Sagnac Effect/Interferometer

  • Thread starter n0_3sc
  • Start date
  • Tags
    sagnac
In summary, the Sagnac Effect involves a ring cavity with two beams traveling in opposite directions. This causes an interference pattern due to the rotation of the entire cavity at some angular velocity. This can be better understood with an external light source, where the beams travel through different path lengths before meeting at the detector. If the source is also part of the rotating setup, a more careful explanation is needed. It is recommended to refer to a good source for further understanding.
  • #1
n0_3sc
243
1
I'm having trouble understanding the Sagnac Effect.
So far all I know is that a ring cavity is formed where 2 beams travel in opposite directions. My question is:
Why do the 2 beams form an interference pattern if the entire cavity is rotating at some angular velocity?
 
Physics news on Phys.org
  • #2
This is easier to see when you have an external light source, in which case, even thinking non-relativistically, you can see that the beams traveling in opposite directions travel through different path lengths before meeting at the detector. (This is similar to what Michelson and Morley were hoping to see).

For the case where the source is also part of the rotating setup, this requires a more careful explanation. It might be better to just refer you to a good source. I can't think of one at the moment, but I will, in a bit.
 
  • #3
if you had an external light source, is this rotating as well? if not wouldn't that mean that all the mirrors in the cavity would have to be beam splitters?
Thanks for the help.
 

1. What is the Sagnac effect?

The Sagnac effect, also known as the Sagnac Interferometer, is an optical phenomenon that occurs when a beam of light travels in opposite directions along a closed path. It was first observed by French physicist Georges Sagnac in 1913 and is used in modern technologies such as fiber optic gyroscopes.

2. How does the Sagnac Interferometer work?

The Sagnac Interferometer uses a beam splitter to split a single beam of light into two beams. These beams then travel in opposite directions along a closed path, and when they are recombined, they create an interference pattern. This pattern is affected by the rotation of the interferometer, allowing for measurement of rotation rate or angular velocity.

3. What is the principle behind the Sagnac Interferometer?

The Sagnac Interferometer is based on the principle of interference, where two or more waves combine to form a resultant wave. In this case, the two beams of light traveling in opposite directions create a resultant wave that is affected by the rotation of the interferometer, allowing for measurement of rotation rate.

4. What are the applications of the Sagnac Interferometer?

The Sagnac Interferometer has various applications in scientific research, navigation, and engineering. It is commonly used in fiber optic gyroscopes for precise measurement of rotation rate and in ring laser gyroscopes for navigation and guidance systems. It is also used in interferometric sensors for measuring small changes in length or displacement.

5. What are the advantages of using a Sagnac Interferometer?

The Sagnac Interferometer has several advantages over other types of interferometers. It is highly sensitive and can detect small changes in rotation rate or displacement. It is also compact, easy to align, and has a long-term stability, making it ideal for use in various applications. Additionally, it does not require a reference beam, which simplifies the setup and reduces cost.

Similar threads

  • Optics
Replies
1
Views
781
  • Special and General Relativity
Replies
19
Views
929
  • Special and General Relativity
2
Replies
40
Views
2K
  • Other Physics Topics
Replies
5
Views
9K
  • Quantum Physics
Replies
2
Views
161
  • Advanced Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Atomic and Condensed Matter
Replies
3
Views
2K
Replies
12
Views
924
  • Special and General Relativity
Replies
8
Views
427
Back
Top