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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How can some optical microscopes measure height differences of different sample planes with nanometer accuracy?
I could use last week an optical microscope, didn't seem special in any way, 50x magnification, image viewable per a CCD camera on a computer screen besides through the ocular.
But the software of ...
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149 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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114 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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2answers
146 views
How to adjust feather touch focuser for collimation?
I have a Starlight Instruments feather touch focuser for my Dobsonian telescope.
While trying to collimate the secondary mirror with the focus all the way in, I noticed that my Howie Glatter laser ...
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36 views
Should I be concerned about spot corrosion on a telescope's primary mirror?
I am considering buying a telescope with a large primary mirror that is about seven years old - it has a small spot of corrosion on the mirror, that the owner says is stable.
Should I be concerned ...
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188 views
What sets the resolution on analog film?
When taking a picture with old fashioned film what sets the resolution of the picture? Is it the wavelength, or the chemical makeup of the film?
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790 views
What happens to light in a perfect reflective sphere?
Let's say you have the ability to shine some light into a perfectly round sphere and the sphere's interior surface was perfectly smooth and reflective and there was no way for the light to escape.
If ...
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147 views
Impact of covering glass on lens performance
I've seen microscope lenses optimized for 0.17mm covering glass. I don't see what needs to be optimized here? As glass does not touch the lens (as in case of oil/water immersion) - it should just ...
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422 views
How does phase modulation conspire to eliminate power variations?
A purely phase-modulated signal has no power modulation. This is obvious enough if you look at the time series, but I'd like to "see" it in the frequency domain.
In physical terms, if we take a ...
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35 views
The weight of a cavity of radiation
A sealed cavity full of light weighs more than an empty one. So consider a cavity consisting of parallel mirrors, with a pair of beams bouncing between the mirrors. The question is whether that weight ...
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130 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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163 views
what is the probability distribution for the angle of an approximate laserbeam
I'm trying to simulate the light distribution characteristics from a Gaussian laser beam, but having difficulty with the angular distribution.
I need to generate a large number of points on an x/y ...
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47 views
Is it possible to surpass the diffraction limit for telescopes?
Telescopes have angular diffraction limit depending on the observed wavelength and aperture diameter.
I've read that it's possible to go beyond the limit for microscopes. But is it possible to do the ...
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221 views
Maximum theoretical bandwidth of fibre-optics
Ignoring hardware at either end and their technological limitations, what is the maximum theoretical bandwidth of fibre optic cables currently in use / being deployed in a FTTH type situations? I ...
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100 views
Liouville's theorem and gravitationally deflected lightpaths
It is customary in gravitational lensing problems, to project both the background source and the deflecting mass (e.g. a background quasar, and a foreground galaxy acting as a lens) in a plane.
Then, ...
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3k views
Is it possible to witness a circular rainbow?
What conditions would make it possible to see a naturally occurring fully 360° circular rainbow? Would it even be possible?
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810 views
What does an atom radiate: a wave packet or a single photon?
What does an atom radiate: a wave packet or a single photon?
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What is a two-photon process?
I am reading some introductory materials on modern optics, in which they mention two-photon processes everywhere. I know fundamental optics and a bit on quantum mechanics. Can anyone explain in a ...
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356 views
Human perception of distance
When we see things around us, distant objects look smaller to our eyes than nearby objects do.
Is there any physics-related reason why our eyes or brain perceive things like this?
Or if this is ...
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266 views
Eye sensitivity & Danger signal
Why are danger signal in red, when the eye is most sensitive to yellow-green?
You can check luminosity function for more details...
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In optics, how does the vacuum state compare to thermal radiation?
In quantum optics, a perfect absorber of light is said to emit the "vacuum field". In practice, any beam dump will be at finite temperature, so it will emit blackbody radiation. How do these fields ...
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Rainbow around Sun
From the perspective of a person, a rainbow is formed when the Sun is behind the person, and there is a critical angle made by the rainbow.
However, on several occasions, usually at noon when the Sun ...
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376 views
How to make mirrors give more authentic image of myself
My friend bought two normal mirrors from some shop probably IKEA, looking like this one:
My images are different from the two. One is a little fatter and shorter, and the other a little thinner and ...
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3answers
47 views
Quality loss when adding more components to a telescope?
I would think this would be inherently true, but I'm curious:
(Assuming the highest quality amateur instruments are used.)
Is quality lost when, say, adding a T-mount adapter, diagonal or any other ...
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4answers
147 views
Effects of surface roughness on specularity
Say you have a piece of glass, which looks specular if propery cut/polished. But if you sand the surface using say sand paper, it will look hazy and glossy. I'm wondering how much surface roughness ...
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How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?
I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm.
I ...
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For resolving different objects, are there any alternative coefficients to the one used in the Rayleigh criterion? (which is 1.22)
http://en.wikipedia.org/wiki/Angular_resolution#Explanation
It's the point where you can't distinguish between the maxima and the first minima.
But could there be cases where you have a more ...
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138 views
Why (infra-)red light is not used in diagnostics?
I noticed that human body conducts red visible light quite well. A hand placed over a powerful red lamp seems to be semi-transparent while over any other color it does not.
Possibly the light ...
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Is there a way to create a flickering frequency to be dependent on speed of the person looking at it?
Is there a way to make a screen or a road sign flash at different rates, depending on the velocity of the observer looking at it?
I would like to achieve a state where two observers going at ...
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Why is $\vec j\cdot \vec e$ the joule dissipation?
I always see $\vec j\cdot \vec e$ as Joule's dissipation and I don't understand why. For example, if we have a uniform electric field $\vec e=e_o\vec u_x$ and we release an electron in it, it will ...
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285 views
Beam splitters- Direction of use
There are two cases I'm asking about. The square in the middle is a cube beam splitter in the same orientation for both cases. We are looking at the beam splitter from the top. In the first case, ...
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Linearizing Quantum Operators [duplicate]
Possible Duplicate:
Linearizing Quantum Operators
I was reading an article on harmonic generation and came across the following way of decomposing the photon field operator.
$$ ...
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331 views
Nonlinear polarization (second and third order)
Why does second order nonlinear polarization occur only in crystal materials with a non-centrosymmetric crystal structure? (Nonlinear effects at crystal surfaces are an exception). Why does third ...
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886 views
What is the effect of polarization on diffraction by a narrow slit?
Consider the well known demonstration of diffraction by a narrowing slit.
(See for example the demonstration at the 30 minute mark of this lecture at MIT by Walter Lewin)
It is my (possibly mistaken) ...
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How do contact lenses work?
I understand how telescope, microscope and glasses work.
But how do contact lenses work?
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Optics, lenses and our eyes
When we view an image, is the focal point of our eye on our retina? Shouldn't that hurt?
Also, if that is how our eye works, then why don't lenses put the focal point their equivalent retina? I was ...
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86 views
Three polarizers, 45° apart
If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
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2answers
172 views
Redirecting light beams from beam splitters
I'm doing a project where I am taking a laser beam and sending it through a beam splitter. As I understand, approximately 50% of the light will go pass through and 50% will be reflected. So this means ...
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151 views
Does a fluid's temperature affect the way light passes through it?
For example, if I were to supercool water would it's refractive index still be 1.33 or would it be 1.31, the same as water-based ice even though it's still in liquid form?
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Hartmann mask based collimation
Is there a detailed description for a Hartmann mask based collimation process?
I've been told by a friend that is possible to collimate an SCT by placing a three round holes Hartmann mask at the ...
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177 views
Fermat principle: which index of refraction?
I am somewhat puzzled by a common formulation of the Fermat principle (light travel time), because it contains index of refraction related to phase velocity while light travel time through a slab of ...
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285 views
Calculating Fraunhofer diffraction patterns
How does one calculate the Fraunhofer diffraction pattern for the following arrangement of slits:
|...|...........|...|
..a.....3a......a
(Four slits arranged linearly, spaced a distance a, 3a and ...
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Why is the observed signal the convolution of the true signal with the instrumental function?
Imagine we are observing a star. The light coming from a star enters an optical instrument that will give us some observed data, such as the spectrum of light say.
What we observe is not the true ...
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313 views
Focusing laser & off-axis illumination & diffraction limit
I've thought I had a good understanding how resolution enhancement tricks works for projection lithography, until I tried to understand if it's possible to get sub-diffraction performance for focused ...
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3answers
310 views
Numerical software to manipulate a light beam in its plane wave representation?
Any light field can be expressed as a sum of plane waves. Such an ensemble of plane waves is called the plane wave spectrum of the light field. The plane wave spectrum is the Fourier transform of the ...
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549 views
Propagation of light in transparent media: absorption and reemission or scattering?
In the two Phys.SE questions What is the mechanism behind the slowdown of light/photons in a transparent medium? and Why glass is transparent? transparent media were discussed. But I'd like to clarify ...
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230 views
Which lens parameters determines it's format?
I'm working with a megapixel sensor with a 1/2" format. I would like to know which parameters have to be taken into account in order to design a lens that can be fit with 1/2" format.
The light ...
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2answers
60 views
How to draw a ray diagram from focal length, object and image heights?
Q. An object of height 8 cm is placed in front of a lens. It's inverted image of height 4.8 cm is formed on the screen. If the focal length of the lens is 12 cm then by drawing at scale calculate the ...
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86 views
How to create visible reflections in shallow water?
Assumption: The only lights I have are candle, table lamp, and sunlight.
What would I need to create visible reflection of an object in the shallow water contained in a 5 liter bucket? Is it even ...
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Gravitational distortion of an object's diameter, at a distance,
Does the curvature of space-time cause objects to look smaller than they really are? What is the relationship between the optical distortion and the mass of the objects?
