Questions tagged [coherence]
Coherence describes properties of correlations among physical quantities of waves, with special emphasis on constant phase differences and frequencies in common. Such collective linkages enable stationary (temporally and spatially constant) interference.
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Understanding interference of non-overlapping pulses [duplicate]
I'm going to show that two delayed pulses can interfere spectrally, and that this interference is measurable, without the two pulses significantly overlapping with each other in time (or space). My ...
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What is the laser linewidth?
I want to measure the linewidth of a laser in practice (ideally both before and after locking it to a ultra-stable cavity). I expect linewidths of 10's kHz, before locking, and 100 Hz - 1 kHz after ...
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Coherence of light
I have several questions about the coherence of light. I hope you can help me.
First of all, what is the most accurate definition for coherence of light? The ability to maintain a constant or ...
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Viewing incoherent light sources as addition of coherent sources
Imagine an extended and incoherent light source like a lightbulb filament as a conglomerate of infinite (or finite, if it makes the explanation easier) point sources, which should coherently emit one ...
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Measuring coherence length of a diode laser
I am using a Michelson interferometer to attempt to measure the coherence length of the 1st order beam of a 667nm diode laser reflecting of a 1200li/mm diffraction grating and passing through a 20 um ...
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How can radio synthesis telescopes do interferometry from atomic hydrogen clouds(say) when the light from the cloud is incoherent?
The atoms in a hydrogen cloud are undergoing 21cm spin flips in an incoherent/asynchronous manner so the light they produce isn't coherent, is it?
If so, how can we do interferometry with multiple ...
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Would the sum of two perfectly monochromatic waves be coherent?
I am struggling to understand classical, first order degree of coherence.
It is often said that coherent light must be monochromatic, i.e. that only a perfectly sinusoidal wave can be considered ...
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What are the conditions for two light sources to be "coherent"?
The sources must have a constant phase relation; a constant phase difference to be more specific. The sources having the same frequency is a natural consequence of this, if phase difference is ...
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What is that relation betweet coherence and supersolidity?
While reading an article about supersolidity I came across the phrase "an ordered crystal structure with a
phase coherence that allows for partial superfluid flow
through the solid ". What ...
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A simple fact I can not explain to myself using Copenhagen interpretation?
Let’s describe briefly the Michelson-Morley experiment in terms of single photons. A photon is launched by a laser from point A and meets the BS beam-splitter 50/50 in point B. Then it has two equal ...
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Difference between quantum coherence and quantum superposition
Pretty much as the title suggests, is there any concrete difference between the two phenomena? Or is it stemming from using different words in different areas of quantum mechanics, because as I ...
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How to introduce a linear optical path difference (OPD) across a plane wave?
I'm working on a version of coherance scanning interferometry (CSI) - very similar optically to a Michelson interferometer with a sample and reference beam combined to produce an interferance pattern -...
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Coherent effects in inelastic (neutron) scattering
From my understanding, a neutron scattered in an inelastic scattering event, will always be scattered in a random direction. If this is the case, it seems that any form of interference would be ...
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X-ray diffraction: coherence of the radiation source
In diffraction/interference processes I've always thought that coherence is an important condition for the source. If I well understand this is also why we choose punctiform sources of light which ...
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Is power spectrum a sufficient condition for determining autocorrelation function via Wiener–Khinchin theorem?
For an optical source with power spectrum as 𝐼(𝜔), the autocorrelation function is related to power by a Fourier relation (Wiener–Khinchin theorem).
F{𝑔(𝜏)} = 𝐼(𝜔)
However, the above relation ...
