Interferometry of distant sources

In summary, the conversation discusses the challenges of obtaining accurate measurements of fringes from extended sources with a large energy spectrum. It is noted that when the source is a star, the fringes appear to be pointlike and there may be an advantage in terms of bandwidth. The concept of coherence length is also brought up, with questions about its definition and how it is measured. The speaker is not familiar with the topic but suggests that the coherence length may not apply to broad-spectrum light with random phase variations. Lastly, it is mentioned that the coherence length of light from a star is related to its emitted bandwidth, but it is unclear how this applies to the measurement.
  • #1
naima
Gold Member
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When you try to get fringes, the worse is when the source is extended and the light has a large energy spectrum.
With a star, the source seems pointlike. Is there another advantage as regards with bandwidth?
 
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  • #2
naima said:
Is there another advantage as regards with bandwidth?

What do you mean?
 
  • #3
Suppose that an optical polychromatical signal is emitted at a given pointlike place during T. It has a coherence length there. When the signal propagates its shape changes and its Fourier transform too. If we measure the coherence length at a far distance of the souce, Is it the same?
 
  • #4
I read that the coherence length of the light coming from a star is ##c/ \Delta \omega##
What is the definition of this Delta? How is it measured?
 
  • #5
I'm sorry, I don't know much about this topic, but I'll try to help as best I can.

naima said:
If we measure the coherence length at a far distance of the souce, Is it the same?

If we're talking about broad-spectrum light, then I'm not sure there is a coherence length since the phase varies randomly.

naima said:
I read that the coherence length of the light coming from a star is ##c/ \Delta \omega##
What is the definition of this Delta? How is it measured?

I think delta is given by the bandwidth of the emitted light. I'm not sure how this applies to the light emitted from a star, though.
 

1. What is interferometry of distant sources?

Interferometry of distant sources is a technique used in astronomy to observe and study objects that are located far away from Earth. It involves combining the signals from multiple telescopes to create a high-resolution image of the object being observed.

2. How does interferometry of distant sources work?

Interferometry of distant sources works by combining the signals received from multiple telescopes, which are spaced apart at a certain distance. The signals are then interfered with each other, creating an interference pattern that can be used to reconstruct an image of the distant source.

3. What are the benefits of using interferometry of distant sources?

Interferometry of distant sources allows for a higher resolution of images to be captured, which can provide more detailed information about the object being observed. It also allows for the observation of objects that are too far away to be seen with a single telescope.

4. What are some examples of objects that can be observed using interferometry of distant sources?

Some examples of objects that can be observed using interferometry of distant sources include distant galaxies, quasars, and other celestial bodies that are located millions of light years away from Earth.

5. What are the challenges of using interferometry of distant sources?

One of the main challenges of using interferometry of distant sources is the precise coordination and synchronization of multiple telescopes. The signals from each telescope must be carefully combined and aligned in order to produce a clear and accurate image. Additionally, atmospheric conditions and other sources of interference can also affect the quality of the data collected.

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