Prof. Williams
3.30.2020
Diffraction Gratings/Laser
Purpose: The purpose of this experiment was to demonstrate the properties of diffraction gratings.
It was demonstrated that how would be the interference pattern change when there is different
wavelength, grating lines per mm, and grating distance.
III. DATA
Exp.1
Exp. 2
Exp.3
Exp.4
Exp.5
Exp. 6
Lens to Grating Distance (m)=
5
5
5
5
10
10
Grating Lines per mm=
200
200
400
400
200
200
Wavelength (nm)=
532
650
532
650
532
650
First bright spot on the right(m)=
0.52
0.65
1.1
1.35
1.09
1.3
Second bright spot on the right(m)=
1.1
1.35
2.35
3.05
2.195
2.7
First bright spot on the left(m)=
-0.52
-0.65
-1.1
-1.35
-1.09
-1.3
Second bright spot on the left(m)=
-1.1
-1.35
-2.35
-3.05
-2.195
-2.7
tan0=y/L
dsinO=mX
y=m2L/d
%(e)
exact
V.
CALCULATIONS
A. Calculate the position of the maximums using the diffraction equation.
Exp.1
N=200 lines/mm
d=1/N=1/(200 lines/mm)=5*10-3 mm/line=5*10-6 m/line
dsin0=m^
sin0= mX/d
0=arcsin(m/d)
0=arcsin(1*532*10-9/5*10-6)=6.108
tan0=y/L
y=L*tan0=5*tan(6.108)=0.535 m
%(e)
exact
0.535
calculated y
measured y (m)
0 (rads)
%(e)
EXP.1
(m)
First bright spot on the right(m)=
0.52
0.5350372
0.1066018 2.810494
Second bright spot on the right(m)=
1.1
1.0889414
0.2144397 1.015541
First bright spot on the left(m)=
-0.52
-0.5350372
-0.106602 2.810494
Second bright spot on the left(m)=
-1.1
-1.0889414
-0.21444 1.015541
calculated y
measured y (m)
0 (rads)
%(e)
EXP.2
(m)
First bright spot on the right(m)=
0.65
0.6555631
0.130369 0.848601
Second bright spot on the right(m)=
1.35
1.3463012
0.2630222 0.274741
First bright spot on the left(m)=
-0.65
-0.6555631
-0.130369 0.848601
Second bright spot on the left(m)=
-1.35
-1.3463012
-0.263022 0.274741
calculated y
measured y (m)
0 (rads)
%(e)
EXP.3
(m)
First bright spot on the right(m)=
1.1
1.0889414
0.2144397 1.015541
Second bright spot on the right(m)=
2.35
2.3516114
0.4396248 0.068525
First bright spot on the left(m)=
-1.1
-1.0889414
-0.21444
1.015541
Second bright spot on the left(m)=
-2.35
-2.3516114
-0.439625 0.068525
calculated y
measured y (m)
0 (rads)
%(e)
EXP.4
(m)
First bright spot on the right(m)=
1.35
1.3463012
0.2630222 0.274741
Second bright spot on the right(m)=
3.05
3.0439039
0.546851
0.200273
First bright spot on the left(m)=
-1.35
-1.3463012
-0.263022 0.274741
Second bright spot on the left(m)=
-3.05
-3.0439039
-0.546851 0.200273
calculated y
measured y (m)
0 (rads)
%(e)
EXP.5
(m)
First bright spot on the right(m)=
1.09
1.0700744
0.1066018 1.862078
Second bright spot on the right(m)=
2.195
2.1778827
0.2144397
0.78596
First bright spot on the left(m)=
-1.09
-1.0700744
0.106602
1.862078
Second bright spot on the left(m)=
-2.195
-2.1778827
-0.21444
0.785