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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15 views

Why is the coupling constant in laser theory assumed real?

I'm reading the laser dynamics book "Light Vol. 2 Laser light dynamics" by Haken. On Page 123 of the book, the coupling constant g is assumed to be real. However, from the definition of g (see ...
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49 views

Trapping force in optical tweezer

I am reading a paper on theory of optical tweezers in ray optics regime by A. Ashkin. For reference "click here". It is given that Gradient force $F_g$ is directed perpendicular to the light ray and ...
3
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4answers
232 views

Shining a laser onto a mirror

Theoretically, if I shined a laser at a mirror at an angle of 0 degrees so that the light was perfectly reflected back to the light source, then I should not be able to see the light because it is not ...
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1answer
45 views

How a rangefinder works? [closed]

The speed of light is too high so how does a laser rangefinder calculate such a short time taken by the light to come back?
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1answer
59 views

Find alighment — Sacher diode laser littrow configuration

For a Sacher Diode laser Littrow configuration, I knocked it out of alignment. Does anyone know how I can find back the alignment? I was able to tilt the cylinder a little bit to find the bright spot. ...
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1answer
180 views

Does a laser beam converge and diverge without lens?

In the case of $TEM_{00}$ mode laser produces gaussian beam. I read in wikipedia that it converges till some point called 'beam waist'and then it diverges to infinity. If there is a lens placed along ...
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0answers
31 views

Could two electrolasers be used as a cutting tool for non-conductive materials like rock?

An electrolaser is an ionizing laser that turns the air molecules in its path to a conducting plasma. There have already been experiments with electrolasers as thunderpoles. You can also inject a ...
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1answer
65 views

Stimulated emission role in laser cooling

Laser cooling can be achieved by exciting an atomic system, in order to "pump" atoms in the excited state. This gives a recoil momentum $\hbar k$ the the atom, which then emits spontaneously. As ...
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32 views

How efficient is a self-cooling Zeeman slower?

Suppose a Zeeman slower is set up such that the cooled atom beam output is used to extract waste heat from the laser, then recirculated. Assume further that the magnetic fields are provided by ...
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1answer
61 views

how to scan a diode laser wavelength in certain range?

Is it possible to scan a sacher diode laser in certain wavelength range? For example, when piezo offset is 0 volt, the wavelength of laser (read from a wave-meter) is x. When I set the piezo offset ...
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22 views

Could an electrical pulse with the right properties reach a person's head after striking their chest?

I am trying to figure out if it is possible to build an electrical gun that could instantly and reversibly render a person unconscious. The trouble is that the gun should work when aimed at the ...
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0answers
45 views

How do we calculate the adjustment factor for hyperbolic secant pulse for calculation of peak power in ultrashort laser pulses?

In the formula for peak power it is equal to total energy divided by FWHM pulse width multiplied by an adjustment factor 'a' the value of which depends on the shape of the pulse. For hyperbolic secant ...
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2answers
56 views

What will happen if there is no spontaneous emission in laser? Will the working of the laser be possible?

We can use the Einstein's coefficients and omit the spontaneous term. How do I proceed after that?
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19 views

Interferences while using two ToF cameras

Im using two time-of-flight (ToF) cameras, a DS325 from SoftKinetic and a Creative Senz3D, at the same time with the DepthSense-SDK and the Point-Cloud-Library (on Ubuntu 15.04). But I got strong ...
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0answers
57 views

Acquiring an Active Q-Switched Laser

I'm working on a senior undergraduate project in engineering physics, and I am building an instrument that will use a Q-switched laser as a short-pulse, low-pulse-repetition-rate light source. We need ...
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1answer
59 views

Can we weld two dissimilar metals without using LASER welding? [closed]

It is said that one of the many advantages of LASER welding over ordinary welding is that it can be used to weld two dissimilar metals, what problems do we face while welding two dissimilar metals by ...
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0answers
30 views

Why do we use alcohol as active medium for dye laser?

Why do we use alcohol or ethylene glycol as active medium for dye lasers, they are not liquid organic dyes right? Or do they(alcohol etc.) serve some different purpose here?
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137 views

Lang-Kobayashi rate equation derivation

The Lang-Kobayashi rate equations of a semiconductor laser experiencing feedback are as follows: \begin{align*} \frac{d}{dt}\left(E(t)e^{i\omega t}\right) &= \left[\omega_N(n) + \frac{1}{2}(G(n) -...
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0answers
31 views

Coloring the clouds with lasers

What strength of laser would be needed to color or make projections of images upon clouds in the sky? I am assuming that this is possible, if not, please explain why. For the purposes of this ...
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1answer
211 views

Intersecting Lasers

What happens at the point of intersection of 2 lasers. If 2 lasers of different colour intersect, what will be happening at the point of intersection? Won't colour mixing happen?? Won't that point ...
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1answer
143 views

Simple derivation of the doppler limit and recoil limit

Im doing an essay on laser cooling, and I've got two questions about the derivation of the two limits. Firstly, in the derivation of the Doppler limit, it is stated in many places that the scattering ...
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0answers
28 views

Lower Threshold optical beam limiter?

We would like to implement a very fast beam limiting, so far google search shows that the common threshold ranges is in 1J/cm^2 or more, this could take seconds to activate as our laser ranges from 1 ...
2
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1answer
145 views

Why does the laser change colour? [duplicate]

In the first image, the laser colour is green. When it is shined on the plastic cap of the pink highlighter, the colour changes, why has this happened? Tech Details about the Laser Source are; Max ...
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1answer
311 views

Does laser beam expand along distance or not? [duplicate]

Why does laser dot become bigger at bigger distance? e.g: from millimeter to inches so that it distracts pilots in aircrafts. I knew that laser beam should't expand over distance, but remain stable. ...
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116 views

Gain clamping and threshold gain in quantum optics

We increase the pump power of a laser to the point where laser action starts, i.e. the threshold gain is reached. Now we increase the pump power even more, which increases the intensity of the cavity ...
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1answer
43 views

Can a laser class be lowered by lowering the input duty cycle? [closed]

According to this description, class II lasers have a power output of less than 1mW, class IIIa lasers have a power output of 1-5mW, and class IIIb have a power output of 5-500mW. Can a class IIIb ...
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0answers
78 views

Difference between steady state intensity and saturation intesity in laser

Can some one explain the diffrence between steady state intensity and saturation intensity in lasers. And diffrence between gain at threshold and gain at steady state,why are these two gain equal? ...
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1answer
47 views

How to classify laser output

What are the quantifiable criteria that are used to assign a safety classification to a laser? Googling finds me only vague subjective descriptions, like "safe to use under normal conditions" or "...
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0answers
31 views

How to read CO2 a laser line label?

A line emitted from a CO2 laser is often labelled as 9P36, 10R18(13C), 9R32, etc. What do these labels mean? For example, does 9P36 mean the line is 9.36um from the P-branch? What difference does it ...
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2answers
121 views

Could a civilisation contact us by laser from 50 light years away?

The Kepler Space Mission has discovered over 1,000 planets. These discoveries may increase the confidence of some people that other civilisations exist. That is an opinion issue, and not what I want ...
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30 views

What is Frequecy Pushing/ Pulling in Laser Physics

I heard the term "Frequency Pushing/Pulling" in combination with phenomena like in homogeneous broadening and hole burning but I didn't understand what Frequency Pushing/ Pulling is supposed to mean. ...
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0answers
18 views

Relaxation Times in Quantum Optics

I am studying laser physics and in in the lecture we defined the transversal and longitudinal relaxation times as the relaxation times of the coherent/ population states of the density matrix. The ...
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1answer
198 views

Spectral Line- Width

How does the spectral line-width of light source (let that be ordinary light, LED, LASER etc.) decides for which communication purpose it will be used for ? Is it like spectral line-width effects the ...
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0answers
40 views

Laser Energy Level Transitions

I am new to Laser Physics. While looking at the Energy Levels diagram for the Laser Transition of ND:YAG laser, I see energy levels labeled like 4F(3/2), 4I(15/2),.. I did not come across such energy ...
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1answer
208 views

Using a laser to overhear a room conversation

Movies with science based tricks and gimmicks are generally silly and sometimes even annoying. The science based trick that I don't know enough about to judge is the following (and I have seen it in a ...
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2answers
55 views

Creating nanosecond pulses from a CW laser source

Experimental setup question. If anyone aware of a technique to create pulses of several nanoseconds at a around 10Hz repetition rate from a CW laser source?
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1answer
54 views

Dissolving photoconductor (TiOPc) from Laser Printer drum possible?

When I was thinking of a Lab-On-a Chip Application which combines a lensless microscope and an optical tweezers I saw the ODEP-concept:(http://pubs.rsc.org/en/content/articlelanding/2013/lc/c3lc50351h#...
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2answers
74 views

Light (Laser) operated optical switch

I have searched the web and found that optical switches are activated either through mechanical or electro/magnetics. Making them sort of Optomechanical or optoelectronic switches. Lets exclude ...
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0answers
22 views

Limitation of Rytov approximation for turbulence

I have been working through the textbook "Laser Beam Propagation through Random Media" by Andrews and Phillips and have arrived at an interesting dilemma. For a second-order perturbation in the Born ...
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1answer
77 views

Effect of the refractive index of a transparent layer coating a particle?

I am modelling a cell as a particle coated by a layer of a material whose refraction index might change. This layer is to resemble the membrane. The purpose of the model is to simulate what happens ...
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0answers
153 views

How to calculate the Refractive index of a glass sheet

My question is how to find the $n$ of a glass sheet with just aiming a laser beam to that. I've got lot of ways that let me find the $n$ ( Refractive index ) but I need the whole part of the ...
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1answer
409 views

Are there naturally occurring lasers in nature?

Are there natural processes we've discovered which lead to laser light of some distinct wavelength?
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3answers
374 views

Why does shining a laser into an iPhone camera create these shapes?

When I shine a laser light into an iPhone 6 camera I get these weird shapes: The shapes are in no way in the background behind the laser. What causes these to appear? I know about typical lense ...
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1answer
37 views

Material that changes transparency when lased from side?

I am into photonics research, and have been searching about this topic in vain, but almost nothing from Google shows up. So i turned here for some light. Do you guys know any material that changes ...
2
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0answers
28 views

Inertial frames and Sagnac interferometers

Let's posit: I am in orbit around a large body, like a planet, and I am close enough to be tidally locked to the large body. Am I in an inertial frame? Even without looking at the stars, couldn't ...
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1answer
67 views

Laser: Looking for name for optical component

I'm currently planning a laser setup in which I want to send a (1mW) laser into the environment using a commercial scanning unit (made of two galvanometers). I would like to measure the reflectivity ...
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1answer
48 views

Meaning of “electrostatic” and “nonresonant laser” fields

I just read the following sentence: The molecule is subjected to an electrostatic field $E$ combined with a nonresonant laser field of intensity $I$, whose linear polarization is collinear with $...
4
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2answers
145 views

Is circular masking a laser beam an acceptable way to get the beam diameter you require?

I am wondering what are the down sides to just masking a laser to get the beam diameter you require? For example if you have a collimated eliptical beam of say 2mm width and 4mm height, but you ...
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0answers
49 views

Visible wavelengths of air fluorescence data - needed for school demo laser telephone design

I'm seeking information about fluorescence in visible wavelengths (390-700nm) of any of the main constituents of air ( $ N_2, O_2, CO_2, H_2O, CO, etc. $) that can be excited with a (hopefully low-...
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1answer
1k views

Why do we see brown light?

While researching about lasers (it's my hobby), it suddenly hit me: there are lasers for every color of the visible spectrum, but there are no brown lasers. Brown isn't even on the rainbow. How is it ...