Laser Definition and 1000 Threads

Does laser traveling through air affect the air it travels through?

Homework Statement If a 20-W laser beam, which has an initial diameter of 2.0 mm, spreads out to a diameter of 2.0 m after traveling 10,000 m, what is the final intensity of the beam? A. 20 x 10-4 W/m2 B. 20 x 10-6 W/m2 C. 20 x 10-8 W/m2 D. 6.4 W/m2 E. 6.4 x 10-6 W/m2 Homework...

Homework Statement A scientist needs to focus a helium-neon laser beam (lamda = 633nm) to a 10 micrometre diameter spot 8.0 cm behind the lens. a) What focal-length should she use? b) What minimum diameter should she use? Homework Equations w = (2.44lambda * focal length) /...

Does the energy of laser depend on the wavelength of it? Or the energy of laser depend on the number(flux) of the photon? Which is more harmful? The light with short wavelength or with more photon? Thanks@@

I got a 5mW (class 3A), 650nm laser pointer yesterday and it came with 3 AG-3 button cells and over a day, it was on for about 60 seconds, maybe more however I noticed the beam wasn't as bright as it was when I first put it on. Over 30 seconds worth of use, it seemed to dim further until I...

Hi I'm a student in school and I'm having a mental block on how to do this question. Could some give me a hint as to the principals I'm meant to consider /use. Q) A red, 100mW, laser beam , wavelength 650nm, is incident normally on a perfectly black disk . Calculate the force on the disk...

where can i find a page to get laser simulations or laser models?. thanx

A laser pulse has a duration of 50 fs (50E-15 s) and an energy of 1 mJ. The laser is focused to an area of 50 micrometers square. What is the peak intensity and peak electric field at the focus? I previously tried to do this problem with normal intensity equations using intensity =...

Homework Statement How long would it take a laser beam to go to the Moon and back if the distance to the Moon is 3.8 x 10^8m? Homework Equations a=2d/t^2 d=v1 t + 1/2a t^2 The Attempt at a Solution a=2d/t^2 9.8m/s(Gravity)=2(7.6x10^8)/t^2 t^2=15.2x10^8/9.8 t= 12453.99698 secs...

just wondering why all photons produced in a laser beam are coherent? what forces them to have the same phase?

Homework Statement A laser with wavelength d/8 is shining light on a double slit with slit separation 0.500 rm mm. This results in an interference pattern on a screen a distance L away from the slits. We wish to shine a second laser, with a different wavelength, through the same slits...

Does anyone have one of those military grade green lasers that can set things on fire? I've seen people build them but I don't have a solder iron :(

DARPA, NASA, JPL and various aerospace giants are rushing to learn more about a massless thruster developed by Dr Young Bae: http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=201804852 http://www.photonics.com/content/news/2007/September/7/88894.aspx At the claimed...

1. Homework Statement : Consider two lasers, one blue and one red. Which of the two lasers has the higher intensity? 2. these are my choices: The blue one. Cannot be decided based on the information given. The red one. 3. The Attempt at a Solution : The difference between these...

Is it possible to burn anything with a 5 mW green laser?

Homework Statement A laser beam (\mathrm{Power} = 1\ \mathrm{W}) is completely reflected by a mirror perpendicular to the beam. Light is made of photons, and each photon carries an energy E = h\nu and a momentum P = h/\lambda, where \nu is the frequency, \lambda is the wavelength and h is...

Homework Statement Which of the following can / cannot be used for fiber optic communication. What is the general rule / cut-off (in terms of wavelength) for deciding ? Thank you. Choices (Laser type/wavelength, nm) Argon fluoride (UV) 193 Krypton fluoride (UV) 248 Xenon...

Nobody has been able to give me a solid answer to my question: If you had a red, green and blue laser, and you combine the three beams to one spot will you see a white spot? Since lasers are coherent the three beams should pass through each other without forming a white spot. Right? Or do...

Why the three-levels laser require high energy to start the inversion population? Please answer without mathematical details because I know the solution mathematically, I want the answer physically Thanks

I need to heat a sample of biological materal to a certan tempature with a laser. How do I find the right amplitude/wavelength/power to reach the correct tempature? (sorry my spelling could be better) ^.^

Recently I read the thread "Giant Solar Laser" in the General Astronomy Forums. The author, Ruslan_Sharipov, writes I was just wondering if someone could explain specifically how a laser will be amplified when passing through plasma. Thank you for your time.

It is known that the Sun is a super large source of energy. Only an extremely small part of solar energy is absorbed by Eath and an extremely small part of that absorbed energy is utilized by mankind. The idea is to invent a tool for pumping the energy directly from the Sun staying distant from...

Hi, This latest announcement on the development of something resembling a BEC using polaritons seems interesting: http://physorg.com/news98645866.html http://physicsweb.org/articles/news/11/5/17/1 So I'd like to know what the implications of this development are. Could this...

Im studying gain saturation for homogeneous and inhomogeneously broaded transitions. Im a little confused bout the logistics of laser operation regarding the gain in the cavity. So from ground state, the atoms are optically pumped to produce population inversion(4 level system) where...

Firstly, this is NOT a homework question although it may sound like it. My question pertains to http://youtube.com/watch?v=H5NwRfMJgOQ". My question is this: Could an Infrared Laser (there are varying power output lasers of 2W - 20mW) SPIN a paper of say 25 grams as seen in the vid on the tip...

Is this forum ok for posting EE student questions? I guess I'll find out. :biggrin: Homework Statement How many photons per second does a low power (1 mW) He-Ne laser (\lambda=336nm) emit? At what He-Ne laser power do you expect quantum effects to become important? The Attempt at...

Homework Statement How many photons per second does a low power (1 mW) He-Ne laser (\lambda=336nm) emit? At what He-Ne laser power do you expect quantum effects to become important? The Attempt at a Solution I got the answer to the first part, 1.7\times 10^{15} photons/second. But the...

Is it possible to create gravitons the way photons are created, with electrons falling from quantized systems, or create graviton analogies to photon-lasers?

A laser beam passes through a single slit of width 0.0186 mm and produces a pattern with an intensity distribution like that shown in Figure 13a (page 208), on a screen 105.6 cm away. If the spacing between the minima on either side of the central maximum is 7.16 cm (in other words, 2y1 in...

I need the solution for this problem in 3rd edition "Laser Electronics" by "Joseph T. Verdeyen" : problems in chapter 6(Resonant Optical Cavities):20 please,do not disapoint me.:!)

Right. Even well-documented observations that do not fit easily into a preconceived notion of how the world should work, may be rationalized away or just neglected. One example of this is the observed mean acceleration {\dot n} of the Moon; from lunar laser ranging experiments this has the...

As we know, if we have a group of atoms at a moment N(t) in an exited state, it will exponentially decrease according to the relation: N(t)=N(0) exp(-At)=N(0) exp(-t/(tau)) Where A is the Einsteins constant for the spontaneos emission, In my book they defined tau in the relation I...

Hiya. I'm really stuck on the following questions and so any help would be really appeciated. (a) A laser produces light of wavelength 632nm. Calculate the energy of the laser photons. Speed = Wavelength x Frequency 3 x 108 = 632 x 10^-9 x f f = 4.75 x 10^14 Hz E = hf E =...

A few weeks ago Physical Review published a Letter (an edited version of http://arxiv.org/abs/gr-qc/0702028" ) that says: "At this time, [Lunar Laser Rangefinding] provides the most precise test of [the gravitomagnetic phenomenon,..] likely better than the ultimate result from the GP-B...

Homework Statement A stationary particle of charge q = 3.0 10-8 C is placed in a laser beam whose intensity is 2.5 103 W/m2. (a) Determine the magnitude of the electric force exerted on the charge. (b) Determine the magnitude of the magnetic force exerted on the charge...

Homework Statement A laser produces 15.6 dBm of power. The light is propogated through a 10dB neutral density filter that attenuates the signal so that it can be detected by a photodiode without saturation. The optical signal is steppeddown by 15dB when captured by teh photodiode and converted...

Hallo to all members, this is my first post. Homework Statement A short Laser flush with the Energy E = 1J hits a ideally reflecting mirror, with mass m_m = 2 * 10^(-5) kg . The light has a wave length of 696 nm. The mirror is hanging on a rope with the length l = 0,1m. Homework Equations...

Laser emits due to the stimulated emission. As the photons produce in this process are coherent, I would like to ask why they won't undergo interference and produce alternating bright and dark light when they just come out from the laser source. thanks.

hey guys, I'm currently doing a project on laser beam, and just wondering what material i can use to disperse a laser beam so it hit a surface with more surface area. thx Dazza

I heard that there was a wavelength of "light" that partially permeates through the human bodies skin and can degenerate the nerve endings before the skin succomes to the harmful effects of the "light". This sounds like complete bs to me since the interaction wavelengths of different tissues...

I'm interested in anything you have...links...sugestions...ideas about this field...

I have a class III laser that I'm doing experiments with. The laser makes a point on a wall. I am staring at this point for extended periods of time. I could potentially star at this point for upwards of 10 minutes at very close range(less than 12 inches). I can't really discern weather or...

Hi, I have a few questions about ionizing lasers creating an electrical path that I'm hoping someone here might be able to answer. Does anyone know what kind/power of laser would create a good path of low resistance for an electrical current? I am thinking through normal atmosphere, say up to...

Hey all, I am currently trying to figure out how I can control the direction of a laser beam. Galvos are widely used in order to electronically change the direction of the beam. Although, I was hoping to find a way to do this without mechanical parts. There are two ways I have looked at...

Hi, I am looking to develop a device that would take a single laser beam, and split that one beam into x number of new beams and I was wondering if anyone knew how I could accomplish this. I was thinking I would need some kind of crystal specifically shaped to produce the results I need...

Question. If we had a tuned LASER, at what level of Energy would be required for a tuned LASER beam to spontaneously ignite the Air around its Beam just as a Bolt of Lightning ignites the Air around itself.

http://www.aip.org/pnu/2006/split/779-1.html Diagram: http://aip.org/png/2006/260.htm Paper: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000096000021215504000001&idtype=cvips&gifs=yes

Instead of shooting a single burst of beam, use multiple shots ( say 1000 per second or more ) Theoritically each laser beams should punch a hole through the air, each one traveling further and each one creating a vacuum within its path. The high powered lasers that auto industries use have...

Is this for real? http://www.smh.com.au/news/national/laser-enrichment-could-cut-cost-of-nuclear-power/2006/05/26/1148524888448.html

Hi All, It seems a team of Aussie scientists at our one and only reactor have developed technology to use lasers to enrich Uranium. Sorry about the local rag link, but here is the story...