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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Mathematica FindFit mistake [on hold]
I have data from a knife-edge measurement technique, Power vs. knife position, and i want to obtain the beam radius.
kf = List[{36.2, 2360.0}, {36.3, 2360.0}, {36.4, 2320.0 }, {36.5,
2150}, {36....
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11 views
Gain Coefficient of lasers and intensity paradox?
It can easily be shown that the intensity of a laser is
$$I = I_0e^{z\gamma} \,, \tag{1}$$
where $\gamma$ is the gain coefficient.
It can also be shown that
$$\gamma = \frac{\gamma_0}{1+I/I_{\text{...
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WDM with a channel spacing of 10 nm? [on hold]
I'm looking for a wavelength-division multiplexing (WDM) that offers a channel spacing of 10nm to 15nm, for center wavelength (1521, 1531, ..., 1610).
Do you think such WDM filter is possible ? if ...
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2answers
52 views
Spaceship A and Spaceship B move in opposite directions at half the speed of light, and A fires a laser at B, does the laser light reach Spaceship B? [on hold]
This question has been bugging me for a week now!
I believe it would, but logically, I feel like I'm missing something.
Please give a full explanation.
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How can I focus a laser in the gap between two slits?
I’m trying to focus a green laser in between two slits. The slit width is 0.2mm and gap between the slits is also 0.2mm. I measured the laser’s minimum spot size. It’s elliptical with major and minor ...
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Wavelength vs change in angle of polarization?
My project is on polarimetry. I am searching for a base idea. What is the relationship between Wavelength vs change in angle of polarization? Note- Please do not lin this to optical activity(even ...
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4answers
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Does putting an aperture in a laser beam make the smallest point it can be focused to larger or smaller?
If you put an aperture in a laser beam to block some of it, I would imagine that the spot it can be focused to becomes larger due to diffraction. The numerical aperture of the system is limited by ...
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1answer
40 views
Confused about intensity of a laser beam
For normal natural light coming from the sun, the electromagnetic waves emanate from the sun with a spherical wavefront, then we can calculate the intensity of these waves reaching us on Earth by $ I =...
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spot size in a microscopy experiment
How does a laser spot looks like under a high Numerical Aperture objective. I am attaching the profile I am getting in my case. Just wondering how can I calculate my spot diameter or point spread ...
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1answer
13 views
Finding intensity of laser after round trip in cavity with single mirror [closed]
I came across a question in a text book today, and was wondering if someone could maybe check to see if my physics and workings are correct, as I am getting a intensity value greater the what going ...
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1answer
53 views
Poor man's laser? [closed]
Would it be possible to use a non-laser light source to etch a flat surface? Using lenses or parabolic mirrors to focus the light to a point?
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2answers
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Can lasers cause glare or reflections?
When going to the movie theater I sometimes notice reflections from the projector on my glasses and I find it very annoying. What happens is that the light hits the back of my glasses and i can see a ...
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1answer
23 views
What does 'coupling' mean? (Laser)
I assume this question is so basic that no YT-video or paper I found answers it. But in order to understand I have to know what it refers to.
I'm talking about laser coupling to be exact. I have a '...
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What can be done to a laser' setup to increase its slope efficiency?
Having a fibre laser, whose setup consists of a pump diode, a YDF and of a fully reflecting mirror parallel to the fibre, what can I do in order to improve the slope's efficiency without adding any ...
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DIfference between pump diode power and fibre's input end power?
I am reading some measurements done on a fibre laser, and the first data shown is the Current v Power table of the pump diode used in the experiment.
After that, a fibre is added to the system and a ...
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What characteristics of a fiber laser can I get from the input, output and unabsorbed pump data?
I aligned a pump diode with a fiber laser and added a dichroic mirror in front of the laser to separate the pump light from the light radiated from the fiber.
This way I was able to analyse the power ...
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2answers
26 views
Lasers to direct waste heat?
I've been thinking about ways to cloak ships in space, since they all are warmer than their background they can be seen in the IR spectrum (given a large enough telescope).
So I was thinking, could ...
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1answer
33 views
How to decrease the Q-factor of a resonator?
I was trying to create a mode-locked laser in order to create high-intensity light pulses, this experiment was done a while ago and with someone else, and in our notes says that the laser cavity's q-...
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1answer
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Why do the Einstein rate equations require broadband radiation?
The Einstein rate equations govern the absorption and emission of photons from a two-level system of energy levels.
It states that the rate of absorption of photons is given by $\textrm{N}_{1}\rho\...
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1answer
22 views
Question about units in photonics calculation
My textbook has a photonics example problem, where the absorbed light energy density is calculated as
$$\Psi = 25 \times 9.55 = 238.75 \text{mJ/cm$^3$} = 2.38 \times 10^5 \text{J/m}^3$$
I'm new to ...
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1answer
27 views
Holographic “lens” - controlling light diffraction angles with silver halide film
I'm trying to develop a way to control the "exit angle" (diffraction angle) of a monochromatic light source.
For example:
taking a laser;
spreading the beam; and
directing the light at a piece of ...
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Laser Detection Paint
Does there exist a paint which if a pulsed laser of ~1500-1600nm was fired at it it would emit visible light or IR Radation (3-5 micron)?
I have seen up-converting inks and paints but I can't find ...
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Could you use a laser beam as a modulated carrier wave for radio signal?
There have been successful experiments in modulating sound over a carrier ultrasound wave. Not so long ago, I've even seen an DIY implementation on Hackaday.
I also encountered and tested a program ...
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1answer
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Is it possible to create a black hole in the lab?
https://www.livescience.com/65113-fastest-camera-captures-speed-of-light.html
This is what light looks like when captured by a camera at 10 trillion fps. Interesting. You can find this YouTube video ...
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Pump Probe Spectroscopy Zero Delay
I am setting up a Non Degenerate Pump Probe Experimental Setup, in my lab, as part of my Master's Project. Due to the constraints of the way the lasers have been set up in the lab, I am unable to ...
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Finding the inductance of a laser given things like wire length, peak power, and peak current
I am operating an RCA GaAs diode laser operating near $904$ nm designed to be in pulse mode. The driver circuit for the pulsed diode laser is below:
With the repetition rate of the trigger set at ...
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Radiation Pressure Noise in Gravitational Wave Detection
I am trying to work out where equation 9 comes from in Martynov et al. (2016), who discuss the radiation pressure noise in the LIGO detector.
$$L(f) = \frac{2}{cM\pi^2 f^2} \left(h \nu G_{-} P_{\rm ...
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1answer
56 views
Can gases be heated by absorbing laser light?
I have a narrow gas jet, with a laser pointed at it. I want to figure out whether the gas will absorb any thermal energy from the laser photons, if they are at a wavelength that the gas can absorb.
...
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Proper atmospheric laser propagation including reflections
I'm attempting to model the propagation of a laser beam (specifically, its beam radius) through the atmosphere, bouncing off a (curved) surface. This is fairly simple up to the surface itself, but I'm ...
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1answer
39 views
Can any body suggest me a set up that I can build it up to study the surface roughness of transparent polymeric fibres? [closed]
I need to study the surface of nylon-6 blank fibres with a thickness of nearly 40 micrometre. I work in optics lab with many optical components such as beam splitters, lenses, mirrors, etc; can I ...
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Theoretically, if I swish a laser back and forth fast enough/at the right frequency on a distant surface, will I get an interference pattern?
Just curious. I’m kinda stumped and am interested in how one would go about visualizing/calculating this.
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Can I build up a profilometry set up, to study the surface roughness of polymer fibres?
I need to study the surface roughness of some fibres, I was told that the best way is the profilometer, but can I design and build up a set up of a profilometer?
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1answer
40 views
Why do semiconductor lasers become weaker after extended use (not due to battery)?
Why do semiconductor lasers become less bright as they are used for longer periods of time (assuming their battery is full)? Does it have something to do with the PN junction reaching some kind of ...
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4answers
87 views
Laser beam focus
Why isn't it possible to focus a laser beam to an infinitely small point in space? I am familiar with the shape of a gaussian beam, but why can't my $w_0$ be equal to zero?
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What is a good introductory textbook to Laser Safety?
I was looking for a good textbook about Laser Safety (e.g. protection glasses design, distance of risk calculation, laser classification...). I can't find a complete book with these informations, ...
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2answers
56 views
Accelerating Charge Radiates, so why can't we make a laser emitter out of it?
I've been taking class where we learnt about different types of laser, it reminded me of an old question I had before.
There's been issues with making very short wavelength laser pulse with ...
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Can a laser ever run single mode without active stabilization?
So when we talk about the emission wavelength of a laser, what we actually mean most of the time is the central, brightest emission wavelength, e.g. 852 nm on some diode laser. When we look at this ...
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Air ionization by powerful continuous laser (power calculation)
I am interested about air ionization by the laser beam. Here I found a very good answer, but I would like to clarify it a bit more.
How about a continuous laser? For MPI (multiphoton ionization) ...
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1answer
27 views
Is the spatial coherence of light a requirement for creating a well-collimated light beam?
I was wondering if, for creating a well collimated light beam, the spatial coherence play a role. In particular, I understand that a laser beam can be well-collimated with respect to light coming from ...
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1answer
70 views
Optimal pump wavelength for frequency doubling in periodically poled media
Background
I am currently working on achieving second harmonic generation (SHG) in periodically poled lithium niobate (PPLN) using a 1560 nm pump laser. PPLN makes use of quasi-phase-matching of the ...
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1answer
73 views
How can someone calculate distance between Earth and Moon using a laser?
I have a book stating:
When astronauts of the Apollo missions visited the moon, they placed a mirror on its surface, facing the earth. Then scientists on the earth sent a strong laser beam, which ...
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3answers
51 views
Could a converging beam of light be converted into a parallel one?
A parallel beam of light comes out of a plano-convex lens and start to converge into focus, the question is, at that focal point, could the beam be parallelized again so it maintains the focal point ...
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2answers
80 views
Why does a laser beam stay coherent when it passes through glass?
If I have a coherent laser beam and I shine it through some glass, the light will slow down because it will interact weakly with the atoms in the glass. However, the beam that comes out the other side ...
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How do I relate phase shift to heat capacity or thermal conductivity for frequency domain thermoreflectance?
I'm trying to measure either thermal conductivity or heat capacity of Silicon devices using frequency domain thermoreflectance (FDTR). I can get phase shift between the incoming signal from pump laser ...
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Can I couple 1064 nm and its harmonic 532 nm in a single polarization maintaining fiber?
I have an experiment where I need to get a largish (40 mW) amount of 532 nm light and small amount (<50 µW) of 1064 nm light into a device under test. I need something with stable polarization so ...
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1answer
34 views
Electron density Saha Ionization Equation
Saha-Boltzmann equation describes the ratio of number densities between any two consecutive ionization states and its product with the number electron density i.e.
$$n_e\frac{n_{i+1}}{n_{i}}$$
Here, ...
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40 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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1answer
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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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3answers
115 views
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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25 views
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.
