# Polarization change upon Reflection

• Xyius
In summary: There is no hint of any violation of any physical conservation law here. In fact it is not at all surprising - except possibly at first sight.
Xyius
Hello,

I am trying to determine how an electromagnetic wave changes polarization upon reflection off of an arbitrary object. Here are my confusions in particular.

1. My assumption is that the change in polarization is very much dependent on the geometry of the object, but I don't know the exact mathematical formalism behind it.

2. If the object is a PEC, will polarization be preserved upon reflection independent of geometry?

Xyius said:
Hello,

I am trying to determine how an electromagnetic wave changes polarization upon reflection off of an arbitrary object. Here are my confusions in particular.

1. My assumption is that the change in polarization is very much dependent on the geometry of the object, but I don't know the exact mathematical formalism behind it.

2. If the object is a PEC, will polarization be preserved upon reflection independent of geometry?

I have only a simple view of it which might help slightly, and I have two examples (assume transmitting Horizontal linear polarisation (HP) for illustration):-
1. If we have a rod at an angle to horizontal, then it will have a current induced in it by the component of the field lying along its axis. This current causes radiation polarised in the plane of the rod, and has a vertically polarised field component. The polarisation has been rotated. Complex objects might be studied using antenna analysis techniques.
2. Assume we have a transmitter, plane mirror and receiver all located on a flat table with a wave passing between them. No rotation of polarisation. But if the mirror is raised up so it is not in the plane of the table, and is tilted appropriately, geometry indicates that the reflected wave is now not truly H or V but is rotated. You can also see that an object viewed in the mirror is rotated. This is just geometry, "no physics" involved.

tech99 said:
This is just geometry, "no physics" involved.
Yes. That's the bottom line. There is no hint of any violation of any physical conservation law here. In fact it is not at all surprising - except possibly at first sight.

## 1. How does polarization change upon reflection?

When unpolarized light is reflected off of a non-metallic surface, the reflected light becomes partially polarized. The degree of polarization depends on the angle of incidence and the properties of the surface.

## 2. Why does polarization change upon reflection?

When light is reflected, the electric field of the incident light interacts with the electrons in the reflecting surface. This interaction causes the electric field to be oriented in a specific direction, resulting in a change in polarization.

## 3. Is the polarization change the same for all types of surfaces?

No, the polarization change upon reflection varies depending on the properties of the surface. For example, a smooth, flat surface will result in a different degree of polarization change compared to a rough, uneven surface.

## 4. Can the polarization change upon reflection be controlled?

Yes, the polarization change can be controlled by adjusting the angle of incidence or by using a polarizing filter. By manipulating these factors, the degree of polarization change can be altered.

## 5. What are some applications of polarization change upon reflection?

Polarization change upon reflection is used in various applications, such as polarized sunglasses, LCD screens, and polarizing microscopes. It is also important in understanding the behavior of light in different environments, such as underwater or in outer space.

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