Physics 202, Lecture 28
Today’s Topics
!!Diffraction
!!Reminder of Single-slit Diffraction
!!Reminder of Two-slit Interference
!!Double-Slit Diffraction
!!Diffraction on Circular Apertures
!!The Rayleigh Criterion
Single-Slit Diffraction Pattern Explained
"!The slit is not a point source! Interference
The text also offers a derivation using phasors.
Not to be examed but please read.
!
I=I0
sin(
"
/2)
"
/2
#
$
%
&
'
(
2
"
)2
*
+
Dsin
,
!"
D
#y
$=2%/& ysin! @y"
E0
y
Reminder: Single-slit Diffraction
!
I=I0
sin(
"
/2)
"
/2
#
$
%
&
'
(
2
"
)2
*
+
Dsin
,
D
D
D
D
D
Separation between minima =
!
"
D
Reminder: Two-slit Interference
path length difference
' =dsin! ~ d! ~ d y/l
!
I=Iocos2
"
dsin
#
$
%
&
' (
)
*
Separation between minima =
!
"
d
