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Questions tagged [laser]

Light Amplification by Stimulated Emission of Radiation. A means of creating coherent light by either driving an atomic or molecular transition in an optical cavity or firing a beam of electrons through an undulator.

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What materials can I use to diffuse a laser beam, so that the entire material will light up red when a red laser beam strikes it? [on hold]

What materials can I use to diffuse a laser beam, so that the entire material will light up red when a red laser beam strikes it? Imagine a hockey puck of material, that will light completely when in ...
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Differences between stimulated and spontaneous emission? [on hold]

I would like to know at least 10 differences between the stimulates and spontaneous emissions of light. Even the very small ones are acceptable?
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36 views

When I shine laser light on a mirror, why isn't the reflected beam noisy? [duplicate]

An interesting question popped into my head today regarding laser light. First, we know that all matter is made up of atoms, and that photons are considered to exhibit wave/particle duality. But if ...
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Wavelength of Intermittent Laser vs Prism

The following YouTube video from Sixty Symbols ( What is the maximum Bandwidth? - Sixty Symbols https://www.youtube.com/watch?v=0OOmSyaoAt0 )states that only a laser which always shines truly shines ...
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polarization of ordinary light, laser and photons of atomic transition

The light from thermal sources such as a light bulb is unpolarized but the one from a laser is polarized. Why? Is a photon emitted in an atomic transition linearly or circularly polarized and a ...
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47 views

Distance between Moon and Earth via laser beam, intensity [closed]

I have a question regarding one of my worksheets this semester, the question is the following: The distance between earth and moon can be calculated by measuring the time for a lazer pulse to be send ...
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Is synchronized radiation possible?

Could it be possible to make 2 or more radioactive atoms, maybe plutonium, emit radiation at the same time? A kind of synchronized radiation. Perhaps this can be the basis for some kind of laser too.
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31 views

How is UV light generated in equipment?

I have been wanting to build a spectrophotometer, or a device that emits light in the UV range for measuring properties of proteins in my graduate lab. I am thus looking to find a way to generate UV ...
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Non-Planar Ring Oscillator in LIGO

How does total internal reflection from non-planar surfaces in an NPRO help eliminating standing wave and why a planar structure can't give the same result? I understand that to produce optical diode ...
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Which focal length is needed to determine minimum focused spot size in 2 lens system?

If you calculate the minimum spot size of a beam, it depends on the focal length to to power 2. But if you have a lens system with 2 lenses, does the focal length in this case represents the effective ...
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Does light reflected from a plane mirror at a high angle of incidence lose coherence or intensity?

If a 100% coherent laser was directed onto a mirror at a high angle of incidence, for example 89 degrees from the plane normal, and we assume that the mirror is perfectly or near perfectly flat, does ...
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Momentum Change from Spontaneous Emission

In page 188 of Christopher Foot's book on atomic physics, he talks about the Doppler cooling limit, and how it comes from a random walk caused by spontaneous emission. He claims that each spontaneous ...
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Difference between solid and warm dense matter state

I found a theory paper, in which they discuss the absorption coefficient of a material as a function of the electron temperature. The electrons in the material are heated up by a free-electron laser. ...
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Direct energy weapon vs kinetic energy

Good day, I would love to ask this question. Lets say that I have a energy source capable of delivering 10^30 watts with capacitors to match it and I would like to use this energy as a weapon (sort ...
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1answer
52 views

Laser without a cavity

I am reading the book 'How the laser happended' by Townes. In it, he mentioned the megamaser discovered in the cosmos. It is a maser without a cavity. I am a little bit surprised that a maser or ...
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32 views

How to split a laser in multiple collimated beams

I want to split a collimated laser with a round shape with diameter of 3.5 mm (CPS532-C2 beam, collimated) in 3 collimated lasers in which the third beamlet will still have at least 3 percent of the ...
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1answer
28 views

Field intensity for electric field and vector potential

In general, the intensity of an electric field is given by $$ I = \frac{c\epsilon_0}{2}E_0^2 $$ where $E_0$ is the peak amplitude of the electric field. Let's say we have an electric field $$ E(t) = ...
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45 views

How does spot size of a laser depend on wavelength?

Does the spot size of a laser depend on wavelength? We have a laser source that is fed into a spectrometer to set the wavelength we want. No other optics are used after the spectrometer. I was going ...
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Degenerate and Non-Degenerate Pump Probe Spectroscopy

I have just started my Msc Project, working on Pump Probe Spectroscopy. I will be most probably trying to setup a non degenerate pump probe technique, with the setup for degenerate type already done ...
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What causes the upper limit on wavelength in optical fiber?

It's well known that a most given waveguide modes have a cutoff wavelength above which the mode is no longer supported. At low wavelengths, more modes are supported. But what happens at high ...
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21 views

What angle does light leave a 400micron fibre if it entered from a single mode fibre (0.14NA)?

We would like to connect a single mode coupled laser to a 400micron fibre. Ideally, we'd like the light to come out of the 400micron fibre at all angles or close to the maximum divergence angle, ...
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1answer
38 views

Would it be possible to conduct electricity using laser-ionized air?

If you had a high-powered laser and shined it through the atmosphere - causing a large amount of blooming and ionized air/plasma - could you use this as a conductive channel? I'm imagining a kind of ...
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Do red lasers shoot longer than green ones?

I am aware of the fact that our eyes are most sensible to green color and therefore green lasers seem stronger than other colors when being scattered through the air. However, since red wavelength are ...
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Why can an Erbium fiber laser operate in CW mode?

Erbium is a 3-level system, so it operates only in pulsed mode, like a Ruby laser. But why it can operate in CW ("continuous wave") mode when doped in long fiber glass?
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Laser guns and scattering

I recently read an article that explained how the US Navy would like to use laser guns in the infrared region, with a high power - 500,000 W I guess. However, because of Rayleigh scattering that ...
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Shot noise in optics

There are many explanations to be found about shot noise in optics, but the answers I find are incompatible. There are three ways shot noise in optics is explained. (Note that according to ...
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Can laser interferometer be used on light scattering angled objects?

I want to know if it is possible to use laser interferometer on object with rough texture that is not like mirror, kind of like matte paint that scatters incoming light and on object whose geometry ...
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What is the Brillouin Stokes power?

I know what is the brillouin scattering and i also know what is the Stokes power. Do someome knows what is the Brillouin Stokes power ?
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Laser power and coherent state amplitude

How it is possible to relate the power $P$ of a laser light with frequency $\omega$, to the amplitude $\alpha$ of its description as a coherent state $\vert \alpha \rangle$ ? For a massive particle in ...
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Why do thermal currents affect light but wind does not?

I notice if I put heat under a laser beam it will cause the beam to shimmer. The heated air is causing a disturbance in the air which affects the light. Yet, I can blast a stream of air from a ...
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40 views

Curved Light stream?

I was wondering, a while ago, i asked if there is a way to bend light someway, which I got the answer is index of refraction. In this question I wish to know if this mention when applied with a dense ...
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1answer
33 views

What is a pump reflector?

I understand the meaning of laser pumping. But i don't understand what is a pump reflector. As a clear definition does not appear online. In the paper,DESIGN AND DEVELOPMENT OF WIDEBAND HYBRID RAMAN/...
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Difference in spectrum of green laser and green LED

In an experiment I conducted I used a spectrometer to find the spectrum of green laser and green led. this is what I found: LED spectrum: Laser spectrum: why is the spectral width of the LED is ...
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63 views

Are photons in laser entangled?

When energy is pumped into the atom, photon is being emitted which would then get absorbed by another already excited atom causing the atom to emits 2 similar photon. Soon more photons are produced in ...
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What are laser achromats?

I came across "we used Nd:YAG laser achromats" in a paper, and I was wondering what exactly is the purpose of achromats here. The paper in question is "Dynamics of laser-induced cavitation bubbles ...
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Where does laser reflection (1) come from?

I have the above experiment setup where a triangulation-based laser scanner projects a laser (line) towards a transparent glass material. I then took a picture using my phone (indicated in the above ...
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1answer
50 views

How does a dielectric interact with a laser beam? [closed]

A nano-ball made of latex, which is insulating, has no net electrical charge, and is much smaller than the wavelength of the light. The ball is compact, homogeneous with spherical shape. It has ...
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2answers
91 views

Higher-order dispersion in non-linear optics

In many cases, dispersion of an optical medium is presented by saying that the dependence of the wavenumber $k$ on the (angular) frequency $\omega$ can be expanded in Taylor series as: $$ k(\omega) = ...
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Are the bandwidths of a laser pointer and a sodium-vapor lamp comparable?

The question is not about the slightly differing wavelength of the devices caused by manufacturing processes or the shift from changing temperature. A German source says that the spectral width with ...
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High intensity laser and neutrino pair production

Given the very small rest mass of the neutrino, visible photons have plenty energy for neutrino pair creation. What would be the probability of $\gamma \to \nu + \bar\nu$? Would the neutrinos be ...
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Calculating Laser Focal Power & Focused Beam Waist

If I focus a 1 watt, 405nm laser with a 25mm fl lens what is the power at the waist. I see calculators online but none that make sense. Rather than just telling me can you put your equations you use ...
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1answer
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Do solid-state lasers emit hadrons at some exitation state? [closed]

Given an observation at a solid-state emitter at it's current limit where the device creates more photons than the crystal dissipates (reflected and thermally); thus making photons to impact over ...
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3answers
94 views

How to reduce edge diffraction?

I have a simple setup with a diode laser and an object placed in front of it. I want to observe the edge's shadow clearly. However, I get this very annoying effect of diffraction and interference ...
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Why all laser photons are in the same direction?

The lasing process begins when just one photon is accidently emitted. This explains why the photons on the line between the two mirrors are in phase. But what about the neighboring atoms or even ...
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Observation of Strange Pattern with He-Ne Laser passing through a sample of Chlorophyll

We Designed in our lab an experiment with 5mW He-Ne laser, passing through Chlorophyll, which was extracted from Hibiscus rosa-sinensis leaves dipped in Ethanol. The resultant pattern we observed on ...
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Can shining a laser pointer on an Ice Cube melt it?

I heard in videos that if you use a laser pointer (Green if I recall) and point it on a ice cube, that it would cause it to start melting, is that true?
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Spacing of resonant modes in a (laser) cavity

I don't see why the frequency spacing between resonant cavity modes should decrease with higher frequency. Here's what I have: For a laser cavity of length $L$, from the condition of constructive ...
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1answer
46 views

How to measure width of a very narrow spectral peak without expensive instruments?

Lasers typically have very narrow peaks in their spectrum, much narrower than 1 nm. It would require quite a high-resolution spectrometer to measure such a peak precisely. But if I simply need to find ...
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50 views

Is this possible to focus common light (not laser) to a small point in the wall and control it with mirrors?

I want to make something like a laser projector for an experiment but with common light. My question is: is this possible to focus a small point of common light to the wall and control it with ...
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1answer
46 views

Two-level laser rate equation

I am stuck on what I assume is a very basic rearranging of terms in Siegman's Lasers, Page 204. Here, the saturation of a laser medium is introduced. The change of the populations of two energy levels ...