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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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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0answers
12 views

How does a polarizing beam splitter work? [on hold]

How does a polarizing beam splitter work for a S-polarized or P-polarized beam?
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14 views

Shack-Hartmann wavefront sensor concepts, pupil conjugate planes?

I am just starting to looking at the application of wavefront abberommtery to measure abberations in the human eye. I am confused over the pupil conjugate planes, do you use relay lenses to image the ...
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4answers
18k 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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0answers
44 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
54 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
57 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
103 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
45 views

Diffraction to be explained without Huygens principle

Can we explain diffraction without using Huygens principle?
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3answers
528 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
29 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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17 views

Difference b/w angular width and linear width of fringe

In double slit experiment and single slit experiment what is the difference between angular width of fringe and linear width of fringe?
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30 views

Upside down images on the surface of the water [on hold]

If you look up from underneath toward the surface of the water in your aquarium, you may see an upside-down reflection of your pet fish in the surface of the water. Explain how this can happen.
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1answer
70 views

Mode groups in an optical fiber

I know what modes in an optical fiber mean but what are exactly mode groups in an optical fiber? From what I read until now, I have the impression that modes that have close propagation constants ...
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2answers
69 views

Light-Matter Interaction and Object's Appearance

I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories: mirror like glossy or specular diffuse He suggested that the law of reflection is ...
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1answer
19 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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0answers
13 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
24 views

Difference between sound wave and lightwave scattering [on hold]

What are the main differences between sound and light scattering starting with the Helmholtz equation? (Preferably by circular cylinder)
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1answer
26 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
82 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
33 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
161 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
33 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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2answers
41 views

How to make a rotating linearly polarized (not circular polarization) beam from a single beam?

One way to make a linearly polarized beam rotating at frequency $\Delta f\approx10\mbox{MHz}$ is by combining two circularly polarized beams, one left-handed and one right-handed, and where one beam ...
2
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1answer
250 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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2answers
146 views

Magnification in compound microscope

I was studying about compound microscope here I don't see why we multiply linear magnification of objective with angular magnification of eyepiece. Shouldn't it be both angular or both linear? Can ...
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1answer
25 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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2answers
280 views

About partially polarized light and the degree of polariztion

When I was taking Optics course, I found there were several questions about polarization of light. I use the textbook of Hecht. It seems that the definition of degree of polarization may be not so ...
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1answer
2k 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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0answers
29 views

Application of Snell's Law || Basic Optics [closed]

As shown in the diagram the setup consists of a source and a detector in a 2 layered medium-the interface being inclined to the horizontal.Will the travel times for both cases(source to detector and ...
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1answer
103 views

Is it possible to see light intensity fluctuate?

Solutions to Maxwell's equations shows that the $\vec{E}$ and $\vec{H}$ component are of the same phase, which means they go to maximum and zero together, therefore the intensity of the ...
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1answer
17 views

Optics, finding the acceleration of images [closed]

the acceleration of both the blocks of mass m will be g, hence the acceleration of the images will be 2g. acceleration of the two images w.r.t. each other will be 2g + 2g = 4g but the answer is ...
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1answer
34 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
58 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
111 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 ...
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0answers
52 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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2answers
63 views

Some objects seem to have the same color whether the light that we perceive is emitted or reflected

Is color only a property of perception, considering these two examples: The glass used in a green traffic light looks green no matter how it is illuminated, either by a white light bulb behind it or ...
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0answers
28 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.) ...
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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
518 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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4answers
6k views

Are Fresnel lenses widely used for solar electricity? If not, why not?

I was just wondering why Fresnel Lenses are not widely used in the production of solar electricity. Their use there would mean that you could produce heat within a fraction of a second, up to a few ...
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0answers
31 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
30 views

Why do pores make ceramic opaque?

I want to know how a ceramic transparency is mostly affected by the pores, grain boundary, second phases etc. present inside of it, but the major contribution is due to the pores. Let's consider the ...
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2answers
147 views

Cylindrical Fresnel Lens Focus Problem

How to focus beam from the fresnel lens on a flat surface. In my case, instead of producing the light beam, I am receiving the light beam. So, the beam comes from the right and then focuses at a ...
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2answers
161 views

Optics - Faraday Rotator using waveplates

I'm trying to replicate the effect of a 45° Faraday rotator using a series of waveplates instead. I've encountered some difficulties using the jones matrix notation, the main book I'm using is: ...
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1answer
40 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 ...
3
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3answers
100 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 ...
2
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1answer
156 views

Fiber optics with broadband, incoherent light

I wonder if someone could help clarify waveguiding with broadband, incoherent light please. If we take a telecomms fiber, which is single-moded above ~1.4 μm and couple a laser beam in, we assume ...