Laser Definition and 1000 Threads

Ok, so I have a 405nm laser pointer (bluish purple/uv). Had a few miscellaneous glass objects and was shining it through them when I noted a light green line in the glass that it shone through. One of the objects is a sphere of alexandrite, so I assumed that it was a property of the...

Assume a laser with 30kW output energy is pointed at a boiling pot, how much water would it evaporate per second? 30kW=30kJ/s. I assume the water is at boiling point and get: Water heat of vaporization (40,65 kJ·mol−1). Thus we get: (30kJ/s)/(40,65kJ/mol)=0,74mol/s evaporated...

Hi. When I point my red laser pointer at the playable side of a CD at an angle the spot becomes diffracted, a bit like the fringes you can get if you put a hair across the beam. Could you keep to the CD phenomenon, when trying to explain and whether it really is related to Youngs Fringes or...

Question link: http://gyazo.com/4d52ab2521e5b222241718ea1b7ccb08.png I have to solve this using vectors, not geometry My professor said the equation that's required is -v* = 2 proj v onto n - v and v* is reflected vector, so I don't really understand how to do this First off I don't...

Calculating laser fluence -- so confused Hi, I'm now endeavoring to calculate laser fluence using some laser parameters. The required parameters to solve the fluence are given as: Spot size: 10mm diameter Pulse duration: 200ms Repetition rate: 2-3 (Hz) Laser Power: 200mW (when...

I realize that there are two factors that must affect the directivity of a laser. 1, The length of the cavity and number of reflections and 2. The aperture of the exit or the subsequent optics. This must be related somewhat to the respective directivities of Endfire and Broadside RF...

Hi, I have problem understanding some things about this particular LDV system(a Laser Dopler velocimeter). Source is a light source - laser. On the right there is a flow seeded with particles that scatters the light. So here we have a simple directional 3DB coupler. Light goes...

Hello friends, I would like to know the temperature dependence of LASER for its action. At What temperature the laser action is possible and realisable? Any references, links and help is appreciated.

Homework Statement This isn't for a homework problem per say, though it is a coursework question. I'm writing a lab report on Multi-Quantum Well Laser Diodes and am trying to explain the basic semiconductor physics behind it. As such I need a diagram of the band structure. Homework...

How can I be sure that the emission of a He-Ne laser contains only one single mode of laser cavity? The only thing that I know is that if I use a diffraction grating and the light isn't monochromatic, I'll see maximums of the same order at different angles, but I also know that if wavelengths...

Odd hypothetical here- If one detonates/fires a nuclear-pumped x-ray laser (soft x-ray, if you were wondering) and immediately subjects the beam to a high-strength, sustained electromagnetic pulse, would the beam suffer any effects? I've read that EMP does not include ionizing radiation...

Homework Statement A laser emits a monchromic beam of wavelength λ, which is reflected normally from a plane mirror, receding at a speed v. What is the beat frequency between the incident and reflected light? Homework Equations The Attempt at a Solution The solutions starts off...

I'm not sure if this question should be posted in the introductory physics section or the advanced physics section. Consider an amplifying medium, composed of homogeneous broadening four-level atoms as show in figure 26.5, page 557 of textbook. http://img689.imageshack.us/img689/6108/lt2f.png...

Homework Statement A powerful research laser produces pulses of light, wavelength 527nm, containing 300j of energy in 1.0x10^-9 seconds. and concentrated into an area with diameter 1.0x10^-4 m. Assume that the pulse is uniform over its area and uniform in time over its nanosecond...

Homework Statement A plasma is to be used as a shield against a laser in the visible spectrum (400 - 700 nm wavelength light) by attenuating the field amplitudes. (a) What is the minimum electron density that should be used? (b) What thickness of this shield would be needed to reduce the...

hi, I'm measuring my laser pointing stability with a focusing lens and a CCD. Could you guys tell me what would the relationship be between the offset from focal point in CCD and the angle with which the beam exits the laser? CCD is in focus.

I have a question about this old (closed) Thead about the quote: "...but also two separate very low intensity laser beams have been sent through single slits to a common detector and a diffraction pattern resulted. The intensity was so low that the probability of a (semi-classical) photon...

Let's suppose i want to send a message over really big (interplanetary, maybe out of the solar system) distances. I read the Rayleigh formula, but i also read the a telescope array can give even better angular resolution. Does that also means, instead of one giant laser focusing mirror...

I have a diode laser that emits multi-mode light. Two frequencies of this light are selected in an external cavity and reflected back into the laser diode. The laser diode's gain medium then resonate at these two frequencies and emits dual mode light. The laser operates in the 1550nm region...

I just saw an article regarding NASA's Lunar Probe that will use lasers to communicate high resolution images and data from the Earth to the probe for faster comms. My question is...in Outer Space with no atmospheric influence, at what distance would laser communications like this remain...

I can't figure this out. Say 2 frames are in relative motion. When the origins at at the same place, 2 lasers shoot up the positive x-axis and negative x axis. Let's call the 2 frames F and F'. F says the lasers will always hit simultaneous events along the x-axis. Then by the relativity of...

For some reason, can't delete this thread... thank you, UltrafastPED, the below video was very helpful!

Quantum unitary evolution is time symmetric, what leads to retrocausality phenomenas like delayed choice quantum erasure or Wheeler's experiment. However we understand why they don't allow to send information back in time - I would like to ask for help with understanding why another experiment...

Hello, I have to conduct a literature review in regards to Laser Doppler Anemometry and Impinging Air Jet. I am doing a project and it is to compare real velocity data obtained from LDA to CFD data and was wondering if anyone had any good books they could recommend for me to read or good...

Hi, I'm trying to set up a microscope to have wide-field laser epi-illumination. This is to be used with an infinity-focused objective lens. My current plan has the laser expanded 4x using a Galilean beam expander (from 1mm to 4mm) and coupled into the back of the objective using a...

Does anyone know of an article that has a good in-depth, side by side comparison of DFB edge emitting lasers and VCSEL lasers? From my research it seems to me that the VCSEL papers are all trying to justify why laser production should shift towards VCSEL, and mostly list the advantages over an...

Hello, I was hoping someone might be able to help explain what the following are, I have found many articles but non which explain it in Lehman's terms: Probe Volume Bragg Cells Also can someone explain how the effect of varying beam angle is not under our control, but it can tell us...

Hello, this is my first post to this site. I had this idea a few nights ago, and I've been trying to wrap my head around it. Before I go ordering supplies to run some tests, I thought it would be worthwhile to gain some insight from you guys. Anyways, as you probably know, total internal...

Homework Statement So basically I'm given the distance to the moon (384,000,000 meters), and I need to find out how many degrees per second I'd need to move the laser for the spot touching the moon to move faster than the speed of light. Homework Equations w=\frac{v}{r} The Attempt...

In my lab I have a TEM00 laser, so there is no electric or magnetic field in the direction of propagation (call it z direction). However, I know that the intensity of the laser is greatest when my eye is along z direction...why? If there is no electric field along this direction, then what is...

Greeting PFers, I need to use the low pressure region inherent within the cross section of a laser beam for a project. However, I don't know how to calculate the necessary laser power to generate a sufficiently low pressure. The topic is briefly dicussed *here*, but I see no relevant...

I'm new to laser technology and learning it from some lecture videos and a textbook "Optics & Lasers". When I came to the light amplifier part, I got stuck in understanding the difference between "rapid decay" and "metastable state" -- what I can recite now is that "rapid decay" cannot...

Hi, I was wondering if someone could tell me what the best way would be to determine if a semiconductor laser is broken using a multimeter? I have a semiconductgor laser that is still emitting but the signal appears lower than expected and it is hard to tell if it is broken internally...

I wasn't sure where to post this question, so I posted it here. As the title suggests, I want to know how to calculate (at least roughly) the electric field induced by excitation and ionization of a material (such as a metal) using a high intensity laser. My final goal is to compare the...

Hey guys, I'm wondering how come if we're in a completely dark room and shine a laser beam at an object, we see the color of the laser beam (say it's red). How is this consistent with the the theory that objects appear a certain color since that is the frequency of light that they reflect? For...

i am just being curious about some details about how laser can induce charges inside a glass bulk? Does anyone else have more knowledge on this?

Homework Statement A circular cannister of some reflective liquid is spinning at some ω. The distance between the cannister and the surface is given by h(r) = h(0) + (ω2/2g)r2 Where g ≈ 9.82 and r is the distance to the axis of revolution. When we shine two parallell laser beams on the...

what is the source of the first photon in the laser ? i understand there is a burst of light or electricity that excites up the medium , but what is the source of the first photon ? is it the light source or is it one atom of the medium itself releasing photon as it gets de-excited * if...

I have a vertically linear polarized laser according to specs. "Polarization ratio 100:1; Vertical linear polarization". However, When I place a polarizer in front of the laser its maximum is at 132 deg. and minimum is at 42deg. Thats 90 degrees apart.. Placing two polariazer infront of...

Hi Please help me to know : if i have a laser beam with 5 millimeter diameter that reduced to 0.5 millimeter diameter with a lens, Can i reduced the 0.5 millimeter diameter beam to 0.05 or less that 0.5 with another the same lens...

Hello all, I'm a new Mechanical engineering graduate student who needs help using a photodiode. I'd like to rig up some kind of circuit that will let me measure the intensity of laser light. This is kind of a new area for me haven't really done anything like this before so forgive me if I come...

Hi, I am just about to go into my 3rd year of my Mechanical Engineering Degree and have decided to do a project with the following description: "Laser Doppler Anemometry (LDA) is a non-intrusive technique used to measure flow velocities and turbulence quantities in a fluid flow. The...

Hello, I am working on a system where a laser does something and then there is a lot of wasted laser radiation. I want to capture this waste radiation in a small array of solar cells then feed the resulting current back into the laser to make it more efficient. The output from the solar cells...

Hi I have a laser beam(engraving laser machine) and then use a lens for focus the beam but my lens has a crack on the center of lens and when i use my laser in high power the beam diameter will bigger and burning area zone is bigger so: 1- Does the crack doesn't let the maximum focus?in law or...

Greetings PFers, I was thinking about methods of delivering mediums used in 3D printing process, specifically 'selective laser sintering'. Currently SLS uses layers of fine metal powder which are fused together, layer by layer. A new coating of powder is applied every layer. Afterwards, the...

Many nations are developing hi-energy laser weapon. My question is, what if target is coated with mirror like coating? Can laser (since laser is still light) penetrate mirror? If it can then how is it possible? Regards

Good morning, Before all, I also posted a question to maths forum, but I am convienced that this is the forum I was more like looking for. Firstly, hello to this forum, secondly I want to apologize if this is not a place I would like to post a question like that, maybe in another thread ?; )...

Hello, I've been helping a graduate student out with his project which is planar laser-induced fluorescence. Part of the procedure involves generating a laser sheet with which to illuminate over the flame under study. Now, typically a usual procedure involves using a beam expander to...

Hi, I wanted to ask some questions about lasers. I'm pretty bored with school and want to work on a project for a while. I though of maybe trying to build a laser, mostly because it's really awesome, it sounds like a project that would be challenging but also teach me a lot, and it's sort of...

Hi there, I'm working on fiber lasers and I'm interested in getting up to speed with the topic of mode-locked fiber lasers. However, I can't seem to find resources suitable for me at this current stage, hope that you guys can help recommend a suitable review paper, book or anything that's...