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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Speed of Light in a Medium [duplicate]
For light travelling in a medium with refractive index greater than one:
The "average" speed of light is slower than the speed of light in a vacuum. As far as I know, the instantaneous speed of light ...
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1answer
78 views
Factors that make beam divergence worse after refocusing
A beam of light of width $W$ and wavelength $\lambda$ with divergence that is diffraction-limited is refocused with an optical element placed at a distance $D$ from the beam source. Will the refocused ...
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1answer
147 views
Computer-Generated Holograms: I'm completely lost. How are they physically implemented?
I have been reading about holography, and I think I understand the general concept, but one thing that has me completely lost is how computer generated holography works in practice.
I think I get the ...
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2answers
56 views
How are X-rays focused? Specifically in XRD. Well do they even focus X-rays in XRD?
I read in a government website that reflecting an x-ray from a parabolic mirror followed by a reflection from a hyperbolic mirror results in focusing the x-ray, but this was for astronomical purposes. ...
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How to calculate the correct coordinates from a distorted video of a projectile?
I am working on a high school project that is related to projectile motion. I am exploring how exactly the position of the center of mass affects the trajectory of a long but thin, javelin-like ...
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1answer
53 views
Erratic light spot in optical projection
I once had an old microscope, that included a projection screen that could be mounted instead the eyepiece. It showed a quite decent palm-sized image.
Now I have a new microscope, and removed the ...
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1answer
62 views
Ratio of distance between mirror and person
In perspective of a given example, if a man was to stand $2\ m$ away from a mirror which was $0.9\ m$ in height and was able to see his full reflection, what would the height of the mirror have to be ...
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2answers
390 views
Can't seem to reconcile geometric optics and wave optics
I was looking at a physics situation involving light, and I can make the correct derivation assuming light is a ray of a given intensity (geometric optics), energy conservation checks out, everything. ...
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1answer
41 views
Optical refocusing efficiency
What is the material for optical focusing that produces the less diffraction losses?
Suppose one have a sequence of serial optical elements $R$ that keep refocusing a beam of collimated light, each a ...
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2answers
180 views
Irradiance (or intensity) of an electromagnetic wave
Is the irradiance (or intensity) of an electromagnetic wave given by
\begin{equation}
I = \left<\|\mathbf{S}\|\right>_{T}
\end{equation}
or by
\begin{equation}
I = ...
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1answer
85 views
Can we project a 4D world using 3D video technology?
Traditional movies, TV, etc, faithfully show our 3-dimensional world using 2 dimensions. So can we have a movie that shows a 4-dimensional world using 3D technology?
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1answer
149 views
3D movie glasses making white light look red and blue
While waiting for a 3D movie to start, I was playing with the glasses they give you. I understand each lens has different polarized filters, so the left and right superimposed images on the screen go ...
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3answers
159 views
Beam waist at extremely long distances
A beam of light of wavelength $\lambda$ and width $W$ needs to be focused at a distance $D$ to a spot not bigger than $w_S$, which stands for 'width of sail'.
Now, the diffraction limit says it ...
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1answer
71 views
How does light get into a stable optical cavity in the first place?
It is supposedly possible to trap a beam of light bouncing back and fourth between two mirrors in a stable configuration. As I understand it, this means the configuration will prevent further spread ...
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1answer
50 views
How reflected objects are composed and who is responsible for that?
Please refer to this image. The scene contains an object close to a mirror in the wall and a window, note that the reflected object is receiving more light than the object itself.
I read some ...
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1answer
78 views
How would I perceive a purple ball when traveling at relativistic speeds
I have a 'thought experiment' which I'd like to ask about.
I was thinking what speed I would have to drive towards a crossing to see a red light as a green light - pretty easy, using the doppler ...
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1answer
146 views
Filter out polarized light
Unpolarized light enters the polarizer and gets polarized at one certain angle. If we place an analyzer behind the polarizer and align them, we observe that all light is transmitted. If we rotate the ...
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47 views
Resolving power [closed]
In strong light, the pupil of a cat narrows to a vertical slit about 0.5mm across. Can a cat resolve two white mice sitting 5 cm apart a distance of 20m away under these conditions?
And why?
Its to ...
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213 views
What is the correct definition of “group velocity dispersion”?
When we talk about a medium with dispersion, we can define the phase velocity $v_\phi = \omega/k$ and the group velocity $v_g = d\omega/dk$. Likewise the phase index $n = c/v_\phi$ and the group index ...
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1answer
127 views
On the optics of high-resolution surveillance drones
In this youtube video (which is an except from a documentation I believe) a DARPA development for a high-resolution surveillance camera is presented. This question is regarding the optics that are ...
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22 views
Spectral efficiency of combined light sources
I am creating a white light source using 3 LEDs of Red, Blue and Green with relative spectral efficiencies of 0.0041, 0.06 and 1 respectively. How would I work out the spectral efficiency of the ...
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1answer
43 views
Spectral luminous efficiency as a function of wavelength
I've come across plenty of figures demonstrating the spectral luminous efficiency as a function of wavelength (meaning the humans eye's sensitivity to different wavelengths)
...
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1answer
150 views
How to determine real part of optical conductivity by reflectivity measurements?
In figure 3 of this document, there is data relating $\Re(\sigma(\omega))$ to the Fermi energy. It is claimed that $\Re(\sigma(\omega))$ is determined via reflectivity measurements. How is this done? ...
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67 views
Is it feasible to detect light emitted from planet earth 2,000 years ago by reflection from an object situated 1000 light years away?
The possibility though remote, is intriguing as we may be able in the future to actually "see" our own planet's history.
Though sounding science fiction, if we are able to detect bodies in space that ...
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1answer
288 views
Focal length of Convex lens [closed]
A lens forms a real image of $3\ \text{cm}$ high of an object $1\ \text{cm}$ high. If the separation of object and image is $15\ \text{cm}$, find the focal length of the lens.
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1answer
79 views
Dichroism in uniaxial crystals
I need a same help with it. Some books where i can find a real math explanation of this effect will be good help!!
simple exp of this effect will be good too)
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3answers
122 views
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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1answer
114 views
Can light be canceled by merging with an inverted wave?
Can light waves be canceled by merging them with their inverted waves? Seems like it would violate conservation of energy but waves are added together when they overlap, right? Where is the flaw in ...
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1answer
104 views
How would one generate Brownian light? What would it look like?
When light is an equal mix of all visible frequencies, we call it white light.
By analogy, sound that is a mix of all audible frequencies is called white noise.
For sound, there is an additional ...
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2answers
201 views
Jones vector and matrices
With Jones vectors and matrices one can describe the change in polarization of a EM wave. What is the convention of the reference coordinate system; Is it fixed or does it change whenever the ...
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1answer
149 views
Thin lens formulae
Hi I have a question about applying the thin lens formula
$$ \frac{n_1}{s_o} + \frac{n_2}{s_i} = \frac{n_2 - n_1}{R} \,\text{thin lens formula}$$
for a single lens emerged in medium $n_2$ in the ...
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2answers
104 views
Ideal distance of eye from a lens
I observed that when I keep constant distance between object and lens but I move my eye, I get different magnification. When I am closer to lens I can see large image of the object. But if I go away ...
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2answers
329 views
Circular polarization of variable-frequency light by 3D cinema glasses
A dominant method to obtain 3D images in the cinemas seems to be circular polarization. Separate pictures are projected with (alternating) circular polarization filters and passive glasses of the ...
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1answer
402 views
Why doesn't my pinhole camera work?
We all know that light travels in straight a line, which can be proved by pinhole imaging as in the picture shown :
But when I'm doing this little experiment with an apple, no matter how I change ...
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1answer
132 views
What is the cause of orange sky glow?
I live in the Netherlands and recently I have been seeing an orange glow in the sky at night, in the northwestern direction. What is the cause of this? And why is it in the northwestern direction (I ...
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1answer
87 views
Why does the shadow of the hairs on my leg seemingly only appear when the leg is moving slowly?
I happened to notice the shadow of my legs in the sunlight on the floor and I noticed that I could see the shadow of the hairs on my legs only when I moved my leg slowly (slowly moving onto my toes ...
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90 views
Extracting Optical Conductivity From Optical Transmission Data in Graphene on SiC Wafer:
In this paper, the authors write
Matching the optical boundary conditions at the air/graphene/SiC interfaces, the optical transmission $t(\omega)$ through $N$ graphene layers on a SiC wafer ...
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2answers
179 views
Goldfish perspective
What does the world look like from the Goldfish point of view, from inside a spherical aquarium?
If our eyes were inside, would we be able to see the straight lines, focus on different objects and ...
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1answer
201 views
What's the difference between photoelastic constant, photoelastic coefficient and the acousto-optic coefficient
I'm reading a few papers about how the optical properties of materials change when a under stress or a force acts upon them. I seem to be encountering the following three terms:
Photoelastic ...
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1answer
105 views
Kiessig fringes
I have come across many papers but still couldn't find the relationship between index of refraction or atomic scattering factors, and reflectivity.
My flow of thought goes as follows:
Get the ...
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2answers
513 views
How do head mounted displays simulate infinite focus?
First, when I say infinite focus, I am using the term from photography, perhaps incorrectly. Secondly, I believe am not talking about convergence, but about focus. If I am not mistaken, with ...
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3answers
165 views
Counterpropagating beams in a ring cavity lasers
Ring cavity lasers usually has a intracavity element like a optical diode to forbid standing wave pattern and, consequently, spacial hole burning and related instabilities. So, my question is: why to ...
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77 views
How to calculate radiative transition rate of exciton in a quantum dot with specific dimension?
I am writing rate equations for a nanophotonic system including three quantum dots. I need to calculate that radiative transition rates of exciton in ground state in those quantum dots.
In the paper ...
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2answers
131 views
Wavelength comparison of two waves
Is there any non-digital (naturally existing) mechanism to compare two or more waves in such a way:
...
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1answer
98 views
Correcting for bad eyesight on display monitors [duplicate]
I think it would be neat if one could configure one's eyesight parameters (astigmatism and myopia in my case), viewing distance, and perhaps age into a special display driver, such that a computer ...
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1answer
104 views
Do wide-angle videos make the first-person view seem slower than perceived in real life?
I considered posting this on other SE sites such as Audio-Video Production and Photography, but I didn't feel I'd get the definitive, fact-based (rather than experience-based) answer I'm seeking.
...
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6answers
249 views
optical equivalent of a superconductor
Is there some material state that can propagate light indefinitely without dissipation or absorption, like superconductors are able to trasmit current indefinitely?
If not, then the question is, why ...
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3answers
313 views
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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1answer
74 views
Does light shine better through a matt surface or a glossy surface?
I am currently designing a lighting solution for Phillips as part of my university degree. However I am stuck on a small problem, as stated above. If I was to have a strip of perspex, with the sides ...
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213 views
Malus' Law (Polarization) [closed]
Consider the image below:
Let $\theta_2$ be the angle between the axes of transmission of Polarizer 2 and Polarizer 3 and $\theta_3$ be the angle between the axes of transmission of Polarizer 3 ...
