Coherence Definition and 124 Threads

I'm trying to understand Newton's rings. So we have a plano-convex lens supported in a plane (please, see image here http://scienceworld.wolfram.com/physics/NewtonsRings.html). The incident light is divided into the light that is reflected at the convex surface and the light that is reflected at...

Hi, 1. I am studying dynamic light scattering in which one experimentally measures intensity correlation i.e., <I(t)I(t+tau)>. Therefore, if the detector looks at a scattering signal from a solution of particles undergoing Brownian motion, under right experimental conditions one can detect the...

I want a clarification in the idea of superposition principle.Perhaps,I should rather say that the distinction of superposition principle in QM and in classical physics. Few weeks back,I was spending time with Gottfried's book. He explains the novelty of superposition principle with the help...

Coherent states are defined as eigenstates of the annihilation (lowering) operator for the quantum harmonic oscillator. So why are these called "coherent"? What does "coherence" generally mean in physics? And what does it have to do with what is known as "quantum de-coherence?" Edit: I...

Homework Statement Monochromatic light (λ = 500 nm) from a particular light source has a frequency bandwidth Δν = 6 x 1011 Hz. (a) What is the coherence length Δx and the coherence time Δt of this light? (b) What is approximately the largest optical path length difference in an...

Ranges of coherence lengths for... I am dealing with a bit of a problem here figuring out a table of ranges of coherence lengths for; white light, filtered gas discharge tubes and lasers. I would greatly appreciate it if someone would be able to give me a hand with obtaining these values...

Hello, I don't know if anyone is familiar with OCT, but my question is rather specific and a well explained answer is in my opinion nowhere to be found ... In OCT, a low coherent light source is used in a simple Michelson interferometer setup. One beam (reference beam) is sent onto a...

hello forum, coherence function and correlation functions are the same thing. If we consider a sinusoidal signal like cos(t), and we calculate the correlation function, we obtain a periodic function. That means that in some cases cos(t) and cos(t+tau) are very similar, for some other time...

Hey folks. I'm giving a poster at a conference in a month or so and I'm supposed to explain my research (optimal control of quantum systems in dissipative environments) to people from many other disciplines (psychology, biology, etc). I'd like to hear any tips those on this board have on how to...

Is there an established context in which the oscillation of a pendulum between potential and kinetic forms of energy can be described in term of coherence, that is, viewed as an oscillation between coherence and incoherence? (here incoherence is taken as the antonym of coherence)

Hi. I have 2 questions about second-order coherence – g2(t): 1) For collision-broadened light according to the literature g2(t)=1+|g1(t)|^2, where g1(t) is the 1st order coherence. Therefore for very low collision rate g1(t) =1 and thus g2(t)=2. However I would expect collision broadened...

Homework Statement light is incident on an equilateral triangular prism (n=1.55) at a 35 degree angle from the normal to one of the faces. What is the exit angle?Homework Equations The Attempt at a Solution 45 degree

Homework Statement What is partial coherence , its in my syllabus but teacher has not taught us & my university exam is in a few days ? Any links will be useful Homework Equations The Attempt at a Solution

I'm bit confused about using terms temporal coherence and transverse/longitudinal spatial coherence when speaking about electro-magnetic radiation. I have understood that temporal coherence basically means how monochromatic light is. But I don't understand why temporal coherence is related...

Hi, I just passed a course of a quantum coherence theory (or quantum optics). However, during the course i found more questions rather than answers. One particular: Imagine there's a white light coming from the sun. What is the coherence length of this light, according to the quantum...

Please,can someone explain me spatial coherence?

Hi, I would like to know what do you think about the Giuliano Preparata theory on QED coherence in matter. He studied the problem of the ground state in condensed matter under the hypotesis that the standard perturbative vacuum is unstable with respect to a new coherent vacuum, whose...

just wondering why all photons produced in a laser beam are coherent? what forces them to have the same phase?

why do different probability waves synchronize into one coherent wave at low temperatures? I'd like to research this but I don't know what this effect is called. Also, what is the quantum mechanical explanation for why the resistance in a super-conductive metal drops down to 0? Is it that the...

I'm having some trouble understanding the idea of coherence. Consider the phrase: "a coherent superposition of states." Here I understand the coherence to refer to the states being coupled to each other and capable of interfering, due to a perturbing field. How does this relate to...

To spin my last post a bit further: It appears that one could say then that the temporal coherence of a given frequency spectrum can not be less than the coherence time associated with the spectral width of any absorption features in the spectrum. Thomas

Hi! I'm new here, but I hope that someone would evenly help me! My first question is about the problem (3.3 on page 100 from Loudon - The Quantum Theory of Light 3ed) in the attachment; the second question is about discussing (I)the physical origin of fluctuations of the electromagnetic...

Pascal principle with light pressure Hello, Supose you have an U tube, in which the inner walls are made absolutelly reflective. Now, put a termical state (temperature T) for the radiation field inside the tube and close it with reflective discs which can slide without friction. Supose...

Optical "coherence" A question on the nature of coherence that came up on Wikipedia... If we pass the light from a laser through a stack of frosted plates, is the result still "coherent light?" For most optical applications requiring coherent light, this type of heavily diffused laser light...