Laser Definition and 1000 Threads

In a gas laser, an electron in the highest energy state absorbs photon for stimulated emission to occur, but now since it has more energy than its highest state, shouldn't it escape the atom and the active medium be left only with positive ions?

Hello. I've been struggling with this problem for some time, and honestly I do not know how to solve it. Homework Statement Two positive lenses are to be used as a laser beam expander. An axial 1.0 mm diameter beam enters the short focal length positive lens, which is followed by a...

i know light is also a particle, but if a laser can hit an open slit and spread out i can't see how it couldn't be more spread out when it came out of the laser in the first place

Hi, I am working on building a laser range finder and wanted to know if there is any relation between the frequency/wavelength of laser wave and the maximum distance it can measure. I read that the maximum distance it can measure depends on the power of the laser. Any other links...

Homework Statement A laser of frequency f0 is connected to a spring which oscillates in one dimension with a period T and amplitude A. The laser excites the 1st four Paschen series lines of hydrogen. What is f0 Homework Equations I'm assuming that I'll need the Doppler shift equations, f =...

Homework Statement A helium-neon laser beam has a wavelength in air of 633nm. It takes 1.38 ns for the light to travel through 30cm of an unknown liquid. What is the wavelength of the laser beam in the liquid? (IN NM) Homework Equations v=wavelength*frequency v= d/t The Attempt...

I don't know if this is the right place to post this but here goes. I'm a Highschool student building a nitrogen laser for an independent research project. I don't know much about lasers besides what I've read in physics textbooks and amateur laser pages. My and my mentor have already...

Hello! I recently purchased a basic 6-inch Equatorial Reflector telescope. I bought it because I loved doing astronomy with large binoculars, and I assumed the next step was a small reflector telescope. However, I find myself barely using the new scope because the bulky Equatorial mount is...

Hi guys I'm reading a section in a book about non-linear optics. They have an expression for the polarization for the second harmonic field. They say that this expression has a linear and a non-linear contribution at frequency 2ω, but they don't explain this any further. I am a little...

I'm aware that photons carry momentum while technically having no mass. However I recently saw a video of a laser used to propel a small silvered object up several meters in the air just using the momentum of the light. So what about the reaction force? As the light is coming out of the laser...

Hi! I hope this is the right forum. I know how laser works (population inversion, electronic transitions etc...), but I can't understand why the light emitted is coherent

Hi all, i am doing a project to make a laser pointer that can connect to the PC wirelessly. Here's how it works. -using the modified laser pointer, shine it on the screen from anywhere in the room and the dots/lines will remain on the screen until the user changes slide. Background: once...

Is it possible to send information by laser? If so, how much faster is this than radio signal?

[SIZE="5"]I want to simulate the reference’s passive Q switch process. The reference is Shengzhi Zhao, Lei Chen, Hongming Zhao, Guiqiu Li, Lu Zhang, Kejian Yang. Laser–diode-pumped passively Q-switched Nd3+:NaY(WO4)2 laser with GaAs saturable absorber. Optics & Laser Technology 37 (2005)...

Hi I just started a PhD where I am going to use lasers to measure fluid flow among other things. I am looking for some helpful information about otpical components and techniques mainly relating to lasers. How to correctly design a setup, how to split beams, how to expand/contract beam...

I apologize if threads on this topic have been posted already. I don't frequent the medical sciences forum. My question is whether there are any rigorous scientific results published in peer-reviewed journals on the efficacy of what seems have been dubbed "low level laser therapy" (LLLT) as a...

Hi At continuous-wave oscillation the gain is equal to the threshold gain, i.e. g = gthreshold. Now in my book, I have the following expression for the steady-state population-inversion for a three-level laser N2, steady state - N1, steady state = (P-Γ12)/(P+Γ12)NT where NT=N1, steady...

Hi there. i solved most of this question, but am not sure about the last part and i was hoping someone would help me. As part of a laser light show a technician is adjusting a diffraction grating. A green laser with a wavelength of 532 nm is shone on a diffraction grating with 2700...

I'm interested in hearing stories about the very early days of lasers. This is easily one of the top few inventions of the last century, and it's turning 50 next year. I'm particularly interested in the first half of the decade, from handbuilt instruments in labs to on-the-shelf product in many...

I've become interested in lasers and this question came to me today. Let's say we have two 10 mW lasers. One has a spot size of 1mm and one has a spot size of 10mm. Therefore, the first laser has a greater intensity. In classical physics we are told the wave amplitude increases. In modern...

Homework Statement I am to calculated the wavelength of the laser I shone through different slit patterns to create diffraction patters on a screen. For the single slit diffraction, Data: xm is the distance from the central image to the mth minimum. x1 0.008 x2 0.015 x3 0.023 x4...

Homework Statement A laser passes through a body of water and later hits a screen, as shown: http://img80.imageshack.us/img80/7417/20478103.jpg However, suspended in the water is a piezoelectric quartz crystal which can produce waves within the water. When set at 5.5MHz, the following is...

Does anyone know what those tiny spots are you can see inside a laser spot on a wall. They seem arranged something like a honeycomb - hexagonally packed tightly against each other. They seem to follow the motion of your head around when you see them too, so I guessed that maybe I'm seeing my...

A small spaceship, with a mass of 1500 kg (including occupants), is at rest in outer space with negligible gravitational forces acting on it. If the astronaut turns on a 10kW laser beam that points out of the ship into the deep of space, what speed will the ship attain in 1 day because of the...

I found this nice book on Google http://tinyurl.com/yh2y2zb that does a great job explaining relativity, however, even though the conclusions make perfect sense to me so far, I'm stuck on a conceptual issue when reading over the classic thought experiments that makes me feel like I'm still...

Homework Statement An argon laser emits 1 watt of continuous light (λ= 5.145 x 10-7 m) in a parallel beam of 2 mm diameter in vacuum. Homework Equations (a) What is the wavelength, frequency, period, wave number, velocity, intensity, and amplitude of the electric field of the laser...

I know that lasers can be extremely dangerous to the eyes. Causing severe vision damage and/or blindness if a laser gets in your eye. I know that this holds true with laser pens, but does the little red laser from a laser mouse pose that same hazard? Or is it harmless?

Homework Statement A rubidium atom traveling at the speed of sound absorbs photons from an oncoming laser beam Each photon can be viewed as a tiny ping pong ball having momentum 7.79 x 10-28 Nt/sec. The atom absorbs a photon which is then reradiated in any direction. Hence, on average each...

I suppose this thread should belong to a separate group called Light - that is, I suppose this should be where Quantum Physics should be. As for the question, I'd gladly explain that it is of a laser. I wanted to get a laser at Wicked Lasers (I know, with the LaserShades, of course), but here...

Homework Statement A laser emits a monochromatic beam of wavelength \lambda , which is reflected normally from a plane mirror, receding at speed v . What is the beat frequency between the incident and reflected light? I know that the f_{beat} = |f_2 - f_1|. When the wave hits the...

How is fusion initiated with a laser? What are the difficulties that are preventing physicists from using it?

I've looked for this subject but perhaps I'm asking the question the wrong way. Please advise. Is there an extension of magnetic field (flux) beyond the beam axis of a laser? In other words, can one detect (or has anypone attempted to detect) the magnetic field around the a light beam in a...

For my experiment I need to take a 0.8 mm HeNe beam to 20 mm beam. Since we just want illumination, it appears there is not need for beam expander or a setup of special lens (there are a few configurations online). It was suggest to use a Plano-convex cylindrical lens. I talked to...

In many paper or book on laser, it is quite oftern to mention the pump and probe field. I understand what the pump field is, but what about the probe field? What we need a probe field? How does it work (how to "probe")? And why a probe field is always a weak field?

Hi, I am writing a program in MATLAB for robot localization based on scan matching and have the following problem: I have recorded 1228 laser scans at different positions and extracted extreme points from these scans. So that gives me 1228 sets of extreme points (every set might have...

Homework Statement I have a few questions because of the fact I just don't understand any of this... 1.A helium-neon laser (l=656 nm) illuminates a single slit and is observed on a screen 1.9 m behind the slit. The distance between the first and second minima in the diffraction pattern is...

Recently, i obtained a 100mW green laser pointer, and the thing gets me confused. On one side, the beam is bright enough to see from some distance at 90* angle to it, and the point is visible on a hillside some miles away. On the other hand, it doesn't burn anything, like advertisements often...

I ran across this site from 2001: http://www.afineline.org/projects/paint.html Apparently it didn't work very well. Anybody care to guess what kind of equipment it would take to make a red splotch appear on the moon to the naked eye from earth?

I would appreciate assistance with a thought experiment I've been having trouble with. What I asked myself was, If I had two Lasers of equal Intensity/power, say 200 milliwatts, one appearing green and the other red, with wavelenghts of say 555 nanometres and the other 660 nm, which laser...

ok, second question today: if we shine a laser (ideal laser; no spreading out whatsoever of the ray) in Earth's atmosphere, at some distance the intensity of the laser will die out due to it hitting air particles. what if we shine it in a vacuum? e.g outer space My guess is that it will...

Hi all, can a laser light be magnified by means of a magnifying glass?

Hey everyone, I am not knowledgeable in the field of physics, so please excuse me if my question is obvious or poorly worded. I have found myself reading recently about various Nuclear Fusion research, and just now I came across an overview of fusion contained by lasers, specifically at the...

Homework Statement wavelength 1.08um pulse duration 20ns pulsed energy 700mJ pulse rate 15Hz => Total number of pulses ~1800 per run Came across in a paper published. Was thinking a way to calculate the numbers of pulses ? Homework Equations laser beam comes in pulses with pulse...

Homework Statement A 200 mW horizontally polarized laser beam passes through a polarizing filter whose axis is 25 degrees from vertical. What is the power of the laser beam as it emerges from the filter? P=mW Homework Equations E (transmitted) = E (incident)cos() The Attempt at a...

Homework Statement In our Lab we have a Nd:YAG pulsed laser of 420mj ,10 ns pulse width...focused to 1 mm spot Homework Equations what's the power density? how it calculate? The Attempt at a Solution

Hey guys, I'm not exactly sure on which forum I should be posting this topic but I decided to post it here. Any mod can move it if deemed necessary. Anyway, I have been wondering about the infrared wavelengths that a remote control emits when trying to control, say, a TV or VCR/DVD player...

If you shine a beam of light at a black hole, most of it will either fall into the black hole, or will just graze past it, hardly being bent at all. But any photon that just happens to have L/E (angular momentum per energy) = M√27 will orbit forever (or until it hits infalling matter), with...

Not really a problem but a concept I am having trouble understanding and I was hoping someone can explain to me better. We performed an experiment in lab last week on finding the Young's modulus of copper by projecting a laser on the wall to magnify the effect of the change in length of the...

I'm a science fiction writer, currently I write a novel related to laser fusion. As I know in chemistry, catalysis is the process in which the rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst. Are there catalysts in the nuclear...

In Quantum mechanics lectures we are learning that several factors influence the wavelength produced from a laser. These factors include doppler broadening of moving atoms in the laser, the uncertainty of the transition energy levels themselves due to the uncertainty principle, etc. Previously...