc nD!5I@D ok = Dialog (dlg) Lb0B m R%0 *GC9o/ If ok=0 Then 'cancel button was pressed (R^Ca7F Print "Execution cancelled." j9O"!9$vQ End 4^{~MgQWK+ End If e)kVS}e? oF=UjA 'Assign accommodation and pupil diameter & use defaults if field left empty U,tWLX$@ If dlg.TextBox1 = "" Then X@^"@ A = 0 'Default accommodation }^Ky)** Else :eL
ja* A = CDbl(dlg.TextBox1) k(R&` End If :=2l1Y[-G jbs)]fqC; If dlg.TextBox2 = "" Then }x+s5a;!3/ pupilDiam = 4 'Default pupil diameter (nt= Else \"=b8x pupilDiam = CDbl(dlg.TextBox2) 0RkiD8U5 End If iNEE2BPp :'K%&e?7s Print " " )jm u*D5N Print "Accommodation = " & A & " Diopters" &/{x7;e Print "Pupil Diameter = " & pupilDiam & " mm" hgI;^ia
nI<Ab_EB ' Calculate new parameters with accommodation mqKr+
taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness Bw*6X`'Q =7 ${bp! Rant = 12.0 - 0.4*A 'Radius of anterior lens .>+jtp} CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens x
L]Z3"p% vw/X Rpost = -5.224557 + 0.2*A 'Radius of posterior lens U
Y')|2y
5 CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens XZ1WY( p<AzpkU,A tlens = 3.767 + 0.04*A 'Lens thickness YfUUbV "bk'#?9 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction }@NT#hD `'}c-
Q 'Adjust parameters to account for accommodation |c3Yh,Sv [y1
x`WOk9 '************************************************************************* vGI?X#w3 'Aqueous thickness (Position of Lens) UWW_[dJr '************************************************************************* YRs32vVz eID = FindFullName( "Geometry.Arizona Eye.Lens" ) <s(<ax30 GetCustomElement eID, entity B4ky%gF4 8VLD yX2- parID = FindFullName( "Geometry.Arizona Eye" ) [;8vO=Z N[8y+2SZ ' Delete any shift(s) in z 4xnM7t\ count = 0 <o.?T*Q9 While GetOperationCount(eID)>count Sp^jC
Xu GetOperation eID, count, op d}_%xkC If op.Type="ShiftZ" Then ?j-;;NNf DeleteOperation eID,count G,JK$j>*l
count=count-1 J<=k
[Q End If _.G p}0a count=count+1 IiRII)
Wend v
%GcNjZk5 k=r)kkO) 'Set new shift in n>
O3p
~ op.Type = "ShiftZ" (N` x op.val1 = taq 0F|DD8tHR op.parent = parID d vTsbs/6 AddOperation eID, op n;,>Fv Print "Set aqueous humor thickness = " & taq-0.55 {5N!udLDr5 TWk1`1| '************************************************************************* L2m~ GnP|? 'Radius and conic constant of anterior lens ye-R '************************************************************************* Fu6~8uDV{{ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) yHt
`kb2 GetConic eID, entity, curv, conic .*+KQA8 X'KkIo
: SetConic eID, entity, 1/Rant, CCant ?f ]!~ Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant Bq) aA)gF 5Sfz0 '************************************************************************* o6~9.~_e 'Radius and conic constant of posterior lens X__>r ?oJ '************************************************************************* H&3i[D!p eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) -)2sR>`A% GetConic eID, entity, curv, conic #}U*gVYe t:<dirw,o SetConic eID, entity, 1/Rpost, CCpost H<bK9k)E Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost XP'7+/A 9Di@r!Db '************************************************************************* g4fe(.?c, 'Lens thickness (Position of posterior lens surface) iQnIk|8 '************************************************************************* XexslzI {Y#$ parID = FindFullName( "Geometry.Arizona Eye.Lens" ) nax(V G,6Zy-Y9 ' Delete any z-shift(s) "Ooc;xD3< count = 0 e$+/;MRq While GetOperationCount(eID)>count 3(/J(8 GetOperation eID, count, op !1s^TB>N If op.Type="ShiftZ" Then XK7$Xbd DeleteOperation eID,count Q-,,Kn count=count-1 GI40Ztms End If [~_()i=Y count=count+1 ;`P}\Q{ Wend uh_2yw_ 2UGnRZ8:1Y 'Set new z-shift lImg+r T{ op.Type = "ShiftZ" 16N+ op.val1 = tlens nC>'kgRt op.parent = parID K@UQ O AddOperation eID, op CYCG5)<9 Print "Set lens thickness = " & tlens @|cfFT
W C0bOPn '************************************************************************* }co*%F{1 'Lens index of refraction Zg#VZg1
2 '************************************************************************* 3.^Tm+ C eID = FindMaterial( "Lens" ) ?U;KwS]% GetModelMaterial eID, mat Qso"jYl< |`50Tf\J mat.Nd = nlens JO `KNI SetModelMaterial eID, mat 8^FAeV# Print "Set lens index of refraction = " & nlens n6f ^KeJ=VT '************************************************************************* QIg.r\>o 'Pupil diameter uK5&HdoM '************************************************************************* z#!}4@_i3 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) =Hs[peO* rL=_z^.P 'Adjust pupil diameter (trimming volume inner hole) *+wGXm wC~ra:/?:7 SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" :jc
?T bim
82<F ' Adjust pupil location to just in front of the lens 'l| e}eti> parID = FindFullName( "Geometry.Arizona Eye" ) xc HG5bg| eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ."#M
X! count = 0 E
=7m@"0 While GetOperationCount(eID)>count 8 FqhSzw GetOperation eID, count, op b+ g(=z+ If op.Type="ShiftZ" Then |Qe#[Q7 DeleteOperation eID,count =h<LlI^v count=count-1 ?pAO?5Z:} End If Z.]=u(=a count=count+1 _FJ,, /~ Wend TL?(0]Hfe op.Type = "ShiftZ" mx'!I7b(L/ op.val1 = taq-0.01 .1&~@e%=- op.parent = parID ZM~kc|& AddOperation eID, op <e
s>FD y[W<vb+F Print "Set pupil diameter = " & pupilDiam ?1G7=R ;hsem,C h7 'Update AZ Eye subassembly Description ,>^6ztM eID = FindFullName( "Geometry.Arizona Eye" ) u6,NQ^4 GetEntity eID, entity }c"1;C&{ entity.Description = "Accommodation = " & A & "D" (np %urx! SetEntity eID, entity P9\!JH! @vC7j>*4B Update Q^iE,_Zq Print "DONE!" p..O;_U J9kmIMq-C End Sub >brf7h J*lKXFq7 如果屈光度是4,光瞳直径是4,则会输出如下数据: c:R`]4o n8!qz:z/ Accommodation = 4 Diopters ):Vzv Pupil Diameter = 4 mm A@W/ Set aqueous humor thickness = 2.81 *7ggw[~ Set anterior lens radius = 10.4 and conic constant = -2.375869 Gg\805L@ Set posterior lens radius = -4.424557 and conic constant = -3.081019 }nQni? Set lens thickness = 3.927 `o.DuvQ
E Set lens index of refraction = 1.42672 JMUk=p<\ Set pupil diameter = 4 AV%?8- DONE! _msV3JBr
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