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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what is the best way to collimate light emitted by a led?

I'm new to this forum. This is half a question, half a challenge. And it's more engineering then physics but I thought I might get good insights from a physics forum. I would like to cure a UV ...
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3answers
131 views

Divergent thin lens producing real images

The question is as in the title, can a divergent lens produce a real image, when backed by a convergent lens? Which are the conditions to be respected? This was a homework and I have received the ...
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194 views

Fermat's principle to prove the law of reflection

Fermat's principle tells that a light ray will follow a path from point $A$ to point $B$ so that the optical path length of this path is an extremum over neighboring paths. I wanted to use this ...
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1answer
87 views

Identifying an optics equation in a code refactoring project

I apologise if this a somewhat naive post. My knowledge of optics is limited, and I am learning on the job, so to speak. I'm a computational biologist, dabbling in a bit of physics. I'm currently ...
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What are the current experimental limits on the polarizability of the vacuum?

Many (all?) materials are polarizable at some level; meaning that when we apply an electric field across the material, there is an induced dipole moment $$ \vec{p}=\alpha(\omega)\vec{E}, $$ where ...
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Is 'color' characteristics of a body or characteristics of light?

In situation when body exposed by light, is 'color' characteristics of a body or characteristics of light? Is there any difference on macro/micro levels? Will exist such term as 'color' in parallel ...
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92 views

If photons don't have mass, how can they accelerate objects? [duplicate]

As far as I know photons don't have mass but they do have momentum ($p=mv$). Scientists say that if we put a shiny (reflective) shield of large radius in the vacuum of space, then light from sun will ...
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1answer
115 views

How to compensate ray displacement caused by refraction in glass slab

I need a nudge in the right direction, i guess (this is not a homework question). I want to calculate the total length of a ray from an emitter to a target which passes through a slab with known ...
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446 views

How much light can pass through a point?

Analogy: an infinite number of lines can pass through a point. Is there a limit on the number of lasers that can pass through a point? Obviously, with lasers the “point” would be a sphere with the ...
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19 views

Radiometric Intensity of Non-Monochromatic LED

So I have a problem with the LED with the spectrum shown below I am asked to find the radiometric intensity in Watts/steradian given that the LED produces $5.6\times 10^{-3}$ mcd. We are also told ...
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0answers
43 views

Relection of light [duplicate]

If I recall my physics correctly, and it was a long time ago, when a photon strikes a reflecting surface that specific photon is not what is reflected--rather the photon excites an electron which ...
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32 views

Rotation speed measurment

Could anyone please explain with simply how we can measure the rotation speed of an object using the Sagnac Interferometer ?
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1answer
43 views

What Material for reflective surface of a solar grill/barbecue? [closed]

I have been planning on building a solar grill for quite a time now, and the one problem, which is also the biggest - I need to shape a mirror into a paraboloid, so it bundles solar energy ...
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1answer
77 views

Apparent depth and the viewing angle [closed]

Does the viewing angle of a person observing a coin placed in a bucket of water affect the apparent depth in any way?
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1answer
102 views

Why is a rainbow curved in shape?

Why is a rainbow curved in shape? When dispersion of light takes place, light splits into seven colors, but when rainbow is formed it appear to be bent. Why does this happen even though light travels ...
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1answer
54 views

Pfund's method for refractive index

I wish to obtain the refractive index of a smooth surface using only a laser of given wavelength and a light sensor. I thought of using the Pfund method (attached), but I can't understand how the ...
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2answers
49 views

The velocity of light changes from one medium to another, but does its energy change?

Does energy of light change when a light travels from a medium to another of different optical density?
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1answer
52 views

Can a full image be made in mirror if we change the distance between object and mirror?

To see the full height of man, the height of mirror should be half of the height of the man. What happens when we decrease the distance between mirror and man?
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1answer
42 views

Can zinc nitride be used as light emitting material?

I cannot manage to find any journal papers about the applicability of zinc nitride as active layer of an light emitting diode (LED). But certain papers got mention that zinc nitride with a direct ...
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105 views

Optics Brewster's Angle Reflection Intensity

An incident unpolarised light beam of intensity $I_{0}$ strikes glass plate B at Brewster's Angle. The reflected light travels vertically and strikes a second glass plate A, again at Brewster's Angle. ...
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3answers
56 views

Clear vs black in terms of light reflection?

I've heard that clear things such as the gaseous components of the atmosphere or water reflect no light, and that is why they are clear. I've also heard that black things such as asphalt are such ...
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1answer
25 views

Equivalent temperature: laser and cell containing Rb

What's the meaning of "equivalent temperature" related to a cell containing rubidium and crossed by laser?
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1answer
22 views

Practical hardware question regarding optical source for an array of fiber bragg gratings

I have a single 1 meter array of 5 fiber bragg gratings that has FC/APC connectors on both ends. I will be embedding the array in a material and want to be able to do a quick check that the array is ...
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2answers
80 views

What really makes a rainbow happen?

Yes, a rainbow is formed when a raindrop refracts light, but why then does the whole sky not become a huge rainbow when it rains? Would the light not be dispersed into ordinary 'white' light? What ...
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1answer
68 views

Diffraction problem - How do I interpret

Here is a problem on diffraction - Diffraction pattern of single slit of width 0.5 cm is formed by a lens of focal length of 40 cm. calculate the distance between first dark and next bright fringe ...
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1answer
45 views

Characteristic quantities in Fiber optics

I'm having trouble finding typical quantities in fiber optic communication. In particular, what kind of powers are generally used (or what is the minimum that fiber optics receivers can detect ...
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3answers
61 views

Simple Experimental Laser Characterization Parameters Ideas?

I have 2 months to do a project on characterization of a laser parameter. We have typical optics lab equipment (DFB Lasers, oscilloscopes, random number generator, etc.). I was told to choose a laser ...
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1answer
25 views

Microscopic origin of optical transmission

When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy ...
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640 views

What causes multiple colored patches on a wet road?

I was going to school (after a rainy hour) when I saw some patches of shiny colours lying on road. Some small children surrounded that area and thought that it's a rainbow falling on the Earth. (For ...
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3answers
128 views

Does optical fiber preserve the angles of incoming light?

I am reading up on optical fibers and there's one thing I haven't understood yet: Does an optical fiber preserve the angles of incoming light? For example, if we light two LEDs in front of an ...
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2answers
95 views

Why does a picture of a person seem to be looking in the same direction irrespective of the angle of observation? [closed]

If you observe a picture of a person hanging on a wall who seems to be looking directly towards you always seems to be looking at you even though you change your angle of observation to the extremes. ...
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1answer
25 views

Isotropic systems and homogeneity

In isotropic systems, the atomic arrangement is homogeneous in all directions. In the case of glass, which has the atomic structure of a liquid and, therefore, a random atomic structure that is ...
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1answer
38 views

What type of interferometry set up do I need to image a small structure at a distance?

Please forgive me, optics isn't my forte. I'm trying to work out how to image the surface structure of an object at a distance. Considerations are: Monochromatic light- it must be imaged in the ...
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1answer
80 views

Phase Shift of Tunneling Wave

What is the phase shift of a wave that tunnels through a barrier, meaning the difference in phase between the incoming (in front of the barrier) and the outgoing (behind the barrier) waves? For ...
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1answer
34 views

How would the composition of the Venusian atmosphere visually affect the sunrise and sunset there?

The Venusian atmosphere is according to CalTech's webpage What is the atmosphere of Venus like? is 90 times heavier, than Earth's, containing predominantly carbon dioxide, some nitrogen, sulfuric acid ...
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55 views

How can fiber optic image conduits consist of only fiber core, no cladding?

Looking at fiber optic image conduits, I found that they have a packing fraction (the ratio of the fiber core's area to the total area) of 100% (source here). In other words, they consist only of ...
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355 views

Proof of minimum distance between object and image of a convex lens image being 4*focal length

I can prove that the minimum distance between an object and its image, through a convex lens is 4*focal length, if I assume that the distance between the object and the lens is the same as the ...
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1answer
59 views

Determining a person's sight from his speech [closed]

Suppose we meet a person wearing glasses.Can we determine whether the person is short-sighted or long-sighted? However,due to courtesy,we are not allowed to ask him to try the glasses and in general ...
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1answer
81 views

Visible light through a single-mode optical fiber?

If I understand things correctly, the optical fibers used for (long-range) data transmissions are generally single-mode fibers, transmitting light in the 1300-1500 nm spectrum. Now, could such a ...
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2answers
146 views

Is the frequency/wavelength of light modified when multiple light sources are combined?

Let's say I light a wall with two spotlights: One red and one green one. Where they overlap, I'll see a yellow area at the wall. My question is, whether this is caused by an modification of the ...
2
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1answer
93 views

Shot noise at high frequencies (can it really be ideal white noise?)

Quantum shot noise (either optical intensity noise or electrical current noise) described by the noise spectral density of $2 e I$ (electrically) or $2 h \nu P$ (optically). So it is white noise. I ...
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2answers
87 views

what is the 'resolution' of the reality in pixel terms

1.What resolution should a TV screen have so that its image were so faithful as reality as if the TV were a window ? 2.Also what would happen if Physics could reproduce a 'pixel' of the size $ ...
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34 views

Spatial light modulation for mode multiplexing, how does it work?

If a laser light becomes spatial phase modulated (by phase only spatial light modulator) what happens to the intensity distribution and frequency spectrum of the laser light ? I know that this ...
3
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2answers
143 views

White light diffraction

I have a hard time understanding why light waves of different wavelengths diffract in a different manner. According to Huygens' principle, every point on the wavefront is a source of a secondary wave. ...
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1answer
59 views

Why is the angle of a triangular prism equal to the result of the following 2 calculations? (Experiment with optical goniometer)

I know there are two ways of measuring the angle of a prism with a goniometer: let the collimator shine (monochromatic) light on 2 sides of the prism and measure the angle between the 2 reflected ...
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2answers
60 views

Do acousto-optic modulators shift the frequency of the diffracted beams?

Today I read an introduction on an optical device called an acousto-optic modulator, which is used in many optical experiments. It is the first time I have heard of this element. The material showed ...
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2answers
59 views

How does one measure the frequency of a laser?

I am taking a short introduction course on lasers. I never knew that the frequency of a laser is so high for a given wavelength (e.g. 780nm). I am wondering how people can measure the frequency of the ...
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2answers
147 views

Is it possible to project an image onto water? [closed]

Is there a way to create an image/projection in the water? Or form the water to project an image, little dot/pixel? Use some type of frequency to modulate the little dot in the fluid?
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30 views

How does a liquid crystal on Silicon affect the phase of incident light?

When a polarized light beam is directed to a phase-only LCoS system how is the phase modulated ? What is the physical effect behind ? Does voltage modulation has an impact on birefringence ?
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103 views

Why doesn't a typical beam splitter cause a photon to decohere?

In many experiments in quantum mechanics, a single photon is sent to a mirror which it passes through or bounces off with 50% probability, then the same for some more similar mirrors, and at the end ...