Laser Definition and 1000 Threads

Hey everyone! Im currently an MSc student in laser physics. My work focuses on high power thulium fibre lasers. I would like to do my PhD overseas, in the same field (not necessaily a similar topic). So I have browsed around earlier rather than later and doing my PhD overseas is definitely...

I am trying to build the instrument according to this link http://www.inventgeek.com/2009-Projects/Laser-Instrument/page5.aspx I am having problems with lasers.I can not focus the laser dot on the photoresistor.So I thought about laser array(fabricated)but i could not find it.So I am now...

Hello folks of physics. Can anyone tell me about some exotic photon lifetime definitions for photons in laser cavity? I mean, I looked in all sorts of books related to that topic, and the entire bunch of authors use the same definition: cavity exiting energy through dissipated power; or...

Homework Statement A laser is used to focus 25 MW of light onto a missile for 15 seconds. If the mass of the missile is 200 kg, determine the speed change imparted to the missile in the direction of the laser beam. Homework Equations E=hf p=h/\lambda F=dp/dt \lambdaf=c F=ma The Attempt at a...

Homework Statement A very short pulse UV laser is used to liberate a number of electrons from the negative plate in the arrangement in (ii) above(describes parallel plate capacitor system, states plate thickness and separation in vacuum ignore edge effects, charge density and electric field...

Homework Statement A 50W lamp radiates isotropically and has a spectral width of 750 nm and a centre frequency of 600 nm. How much of its total output power is emitted into a solid angle of 10^-6 Sr? What is the diameter of the spot that a beam subtending this solid angle makes on a...

I do not know anything about physics but in order to sort my problem out I have been told to look into the impossibility of photon collisions. What I would like to achieve is to take two Class 1 lasers (any wave length you like) and cross the two, in doing so I was hoping that their infinite...

I need to know the beam width of a pulsed yag laser (280.5 nm) when focused, assuming its completely guassian. The laser is focused through a bi-convex lens with f=15cm. I've found expressions for w(z), but they are all in terms of the minimum waist, w0, which I don't have and is probably the...

I am merely getting curious in thinking about building a radio-wave laser. I'm not seriously pursuing this, but I think it would be cool to build a laser that is ~10km in length. Is anyone aware of any research into this type of monstrosity? Any thoughts about the feasibility or the potential...

Homework Statement Thought Project 7 Skill Level III Problem Laser, which use light rays of set wavelengths (colors), are in constant use in our world, in everything from surgery to supermarket checkout scanners. Execute the necessary research to determine whether the color of a laser...

I am designing a laser targeting system on which various control methods will be implemented and compared. The system consists of a laser pointer mounted on a two axis gimbal. The laser shines on a 30 cm x 30 cm white screen, behind which is a digital camera. The camera sends all information...

Hi guys, so I'm at my wit's end. I'm trying to measure fluorescence/phosphorescence lifetime. I have a laser pumping at 532nm and it's pulsed at 25 picoseconds. I also have a ICCD/spectrometer. Here's the problem: Currently I'm using the spectrometer triggered internally with a gate pulse width...

I took a cube polycarbonate sample and put a laser through it (perpendicular to a face). When light crosses both faces (front and back), some of the light will reflect while some goes through. My questions are: 1) For the light that reflects off the first face and goes straight back into the...

If a TEM00 output laser source (regarding both cases of single frequency vs multifrequency) is used as input into a multimode optical fiber, is it possible for the output of the optical fiber to be multimode?

Hey guys, I'm wondering.. If I were to reflect a green laser pointer to the mirror, will the reflected laser be hot too? Or will I be heating the mirror?

I'm sure most of you on this board know what the VASIMR plasma rocket engine that is being prepared to be tested on the ISS. I read that high-powered radio waves are used to heat the argon gas to the plasma state of matter and then the superconducting magnets eject the superheated gas out of the...

I have a question, I used pulsed Nd:YAG laser to weld a steel part but I didn’t measure the pulse energy during the experiment. I was wondering if there is a way to calculate it somehow? I have laser pulse duration, frequency (repetition rate), and laser (mean) power. Thanks

Hi I keep reading that an atom cannot be cooled to v=0 because of random recoil from spontaneous emission, i.e. a random walk in momentum space. If it is a random walk, then - on average - we don't have any net motion, i.e. we stay at the initial position. This also holds in momentum...

I just purchased a HeNe laser with a power supply that came with it. I am not sure how to wire the powersupply to test the laser. There are 4 input wires, Brown, Blue, Green and white. The output is already plugged in correctly. I can take pictures if needed.

Hi, Is there a such mirror which can reflects a UV laser (~190nm wavelength) with Reflectance greater than 95% and also invisible laser (not necessarily in a high Reflectance)? Thanks

Hi is there a broad laser mirror for UV laser in the range which contain the invisible light and a 190nm? and where can I find such mirror? Thanks

Hello all, I'm new to the forum, and probably i post in the wrong place, but i will appreciate your help. I do my PhD in Chemical Physics on the topic of nano materials, we do all kind of optical experiments (PL, LT, Confocal microscopy and so on), and till now used a very old laser Ar ion...

Homework Statement You are making a laser with light of wavelength 310 nanometers using a MgF2 window (which will transmit the UV). The mirrors will be external so each end of the 'pumping' gas discharge tube must be cut at Brewster's angle so that there is no reflection from the surface as...

Hi, I'm new to this forum so please don't get mad if this post is in the wrong place. I have a laser beam pointed at a solar panel (regular PV cells) and the current comes out as expected on my oscilloscope (small waves varying like pulses between 0.45 and 0.50 V regularly). I tried...

I wanted to make tiny movements of the Earth visible by reflecting laser light off liquid gallium metal. It did produce nice reflections on my wall, showing dramatic wobbles of very tiny movements of the liquid gallium. It did however produce light interference patterns which I cannot explain...

Question: If you were to theoretically shine a laser into the intersection of two mirrors, what would happen to the reflected beam? When I say 'theoretically' I mean that the beam would hit the corner perfectly. I'm confused by this because the derivative of a sharp point on a graph is...

Hi, I have a problem with an optics experiment, the experiment involves measuring the interference patterns created by the tracks of a CD. But as soon as I put a lense in between we get an really odd pattern, this pattern seems to not move along with the laser as the beam is being shifted...

I have a cheap $8 USD 5mW green laser for pointing out stars to my daughters and neighbours. This laser does not have a safety rating on it, so I treat it as a class 3. It is getting weak and I need to replace it. My first thought was to order from Wicked Lasers [1], who had been recommended...

What is the pattern made of balls? https://www.youtube.com/watch?v=KrUhKQxOPx0 I have some hypotesis: Something related to the CCD, a diffraction pattern caused by some dirt on the lens, or, but i think it's absurd, the Bravais lattice of the lens? I'm very curious!

A laser beam whose intensity is modulated (at frequency, f) is falling on a black absorber. For the surface temperature, there will be two components: (1) modulated temperature or photothermal wave and (2) a static dc temperature component. The photothermal signal properties are well known...

Are their laser pointers that are totally safe for the eyes? What kind to look for?

http://nerdapproved.com/misc-gadgets/dolphin-laser-pointer-keychain/" So in the above image they have little attachments for laser pointers that can make different designs. I've played around with similar types of attachments for laser pointers and have never thought about the physics...

Homework Statement A CD stores data in digital form by encoding it into a grooves as a series of bumps of height 160 nm above the base of the groove. Explain how infromation is picked up from the CD using a laser and calculate its wavelength. Can someone please explain how to do this...

Hi, I have the book by Peter Milonni, Laser Physics. Does anyone who has this know what the p(z) and q(z) represent in the equation on gaussian beam solution to a 'beamlike' wave on page 282, under the chapter 7.5 "Gaussian beams"? \epsilon(\bar{r})=Ae^{ik(x^{2}+y^{2})/{2q(z)}}e^{ip(z)}...

See what I mean http://www.lanl.gov/orgs/tt/pdf/techs/3dlaser_pointer.pdf". Actually, coming to the point, how is this laser pointer at the Los Alamos National Laboratory able to control the z-axis with the slider? There was a previous thread by someone else which was replied with something...

We're trying to build a circuit that will detect when a laser crosses a photoresistor and light an LED. What we're trying to do is have three different photoresistors, and three diffferent LED's, each of which correspond to one photoresistor. The idea is that when one photoresistor is struck...

Homework Statement Reflection at a surface takes place under the condition that the field amplitude is zero at the reflecting surface. As a result, the axial modes i of wavelength λi inside a laser cavity can be defined by their number ni of sine-wave half cycles that fit exactly into the...

I currently have a laser set up that sends three lasers (red, yellow, green) into an optical fiber. On the other end of the fiber, the emitting light is shooting in essentially one forward direction. Does anyone have any suggestions or a suggestion on a certain material that if put on the end...

When we are considering the how much optical power a component/pin detector can withstand, are we more concerned about keeping an eye on the peak power or can we ignore the peak power so long as the average power is below some threshold value?

Bad news: http://blogs.discovermagazine.com/cosmicvariance/2011/04/06/nasa-gives-up-on-lisa/

A beam of light from a laser projected on a screen with a very small hole in it will spread after it traverses the pin hole because of the HUP: Measuring position so accurately causes loss of information about the momentum. I believe that in the case of laser light, only information about the...

Hi I would like to understand the statement that "there cannot be a two-level laser" in a bit more detail. I understand that given an active medium consisting of two-level systems, one cannot pump it using photons with an energy equal to the energy gap to reach population inversion, because...

So this is the case - I've bought some shocking laser tag guns to play with my friends, though I am unsatisfied with their range which is merely 5 meters. I was wondering if I could add some convex lenses in front of the laser gun in order to increase the range of the laser, would that work...

Hello I have a question regarding reflected light from a surface of higher index of refraction. Suppose I have a ideal laser, and an ideal surface with reflection coefficient 0.7 or something like that. Say I shine my laser directly perpendicular to the surface (at 90 degrees). I...

Hi guys, I am currently doing a project which involves firing a class 4 laser into a small enclosure (200mmx200mm) and onto a target, which is to emit IR. I am trying to theoretically prove that there will be no ionization of the air (i.e. turn the air into plasma) inside the enclosure...

I have a question about Ring Laser Interferometry. A couple of years ago I contributed some text and several pictures to the http://en.wikipedia.org/wiki/Sagnac_effect" . Ever since I have been curious about the quantum interpretation of Ring laser interferometry. The special thing about...

Hello everyone, hope you can help me! I am doing research involving illumination of an object in a cylindrical acrylin tube filled with water using a Nd:Yag laser. Homework Statement I am trying to figure out the refraction of the laser as it passes from air through the curved acrylic then...

I am working on a project and am combining three laser beams in an effort to make artificial white light out of the end of the fiber. It is currently producing about 1 mw of power. How could I increase the power out of the end of the optical fiber?

Homework Statement (1) A Physics lecturer, on a dark night, shines his laser pointer towards the star Vega. (a) Roughly, how many optical photons from the Sun per second enter the eye of an astronomer standing on a planet orbiting Vega ? Assume that 50 % of the light from the Sun is...

Hi, I'm currently recalibrating an optical tweezer for my undergraduate thesis. The alignment did turn out well so far but I'm a little bit concerned about the power loss within the microscope (here's a picture of the relevant part, without prisms). I read in a paper that 20 to 100mW are...