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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Does shortening the path length of an excited Etalon do work? What about LIGO?

Start with a high-Q etalon excited on-resonance with a laser for a time long enough that it has built up an essentially stable standing wave. There is a constant outwards-directed force on each mirror,...
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How exactly to build the band diagram for photonic crystal?

How to build a band structure for the photonic crystal? I'd like to understand the full train of thought. I understand that we go on the perimeter of irreducible first Brillouin zone and somehow copy ...
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55 views

What is the angular divergence of sun-rays? [on hold]

I just want to find a number and I could not. Does anyone has it or can calculate it easily? Just in geometric optics, without diffraction, atmospheric effects and etc. Update: I think for me will be ...
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Free Optics Simulation Programs

I'm having an extremely difficult time finding an optics program that is easy to use and offers accurate physics simulations. I'm not asking for much, I just want to be able to simulate a laser going ...
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How does a photon 'know' when to reflect in case of refraction? [on hold]

In thin-film interference and in glass fibers refraction is involved. Depending on the angle of which a light ray enters the material it will be reflected or transmitted. The refraction depends on the ...
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Which optics should be used for a long range optic until around 800-1000m? [on hold]

I am planning in making a optics for long ranges to see up to 800-1000 meters. With a magnification of 10x-20x. How could I calculate the details of the objective lens, its diameter of tube and the ...
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31 views

Transition between raytracing and physical(wave) optics

In the past I have done raytracing simulations for large things, and physical optics (FEM, FDTD) for small wavelength-scale things. Now I have a very large lens that focuses down on a waveguide. I ...
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Is fluorescence from a single atom/ion visible with the naked eye (e.g. in a strongly coupled trap or cavity)

I remember sitting in on a conference talk by a person (possibly Rainer Blatt) doing research with trapped ions (or single atoms strongly coupled to light in an optical cavity), and the person showed ...
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What is the minimum optical power detectable by human eye?

If one is in complete darkness, what is the minimum optical power that the eye can "see" (let's say in 500-600 nm range). I found that for 510 nm, 90 photons can be detected (http://en.wikipedia.org/...
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355 views

Principle of Reflection on atomic level

The well observed phenomenon has besides several others has always been a fascination to me, we are well aware of several theories, experiments and practical applications of the well known phenomenon. ...
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Explain reflection laws at the atomic level

The "equal angles" law of refection on a flat mirror is a macroscopic phenomenon. To put it in anthropomorphic terms, how do individual photons know the orientation of the mirror so as to bounce off ...
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How to correctly calculate the colour of the sky?

It is well-known that the sky is blue due to Rayleigh-scattering. What bothers me though is the question how to actually calculate the spectrum of the scattered sunlight. Yes, use one of the ...
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Does a Polarizing Beam Splitter Cause Wave Function Collapse?

For a single photon, its polarization can be a superposition of two orthogonal bases (e.g. horizontal or vertical). However, as I understand, once it has been measured, it must collapse into one of ...
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How would we see the earth if refraction of light was significantly stronger?

On worldbuilding.SE there is a question about the cosmological consequences of a world with super-high refraction and atmosphere opaqueness. I'm assuming the easiest way to minimally change the laws ...
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44 views

Which materials redshift light?

I'm currently researching ways to get the human perceived colors red, green and blue when you only have a mostly blue spectrum available at your source (using electroluminescence). The solution should ...
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Wouldn't any structured beam of light be expected to travel slower than a plane wave?

There aren't many new, actual bona-fide discoveries in classical optics these days. I saw this news item in Phys.org: Observation of twisted optical beam traveling slower than the speed of light ...
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538 views

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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Can focal point of a lens be a line instead of a point

Is there any lens OR can we have a lens that will focus light in form of a line instead of a point. Some sort of a rectangular convex lens.
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644 views

How to use a magnifying glass or any lens to enhance small light power?

I am currently trying to amplify a tiny amount of light so that a photodiode will recognize it. In order to amplify the light I thought about using a magnifying glass since I got to know that such ...
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308 views

Luminance from multiple light sources

I have a LED diode: Given Luminance intensity [I] of $1.85$ cd. I want to have Luminance [B] from the light source of $75 \ {\rm cd/m^2}$. From $B=I/S$, where S is light source plane area, I get $S=...
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Jones formalism for calculating quarter waveplate angle for circular polarized light

I am planning to change the polarization of a vertically linear polarized laser to circular polarized light with the help of a quarter waveplate. I know the final result: I have to rotate the fast ...
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132 views

What's the meaning of partial derivative for radiance?

The definition of radiance is: $$L\equiv\frac {\partial^2 \Phi}{\partial A\,\partial\omega\,\cos\theta}$$ where: $\Phi$ is the radiant flux $\omega$ is the solid angle $A\cos\theta$ is the ...
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Increasing brightness of light source by reducing apature and reflecting the remainder?

Can the amount of light per area be increased by reflecting all but a small area of the lamp back on the light sources rear reflector or would the reflected light just end up as heat? I attempted a ...
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Why are magnetic quantum numbers assigned like they are assigned in the paper on WS2 monolayers?

Now I'm reading the following paper: Sie, E.J., et al., 2015. Valley-Selective Optical Stark Effect in Monolayer WS2. ‎Nat. Mater., 14, 290-294 And they assigned magnetic quantum number to valence ...
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75 views

What do we mean by speed of light dependent on direction?

I have a statement in textbook saying: When the speed of light is independent of direction, the secondary waves are spherical. When is it dependent on direction and how will the secondary ...
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Apparent depth is supposed to be independent of viewing angle but this seems inconsistent with critical angle diffraction

When rays from the object at some depth are draw so as to be incident at the critical angle (or some angle just lower) the ray is refracted along the surface. Retracing this line would give you an ...
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39 views

Water droplet lensing

Suppose I have a camera that is looking straight down at a single droplet of water resting on a flat surface. The droplet is small enough that surface tension forms it into a rounded shape. Inside ...
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282 views

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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Diffraction and $k$-space

Regarding diffraction I am a little bit lost reading about reciprocal space and the space of $k$'s. As I understand it the Fourier relationship between a wavepacket $\Psi(\vec r,t)$ and the complex ...
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Change in Speed of Light [duplicate]

Whenever light enters from air to glass its speed decreases but when it cross the glass and again come in air its speed increases. What is the reason behind this property? What is slowing it and what ...
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What is the difference between the words transparent and translucent?

Merriam Webster defines transparent as: Having the property of transmitting light without appreciable scattering so that bodies lying beyond are seen clearly. And translucent as: ...
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To what extent can speed of light be reduced? [duplicate]

Light slows down upon entering different transparent objects, and the ratio is taken as refractive index of the object. If light can be slowed down, then is there a limit up to which it can be slowed ...
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How do the optical properties of glass influence the efficiency of solar thermal flat plate collectors

A solar thermal flat plate collector (FPC) converts irradiation into heat. The usfull energy gain of such a FPC can be expressed as: $$ Q_u = F_R \cdot A \left[ I\tau \alpha - U_L \cdot \left(T_i - ...
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Why LiFi can't penetrate like WiFi? [closed]

My common sense says that Lifi signals can't penetrate through walls (since visible light cannot) but other part of the electromagnetic spectrum can, I mean radio signals which power WiFi. So is ...
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Can the speed of light become complex inside a metamaterial?

The speed of light in a material is defined as $c = \frac{1}{\sqrt{\epsilon \mu}}$. There are metamaterials with negative permittivity $\epsilon < 0$ and permeability $\mu < 0$ at the same time. ...
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Is optical path length (OPL) usually in units of length, or wavelength?

When I do calculations, I usually define optical path length (OPL) of a path as the integral of index $n$ along a path divided by the vacuum wavelength, so that I can get the phase easily. So for a ...
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837 views

Definition of pole of a spherical mirror

what can be a suitable definition to a pole of the spherical mirror. It cant be the geometrical center of a spherical mirror as if a mirror is cut then its pole does not change. moreover if a ...
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70 views

Using starlight to create a fire

It is easily experimentally demonstrated that a focussed image of the Sun can be used to start a fire. Furthermore, by thermodynamic considerations or the conservation of étendue, it can be shown that ...
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Spherical aberration: circle of least confusion and diffraction limited spot size

I need an estimate of the relative sizes of the circle of least confusion (spherical aberration) and the diffraction limited spot size for typical real lenses. I've seen plenty of discussions, but ...
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Commutation Relation between Annihilation & Creation Operators and Ascending & Descending Operators

I am currently working on a QD-Cavity system. After the point Heisenberg Equation of motion is obtained from corresponding Hamiltonian of the system, in order to find the expression for bosonic ...
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Bandgap calculation in MQW structure

In advance I want to apologize for my bad english. My question is about the calculation of a Bandgap of a multiple structure crystal. In this case: AlGaInAs. Lets assume that the distribution is: Al ...
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In geometrical optics, how can we say that rays coming from a distant object are parallel to one another?

If two rays are not parallel in the start, how can they become parallel at the instant when they strike the lens of a telescope? If they don't become parallel, why do we consider them to be, in the ...
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Curvature of a laser beam with M2 parameter greater than 1

Usually a laser beam is characterized with parameter $M^2$ which shows how much does the beam size diverge in comparison to the Gaussian beam. $w=w_0\sqrt{1+M^2(\frac{z-z_0}{z_R})^2}$ But what in ...
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Mueller matrix and Lorentz group

I have just learned about Stokes vectors and Mueller matrices for description of polarized light. In the text I studied there is clear restriction for the Stokes vector $\vec S$ that $S^2_0=S^2_1+S^...
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Question about Eric D. Black's Pound–Drever–Hall laser frequency stabilization paper

My question is about equation 3.3 on page 4 of in this article. The equation gives the reflected power of a beam that is injected into a Fabry Perot cavity (the power of the beam leaving the same way ...
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332 views

Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...
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What is the purpose of glass in common mirrors? [closed]

We know that the image is formed by the silver layer, so why don't we use silver layer on some other material in household mirrors?
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265 views

Can spatial coherence be maintained in fiber optic cables over time?

I am doing research with a double slit experiment, using a beam splitter and 2 lengths of fiber optic cable, whose ends brought close together form the effective double slit. I notice that the ...
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Spatial coherence of SLED light (width of active region?)

As far as I know, super-luminescent diodes (a.k.a. SLEDs) have a very similar structure to laser diodes, except that the front faces of the active region are tilted to prevent the sort of reflections ...
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Why do everyday plastic items interfere with light polarizers?

I recently bought a few pieces of linearly polarized film (the one intended for smartphone LCD screens). At first I was confused because I could not make the polarizers work as they should - no matter,...