Questions tagged [optics]
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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What makes diffraction spikes move with the focus?
This is a bit of a follow up on The Bahtinov focusing mask and it came with this question on Astronomy. But I think the effect can also be observed when looking through a hazy atmosphere or a stained ...
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How can daylight have a higher colour temperature (e.g. 6500 K or D65) than sunlight in space?
Supposedly, daylight at midday has a colour temperature of 6500 K. This reference is also the standard for calibrating computer screens (that's how I fell into this). However, outside the atmosphere ...
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Images formed by a pair of plane mirrors
I've been taught that if a point-sized object is placed between two plane mirrors at an angle theta with each other, then the number of images formed is $360^{\circ}/\theta$ or $360^{\circ}/\theta - 1$...
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What is the energy loss in total internal reflection?
In total internal reflection light inside a dense medium reflects from the boundary to a less dense medium. Since by Snell's law there is no allowed refracted ray, all energy continues along the ...
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Why does sunlight on these windows form caustics with a seemingly hyperbolic pattern?
I noticed these caustics outside my office about a month ago and took pictures: one facing towards the sun and one facing towards the reflective surface (a set of double-paned windows).
The seemingly-...
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Complex part of second-order susceptibility in nonlinear optics
In optics, the absorption of photons by a material can be described by considering the material's susceptibility. For linear absorption (involving a single photon), we think about the imaginary part ...
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Explanation for possible interference on a home mirror?
I've noticed that a few peculiar things about home commercial mirrors that aren't present with industrial/scientific mirrors.
This is one of the mirrors I used.
With the mirror like the one above, ...
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Are there yet Optical Magnetic Mirrors (OMMs) which reflect via interaction with the magnetic field?
update 2021: As the question has remained unanswered for five years and the field of optical metamaterials has advanced, I think this question can be revisited.
The most familiar mirror relies on ...
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Why is an exciton only observed when we excite to the conduction band and not to other electronic level inside the bandgap?
Excitons can be observed when we excite electrons to the conduction band.
I don't know about excitons being observed when we excite the electrons to an electronic level that would eventually be in ...
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Explaining phase shift from a half-silvered mirror
I am trying to understand why light undergoes a phase shift when reflecting off one side of a half-silvered mirror, but not the other side.
This Wikipedia page and this answer both give the following ...
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Spatial wave-function of a single photon and its measurement
In the last decade there were several papers claiming that they've measured a "transverse quantum state" / "quantum wave-function" / "spatial Wigner function" of a single photon:
Measurement of the ...
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How does the fractional Fourier transform apply to an out-of-focus imaging system? Do we use the fractional distance to the focal plane?
In Fourier optics it is sometimes convenient to think of lenses as "Fourier transformers". For an imaging system between two planes with a pupil in the center, the amplitude in the pupil is ...
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Books recommendation to understand Quantum Confined Stark Effect
I am starting a PhD on a photonic component involved with QCSE. The problem is that I have a Master degree in electronical engineering, not in fundamental physics, and I need to understand the QCSE in ...
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Simulation of a dispersive crystal mirror
I am trying to simulate a simple setup where I have a point source of broadband light whose light is incident upon a spherical crystal at a central angle $\theta_i$. Assuming Bragg diffraction some of ...
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Deriving the non-paraxial form of Rayleigh criterion
Background
The Rayleigh criterion of imaging resolution says that two incoherent point sources are barely resolved by a diffraction-limited system with a circular aperture where the center of the ...
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Is it caustic reflection or hyperbolic projection?
actually last night I noticed a strange form of light rays on the wall of my room which were reflected off a CD. Here is its photo:
Please let me know what is it exactly? A caustic projection or ...
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What is Curvature of eye lens?
I wanted to know what do we mean by "curvature of eye lens", is it the reciprocal of $r$ i.e $c=1/r$ or is it synonymous to radius of curvature of the eye lens. Moreover how does aperture relate to ...
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Finding the illuminance from a triangular light source
Since most light sources in games are point-like, it's pretty difficult to approximate area light sources with point sources. As triangles are a universal form to represent 3D models (thus area light ...
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Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon?
Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon? I don't think they have, because according to the theory, the illusion of the moon ...
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Homogeneous gain saturation and single-longitudinal-mode lasing
I am currently studying Laser Systems Engineering by Keith Kasunic. Chapter 1.2.1 Temporal Coherence says the following:
Whether or not multiple axial modes will lase depends, in part, on the cavity-...
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Is Hong–Ou–Mandel effect reversible?
According to Hong–Ou–Mandel effect, two photons coming from the different ports will output by the same port with 2 photons since the cross term is canceled by a 1:1 beamsplitter. Since "light ...
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Why does the sun not burn your retinas when in peripheral vision?
After going to the ophthalmologist and having bright lights shone in my eyes, I was thinking about how the brightness only hurts when I looked at the light. When it was in my peripheral vision, it ...
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How is the phase gain of a Fabry-Perot resonator for gravitational wave detection derived?
I am trying to understand the use of the Fabry-Perot (FP) resonator in the arms of a gravitational wave detector. A typical explanation is that the gain in power in the arms is equal to $\sqrt{F}$ (...
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Huygens principle and path integral for classical waves
I want to better understand what the path integral is and what it isn't.
Even though I do this to learn QFT, this question is purely concerned with classical fields, no quantization is intended at all....
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Confusion regarding Young's double slit experiment in different media
The Problem
Consider the given arrangement:
Point $P$ is equidistant from $S_1$ and $S_2$ .The glass slab in air has refractive index $\mu_{2}$, and the one in water($\mu_{1}$) has refractive index $...
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How smooth/rough is a liquid surface?
Surface tension makes liquid surfaces smooth, but how smooth? How rough?
This question has an Experimental version and a Theoretical version:
E : Optics manufacturers quote specs like $1/4$ or $1/8$ ...
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What causes this circular reflection to form?
Holed up at home, I was distracting myself by shining my green laser pointer around. Something particularly interesting happened when I pointed the laser at a reflective black plastic surface. The ...
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Interference of single photons emitted from solid state sources
Solid state emitters such as quantum dots are thought of as being amongst the best single photon sources for quantum technology.
There have been impressive demonstrations of >10 photon experiments ...
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Electromagnetic energy density in a nonlinear medium
The energy density associated with the electric field in a linear medium of permitivity $ \epsilon $ is given as
$$
U = \frac{1}{2}\epsilon\left | E \right |^{2}
$$
As Robert Boyd mentions in the ...
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Amplitude of single-mode field in a cavity
I have two contradictory result about the amplitude of single mode field when it is quantized
In C. Gerry and P. Knight's Introductory quantum optics, the amplitude is given by
$$\sqrt{\frac{2\omega^...
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Can I couple 1064 nm and its harmonic 532 nm in a single polarization maintaining fiber?
I have an experiment where I need to get a largish (40 mW) amount of 532 nm light and small amount (<50 µW) of 1064 nm light into a device under test. I need something with stable polarization so ...
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While flying over Rome we noticed that during sunset, there was a green color between the red and blue of the sunset sky. What causes it?
The picture has only been trimmed and not edited. The green is visible when the red or orange tapers off into the blue. Is this different from what causes the green flash? We were flying from Rome.
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Is there a material that allows light to pass perpendicular to the surface, but reflects at an angle?
This is inspired by Michael Steven's new video about optics.
He shows off Selenite, which has the property that light entering on one side travels perpendicularly down the crystal until it exits the ...
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How does "coherence" contribute to inverting a two-level system?
In laser physics I am told that inverting a two-level system is not possible, since it will become transparent once the inversion reaches 50% and no longer be able to absorb more photons. This makes ...
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The Purcell effect, it's influence on the lifetime and quantum yield (of fluorophores)
So I've been looking into the Purcell effect and how it interacts with fluorophores (fluorescent molecules). The Purcell arises when you have a dipole in a cavity or even just near a dielectric or ...
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Different Color Intenensities from simple ON/OFF RGB subpixels
I recently got interested in electronic paper.
One design that I liked was the one from Mirasol:
https://en.wikipedia.org/wiki/Interferometric_modulator_display
However, what I don't understand, is ...
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Location of lens having effective focal length
We know a/c to Gullstrand's equation that the effective focal length of two lenses separated by a distance $d$ is given as $$\frac{1}{f_{eq}}=\frac{1}{f_1}+\frac{1}{f_2}-\frac{d}{f_1f_2},$$ but the ...
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Why aren't all insulators transparent, since they have a large band gap?
According to Floris' answer in this link, diamonds are transparent as they have large band gaps while graphite is black as it is a conductor.
As electrical insulators generally have a large band gap, ...
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Quantify shade-off and halo effect in phase contrast microscopy
Shade-off and halo effect introduce distortion to phase contrast images. I am trying to utilize these features to write a program which could identify spherical cells from (positive) phase contrast ...
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Why does Light change color through Glass slab?
I shone a green laser light(~532 nm) through a glass slab and what I saw inside was that the light beam was now red.
Imagine a regular refraction diagram but color the beam outside green and that on ...
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Recommended books that describe emission and absorption of light and light/matter interactions
Hello I am a Chemical Engineer that has ventured into the field of optics and I was wondering if there is any recommended book/books to understand the maths and also some answered exercises or ...
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Optical Bloch oscillation
I have a doubt about how the optical Bloch oscillations happen in a 1D photonic crystal. I try to explain: in a photonic crystal with discrete translational symmetry in one direction I superimpose a ...
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Mathematical approaches to atmospheric refraction
Understanding atmospheric refraction, particularly of ultraviolet, and into the blue part of the visible spectrum is of great interest to me. Although, I have a strong background in trigonometry and ...
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Maximum-Entropy Method deconvolution implementation?
I am looking for an implementation of the Maximum Entropy Method for image deconvolution, ideally in MATLAB or Mathematica.
I'm trying to reconstruct an image from fringe visibilities, as is often ...
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Is it possible to calculate the work function of a metal with basic lab equipment?
I have been given a problem in physics, its to prove if a lump of metal we have been given is real gold or not. One way to to do it would be to work out its density, which is fairly easy, mass/volume. ...
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How does a broadband dielectric Mirror work?
It is widely known that dielectric mirrors work with several layers of at least two materials which differ in refractive index that are layered, such that partially reflected waves interfere ...
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Does conservation of Etendue mean focusing+filtering a larger led bulb into a point light in a way that casts shadows like a point light is impossible
I unfortunately never took a class on photonics but this law of Etendue seems to be very relevant to a project I am not even sure is possible. I am trying to create a lamp that does something like ...
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Book recommendation: adaptive optics
Does anyone know any good books for adaptive optics? It should at least include decomposition into Zernike polynomials. It is for PhD level, but any level is welcome.
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Numerical procedure for finding steady eigenstate for a non-Hermitian effective model
I am working with an effective model describing an exciton-polariton system. I need to solve the Schrödinger equation (eigenvalue problem). To describe the presence of losses the diagonal terms are ...
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Why is sunset in mars blue?
This is the Martian sunset, as captured by the Spirit rover of NASA. Notice the colors are inverted, i.e. the direct rays blue and diffused rays red, which is exactly the opposite of what you would ...
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