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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Fourier optics (diffraction from pinholes)

A plane wave of wavelength $\lambda$ and unit amplitude is normally incident on a mask placed in the xy-plane at $z=0$. The mask contains two infinitesimally small pinholes, located on the x-axis ($y=...
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Calculation of Phase Delay of a Curved Planar Dielectric Waveguide (i.e., bend)

I am working on a very phase sensitive planar dielectric waveguide device and I need to calculate the phase delay induced by a bend of some radius, $r$ and of $\phi$ radians for a give planar ...
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99 views

What is the amplitude of a light wave?

Referring to this question How can I measure the amplitude of a light wave? I'm curious about what is a amplitude of a light wave. Especially for light from a thermic source.
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How can I measure the amplitude of a light wave?

Suppose I have a light wave and I want to measure its amplitude, or check to see if it has an amplitude of a certain value: how would one go about doing this?
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What is the relation between polarization and wave front?

I'm reading about the angular momentum of light, in which wave fronts are like helix. When I checked for a circular polarization on the web, shapes look very similar to these helical structures, So I'...
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79 views

Is this incredible microscope technology real? [closed]

I recall reading about the relatively old invention of a microscope-like device; apparently able to zoom much further (and with greater clarity) than more "advanced" modern technology. I don't recall ...
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Can Schrödinger Equation be derived from Huygens' Principle?

Notes of Enrico Fermi start from an analogy between mechanics and optics and with 4 pages he derives the Schrödinger equation. In all my courses, I have seen as an axiom - this is how wave-particles ...
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39 views

What is the difference between reflection and total internal reflection (TIR)?

I look at what TIR is and then what reflection is - when the angle of incidence and the angle of election are the same. And TIR is when the angle of incidence is greater than the critical angle. TIR ...
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50 views

What does J cm-1 stand?

For an optical component, I got following number as an optical damage threshold from the company, damage threshold = 10 Jcm-1,20ns, 20Hz It looks like 20ns is ...
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39 views

what causes water to be white in a river?

I know it is because of turbulance, causing air to enter the water. But neither air nor water are White, why does the combination of the two make White.
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101 views

Validity of the 'photon wavetrain' model of coherence

In some optics textbooks, coherence is introduced with the "photon wavetrain" model. In this model, we consider light generated by many atoms each making the same transition. During each transition, a ...
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Relation between phase of dark field and bright field images

I am trying to understand how the super-resolution technique based on Fourier Ptychography 1. In the paper, we run phase retrieval algorithms using images captured using illumination at different ...
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55 views

Why don't reflector telescopes place their reflectors at an angle?

To avoid placing a secondary mirror in front of the objective mirror, why not tilt the objective and design the eyepiece in such a way that comatic aberration is minimized?
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What is a good book to self-teach optics?

I'm interested in camera lenses and how things like barrel distortion and lens flare happens, but know that one cannot just start there. I'm a math major and I've worked out of Strauss PDE book so I ...
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Optical bandpass filter at focal point of lens

Optical bandpass filters are designed for a particular angle of incidence (AOI), e.g. see Fig 4 here. However that is for the ray picture of light. Imagine I have a thin bandpass filter positioned ...
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1answer
25 views

How thin lens model work when there are two images with different distances from the lens?

I am trying to understand how thin lens camera work. From what I understand of thins lens model, the image is formed on image plane that obey the equation $$\frac1S_1 + \frac1S_2 = \frac1f$$ So ...
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56 views

Could a photon also be a fermion? [duplicate]

Some phycisits have found photons that has a spin of 1,5. Now fermions has always a half spin and bosons like photons always with a whole spin. But if those photons really exists are they than ...
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Parity conservation in second harmonic generation?

The second harmonic arises from susceptibility of third rank tensor $X^{(2)}$ which have (-1) parity. page 28 Let say two photons are absorbed and one is emitted, so the total change in parity is $(...
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Why is window glass only transparent from one directional axis?

If you look through a pane of common window glass the way it was meant to be looked through, it's clear. But if you look at it from the side it's not very clear at all, but a dark green color. One ...
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How is the Rayleigh criterion connected to the Abbe limit

I am interrested whether one can derive a formula for the point resolution (like Abbe did) of an optical system from the Rayleigh criterion (without the use of small angle approximation i.e. $\rm{sin}(...
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29 views

How do I find the constants in Cauchys equation for index of refraction for different wavelengths?

Im trying to find the indexes of refraction for my Dispersion of a Glass Prism lab. Specifically I need to use Cauchy's equation to find the index of refraction for different wavelengths. $$ n=a+\...
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How do those T-shirts that change color in the sun work?

When I was a kid, I asked my dad about them and he said (not in so many words) that it was because sunlight and artificial light have different spectrums and they picked colors that reflect only the ...
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Diffractive peak for high-frequency scattering from a sphere with small index of refraction?

How does a transparent sphere's shadow fade as $n\to 1$? Consider radiation of wavenumber $k$ incident on a transparent sphere of radius $a$ and index of refraction $n$ in the limit $ka \gg 1$. (...
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What's the conductivity of graphene nanostructres (nanoribbon, nanomesh)?

As we know, the conductivity of graphene can be expressed with Kubo formula,including intra transition and inter transition. But does graphene nanoribbon or graphene nanomesh have the same ...
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38 views

Relationship between angular magnification and how much bigger the image appears

How is the angular magnification of a magnifying glass related with how much bigger the image appears to the user? Is it simply the same? If yes, why? (Let's assume that the object is placed in the ...
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59 views

Refractive index of red and blue light

if $\frac{\sin(I)}{n}=\sin(r)$ where $n$ is the refractive index, $I$ is angle of incidence and $r$ is angle of refraction (these are relative to the normal). How come blue light refracts at a ...
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Optical Retroreflectors: How Are the Faces So Accurately Righted?

This question is about Optical Retroreflectors (corner cubes) and how the extreme precision in their manufacturing is achieved. I suspect there is interesting basic physics involved, which is why the ...
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64 views

Why should the image screen be placed at fourth focal plane in 4f setup?

They call it the 4f setup. But when the image coming from the second lens is anyway collimated, why is it necessary to place the image screen at the fourth focal plane?
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124 views

Why one should follow Snell's law for shortest time?

whenever two media and two velocities are involved, one must follow Snell's law if one wants to take the shortest time. Why snells law must be followed to travel diffrent media in shortest time? ...
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1answer
33 views

Calculating f-stop with given focal length and desired depth of field?

I have a varifocal zoom lens set to a desired focal length and at known distance from the subject. I also have a desired depth of field. Given this information, can I calculate a theoretical f-number ...
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36 views

What is the explanation of the glory (optical phenomenon)?

Yesterday, I took the following picture. I was looking downwards from within an aircraft and I saw the 'glory' around the shadow of the plane on the clouds below. Wikipedia has an entry on the ...
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47 views

Explanation of ray caustics in E&M

My understanding (now) of a real caustic is that it is envelope of curves or ray-paths that arise due to reflection or refraction from the medium/manifold. My main question is, I am seeing the term "...
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35 views

Will these two coherent electromagnetic waves be in phase?

My question is how will I know if two coherent electromagnetic waves are in phase based on their phase difference. I just solved a problem which stated... Two coherent sources A & B send ...
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Gaussian beam interference

The superposition of a gaussian beam and a plane wave generates a pattern of rings whose phase shift before and after the focal plane (of the gaussian beam) is $\pi$. This means that if you measure ...
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Within what range of defocus from the object/image plane does the Fraunhoffer approximation hold?

The Fraunhoffer apporximation of diffraction is said to hold for an image "at infinity," or to be quantitative, for any observation point $R >> \frac{a^2}{\lambda}$. But it is said that, ...
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why interference pattern changes with given relation when the source slit changes?

Why for interference condition to be seen the dependence relation should be like $${\frac{s}{S}}<{\frac{\lambda}{d}}$$.Where $s$ is width of source slit and $S$ is the distance between the source ...
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61 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". Can someone tell when it is dependent on direction and how the secondary ...
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What happens if we stand in the centre of a sphere inside covered with as a mirror? [duplicate]

What happens if we stand inside a sphere covered with as a mirror? That is when we are at the centre of a spherical mirror, how the image of us is formed?
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19 views

addition of two lenses with a finite separation in between

Suppose there are two lenses with focal length $f_1$ and $f_2$ respectively. The effective focal length $f$ when they are combined is $1/f=1/f_1+1/f_2$, but this formula assumes the separation between ...
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43 views

Calculating angle of min deviation of prism [closed]

Two rays incident with angle 40 and 60 on one face of equilateral triangular prism the angle of deviation are equal .find angle of minimum deviation?
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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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90 views

How far apart can the slits be in a double-slit experiment using direct sunlight?

In a normal double slit experiment, I'm told that sunlight doesn't produce a visible interference pattern because there is no stable phase relationship between the two slits. However, sunlight ...
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Reflection and angle of refraction

Does the angle of refraction depend on the properties of the material if the angle of the incidence is the same for two different materials? Say I shed light on a surface with angle $ \theta $ and ...
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Unpolarized wave, $\Delta\varphi =\Delta \varphi(t)$?

I have seen a unpolarized wave defined in a number of places (e.g. here) as a wave such that: \begin{align} E_x&=E_0 \cos(kz-\omega t) \\ E_y&=E_0 \cos(kz-\omega t+\varphi) \end{align} Where $\...
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Introducing a phase, what changes?

This question is related to: Mach-Zehnder interferometer and the Fresnel-Arago laws Let us say we have unpolarised wave taking the form: $$\psi=\psi_0 e^{i(kx-\omega t)+i\phi(t)}$$ Where $\phi$ ...
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Mach-Zehnder interferometer and the Fresnel-Arago laws

I have been reading this paper on a mathematical treatment of the Fresnel-Argo laws. In the paper they essentially they take the electric field: $$E_i=E_i(t)$$ and introduce a phase factor, $e^{-i\...
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Why is the wavelength of light proportional to the minimum angle of resolution?

E.g. why does the minimum angle of resolution increase as wavelength increases?
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Why long range ordering and higher order rotational symmetry leads to dense K-space ?

In case of Quasicrystals Why long range ordering and higher-order rotational symmetry leads to dense K-space ? And high rotational symmetry include modification in discrete spectral feature to ...
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Sech laser pulse time-bandwidth product calculation

Find the time bandwidth product for a $\operatorname{sech}$ shaped pulse. Attempt: I know that the time bandwidth product $\Delta t \Delta \omega$ for a $\operatorname{sech}$ shaped pulse must be $...
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Structured light, infinite focus

Im interested in projecting a static image across a room that stays focused over a wide range of distances from the projector, without re-adjustment, for a structured light setup. ie, the target may ...