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.
1,720
questions with no upvoted or accepted answers
7
votes
0
answers
126
views
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 ...
user265136
7
votes
3
answers
803
views
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 $360^{\circ}/\theta - 1$...
7
votes
1
answer
787
views
Paint: "Darker When Dry"?
A great question I enjoy bringing up is why are things, in general, "darker when wet". This applies to porous and granular materials like wetted stone, paper, sand etc. It also comes up in ...
- 79
7
votes
1
answer
436
views
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 ...
- 30.9k
6
votes
0
answers
174
views
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-...
- 1,190
6
votes
0
answers
398
views
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, ...
- 8,052
6
votes
0
answers
239
views
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 ...
- 6,768
6
votes
1
answer
889
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 ...
- 1,344
6
votes
2
answers
274
views
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 ...
- 71
5
votes
0
answers
85
views
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 ...
5
votes
0
answers
212
views
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 ...
- 6,768
5
votes
0
answers
82
views
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 ...
5
votes
0
answers
84
views
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 ...
- 1,027
5
votes
2
answers
767
views
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 ...
- 1,226
5
votes
2
answers
1k
views
Explanation of formation of Newton's rings
I was asked to do a lab report in my University about Newton's rings experiment that we made in lab. I understand that the aim of the experiment is to measure the wavelength of a light after the ...
- 163
5
votes
0
answers
536
views
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 ...
- 352
5
votes
0
answers
121
views
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 ...
5
votes
0
answers
7k
views
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 ...
- 159
5
votes
1
answer
493
views
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-...
- 819
4
votes
0
answers
253
views
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 ...
- 159
4
votes
0
answers
268
views
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....
- 136
4
votes
0
answers
113
views
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 $...
- 1,255
4
votes
0
answers
160
views
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 $1/8$ ...
- 572
4
votes
0
answers
99
views
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 ...
- 161
4
votes
1
answer
146
views
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 ...
- 1,650
4
votes
2
answers
227
views
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 ...
- 1,972
4
votes
0
answers
106
views
Difference between permittivities eps-opt and eps-inf?
Very often in materials physics we are interested in the relative permittivity at optical frequencies, which is usually denoted by $\varepsilon_\text{opt}$ or $\varepsilon_\infty$.
But I'm confused ...
- 41
4
votes
0
answers
95
views
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 ...
- 41
4
votes
1
answer
166
views
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.
- 41
4
votes
1
answer
249
views
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 ...
- 163
4
votes
1
answer
165
views
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 ...
- 855
4
votes
0
answers
475
views
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 ...
4
votes
1
answer
94
views
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 ...
- 819
4
votes
0
answers
415
views
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 ...
- 41
4
votes
2
answers
1k
views
Point and Line Spread Functions
For optical systems, is there a way to estimate its point-spread function from its line-spread function?
In particular, I wish to estimate the encircled energy.
4
votes
1
answer
343
views
Derivation of relativistic mean free path
I am working through a short derivation found in Abramowicz 1991 regarding the mean free path of a photon.
We have a fluid moving in a particular direction with velocity $v$ and in an inertial rest ...
- 75
4
votes
0
answers
93
views
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 ...
4
votes
0
answers
337
views
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 ...
- 41
4
votes
0
answers
138
views
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 ...
4
votes
0
answers
410
views
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 ...
- 41
4
votes
3
answers
1k
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 ...
4
votes
0
answers
316
views
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. ...
3
votes
0
answers
91
views
Out-of-focus color in reflective microscopy with Köhler EPI-illumination
It is well known that Köhler illuminator in optical microscopy is designed in a way to ensure uniform illumination of the field, often with adjustable apertures to allow as little light as possible to ...
- 2,359
3
votes
0
answers
85
views
What creates the orange hue when there is wildfire smoke?
I find a variety of opposing arguments on the internet:
That this is due to Rayleigh scattering, which "removes" the blue light from reaching our eyes. This is similar to how the sunset ...
- 131
3
votes
1
answer
90
views
Can you observe Rayleigh scattering of water waves?
I understand roughly that Rayleigh scattering occurs when white light encounters particles smaller than the wavelength of visible light, and short wavelengths are preferentially scattered.
I'm ...
- 151
3
votes
0
answers
42
views
What is a stochastic electromagnetic wave?
In statistical optics we always talking about stochastic electromagnetic wave but I am not able to understand how this wave is different from electromagnetic wave
- 31
3
votes
0
answers
465
views
Difference between Poincaré and Bloch sphere for single photons
The Bloch sphere is a geometrical representation of a two-levels quantum system, for example we can use it to represent the spin of a single qubit in the basis $\{\lvert H \rangle, \lvert V \rangle\}$....
- 715
3
votes
0
answers
32
views
Changing the apparent focal distance of an object
I'm not completely confident this is the write SE site to post this on, but it seems like the most relevant one.
I want to make an object (with negligible thickness) that is around one to five ...
- 31
3
votes
0
answers
45
views
Composition of free space propagation and Huygens' principle
With paraxial approximation, the free space propagation operator with distance $d$ boils down to
\begin{align}
(\mathcal{R}_df)(x,y)= \frac{e^{jkd}}{j\lambda d}\iint e^{-j\frac{k}{2d}((x-x')^2+(y-y')^...
- 131
3
votes
0
answers
182
views
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 ...
- 171