线偏振光or平面偏振光
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I. Polarizing and polarization analyzing (起偏和检偏) F Polaroid (偏振片) FPolarizing direction(偏振化方向)：permitting
the light vector passing through.
Poleroid
I0
Polarizing direction
the absorption ratio equals to 10%
1 I1 2 I0 (1 10%)
I2 I1 cos2 (1 10%)
I2 3 0.92 0.3
I0 8
FPolarized state:the oscillating state of light vector.
Classification Natural light Plane polarized light Partially polarized light Elliptically polarized light Circularly polarized light
the intensity is
1 I1 2 I0
After I1 passes through P2 , its polarized direction
is parallel to P2 and the intensity is
I2
I1 cos2
1 2
I0
cos2
300
I2 3 I0 8
3. Partially polarized light (部分偏振光) F The amplitudes of light vectors along all
directions at the plane which is perpendicular to the direction of propagation have different magnitude.
§17-11 Polarization state of light
F Electromagnetic wave is transverse wave F The electric field vector E in electromagnetic
wave are sensitive for most detectors. -- E-vector is called light vector.
I0
Ix
Iy
1 2
I0
2. Plane polarized light (线偏振光 or 平面偏振光) F The oscillating direction of light vector is
always located in a fixed plane.
Light vector
E
Oscillating plane
I0
4. Circularly or Elliptically polarized light
(圆 or 椭圆偏振光)
The end of the light vector moves with constant speed in a circle, or in an ellipse.
I0
I0
§17-12 Polarization of light Law of Malus
Discussion：
=0 or =1800, I2=I1 -- maximum =900 or =2700, I=0 -- minimum
I2 I1
-1800 -900 0 900 1800 2700
[Example] Two polarizing sheets are put parallely. Their polarized directions have the angle 300. Calculate when the natural light is incident on the polaroids normally, the intensity ratio of transmitting and incident light. (discuss two cases: the polaroids have not absorption the polaroids have 10% ratio of absorption.)
1. N源自文库tural light (Unpolarized light) F The amplitudes of light vectors along all
directions at the plane which is perpendicular to the direction of propagation have same magnitude.
I0 P1
I1 P2
I2
Solution ： no absorption
Assume the intensity of incident natural light
is I0 .
The light is fully polarized after passing P1 .
The polarized direction is parallel to P1 and
I0 P1
I1 P2
I2
polarizer
analyzer
F Polarizing--natural light polarizer plane
polarized light
I1
1 2
I0
F Polarization analyzing--to test whether the
incident light is polarized.
I2 ?
II. Malus law
I0 P1
A1, A2—amplitudes of
the polarized light.
I1 P2
A1
I2 A2
I2 I1
A22 A12
cos2
I2 I1 cos2
----Malus law
P1 A1 P2
A2
A1 sin A1 cos
the light vector passing through.
Poleroid
I0
Polarizing direction
the absorption ratio equals to 10%
1 I1 2 I0 (1 10%)
I2 I1 cos2 (1 10%)
I2 3 0.92 0.3
I0 8
FPolarized state:the oscillating state of light vector.
Classification Natural light Plane polarized light Partially polarized light Elliptically polarized light Circularly polarized light
the intensity is
1 I1 2 I0
After I1 passes through P2 , its polarized direction
is parallel to P2 and the intensity is
I2
I1 cos2
1 2
I0
cos2
300
I2 3 I0 8
3. Partially polarized light (部分偏振光) F The amplitudes of light vectors along all
directions at the plane which is perpendicular to the direction of propagation have different magnitude.
§17-11 Polarization state of light
F Electromagnetic wave is transverse wave F The electric field vector E in electromagnetic
wave are sensitive for most detectors. -- E-vector is called light vector.
I0
Ix
Iy
1 2
I0
2. Plane polarized light (线偏振光 or 平面偏振光) F The oscillating direction of light vector is
always located in a fixed plane.
Light vector
E
Oscillating plane
I0
4. Circularly or Elliptically polarized light
(圆 or 椭圆偏振光)
The end of the light vector moves with constant speed in a circle, or in an ellipse.
I0
I0
§17-12 Polarization of light Law of Malus
Discussion：
=0 or =1800, I2=I1 -- maximum =900 or =2700, I=0 -- minimum
I2 I1
-1800 -900 0 900 1800 2700
[Example] Two polarizing sheets are put parallely. Their polarized directions have the angle 300. Calculate when the natural light is incident on the polaroids normally, the intensity ratio of transmitting and incident light. (discuss two cases: the polaroids have not absorption the polaroids have 10% ratio of absorption.)
1. N源自文库tural light (Unpolarized light) F The amplitudes of light vectors along all
directions at the plane which is perpendicular to the direction of propagation have same magnitude.
I0 P1
I1 P2
I2
Solution ： no absorption
Assume the intensity of incident natural light
is I0 .
The light is fully polarized after passing P1 .
The polarized direction is parallel to P1 and
I0 P1
I1 P2
I2
polarizer
analyzer
F Polarizing--natural light polarizer plane
polarized light
I1
1 2
I0
F Polarization analyzing--to test whether the
incident light is polarized.
I2 ?
II. Malus law
I0 P1
A1, A2—amplitudes of
the polarized light.
I1 P2
A1
I2 A2
I2 I1
A22 A12
cos2
I2 I1 cos2
----Malus law
P1 A1 P2
A2
A1 sin A1 cos