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简介 7yG%E % M_F/ O 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。 [g==#[ 3
JlM{N6+ 模型 6ZjUC1 BD$Lf,_ 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。 5-4 6=%\@ Table 1. AZ眼睛模型的定义 'QpDx&~QP 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. ,jnaa (n (wH+ 0 光源 6Po{tKU ;Gp9
? 0 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。 xJ^B.;> $LBgBH&z ;Gu(Yoa}y 图1. 光源和提示信息使用 .'
v$PEy 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。 %f\j)qw AO-~dV 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。 {Zs
EYUP ,\T `gh 图2. 字母F光源的设定方法光 sCf)#6mI E.B6u, Te 图3. 字母F在视网膜上位置点列图 ?J| 视网膜的散射 ^c}kVQ\g3 TPj,4&| 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@2MEo D7IhNWrgj ^]/V-!j 图4. 视网膜朗伯散射设定 \+
Ese-la 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。 cI6Td*vM ZKS]BbMZa Ea[SS@'R 图5. 视网膜重点采样规格设定 @]]\r.DG 脚本 s=R^2;^ jlyuu 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: $|@-u0sv l:a#B
图6. 用户对话框的创建与编辑 ;+3@S`2r 图7. 用户对话框编辑器 6/0bis
H 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 dM -<aq 余下的脚本计算与屈光度有关的所有参数。 ?5[$d{ Gjl 6ZXRb 分析 1O2V!?P WxJaE;`Ige 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 ;e2D} X4k|k> 图7. 字母F在视网膜上颜色分析 hBDmC_\~ 脚本代码 y?iW^>|?L= b-#oE{(\' Option Explicit 'Remove this to enable non-dimensioned variables to be used. gd0a,_`M /mn'9=ks Dim entity As T_ENTITY 7a4Z~r27/ Dim op As T_OPERATION [.;I} Dim mat As T_MODELMATERIAL x45F-w{ Dim A As Double H@|m^1 Dim pupilDiam As Double b6""q9S! Dim eID As Long VTO92Eo Dim parID As Long u`*1OqU Dim count As Integer HSACaTVK Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double [t?:CgI)E Dim tlens As Double, nlens As Double 'kJyE9*xU. Dim curv As Double, conic As Double ~'Korxa Dim ok As Long OP``+z> 3my_Gp Sub Main C)cuy7< rj29$d?Y9 '用户输入对话框 S`h yRw Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ] `;Fc8$ TextBox 220,21,40,21,.TextBox1 'default: 0 YCG$GD Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 DU@SXb OKButton 40,91,90,21 %y+v0.aWH+ CancelButton 190,91,90,21 =|V#~p* Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 CSzu$Hnq TextBox 220,49,40,21,.TextBox2 'default: 4 pWeD,!f End Dialog m&--$sr Dim dlg As UserDialog q^}iXE~ cOdgBi ok = Dialog (dlg) !3ji]q;uF h\|T(597. If ok=0 Then 'cancel button was pressed 2t3)$\ylQp Print "Execution cancelled." Dyj>dh- End <,t6A?YoMP End If ,/eAns`ZU F{eI[A 'Assign accommodation and pupil diameter & use defaults if field left empty i&L!?6 5-f If dlg.TextBox1 = "" Then 1Uc/r>u9 A = 0 'Default accommodation &3 x
[0DV Else :>3?|Z"Aj A = CDbl(dlg.TextBox1) CeUC[cUQU End If T?*f}J Bf$`Hf6 If dlg.TextBox2 = "" Then <SSkCw pupilDiam = 4 'Default pupil diameter .6pVt_f0/ Else U ?6.UtNf pupilDiam = CDbl(dlg.TextBox2) C|S~>4` End If XrGP]k6.^ 4@9xq<<5 Print " " =<r1sqf
Print "Accommodation = " & A & " Diopters" +o K*5 Y Print "Pupil Diameter = " & pupilDiam & " mm" pE{Ecrc3| CE|rn8MB ' Calculate new parameters with accommodation CS;4 ysNf taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness =DXN`]uN mv#*%St5 Rant = 12.0 - 0.4*A 'Radius of anterior lens ~6#O5plKc CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens O-n JuZJgX &[5pR60 Rpost = -5.224557 + 0.2*A 'Radius of posterior lens rb]?"lizi CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens |+Tq[5&R V=H :`n3k tlens = 3.767 + 0.04*A 'Lens thickness 5wC,:c[H7
=tc!"{ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction Fzy5k?R yg82a7D 'Adjust parameters to account for accommodation z6 .^a-sU5 MAL;XcRR '************************************************************************* HnKXO 'Aqueous thickness (Position of Lens) gCx#&aXS '************************************************************************* $-paYQ4 eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 9`7>"[=P GetCustomElement eID, entity bv}e[yH vU9:`@beu parID = FindFullName( "Geometry.Arizona Eye" ) qTe@?j D=}\]Krmay ' Delete any shift(s) in z c-ql count = 0 0CK3jdZ+X While GetOperationCount(eID)>count HbJ^L:/ GetOperation eID, count, op A}(o1wuw If op.Type="ShiftZ" Then dEZlJo@J DeleteOperation eID,count <4582x,G count=count-1 V+t's*9o3 End If wJh/tb=$o count=count+1 k +Cwnp Wend _Sl3) ==EB\>g| 'Set new shift in ZWQ/BgKB op.Type = "ShiftZ" ;?%_jB$P op.val1 = taq P+DIo7VTX op.parent = parID 6 !wk5# AddOperation eID, op -!
^D8^s Print "Set aqueous humor thickness = " & taq-0.55 ]AX3ov6z9; ~nApRC)0 '************************************************************************* S:1g(f*85 'Radius and conic constant of anterior lens #@F.wV0 '************************************************************************* ?/8V%PL~$ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) -B?cF9 GetConic eID, entity, curv, conic :TkMS8 S q{@4F}d SetConic eID, entity, 1/Rant, CCant DKF
'* Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant %^[D+1ULb HEw&' '************************************************************************* !@ {sM6U 'Radius and conic constant of posterior lens X!m
lC51 '************************************************************************* L+}<gQJ( eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) Zn[ppsz| GetConic eID, entity, curv, conic %< `D'V@ nkf7Fq} SetConic eID, entity, 1/Rpost, CCpost .br6x^\< Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost W||&Xb :aH5=@[!y '************************************************************************* }Eh &' 'Lens thickness (Position of posterior lens surface) o7@C$R_# '************************************************************************* <T&v\DN \>X!n2rLZe parID = FindFullName( "Geometry.Arizona Eye.Lens" ) !s:e Hz)i.AA 4 ' Delete any z-shift(s) F~eY'~&H} count = 0 8|zOgn{ While GetOperationCount(eID)>count KC)}Mzt6_ GetOperation eID, count, op b`@J"E} If op.Type="ShiftZ" Then <_#2+7Qs DeleteOperation eID,count E;[Uhh|78! count=count-1 [bRE=Zr$Ry End If Ov^##E count=count+1 dCeLW Wend "p7nngn~ -:E~Z_J` 'Set new z-shift Np aS2q-d op.Type = "ShiftZ" u@CQ+pnf:( op.val1 = tlens W/AF op.parent = parID eTuKu(0
E AddOperation eID, op keFH
CC Print "Set lens thickness = " & tlens [c;#>UQMf FRQ0t!b<M1 '************************************************************************* T^(> 8/O 'Lens index of refraction .ws86stFSb '************************************************************************* *l=(?Pe< eID = FindMaterial( "Lens" ) EC 1|$Co GetModelMaterial eID, mat aYDo0?kF' hidQO h mat.Nd = nlens ,[)l>!0\H SetModelMaterial eID, mat uxB` Print "Set lens index of refraction = " & nlens Fk^N7EJ:$
Hf\sF(, ( '************************************************************************* tRZ4\Bu 'Pupil diameter {M5t)-
'************************************************************************* |<5F08]v eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) -J8Hsqf@ *3rs+0 'Adjust pupil diameter (trimming volume inner hole) O1S7t)ag ts9wSx~[+ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" {ywwJ Jv+w{"& ' Adjust pupil location to just in front of the lens QXN_ ?E,g/ parID = FindFullName( "Geometry.Arizona Eye" ) O9p s?{g eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) sRA2O/yKCE count = 0 _OyQ:>M6P While GetOperationCount(eID)>count EK Vcz'w GetOperation eID, count, op
\2e^x If op.Type="ShiftZ" Then c!/+0[ DeleteOperation eID,count kS8?N`2}LV count=count-1 %1.F;-GdsW End If zX4RqI count=count+1 e6Y>Bk Wend yCvtglAJ4 op.Type = "ShiftZ" ,(pp+hNq op.val1 = taq-0.01 y<E];ub op.parent = parID zh*D2/r AddOperation eID, op _p*8ke *LU/3H|} Print "Set pupil diameter = " & pupilDiam :C(/yg #Pp:H/b 'Update AZ Eye subassembly Description )Wr_*>xj eID = FindFullName( "Geometry.Arizona Eye" ) .Zv~a&GE GetEntity eID, entity ?VmgM"'md entity.Description = "Accommodation = " & A & "D" mXOI"B9Sq SetEntity eID, entity (8)9S6 [I3Nu8 Update t4[q:[1 Print "DONE!" %,_ZVgh0 <Q\KS End Sub o+'|j#P wlJi_)! 如果屈光度是4,光瞳直径是4,则会输出如下数据: !>n!Q*\(Ov rR-[CT Accommodation = 4 Diopters rZJJ\ , | Pupil Diameter = 4 mm 45sEhs[$ Set aqueous humor thickness = 2.81 C2"^YRN, Set anterior lens radius = 10.4 and conic constant = -2.375869 uC^)#Y\" Set posterior lens radius = -4.424557 and conic constant = -3.081019 suwR`2 Set lens thickness = 3.927 +w^,!gA& Set lens index of refraction = 1.42672 g"1V] Set pupil diameter = 4
,"(G DONE! uBx\xeI
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