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简介 uHI(-!O ?CAU+/ 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。 'V7LL1K^> -i8KJzPL f 模型 z&gmaYwq FY'0?CT$ 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。 J|BElBY B2[f1IMI Table 1. AZ眼睛模型的定义 ]u5TvI,C 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. 6o^>q&e}% yq-~5ui 光源 2?~nA2+vm 8@rYT5e3c 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。 R0=f` ; i%9vZ WRD
z*Zf 图1. 光源和提示信息使用 t,9+G<)>H 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。 `Xos]L'w T!H(Y4A 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。 |<c9ZS+ 0ZjT.Ep 图2. 字母F光源的设定方法光 h*VDd3[# &|XgWZS5 图3. 字母F在视网膜上位置点列图 %<>:$4U@] 视网膜的散射 IMWt!#vuY %"f85VfZ 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。 5b:1+5iF- ZhY{,sy?QO zls^JTE 图4. 视网膜朗伯散射设定 pX_ 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。 MZ"V\6T] Yd3lL:M Bb=r?;zjO 图5. 视网膜重点采样规格设定 MUl`0H"tR 脚本 ''9]`B,:a0 0HWSdf|w 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: sc]#T)xG \)dp 图6. 用户对话框的创建与编辑 7SHllZ 图7. 用户对话框编辑器 >3/mV<g f 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。
b*Qd9 余下的脚本计算与屈光度有关的所有参数。 |6Y:W$7k C?|sQcCE 分析 C)U4Fr ?E: @S3 L%lOH 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 "9xJ},:- T)e2IXGN 图7. 字母F在视网膜上颜色分析 ~a_hOKU5 脚本代码 Y)k"KRW+ h>bjG Option Explicit 'Remove this to enable non-dimensioned variables to be used. JAHg_! sN1H{W Dim entity As T_ENTITY 2@MpWj4 Dim op As T_OPERATION YA,.C4=s Dim mat As T_MODELMATERIAL yr},pB Dim A As Double ^!B]V>L- Dim pupilDiam As Double 3YLK?X8 Dim eID As Long h1q3}- Dim parID As Long f1:>H.m`
Dim count As Integer oqvu8" Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double }m<+tn3m Dim tlens As Double, nlens As Double p8 S~`fjV Dim curv As Double, conic As Double x9F* $G Dim ok As Long yreH/$Ou8 (^~a1@f,J Sub Main pbG-uH^ =EVB?k
, '用户输入对话框 (tA[] ne2 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 U>kaQ54/ TextBox 220,21,40,21,.TextBox1 'default: 0 <&[`
+ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ]A[}:E 5} OKButton 40,91,90,21 .~I:Hcf/ CancelButton 190,91,90,21 Srw`vql{( Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 `}t5` :#k TextBox 220,49,40,21,.TextBox2 'default: 4 (;g/wb: End Dialog |m\7/&@< Dim dlg As UserDialog kR1
12J9P {KSLB8gtL ok = Dialog (dlg) x(>XM:| B[mZQ&Gz`a If ok=0 Then 'cancel button was pressed 5q4wREh Print "Execution cancelled." .Od@i$E>& End <>KQ8: End If uLv L"0dB. 'Assign accommodation and pupil diameter & use defaults if field left empty lre(]oBXA If dlg.TextBox1 = "" Then nEUH; z A = 0 'Default accommodation 0Bgj.?l Else 6 [bQ'Ir^8 A = CDbl(dlg.TextBox1) |9i[*] End If !gyW15z' 6a9:P@tY If dlg.TextBox2 = "" Then `!X8Cn
pupilDiam = 4 'Default pupil diameter @ebY_* Else >G1]#'6; pupilDiam = CDbl(dlg.TextBox2) r+Sv(KS4i^ End If 0{d)f1 ymrnu-p o Print " " DQObHB8L Print "Accommodation = " & A & " Diopters" xGOmvn^lQ Print "Pupil Diameter = " & pupilDiam & " mm" DQ$m@_/4w ~2[kCuu ' Calculate new parameters with accommodation ??Urm[Y.Z taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness \Dr( /n v\(6uej^ Rant = 12.0 - 0.4*A 'Radius of anterior lens Q-iBK*-w CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens c;KMox/ Wt5pK[JV Rpost = -5.224557 + 0.2*A 'Radius of posterior lens gr!!pp; CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens 9h+TO_T@F ?W dY{;& tlens = 3.767 + 0.04*A 'Lens thickness M!hD`5.3 sc-+?i nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction #3>jgluM' modem6#x' 'Adjust parameters to account for accommodation *k&V;?x|wt U$@}!X '************************************************************************* nql{k/6 'Aqueous thickness (Position of Lens) 6*1f -IbV '************************************************************************* ( ?e
Et& eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ,<7HLV GetCustomElement eID, entity #xR=U" mDt!b6N/ parID = FindFullName( "Geometry.Arizona Eye" ) =^zGn+@z $qpW?<>,0 ' Delete any shift(s) in z hBz>E 4mEv count = 0 W3('1 While GetOperationCount(eID)>count Bs '=YK$ GetOperation eID, count, op J}-e9vK-# If op.Type="ShiftZ" Then o=zl{tZV DeleteOperation eID,count 4j,6t|T count=count-1 ifl
LY7j End If %b h:c5 count=count+1 av'[k< Wend -:!Wds ~USyN'5lU7 'Set new shift in S%?%06$ op.Type = "ShiftZ" J`; 9Z op.val1 = taq (bpxj3@R op.parent = parID mU[ AddOperation eID, op $E8}||d Print "Set aqueous humor thickness = " & taq-0.55 J}bLp
Z U.Z5;E0: '************************************************************************* trA ^JY 'Radius and conic constant of anterior lens oFzmH!&ED '************************************************************************* ?{L'd eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 2H] 7 =j GetConic eID, entity, curv, conic ,l,q;]C% EKuLt*a/ SetConic eID, entity, 1/Rant, CCant ym` 4v5w Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant qx0F*EH| SpIiMu( '************************************************************************* AYsHA w 'Radius and conic constant of posterior lens g^#,!e '************************************************************************* #N"QTD|i eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) O"X7 DgbC GetConic eID, entity, curv, conic pFBK'NE E
KJ2P$ SetConic eID, entity, 1/Rpost, CCpost [_KOU2 Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost XKOPW/ K|D1 '************************************************************************* fU.z_T[@ 'Lens thickness (Position of posterior lens surface) 2PNe~9)*# '************************************************************************* $
\!OO) 6!Mm") parID = FindFullName( "Geometry.Arizona Eye.Lens" ) #*S.26P^4 Qip@L WvT ' Delete any z-shift(s) bx-:aC)]2 count = 0 lG[j,MDs While GetOperationCount(eID)>count "d0D8B7HI@ GetOperation eID, count, op o>]z~^c If op.Type="ShiftZ" Then `0+-:sXZ6 DeleteOperation eID,count +'VYqu/ count=count-1 L@?3E`4/v End If wT,=C' count=count+1 s._,IW;
Wend 4~;M\h Vhe$vH 'Set new z-shift ]1[:fQF7/L op.Type = "ShiftZ" ]{t!J^Xn op.val1 = tlens :+?rnb)N op.parent = parID /*"pylm AddOperation eID, op {=U*!`D Print "Set lens thickness = " & tlens fMM%,/b{ PH^Gjm '************************************************************************* }Q6o#oZ 'Lens index of refraction : Hu{MN\ '************************************************************************* #D ]CuSi eID = FindMaterial( "Lens" ) )tS;gn GetModelMaterial eID, mat Ef@Et(f_mQ >4+KEK mat.Nd = nlens o?IrDQ2gmh SetModelMaterial eID, mat )4,U Print "Set lens index of refraction = " & nlens I_R 6
M1 5-&"nn2*}1 '************************************************************************* x2OAkkH\]i 'Pupil diameter
rrphOG '************************************************************************* mGJRCK_ eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) {/,AMJ<:G] 2,|;qFJY-@ 'Adjust pupil diameter (trimming volume inner hole) )$d~HA@B @a
7U0$,O# SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" zXbA$c AYp~;@ ' Adjust pupil location to just in front of the lens P>`|.@ parID = FindFullName( "Geometry.Arizona Eye" ) ovi^bNQ eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) !?|xeQ} count = 0 @Q;s[Kg{! While GetOperationCount(eID)>count m4'jTC$ GetOperation eID, count, op 6V#EEb If op.Type="ShiftZ" Then (I35i!F+tY DeleteOperation eID,count {:Kr't<XzF count=count-1 #k)t.P
Q End If NBLjBa%eL count=count+1 A<( DYd1H Wend &H+n0v op.Type = "ShiftZ" B$hog_=s op.val1 = taq-0.01 &rl;+QS op.parent = parID #~.RJ% AddOperation eID, op U;!J(Us +F2X2e)g" Print "Set pupil diameter = " & pupilDiam #5{BxX&\ L1y71+iqU 'Update AZ Eye subassembly Description "{Y6.)x eID = FindFullName( "Geometry.Arizona Eye" ) _c5*9')-) GetEntity eID, entity ,@Kn@%?$ entity.Description = "Accommodation = " & A & "D" /?Mr2!3N SetEntity eID, entity $q.}eb0 g=,}j]tl Update 9b@yDq3hQ Print "DONE!" ;BKU
_}k= B<a` o&? End Sub 8lA,3'z dep"$pys> 如果屈光度是4,光瞳直径是4,则会输出如下数据: uv^x JO90TP
$ Accommodation = 4 Diopters k]`-Y E Pupil Diameter = 4 mm 4%I[.dBnM Set aqueous humor thickness = 2.81 >VX'`5r>uw Set anterior lens radius = 10.4 and conic constant = -2.375869 tCar:p4$ Set posterior lens radius = -4.424557 and conic constant = -3.081019 MX.?tN#F|H Set lens thickness = 3.927 ErQ6a%~, Set lens index of refraction = 1.42672 <iGW~COd Set pupil diameter = 4 Wcm8,?* DONE! ]0j_yX L'
bY,D(J> f*9O39&| QQ:2987619807 9.il1mAKg
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