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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Changing light beam direction

I'm using a rotating mirror to reflect a beam of light like that: where A is the beam source, B is the projection of the reflected beam on a surface at a distance y from the mirror, x is the ...
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4answers
94 views

Is there a limit to the frame rate achievable with a high-speed camera?

A high-speed camera is a device used for recording fast- moving objects as a photographic image(s) onto a storage medium. A normal motion picture is filmed and played back at 24 frames per second, ...
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6answers
3k views

Why did high quality mirrors use aluminum coatings instead of silver?

I have two questions on mirrors. I’ve read that in the past quality mirrors were coated with silver but that today vacuum evaporated coatings of aluminum are the accepted standard. When I look at ...
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1answer
136 views

Third-order susceptibilities of metals?

Can anyone point me to a source for measurements of the third-order nonlinear electric susceptibilities $\chi^{(3)}$ of various metals? Specifically in relation to the AC Kerr effect, so measurements ...
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1answer
62 views

Can one calculate the distance from Earth to the camera, given a single picture?

Given an image of (part of) a sphere of known size, can one calculate the distance to the camera based on the relative size of the sphere in the image? My instinct is "no" unless you have some fixed ...
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1answer
32 views

What temperature is achieved in focus point by 5000 flat 1x1cm mirrors onto a satellite dish?

There is this video ("R5800 Solar Death Ray") where teenager built a 5000 mirror device which concetrates the solar rays which is showing the potency of the mosaic method of concentrating sunlight ...
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34 views

How can colors from heat tinting depend on temperature only?

Colors caused by heat tinting of a material can be listed by temperature. For example, for carbon steel: ...
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5answers
2k views

Focusing Light with Flat Mirrors

What is the best way to focus (sun)light using flat mirrors? My goal is to start a fire. Cutting the mirrors is easy.
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1answer
51 views

How does the atmospheric UVB attenuation of terrestrial planets compare?

On Earth, UVB (280nm - 315nm or 320nm depending on the source) undergoes extensive attenuation through the atmosphere, when observed at the planet's surface, as illustrated below: Image source ...
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2answers
98 views

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 ...
2
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1answer
90 views

Laser beam divergence

How can I calculate the divergence of a laser beam by diffraction? I want to find the following relation, $$ \Delta\Omega = \frac{\lambda^2}{A}, $$ where $\lambda$ is the wavelength and $A$ is the ...
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1answer
446 views

The physics behind Google Glass' “prism”

In writing a bachelor's thesis about applicable use cases for Google Glass in retail I also strive to explain the physics behind Glass' optics. So far I've come to the following conclusions: Glass ...
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2answers
110 views

What is “field size” when referring to perspective?

I'm trying to get my head around perspective. If you look at the animation in Wikipedia : You can see that the cube looks very distorted, then the edges go more parallel. From my understanding, ...
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2answers
51 views

Sellmeier Refractive Index of Standard Air

The question: What is the Sellmeier description of the refractive index of air at some reasonable temperature, pressure, and water content? The description must be in the following form:$$ ...
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1answer
52 views

is it possible to extract spectrum (color in general) from an animal [closed]

if i may ask....can this be ASAP? :3 my problem: okay this is going to sound lame, but i was wondering if it is possible to extract color (specifically spectrum) from an animal. this question ...
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2answers
97 views

Why can't we reach the ends of rainbow?

Rainbows are spectacular things. But I imagine why we can't reach to the ends of rainbows. Do rainbows have no ends ? If so, why can't we reach at them? If you go closer,they will go further. Why?
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2answers
60 views

Safety glasses for a CO₂ laser

I am working on a CO$_2$ laser project and I know glass blocks the wavelength of the laser, 10,600 nm, well. So, should normal glasses work good as safety glasses or do I need to buy a specific one? ...
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4answers
19k 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
95 views

Spherical mirror ray diagram question

why does a ray, parallel to the principle axis, intersect the principal axis at half the radius of curvature, i.e. focus? EDIT I was taught that in a spherical concave mirror, the rays parallel to ...
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1answer
64 views

Why do propellers look like they are moving really slow when they are moving really fast?

I was just looking at an airplane video and was wondering why it looks like the propellers are moving relatively slowly when they infact have a RPM in the thousands probably.
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1answer
109 views

Intuitive explanation of Huygens construction?

I am having problems thinking about Huygens construction when a wave front hits a surface and am looking for an intuitive / easy to understand answers of the following points consider the diagram ...
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1answer
60 views
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3answers
558 views

Light Ray Reflection from concave mirror

Suppose a ray of light hits a concave mirror and is parallel to the principal axis but far away from it such that it doesn't follow paraxial ray approximation. Will it pass through focus or between ...
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1answer
31 views

Does Bragg's law take into account atom size? (And should it?)

Bragg's law explains wave diffraction and interaction when electromagnetic waves hit a lattice structure: $$n \lambda = 2 d \sin \theta$$ See picture and details on Wikipedia. I am wondering if ...
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1answer
26 views

How can you determine the direction of the polarizing axis of a single polarizer?

How can you determine the direction of the polarizing axis of a single polarizer?
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14 views

Proof of the Burns-Schlueter Theorem

In a multiple lens system, when the image of the first lens lies behind the second lens, you treat the second lens as a lens of its negative focal length. That is, a converging lens becomes a ...
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1answer
30 views

Ideas for improvised UV filter

I am doing a project where I would like to do some UV exposure to some concrete and stone samples. Therefore I have bought a couple of 400 watt UV bulbs, the product specification says it has an ...
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1answer
95 views

Is the Wikipedia article on the Kramers-Kronig relations correct?

Reading the "Physical interpretation and alternate form" section of the Wikipedia article on the Kramers-Kronig relations, it says: The imaginary part of a response function describes how a system ...
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1answer
36 views

Why does an external laser drive only couples certain levels?

I was always wondering how is it that all the quantum optics levels schemes are depicted as if the laser couples only two certain levels with some frequency. For exmaple the standard lambda system ...
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2answers
174 views

Is manufacturing roughness really the only reason we don't see optical interference in thick dielectrics like windows?

I had always kind of wondered why we didn't see interference in things like windows -- we were taught that the condition is that the thickness of the film/slab/medium just has to be an integral number ...
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0answers
34 views

Caustic airy equation and divergent series [closed]

How is the behaviour or creation or mathematical explanation of a caustic related to the divergent power asymptotic series in the limit $ x \to \infty $?
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1answer
266 views

How “wide” is a beam of light? What is its half-diameter?

If you believe ray optics where a light ray is a straight line, a light beam is infinitely thin. If you think of fiber optics, you can guide a whole lot of photons down a fiber only one or a few ...
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1answer
35 views

Can circularly polarized light be transmitted through a fiber

Can circularly polarized light be transmitted through a fiber without loss of this polarization or will it just end up as linearly polarized light on the other side? Does polarization-maintaining ...
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1answer
3k views

Minimum height of mirror required to view image

I wanted to know the minimum height of mirror required to be able to view a complete image of a person. I considered the following setup: $HF$ is the person in question. $H$ denotes the head, $F$ ...
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1answer
37 views

Why we take two focuses in concave and convex lenses before the lens and behind the lens [closed]

we take f(one) and 2f(one) before the lens and f(two) and 2f(two) behind the lens.
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2answers
65 views

Collinearity of two infrared (10.6um) beams

I'm interested in aligning two infrared (10.6um) beams so that they are as collinear as possible. What is the best way to do this while maintaining the polarization of the two beams? Is there a ...
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3answers
1k views

Liquid crystal shutter with >90% transmission?

Today's liquid crystal shutter glasses, when in the "transparent" state, exhibit only 40% light transmission. They work using two polarizer layers, one which is liquid crystal and goes {vertical ...
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2answers
119 views

Are there any ways to alter frequency of wave?

I want to know how can we change frequency of wave, both sound and light, and what is the nature of "changing frequency" Such as, any material could absorb and re-emit wave in another wavelength. Or ...
2
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0answers
56 views

Can time pass for a photon if it's moving in a medium? [duplicate]

If time does not pass for a photon traveling at the speed of light, which can only occur when traveling in a vacuum, what happens when it is slowed down by traveling through non vacuum space like ...
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0answers
51 views

Off-Axis Parabolic Mirror Elliptical Collimated Beam Shape

When you collimate a point source using an off-axis parabolic mirror (OAP) with a circular shape, the beam area of the collimated light becomes more and more elliptical (x-dir. is smaller than y-dir.) ...
101
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8answers
11k views

Could Legolas actually see that far?

The video “How Far Can Legolas See?” by MinutePhysics recently went viral. The video states that although Legolas would in principle be able to count $105$ horsemen $24\text{ km}$ away, he shouldn't ...
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3answers
792 views

What happens to the index of refraction of a lens if placed in water?

What happens to the index of refraction and focal length of a lens that is initially in air that is then placed in water?
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5answers
5k views

What challenges needed to be overcome to create (blue) LEDs?

In light of today's announcement of the 2014 Nobel laureates, and because of a discussion among colleagues about the physical significance of these devices, let me ask: What is the physical ...
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0answers
33 views

Why the Caustic of a circle is the most bright curve in the circle?

Caustic of a cirle is the envelope of light rays reflected by a circle, which is the most bright curve in the circle. But why? Here is the picture shows the Caustic of a circle.
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1answer
42 views

Trouble understanding phase matching equation

consider a 2nd order non linear optical material, i.e. a material in which it holds that $ P = \epsilon_0 E + 2dE^2$. In the Born approximation, the non linear contribution to the polarization density ...
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3answers
107 views

Visible light and colors

I recently read an article about quantum chromodynamics which suggested that quarks do not have actually colors because their dimensions are smaller than the wave length of visible light. My question ...
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1answer
13 views

How to create crystalographic orientation map from indexed Kikuchi bands?

Can somebody explain a detailed procedure, of producing orientation maps? I need to implement this into a software. Right now im able to transform EBSD pattern to probabilistic Hough space, get lines ...
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1answer
28 views

Optical Activity

I was wondering, does the optical activity of a material change under a magnetic field? Assuming it did, how would one analyze this phenomenon in the eyes of classical electrodynamics or classical ...
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0answers
50 views

How would we see the earth if refraction of light was significantly stronger?

On worldbuilders there is a question about the cosmological consequences of a world with super-high refraction and atmosphere opaqueness. I'm assuming the easiest way to minimally change the laws of ...
2
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1answer
41 views

What are the 'types' of parametric down conversion?

I'm looking at photon entanglement, and everywhere in the literature there's a reference to 'type-II' parametric down conversion as a source of entangled photon pairs. I know what parametric down ...