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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Why does light refract if photons are not bound by an axle?
In the classic metaphor, a light beam bends for the same reason that a wagon getting one wheel stuck in the sand does...the wheels travel at uneven speeds, and the wheel on the smoother surface ...
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1answer
39 views
State emitting from an extended thermal source
This calculation is for a double slit experiment setup which is experiencing a far field radiation from an extended monochromatic thermal source. I assume the source is 1-D and it's length is $b$. ...
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1answer
87 views
Why do focal lengths affect magnification?
For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens.
In telescopes, the objective lens projects an image on its focal point which works as the object ...
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1answer
57 views
Fraunhofer diffraction simulation for a hexagonal aperture, what are the typical units?
Kostya answered a question that was asking what the diffraction pattern looks like for a hexagonal aperture in front of a lens. He lists an equation which was derived using a Heaviside function to ...
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1answer
83 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
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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2answers
192 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
86 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
134 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
89 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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2answers
93 views
Is it possible to create a head-mounted optical device that allows the user to see the wind?
Is it possible to create a head-mounted optical device that allows the user to see the wind, by means of thermal imaging / infrared detection, variations in the light's refractive index, or something ...
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1answer
180 views
Different colors in LED/LCD display when viewed from different angle?
I want to know why different colours appear when viewed with a different angle. Can anyone tell me why?
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1answer
1k views
How to find focal length of a single convex lens?
I need help finding the focal length of a single convex lens. The radius of curvature is 200mm. left side is air and the glass has a index of 1.5. I search on google but there was only formulas for ...
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2answers
141 views
Reflectance of Titanium as Function of Thin Film Thickness
As far as I know, transmittance equals e^(-αx), where α is absorption coefficient and x is thin film thickness(100-300nm). My team and I have engineered a way to find absorption. Transmittance, T= ...
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2answers
260 views
Mean free path of UV photon
I was wondering if there's a simple way to compute the mean free path of UV photons in a optically thick medium with density n.
I've looked up at the literature ...
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1answer
290 views
What's the mathematical background to the representation for Gaussian beams?
Background
A general optical system (not necessarily having an axis of
rotational symmetry) can be represented, for small deviations from a base ray,
by the matrix transfer equation,
$$
...
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1answer
146 views
Curved lines in a picture (Photography)
My problem is when I take a picture (a close one) the straight edge looks a little curved. In a standard camera, like a CyberShot.
I would like to know if there is some relationship between the ...
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1answer
287 views
How to compute the intensity of a polarized wave going through a polaroid?
If an electromagnetic wave is linearly polarized, the intensity of the light that goes through a polaroid is proportional to the square of the cosine of the angle between the polarization plane and ...
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1answer
558 views
How to determine the field of view for a pinhole camera with given parameters?
I am reviewing some old material I learned years ago and am having trouble figuring this one out. Can somebody confirm that I have done my math correctly, and tell me how I can recover the field of ...
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1answer
506 views
Effects of high frequency lighting on human vision?
I have a couple of different LED flashlights. One of them has three different "modes" of brightness, and the way it controls it is via pulse width modulation (PWM). Here is a picture that illustrates ...
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2answers
159 views
Is the Sun-set and the Sun-rise Symmetrical for the Observer?
Is there the effect of sun rising and sun setting, in terms of Rayleigh scattering and visual spectrum and other factors completely similar and symmetric? I mean can one recognise them from a picture ...
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1answer
310 views
direction of Pockels Effect. Refractive index eigendirections
There is a linear electro-optic effect called Pockels Effect
The brief is that refractive index changes due to electric field.
If there is an anisotropy (like birefringence) and electric field is in ...
2
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1answer
386 views
In interferometry, what is the origin of the name “Airy function”?
In interferometry (specifically, in the domain of Fabry-Perot cavities), the function $$f(\phi) = \frac{1}{1 + F \sin^2 \phi}$$ , which describes the shape of the resonant structure of the cavity, is ...
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1answer
53 views
Why does the quantum eraser seem to violate energy and momentum conservation?
In the literature of the quantum eraser experiment it is argued that the change in statistics of the system from non-interference to interference is due to the erasing of "distinguishing information". ...
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86 views
Bandgap Spacing in Photonic Crystals
I am doing some self-study on photonics and have encountered the following question:
We know that amorphous electronic crystals such as amorphous silicon have a bandgap. Can amorphous photonic ...
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0answers
125 views
Future space-based telescope array
Radio-telescopes (e.g. the Very Large Array (VLA)) can simulate one gigantic dish by using separate smaller dishes.
Q: Could such an array of optical telescopes potentially see an exoplanet at say 20 ...
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1answer
122 views
Peak deconvolution [closed]
I need some help understanding how much information I can pull out of this data. I have a sample made up of two materials. Materials A and material B. Then I took a picture of the sample.
The two ...
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70 views
How does a 2D MEMS based optical cross-connect control its mirrors?
Concerning fiber optics, I'd like to know how a 2D MEMS based optical cross-connect is able to switch optical signals. I've read that these mirrors are controlled with electrical signals to be either ...
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34 views
Does a “reflected” hologram produce a caustic in the shape of the original object?
Imagine you make a transmission hologram, ala the standard picture. Now you take your photographic plate, and everywhere it is transparent, you put a thin reflective layer on, and everywhere it is ...
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0answers
107 views
How do I use the electro-optic tensor?
I would like to calculate the performance of an optical phase modulator, in which a varying electric field across a crystal modulates the effective refractive index of light passing through the ...
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0answers
84 views
How can I estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of a material?
I am attempting to estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of $\mathrm{TiO}_2$ and $\mathrm{ZrO}_2$, where $p_{11}$ and $p_{12}$ refer to the elements of a strain-optic tensor ...
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42 views
A problem concerning the change of temperature and spectrum of a filament
http://www.flickr.com/photos/83373487@N04/7636968446/in/photostream
The spectrum of a filament is given before, the left one have the lowest tempreture, the middle has the medium and the right one ...
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101 views
Are cylindrical mirror telescopes possible?
Is it possible to use a set of cylindrical mirrors and software correction to build an optical reflector telescope, instead of using a paraboloid reflector? By 'cylindrical' I actually mean a planar ...
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1answer
193 views
How does a flat wedge lens work?
I've been seeing this lens in a lot of places especially microsoft:
http://www.youtube.com/watch?feature=player_detailpage&v=rJ1p5SD3sOM#t=45s
...
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114 views
projective camera: back-projecting a point on the image plane into 3-space
suppose I got a projective camera model. for this model I would like to back-project a ray through a point in the image plane. I know that the equation for this is the following:
$$
y(\lambda) = P^+ ...
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1answer
187 views
Why is the diffraction pattern for an annular aperture the difference of the two Bessel functions?
Inspired by this question, the pattern for the annular intensity is given by the square of the difference of the two Bessel functions. I would have thought the sum was more appropriate, could someone ...
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63 views
Optics: finding total power of a syste, including wavelength
Specifically I need to create an ABCD matrix given 2 radii of curvatures, the thickness of the lens, type of glass (BK7) and a given wavelength. I will have to figure this out eventually, so help ...
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0answers
118 views
Modeling a spray painted polyurethane surface reflection
I'm modeling light interaction/reflection from a fiberglass surface with polyurethane epoxy (that is very reflective) that has been spray painted with a matte black paint. I'm looking for some input ...
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517 views
What does the optical zoom in telescopes do?
How does the optical zoom works..
Does it brings the light closer to the object... Or
Does it just enlarges the picture of the object.
In other words... Suppose I have telescope with 1 light-year ...
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1answer
33 views
Photo of reflection in magnifying mirror shows normal magnification. Why?
I just took a picture of myself in one of those magnifying shaving mirrors and in the photo I am unmagnified! Why is this?
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3answers
5k views
What makes some laser beams visible and other laser beams invisible?
What makes the beam of some lasers:
1-visible?
such as the ones used in clubs or such as the laser pointers sold at amazon which if pointed to the sky look like a solid visible beam of light ...
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2answers
352 views
Through a lens, which light beam reaches the screen first?
Imagine three light beams are "sent" to a lens simultaneously, they start at the same position but move towards the lens at different angles. The first light beam passes the lens at its edge, the ...
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4answers
123 views
Projecting image without manual focussing
I was wondering if it was possible to project a magnified image on a wall without the need of focusing, so just by dimensioning the lenses right.
I know I have to use the principal of Maxwellian View ...
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1answer
1k views
How does Telescope lens work?
1.How does a Telescope work?
2.What factors increase the magnification of the lens?
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2answers
226 views
Double slit experiment and perforated walls' properties
I have a doubt about how double slit experiment is made.
Let's think about the perforated wall, what are the requirement for it?
Can a photographic plate could be used as a wall ?
I see a problem ...
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2answers
99 views
Why don't you see multiple images of an object?
Consider the ray model of light. Let's say an object such as a pencil is illuminated, and consider one point on that pencil. Since there could be many rays of light bouncing off the same point on the ...
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1answer
111 views
Why the color motion picture film appears as black?
Why the color motion picture film, or a color photographic slide, appears as black?
The film appears black but when the light from the projector lamp hit it then you can see all the colors.
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1answer
78 views
Calculate the distance between two points from iPhone Camera
I want to calculate the distance between two objects using an iPhone camera.
Suppose I'm standing with my iPhone 10 feet away from the objects. Now, I want to calculate the distance between those ...
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2answers
50 views
Selectively visible laser beam with a controllable means
How can parts of a laser beam be made visible while others left invisible using something electronically controllable (for example, another laser beam crossing it, or a magnetic field, or heat, etc).
