Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.
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How come an anti-reflective coating makes glass *more* transparent?
The book I'm reading about optics says that an anti-reflective film applied on glass* makes the glass more transparent, because the air→film and film→glass reflected waves (originated from a paraxial ...
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557 views
Quantum shot-noise and the fluctuation dissipation theorem
Classically, shot noise observed in the signal generated by a laser incident on a photodiode is explained as being due to the quantization of light into photons, giving rise to a Poisson process. In ...
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Is it possible to make glasses that make everything brighter, but do not magnify or focus?
Corrective glasses are usually intended to help focus light on your retina. Supposing I had good vision already, but simply wanted more light, could I make glasses that would send more light into my ...
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Put a sensor at the focal length, behind, or in front?
My intuition tell me that at the focal length a convex lens all the light converges to a point. Following that logic, it would make sense to me that a camera chip would either need to go slightly in ...
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The principle behind door peepholes
Hotels usually install peepholes in their doors so that a person inside a suite can see who is at the door without having to open it.
I understand that there should be a convex lens within the ...
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Operator norm directly from phase space representation of photonic quantum operator
I'm interested in calculating the operator norm of a Hermitian operator, say $B$, acting on the Hilbert space of square integrable functions. The context is I have an optical system in all its ...
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What is a backlit CCD sensor, and why might I prefer it to other kinds?
I've heard Astronomers talking about backlit CCD sensors, and talking about how much better they are than other types. What are they, why might I want to get one, and what are the pros/cons of this ...
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Why do rainbows have distinct colors?
When I searched on the Internet for the reason of formation of rainbows, I got many explanations like this one & this. All the explanations consider only one spherical water droplet (like this ...
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Fairly Broad Spectrum Light Source Options
I tried this sight before to find filtering options and got fantastic results, so let's try again!
I am setting up an experiment that requires light of two different frequencies (445nm and 350nm). ...
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How are classical optics phenomena explained in QED (color)?
How is the following classical optics phenomenon explained in quantum electrodynamics?
Color
According to Schroedinger's model of the atom, only particular colors are emitted depending on the type ...
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Is light red shifted in optical tweezers?
This is a question I put to my supervisor during my PhD many years ago, and never really got a satisfactory answer to.
In an optical tweezers, assume that a beam of light is used to move a glass ...
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Optimal telescope size?
Consider a diffraction-limited telescope with unobstructed aperture $D$. Such a scope is capable of yielding an angular resolution $\alpha$ that scales as $\lambda/D$, with $\lambda$ denoting the ...
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Why does your reflection stay the same size when you move further away from the mirror?
This was an experiment I saw in my son's workbook. It said to mark out the top of your forehead and the bottom of your chin on a mirror using a whiteboard marker. Then slowly move backwards, and ...
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How much detail can telescopes actually provide?
For example, could the numbers / letters on a postage stamp in a randomly specified location be clearly visible from space.
This is to settle a discussion with a friend that piqued my curiosity.
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Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
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299 views
Where does the energy go, when light is blocked by polarisation
I've been looking around about LCD monitors, and how they polarise light. When a pixel needs to be black, the light is "twisted" so that it can't go through the polarising sheet in front.
What happens ...
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How does the Kinect device work?
Some explanations of the device base it on a simple echo of light: "The camera transmits invisible near-infrared light and measures its “time of flight” after it reflects off the objects. ...
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How does a photon travel through glass?
This was discussed in an answer to a related question but I think that it deserves a separate and, hopefully, more clear answer.
Consider a single photon ($\lambda$=532 nm) traveling through a plate ...
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How is squeezed light produced?
Ordinary laser light has equal uncertainty in phase and amplitude. When an otherwise perfect laser beam is incident onto a photodetector, the uncertainty in photon number will produce shot noise with ...
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Do eyeballs exhibit chromatic aberration?
Fairly straightforward question. If not, why not?
I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.
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What are the differences in using an eyepiece with a barlow instead of a shorter eyepiece?
I intend to start making visual observations, and I want to know more about the difference between using barlow lenses and one or two eyepieces and using a complete kit of eyepieces, both for ...
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What makes a good set of binoculars? [closed]
After trying a bunch of binoculars at Star Parties and the like, I have a pretty good feel for about what aperture and magnification I'd like in a new set binoculars. I'm an eyeglass wearer so a long ...
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complex numbers in optics
I have recently studied optics. But I feel having missed something important: how can amplitudes of light waves be complex numbers?
I suppose this is quite fundamental, but I do not find the answer ...
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Why does light change direction when it travels through glass?
This was explained to me many years ago, by a physics teacher, with the following analogy:
"If someone on the beach wants to reach someone else that is in the water, they will try to travel as much ...
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Do all light rays from a point passing through a thin lens converge at the image?
I have often seen diagrams, like this one on Wikipedia for a thin convex lens that show three lines from a point on the object converging at the image. Do all the other lines from that point on the ...
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Can a photon exhibit multiple frequencies?
Can a photon be a superposition of multiple frequency states? Kind of similar to how an electron can be a superposition of multiple spin states.
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Far-field intensity from scattering of small particles
Howdy, I'm building a simulation for looking at the light field underwater. In order to verify my simulation, I'm looking for some data showing the far-field intensity that comes from single ...
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Is apparent horizon curvature lesser due to refraction of light in the atmosphere?
I have encountered this claim while searching for sources answering " Can we see the curvature of earth from the top of world's tallest building? ".
Wikipedia article on horizon claims (with no ...
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Why does a blue sky at dusk appear nearly black through a telescope?
Earlier this evening I was looking at the Moon through my cheap toy telescope (x150 magnification) when I noticed a (rather mundane) optical effect I couldn't explain. The Sun had just dipped below ...
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Where does energy go in destructive interference? [duplicate]
I have read that when two light waves interfere destructively, the energy contained within is transferred to other parts of the wave which have interfered constructively. However, I am having some ...
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Boundary Conditions Invariant Under Conformal Transformations in Electrostatics?
in two dimensional electrostatics it is assumed that the whole physical system is translationally invariant in one direction. Here, the two-dimensional Laplace equation $$\Delta \phi(x,y) = ...
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Does a perfect mirror behave the same as a blackbody radiator?
If I put a perfect mirror(i.e. reflects with no attenuation) next to a blackbody radiator its spectra should be the same as the blackbody radiator.
Looking only at the spectra - is there any ...
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What does the Rayleigh Phase Function tell us
I am working on some radiative transfer equations, and struggling as I'm fairly new to this field. I have read about the Rayleigh Phase Function which is:
$P(\theta) = \frac{3}{4}(1 + cos^2 \theta)$
...
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light ray 'entropy'
Is there something like an entropy law for light rays?
I came up with the following experiment: A black box has two circular holes in it, a small and a large one. I don't care about there ...
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Converting between brilliance, intensity, and flux
This one should be a bit of a softball, but I can't find it explicitly stated anywhere on the internet, and my basic unit analysis doesn't seem to work.
Suppose you have a beam of synchrotron ...
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Eyes open under water
Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
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Why is visible light used in Optical fibers (instead of other EM waves)?
Why aren't other electromagnetic waves used in optical fibres instead of visible light?
Is it because the wavelength of light fits the internal reflection/refractive index of the material used for the ...
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Why does the sky look black in pictures taken from the summit of everest?
In pictures taken from the summit of Mount Everest (such as this one), the colour of the sky is a very dark blue or even black in some pictures. I remember from my own experiences of hiking in the ...
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Infrared remote flashes blue light in camera
I know that if you held an infrared remote in front of a digital camera, it'll flash a blue/purplish light when you press the buttons. Why?
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Optics of the eye - do we see Fourier transforms?
I've recently been learning about Fourier optics, specifically, that a thin lens can produce the Fourier transform of an object on a screen located in the focal plane.
With this in mind, does the ...
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Why don't waves with different wavelengths interfere with each other in white-light?
The book I'm reading about optics says at some point that "each color (wavelength) contained in the white light interferes only with itself". But why is this so?
Edit: I moved the rest of the ...
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Can anyone explain to me why light is not dispersed into a spectrum through a parallel glass slide, but only through a prism?
The question pretty much sums up what I need to know. Why is it that light only gets dispersed into a spectrum when travelling through two non-parallel sides(like a prism) and not through something ...
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A telescope with a bunch of small mirrors
Together with colleagues we got this question. Imagine to take small mirrors, the size for example of a dentist mirror, and stick them to a wooden frame with a parabolic shape. Each mirror is flat, ...
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How does infrared light 'erase' phosphorescence on zinc sulfide?
I found some sheets of zinc sulfide in my basement that phosphoresce green for up to 24 hours or so after exposure to bright light in the violet range or shorter. One of the first things I tried was ...
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Why does light reflect more intensely when it hits a surface at a large angle?
I mean, what is happening at a microscopic level to cause this behavior? Here's what I got from Wikipedia:
On Reflection (physics)#Reflection of light it says that "solving Maxwell's equations for a ...
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How can we describe the polarization (of light) coming from an arbitrary angle?
In an optics lab, where all optical beams pretty much reside in a plane, it is fairly simple to describe (linear) polarizations as vertical or horizontal (or s and p).
When we start talking about ...
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Why does the index of refraction change the direction of light
I've been studying in optics the macroscopic maxwell's equations, and how electromagnetic fields propagate through different mediums. Over there, the index of refraction appears, as a complex function ...
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How do “holographic plates” work?
I asked a question about laser stage lighting over at Audio Video Production, and received an excellent answer that explained that laser clusters are generated from a single beam via something called ...
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Filming light in motion?
Regarding this video http://www.youtube.com/watch?v=Y_9vd4HWlVA, which claims to "film" light in its motion.
Is it not an absolute nonsense?
Even if photons could even be "seen" (meaning, returning ...
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Optics: Derivation of $\vec\nabla{n} = \frac{d(n\hat{u})}{ds}$
I have been given this formula from optics here, with no background:
$$\vec\nabla{n} = \frac{d(n\hat{u})}{ds}$$
Where $n$ is the refractive index and $\hat{u}$ is a unit vector tangent to the path ...
