ĐỀ CƯƠNG BÀI GIẢNG HỌC PHẦN QUANG HỌC

CHƯƠNG 1
Quang hình học
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*) Mục tiêu:
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1.2. Các định luật và nguyên lý cơ bản của quang hình học
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?6VW|,=)&)&,J,KA"D&!@&(A&)!"#$&T8S/
,=;&)&)&T/13b3
?;)6=!$
~)i,=)&)&$G'44$)(!=A&,KA"D&$G$)(



w3
e/)%&$G&G$T?1!J46$$ /)%&
 
n n n

 
7 43  34 

  3
 
 
 ÷
→ ∆ = − ≈ −
 ÷
 ÷
 
−
 
3b
MY!=A&*K&*>


=1

7 34 

 
∆ = −
 ÷
 
3
?;Y-G
…Q&@)%&! ,j!=A"T$,=)&)&→$j€jj€!J`&$./



jj‡ 4 

 
= −
 ÷
 
3
>O+P
t6&‚/Z&5;/(! <KF@( *+![!\!!5]LT^
 *+B!%&5]-%4/_M
>t"D&A'/)%&0/Z&*>…QZ&*>$G„!=A&*K&*>$)($(
,Z&*>4+$>„|d/)%&{&G$
+$
 n
ˆ

  „δ = + −
 δ$G&%A6$E$ *

=
n

,
„ „
)  )
n n
δ +
→ =
3y
MY„A(?1
„ „
)
n n
≈

( )
,
  „→ δ = −
3a
δ
,
Z&*>,)/+$$F,/0/G>(→0/&2$$G$("#&
(3
1.5. Sự khúc xạ ánh sáng qua mặt cầu khúc xạ (lưỡng chất cầu)
@4(Q%
R=$<*9$78,=$<&Z$%$/,KA"D&!@&>A&)$G$)(*%$

/
@4+, 'R-F-NC+A?
>t'*+"-&! ,
Mt'*+"-&! ,!'*+! $./,J! ,,J! ,3
Mt'*+dF,/T&<A5$$F,/!@&0A(&<A5$$>/$%$/A&
$F,,TA5$$>,J&G$A(Q3
>z"T$4(A&0/&12$d2$'M$'A'%)%&IA%)/&
$2&$![‰3
>dK&:$$./,=$<*9$78

MW`G5]
MWZ4/_

 ‡  ‡   ‡
}  ‡
) )‡ ) )‡ }
−
 
− = − ⇒ − =
 ÷
 
3\
MdK&:$!9&$TA"D&#&@3
@*48B<2B<R-
Xt6&‚/!J5!8"#&
 ‡
$)
}
−
=

!=$A"&$*
Z&*9$78%)%&'/>&2 ;a-5]'/IJ*+Φ!"#$7%$!6

 ‡
}
−
Φ =
3n
_A&!G€<"#$)(,KA"D&$://T$)(,KA"D&$://
*9$783
XejSK$E$)=X∞c,AA5$$>→$F,78J58BAA5$
$>$%$‰,J*&Šm
‰B
m}vn3e!GB!"#$&2!P !=5_$./&"-&Š
!PO$./&"-&*&$%$I![&"-&!! ,$>3
X_4+,=;&K&&G$TA5$$>$:/! ,$>3
@>49H
…Q$./,J;&?K&&G$A5$$>0/,=$<*9$78$%$0"T$'4(
&&"&"-&$<3tJG&!8!"#$7%$!6

‡  )‡
3
  ‡ )
β = =
3n
1.6. Thấu kính mỏng
D4(Q%
X_(*>,J*!@&$(A&)!"#$&T8S/,=*9$78A&!G>(
,J,=$G!J$&*%$*K&
X_(*>,?&!=A&,KA"D&!@&($G $‰


≡‰
n
≡‰)/$,2/)%&
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Xz/&A5$$>!"D&;&!0/`,/,=$<3
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
 n  n
 n
Š Š Š Š
Š
4 Š ‡ Š
= =
δ − +
3na
_I$K&:$3na$/>!"#$$%$$E$./+&Q*!G)P7%$!6!"#$$%$
! ,$>$%$! ,$>3_I!G$G 4E&$./0/+&Q3

*) Tài liệu học tập
3t=&_6R/nn7BY7~%45$fYJ3
n3fsf+\\7BY7~%45$fYJ3
o3t=&_6R/Y&Œj9$_<_A2&_"D&n`&!EL0E%Q !*SFEL
Y7~%45$fYJ3
*) Câu hỏi, bài tập, nội dung ôn tập và thảo luận
A. Câu hỏi ôn tập
3~>$$%$+"#&"D&&=A&!D)&"E$&+E$)E8
F&G&•
n3_$K&:$$-$./,=)&)&Z&*>•_I!G$&‚/
>$./I&$K&:$•
o3_$K&:$$-$./,=$<*9$78•_I!G)A/$K&:$$./(*>
,?&•
b3d%$4E&$./,J0/(*>,?&J5`*s•
3t6&‚/$%$! ,$>,=;&$>! ,$>$E$./+0/&2$
!@&A5$
B. Bài tập:
1. Ž&V/,J$ZO&1K&4+>$n,
n
$GAC,J&2!•3d!•"
,J&@! ,3f^7%$!6!J$/$./!•* I))/$!JA28$%$&G$O&
T(3
2. RJ! ,)%&SA&*&&V//&"-&;&)&)&3WP/)%&I)/
*78<"#A/&"-&!0/,J! ,„$A"T$3
3. RJ&"D$/a,?$<,J&"-&!=;&!:&$G!J4 /
! $&"D!G1(J$./,1
4. „„!:&$8&"-&/|!4<T&"-&C!"D&K&&G$T&"-&
8! ,&V/3f?*//„|l!1(/A&&"-&1/|$O$%$
&"-&/
\

5.f1P4"T!` 4ŒA5$$>RY€$./G0/,J(*>
,?&3|c&$%$P1^7%$!66A>$./(*>8(*>J5/`*1
$%$! ,$./G3

6. _A1n/ 4ŒE$„|„€|€$./G„€|€$G E$=$
0/,J(*>,?&3|c&$%$P^7%$!66A>(*>0/&A5$$>$%$
! ,A9A/*'>$($./E$/'8(*>3
7. RJ&"-&$<@$G%*>nn$,3Y!=$%$&"-&b$,1S!`•tJ
G&!84/•
8. |%*>$%$,=$<$./,J(*>,?&/,=@c&$,3*!=&
*K&*>(*>$G!J5n43
/…%$!6$)($./$(,(*>•
_>!J5$./(*>*!=GA&"T$$)(

mbvoA&4<

n
m•

f1/
f1
f1n/
f1n
CHƯƠNG 2
Sự giao thoa ánh sáng
\yn
*) Mục tiêu:
+) 
 !"#$$(!+I$./%)%&"-&A1)G&%)%&$"D&!J)%&
&$@&$(%)%&

 !"#$!'*+&//$./)G&%)%&)E&//$.//)G&%)%&
*#&//T%)%&Al&"S&$./*>$"T$&@)%&+"#&&//3
45&$%$"-&%0/)%+"#&&//T&@! ,"*C
•&"‘&Z&*>BAC)C"‘&&"-&BAC)C"‘&(*>|C&"-&A4! &$%$
'&//%)%&3
+) 
P1,K$%$+"#&&//I!G7%$!6!"#$A"D&&//
!"#$$K&:$>6A>`)%&`3
&!"#$$%$'0/&12$3
+) 
>$,K2$>$$E$&$:A/!L*:$$./$"-&3
2.1. Bản chất điện từ của ánh sáng. Nguyên lí chồng chất
M,W.%
XN)%&)G&!+IG$G$(!+I",2:$78!+I*%$
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•  f ⊥ ⊥
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R 
n

• • $)  3
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λ
 
 
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∑
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2.2. Sự giao thoa của hai sóng ánh sáng
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X_A"D&&//,'*K&&/$G)E&//%)%&
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( )
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n n n
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 n
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WT
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  n  n  n
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• $) • $)
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α + α
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
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X…Q/A"D&#
M_A"D&#α
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,•vv
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n
0/)%A&A"D&&//! 0/)%`&//

Mf1&//%)%&!-)l$+`&//V&!"D&;&)&)&)%&
7C*P/`A&`,‰3t=,z&Z%)%&AE$I&@T,3
e&`
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4 r
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nA
λ +
=
α
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M
MtJAJ&A"D&&//RY=nr/α≈nrα,4Œ0/)%`&//α?
*@L 'O)7
M_(,.~K!C,=)/! (5$%$/*9$78!.3Y&@!=
A"T$(,.*%7/~! /)%&T4"TV&&G$≈\
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3t=,0/)%K&&G$T
&"-&3
Mf1&//*0$@&$($./$F,/TAE$I&@$F,/
78A,=(,.3
M_E$&+,$:&?8V&! ,!%! ,)%&8! ,&"#$8
→/4/!J&$.//78!^/!L
’"c!!$LGJ@P58!@*:!K%[S!K58!@*:U
![!ML) ; d!5;%*+
π
3@M-!LGJ)&!P55; 
λ
e

Meh!J&//5J$6A>$./`&//A,$&&<`,,! ,
d*h!J$&&,3
*D^ _.%+P \U<, !%))%1203
…QA"D&#*C•&&)i,SAJ&4<*C)%&*!G,k4K$F&•$./*C
$,J+`A&3_L&#($$%$+`)P$,J$"D&!J)%&$&A,•3
Y!JAJ&T-,J&T8!G1*K&0/)%!"#$`&//V/3
2.4. Giao thoa bởi bản mỏng
>M-SH7&+F`a[:<
NO 6JU-0Y
X…Q,J,?&)&)&$G!J44*K&!L$
)(!=A&*K&*>3d)%&c&&@)%&AJ&
$G'$F,/)%&)&)&T$F&&G$T{1n3o3
M_/„T,=vv8„→%$///*9$78
„|/78„}
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M_/*9$78„|T,=4"T8|→%$///
A'0/|_
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/78|d3
M_/|d&=,=A8d→%$///78
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n
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n
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n n
n4  )  n∆ = − − λ
n3y
MY7Q∆∈,*K&5J$6A>„6A>! ,T
M)0Y!
MrF&(*>J5! J5$%$$F,/)%&,0/)%•!=8! ,$./
_e3

M_e,•!=vvT,=→$%$$F,/)%&TT$F&,J&G$T)P$$%$
$=/&//c,7&0/A5$(*>J58$%$! ,c,A!"D&AO`,B€$G
$F&$"D&!J)%&→02@2!`&//$F&!J&&
MY&G$?/,^
*∆ = λ
`AO)%&
( )
n*  n∆ = + λ
`AO
Mf1&//+`&//$F&!J&&&@,V&O&AO!@&`,)%&
7C*P/$G`,! ,B€$./_e$&7/`,`$&7>83
>M-SH7&%`a[:7&
NO 6JU-0Y
X…Q,?&$G!J4/!Ln,=,T/
,J&G$αQ$)(!=A&*K&*>1n3b3
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T,?&//{
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78A@8*9$78S,=A$/G{
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T8|6788,=A$/
78{
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n
//*#→&//T/
MrF&(*>! $1&//,•
!"3@MW
n n
n4  )  n∆ = − − λ
n3a
MY7Q∆∈43W1*h!J$.//$&"-$./,l?&@S*%7/
→$[/!LA&,J&T8?$"*K&!L→∆$[∈4
M)0Y!
X∆$[∈4→V&! ,A$G$F&!J44→$G$F&&%A6$./∆→$G$F&$"D&
!J)%&→8,J`&//0YC ;)&

M4?/,^
*∆ = λ
`)%&
M4?/,^
( )
n*  n∆ = + λ
`
Xf1&//!I`)%&T`)%&C+0/&A1/!L,J
"#&λ!J4/!L,J"#&λvn→"0Y%&f *:$(!J/g
>*bc" Y!9+.%-NH7&%`
HYP5/8/_
Y,*K&*>,JT*K&*>1,&T8&V//.&&T
/&G$α?3
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}

}
n

{

{
n
M
W6A>$%$`&//
MW`
( )
n4 n n*  n 4 * n∆ = + λ = + λ → = λ
MW`)%&
( )

n4 n * n*  b∆ = + λ = λ → − λ
f1&//V&!8;&)%&)&)&/7C*P)&)&T
$8$./,3
e&`
*  *
4 4

/ n/ n
+
− λ λ
= = ≈
α α α
n3\
HY@2
t=,J(*>@%*>$>*9$T,J(,.;&3T*K&*>
&V/(*>(,.,J,?&$G!J4/!L3d(*>$F,)%&vv
⊥,=.3_8,=$&$./(*>$G)E&=/$./$%$/78$%$/*#→
&//`$F&!J48,=$&$./(*>3
XW6A>$%$`&//
MYV&! ,:&TT*K&*>
4 * n= λ
`3T*m/$G`A&`,`
$
MYV&! ,:&TT*K&*>
( )
4 n*  b= − λ
`)%&
’|%*>$%$`&//
MW`:*
*

A }3*3= λ
 *∈–
’
MW`)%&:*
( )
)*
A } n*  3
n
λ
= −
’f1&//$%$`&//$F&!J4V&O&AO!@&`,)%&7C
*P/$G`,! ,79$d0Y@2$&7/`,$%$`$&7>/3
>>b&78.%, !%))%1203
c,$$LGJ@P5])aa3B
c!=5@$5]/_LT]%<!
h)aO!$$@LiL&/_
2.5. Sự giao thoa của nhiều chùm tia (tự học)
@Z, !%))%.%:-%
d%$/GA/*?)/'<78$G$"D&!J
*%$/*K&'→$G*Z&&//T/→!
-!bC5!$
@E29[c Y"<[%))%
M|,=)&)&'44$)(!=A&,K
A"D&$)(

3d$F,/)%&!-)l$)&)&T
4"T&G$T{$%$/G*?€n€o€—n—o—1n3
~2{

$"D&!J$./$F,)%&T{


$"D&!J$./
)G&%)%&A'0/}+)78_+)A'0/3e!G}M_=
|!J$./)G&A'0//—•
—
=_•
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 /n—•
n—
=}_•
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n
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
( )
n
n n n
˜   
{ _ • _ {  } {= = = −
n3n/
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
n n n n n
n˜  
{ _ } • _ } {= =
n3n

b n
o˜ 
{ } _ {=
n3n$
f+0/&A1$.///*'/
[ ] [ ]
„|dr•n˜ „|d˜ n43$)A∆ = − =
n3n
f+)/"-&:&
n b
3 3433$)A
π π
∆ϕ = ∆ =
λ λ
n3nn
d"D&!J$./)G&A'0/
( )
( )
n



n
n
 } 3{
{
 } b} )
n
−
=
∆ϕ
− +
n3no
d"D&!J$./)G&78
( )
n


n
n
b} ) 3{
n
{
 } b} )
n
∆ϕ
=
∆ϕ
− +
n3nb

Kết luận1`$"D&!J)%&A&%)%&A'0/%)%&78
A5/8$k$G`)%&$./%)%&A'0/1$G`$./%)%&78
&"#$83
@*4NR-.%[%))%:-%
Mt 0/)%1&//4F&&@)%&AJ&4F&(*>J5
Mf1&//`&//`$F&!J&&!67:SK$E$
*) Tài liệu học tập
™št=&_6R/nn7BY7~%45$fYJ
™nšfsf+\\7BY7~%45$fYJ
™ošt=&_6R/Y&Œj9$_<_A2&_"D&n`&!EL0E%Q !*SFEL
Y7~%45$fYJ
*) Câu hỏi, bài tập, nội dung ôn tập và thảo luận
A. Câu hỏi ôn tập
3|$(!+I$./%)%&•YJ4&&$@&$(!+A"D&•
n3t'*+&//$./)G&%)%&•E&//$.//)G&%)%&*#•
o3)%+"#&&//T%)%&Al&+"#&&//T%)%&
!-)l$•
b3d"S&$./*>$"T$&@)%&+"#&&//•
3d%$"-&%0/)%+"#&&//T&@! ,*C•&"‘&
&"-&BAC)C&"-&4)G&!:&%)%&•
3e)%&//S,?&,?&$G!J4*K&!L,?&$G!J4
/!L`,`AOYC]3
B. Bài tập
3RJ&@)%&!-)l$%A/%)%&$G"T$)G&µ,3d%)%&A/
*C•)&)&$%$/m,,$%$!'&@)%&3_A,J,!=)&)&
$%$,=;&$://*C,J!8rm,&"D/!"#$,J+&`&//3
a
/_>*&$%$&V//`)%&J+&!=A&*K&*>•
…%$!66A>$.//`!<•
$t=A"T$,JA&/*CS,J,?&;&A&)$G/,=)&)&4

nµ,$G$)(m3e!G+&`&//$G&1/!L•
4Y*K&!=,?&,8!L*&&V/,,=;&$://*C
,J$(?&1'AJ&$./,k`&//`&D€mb,,3_>$)($./$(?&•
n3d,J$F,%)%&!-)l$)&)&"T$)G&λ=µ,,J,&,?&
,=)&)&c,-i&A&*K&*>$G$)(=o4"T,J&G$T=o

3
f?'4?($./,&,?&c&/! $F,/78$G$"D&!J)%&
$E$!8•
o3N)%&Al&$G"T$)G&!'A&$F&**boµ,!\µ,!!
K&&G$,J,?&$G$)(=oo$G!J4*K&!L4=onµ,-i&
A&*K&*>3f?T"T$)G&λ1%)%&78I,?&)%&(!T
&"D0/)%•
b3d,J$F,%)%&!-)l$)&)&$G"T$)G&λ=µ,!"#$A2K&
&G$T,J,=,.$)(=3…%$!6&G$&&$./,3|Ac&
*&$%$&V//`)%&c&,,&G$&&$./,A(Q)α≈α3
3e&$%$&V//*CA&,%&//•&/=,,3e&$%$I,
0/)%T,=;&$://*Cr=o,3t=A"T$,JA&/*C)%&,J,?&$G
/,=)&)&$)(='4C=µ,3N)%&$+&$G"T$
)G&λ=µ,3f^7%$!66A>$./`)%&:/3
3d,J$F,%)%&!-)l$)&)&"T$)G&λ=µ,,J,&,?&
,=)&)&c,-i&A&*K&*>$G$)(=o4"T,J&G$=

3f?
'4?($./,&,?&c&/! $F,/78$G$"D&!J)%&$E$
 •
y3_A,J(,.;&$)(=&"D/.,J,&,?&A&
)$G'4*K&!L$)(€=b3RJ$F,)%&!-)l$)&)&$G"T$)G&λ=
yµ,$K&&G$T,&,?&3f^7%$!6'4 $./,&,?&Ac&
4&//$F,/78$G$"D&!J)%&$E$!83

a3t !'4$./,J,?&A&)&"D/!=A"T$,JA&/*C$./
,%&//•&,J,?&$G'4*K&!L$)(=3N)%&$
+&$G"T$)G&λ=µ,3Y&"D/0/)%(`)%&$>&V/646$$ '
6A>$./`)%&::&T9$$"/!=,?&3f^7%$!6'4$./,?&3
\
CHƯƠNG 3
Sự nhiễu xạ ánh sáng
\yn
*) Mục tiêu:
+) 
!"#$!6&‚/+"#&Œ78%)%&!'*+! 7A/+
"#&Œ78%)%&3
45&&f&C)BAC)C! &>$+"#&Œ78%
)%&3
45&"-&%!T$<BAC)C! >!J4/!J&)%&8,J
! ,A&,KA"D&3_I!G*)%+"#&Œ78$./)G&$<Œ78$./)G&
;&3
!"#$:&45&$./+"#&Œ78$%$i;&,%0/&L
$%$iŒ78/…3
 !"#$Z&)(`&$./$%$45&$50/&2$3
+) 
WP!"#$$%$!T$<$%$1P,K>&+,Œ783
~!"#$$%$'Œ78%)%&3
+) 
>$,K2$>$$E$&$:A/!L*:$$./$"-&3
3.1. Hiện tượng nhiễu xạ ánh sáng, nguyên lí Huysghen - Fresnel
*Z, !d?
j;(0_)a0b!"*+!kJ$$W
W>45rF&*,*`!`,.&,Jk‰A,J(,1/A2!G,J$F,
%)%&%A/I,J&@0/(*>3t=,lS&*%7/F&)%&12$

ƒ!"#$%)%&3
W>45nt=,J!84`*,8,)&)&T,J*C)%&3/!84`/
!=,J,0/)%•)&)&T!84`3e0*0/)%A&F&G&/
($GV&`)%&7C*P3
Y7Qd/>45A!'>&+,Œ78%)%&/(%)%&*K&
`C!6A';&3R$l$Gk‰!84`,$%$$!G&/AO
`8$"D&!J)%&A,0/)%3
!"*+!kJ$$Wf+"#&Œ78%)%&+"#&%)%&
+$*?"-&A';&A&,KA"D&!@&>*&=$3
*;<=ZK
Rk! ,$./,KA"D&,,=!<)G&!8T$G 7C,
",J&@)G&&3R=!<)G&,T/1$./
($$%$)G&%$<&3
**;<=ZKeJ"KK
;!)P%QW|!J/$./&@:$(
!J/4&@E$‰&`A/86A>$./&@:$(3
_) ;$!.MXW
~)i :$$./4/!J&)%&S&@
n
MX

( )

• „$) n  _= π
o3
M…Q,J,=*>σ!G/0/&25]LaL$$,=$G148&
!"#$$2FJ$%$5 →,k,J! ,A,=5!'AS&@
%)%&:$(3r/!J&)%&8R

R

„  A
• $)n
A _
 
= π −
 ÷
λ
 
AmRo3n
„
R
=„vA1,!J4O&Z&"#&%)%&8,J! ,!GA&*K&&/[+
&6$T4+>$$./,=)G&0/! ,!G3
Md/,=5σ'<K$F&?4σ4σ$",J&@53| 
:$4/!J&)%&4&@5c,8R)P&`A/Sj

( )
„   A A‡
4• 4 3 $)n 4
A A‡ _
+
 
σ = χ π − σ
 ÷
λ
 
A€=Rjo3o
χ+)5J$$%$&G$θθ‡θ&G$,S%$./,=σSRT
"-&$./)G&TRθ‡&G$,S%$./,=σ8RT"-&)G&Œ
78Rj3

χ$E$!8*θ=θ‡=χ=*θ‡≥πvn→4σ%)%&,8(C"-&%
*K&%)%&C$%$"-&,T%,J&G$T-πvn3
Mr/!J&4&@&`A/8j

( )
j
„   A A‡
• 4• 4 $)n 4
A A‡ _
σ σ
+
 
= σ = χ × π − σ
 ÷
λ
 
∫ ∫
o3b
Xq! ,&
Md:&?!"#$%)%&*&=$)P6Œ783
M_1,!"#$ :$4/!J&)%&→>!"#$$"D&!J)%&8($:! ,A&
*K&&/3
3.2. Phương pháp đới cầu Fresnel, phương pháp giản đồ véc tơ
*X '99\CJ"KK
9$! [!
X…Q%$45&$./)G&%)%&%A/I&`A/8,J! ,j!G
Md2,=σAF&,=!<)G&,=$<`,3
M~)ij$l,=$<σ8! ,R

3(

j,`,PV&1$<$G%*>jR

=
A

 
 
jR A
n
λ
= +
 
n 
jR A n
n
λ
= +
  H
* 
jR A *
n
λ
= +
YV&1$<$l,=$< σ 
V&!T$<&2 [!'R@%3
_K- [!'MX
Mt=
 * *
R f =
!J$/$./$?,$<R


R
*
R
*
‡
M|%*>!T$<ρ
*
=R
*
f
*

n
MX


*

}A
*
} A
λ
ρ =
+
T*=noHo3
M_>$(%*>$./$%$!T$<›+T$Z$/$%$)&3
r+>$$./,J!T$<



}A

} A
π
∆ = λ
+
o3
M_>$(nr+>$$./$%$!T$<&<c&/3
_!P ;d+L
XY7Q
M_%$45&$./)G&%A/I$%$!TA&”&i!j$&Q&G$&V/%
$./,=!TT"-&A'!j$&T/

x/
n
x/
o
Hx/
*
Hx/

3
|!J4/!J&L&#8j

 
j
/ /
/
n n
= ±

o3y
R{∼
n
j
/
”18j! ,)%&$œ8j! ,3
)_( [!R@%
X…Q,=)G&$<6$lS,J,*K&A&)$GkAO‰%*>ρ

3!T
BAC)C$:/!"#$Ak

n


 
 3
} A
 
ρ
= +
 ÷
λ
 
o3a
A&!G}A

*&$%$I&@)%&TkIkT! ,jλ"T$)G&
%)%&)!T$:/Ak$G%*>ρ


3
*X '99`!97%)GUK)"
Rk,J4/!J&
( )
7 / $) = ω + α
$G  4Œc&C$A
/
r
3
eL&#'4/!J&7

4/!J&L&#


/ /=
∑
r r
&G$,C$A
/
r
,T
A5$‰7)P//!<$./4/!J&L&#3
3.3. Sự nhiễu xạ của sóng cầu (nhiễu xạ Fresnel)
**;d?7)-f"g
9*: ;$!.
MY%l@2U5;(%m [!R@%=oH/$G!J)%&L&#8j


  
j

/ / /
/
n n n
= + >
o3\
r!G$"D&!J)%&8j)PT-$"D&!J)%&{
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**K&$G,$l&V/&@
! ,j3
MY%l@2U5;(n [!R@%=nbH1!J4/!J&)%&L&
#8j

  
j
/ / /
/
n n n
= − <


j 
{
{ {
b
→ < =
o3
W$"D&!J)%&8j)P?-$"D&!J)%&{

8j**K&$G,$l3
nn

Kết luận! ,j$G )%&-/-)T**K&$G,$lFJ$
*>$"T$$./kAO3
MG!kJ
Xt=8j,J,0/)%•K&&G$TA5$73
Xf1Œ78@5!b $%g *+@B!$ b%!3$ *+!.%&
!=5$%m%& !=5(!n0&3%&f02@2!kJ
(!0&$J/g
*;d?7)--&"g+F")c
t=&V/! ,0/)%j,J,AO*K&A&)!‚/AO$l)%&%
*>A

)/$jA5$$./,AO3cG$OLY(*: ;$!.1o3o3
9*: ;$!.
X~)i,AO$C,(,!TBAC)C!<
, o
,  , 
j , n
/
/ /
/ / 333
n n n
+
+ +
+
 
= + − + +
 ÷
 
o3
MWT)!TBAC)C*K&6$CT

, 
j
/
/
n
+
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_($$%$! ,AA5$7$./,AOS)/
,AO!'$%$! ,)%&,=$4FA5$c,
A&,'G&12$3
MG!
ŽA/&T&V/G&12$,'!"#$A2
)%&C0/&12$$G7(+V&O&AO
Œ 784>!7:&0/7$./$%$ A>>
&+,!@&`,7C*P/$G`,KK! ,
)%&c,AA5$!7:&7$./,AO3
3.4. Nhiễu xạ của sóng phẳng (nhiễu xạ Fraunhofer)
|A>>&+,1o3b/(148&$./
Œ785J$148&*>$"T$$./k
A,r"T$)G&%)%&T3
*>;d?$%-+Kh9
~)i$G,J$F,/)%&!-)l$)&)&TA2
K&&G$,=*C•1$V$G!J4K8 
!JAJ&/!G3N)%&T)P6Œ780/*CC
V&&G$ϕ*%$/3_C&f&C)XBAC)C ,k
! ,$./,=)G&!8T*C,J&@%)G&:$(
A'!,2"-&3
NOLY(*: ;$
Md/*CV&4K$F&•)&)&T *C
$8„|$G!JAJ&471o3

MR=)G&AF&T,=*C)G&:$(4$%$4
%A/8$%$! ,A,=*C$G$F&/3
⇒
|!J4/!J&)%&4J*C&`A/SB
ϕ

no
MXX
MX
MX

/ )
)
/ )
• e ) 
/ )
π ϕ
π ϕ
 
λ
= ω −
 ÷
π ϕ
λ
 
λ
o3n
→$"D&!J)%&C"-&Œ78ϕ)P

n


n
)
{ {
ϕ
α
=
α
T
/ )π ϕ
α =
λ
 o3o
_A&!G
n
n
) α
α
I/)Œ78
W$"D&!J)%&A,0/)%5J$&G$ϕ:$5J$6A>$./
! ,B
ϕ
$GV&&%A6$E$!8$E$ {

$"D&!J)%&C"-&$./$F,/T
ϕ=3
?!b/!"O !0&O!=!kJW
Xt'*+$E$ Œ78
) *
/

λ
ϕ =
T*=±±n±oH o3b
W$L*S
ϕ
o5p !b/!"XO!=0b*: ;$F! 
*: ;$qr
Xt'*+$E$!8Œ78
)

π ϕ
=
λ
o3
e!G

• •
ϕ
=


{ {
ϕ
=
3
W! !=5R
r
U0[!
ϕ


=
rO !-*: ;$!$@6%[KFU
%&0Y$@Y59O !&2B!%&O !_
Xd%$$E$!8C$G&%A6+!?-')T$E$!8$>&,
/3d%$$E$!8&2O !Laf=$$G 7%$!6&<!9&C$K&:$
( )
) n* 
n/
λ
ϕ = +
o3
Xd"D&!J"-&!$./$%$$E$!85

( )
*
n
n

{ b
{
n* 
=
+ π
o3y
X|'AJ&$./$E$!8$>
n
4 Š3
/
λ
=

Š$E$./(*>o3a
M)0Y!kJ
M! ,)%&→Œ78,J4^! ,)%&7C*P/c,A,J
!"D&;&K&&G$T,Q*C3
M,J*C)%&•)&)&T*CŒ78→Œ78&@,V&8$)%&
$G$"D&!J&,4<)&)&T/)&)&T$%$*C)%&$%$/c&
V&*&3
W`)%&A&`,AJ&&(!KV&`)%&*%$3tJAJ&$./`)%&A&`,
!"#$7%$!6So3a ;@;-G!kJ35;/sL
*>;d?$%-f"g
X_>&+,d$F,/!-)l$)&)&K&&G$,J,$l$G*Q
,JkAO3
nb
Xf1Œ78
M$G48&,J+)%&AOc,8! ,B$./(*>
n
/0/G,J
O&AO)%&7C*P/3
Md"D&!J)%&$./V&O&AOA(Q)T$"D&!J$./)%&A&`,
&,*%/*$&7/`,3
Mt"D&*>kxxλ18`,B$./,0/)%•/0/)%!"#$,JA†Q
$./&@)%&→$G 7C,Ac&Œ78AF&T0/&12$3
*>*;d?$%+Kh9
|A>>&+,"1Po3
E`$"D&!J)%&A,0/)%
Md%$*C$G $$%$&@*#$
&+"#&Œ78&`S,J*C$O$G
+"#&&//&`S$%$*C3
MW11Œ780/,J*C*K&5
J$6A>$./*C$%$*C!'$$E$ 

Œ788! ,A,•,ϕ?/,^!'*+3
) *
/
λ
ϕ =
T*=±±n±oHo3\
d%$$E$ `&D!"#$&2O!=_
Mϕ=O !_!f
X…Q//*#7(%I/*C**!! ,R//!G$G+0/&
A11o3
4)∆ = ϕ
o3n
MY
4) *∆ = ϕ = λ
14/!J&)%&4//!G&`A/$4/!J&4$%$/
*#I$%$*C*%$&`A/8R!@&//! ,R)P)%&O !_3W6A>$./
$%$$E$!8$>
) *
4
λ
ϕ =
T*=±±nHo3n
M~V//$E$ $>$G $G'$E$!8$>&V//$E$!8$>$G$E$
 $E$ 53
MRJ$E$!8$>&V/ϕ=
Md%$$E$ $>S/$E$!8$>&V/
) *
/
λ
ϕ =

*=±±nH
M~V//$E$ $>*'/$G'$E$!8$>
) *
4
λ
ϕ =
*=±±nH)
$E$!8$>$G!"#$5J$[)4v/3RJ$E$!8:*!G*K&$O0/)%
!"#$$E$!8!GAF&T$E$ :(
) *
4 /
λ λ
ϕ = =
/
4
*
/
=
3|$$/($./
$E$!8$O0/)%!"#$c&
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