Laser Definition and 1000 Threads

Hello PF! I've got a strange question for you physics boffins; assuming for a moment that lasers obeyed the inverse square law, what range would a typical 1mW red laser have in the atmosphere?

Say, has anybody ever heard of this stuff? http://spie.org/x35504.xml It seems that certain specific frequencies/wavelengths in the near-IR band can have a very pronounced effect on parts of the cell, like mitochondria and on production of ATP and ROS. So is it conceivably possible to...

A single slit is illuminated with a helium-neon laser whose wavelength is 633 nm. If the slit width is 2.2 x 10 e-5 m, calculate the position of the third maximum in degrees 2. Homework Equations Sin Theta(m) = (m + 0.5) Lambda/w 3. The Attempt at a Solution Sin Theta(3) = (3 +...

kindly help me understanding energy conservation in laser

I was reading the wikipedia page on laser light, and on a linked article, I saw this image: http://upload.wikimedia.org/wikipedia/commons/b/b0/Flickr_-_Israel_Defense_Forces_-_Nachal_Brigade_Reconnaissance_Battalion_in_%22Commando%22_Training_%282%29.jpg What is causing those red specks to...

Is it ok to use anodized aluminum with anolok (dark brown) finish to terminate laser beams? Most use black anodized aluminum, but can the former be used instead?

So, here I am again, and I have now built a strong laser which can set things on fire. Yay me. :D But, the second step comes in..how am I supposed to expand the laser beam? The beam is a 0.2 cm circle, and I need to get it to at least 2.5 cm. Can somebody explain how I can do this? (Try not...

I would like to have at least a vague idea how coherent is light from an inexpensive 1 mW red semiconductor laser which I have. I tried to find the manufacturer using Google, but I haven't found it. I would like to know the coherence length and the degree of spatial coherence. Is there...

I'm sure someone has tried this, and I'm sure there's a reason it's not something that is widely used, but here's a question: Can a logical NOR gate be created by shining two lasers (an A and B input) through tiny slits (like the double-slit experiment), and determining an output at a known...

Parallel laser light with wavelength 633 nm are incident perpendicular against a double slit. 2.50 m behind the double slit is a screen where the pattern can be seen (link below). Determine with the help of the figure the slit-with and slit-distance...

Hi Homework Statement I have to calculate the force of a laser. Given are the power P= 100W and the velocity of light. Homework Equations equations I considered using: E=f \cdot h and p=\frac {h}{\lambda} The Attempt at a Solution Actually that's all I got so...

Hello, How does an external cavity laser produce ultra narrow line width when it's larger cavity should reduce the free spectral range and thus introduce more longitudinal modes? Thanks.

Homework Statement Currently cd players use laser light in the red portion of the spectrum. What changes would be required in the manufactering of cds if blue laser light were to be used? Homework Equations The Attempt at a Solution Well I'm pretty sure it has something to do with...

I wonder whether an electron can make a transition from one metastable state to an another metastable state, if so it leads to a paradox(atleast according to me) viz for the refrence frame of the metastable state A from which electron makes the transition, it will be a radiative transition and...

Quantum laser diodes. How does light escape? I recently became very interested on the functioning of these amazing devices and so I read online about the topic of quantum wells, semiconductors and lasers. After much reading I believe I can now understand the basics of lasers, resonant...

I am just curious if it is possible to reduce the plasma shielding effect during ns laser ablation on metals by applying an electric field across the sample, and if so, how strong the field needs to be. Also, any experiments or papers you know.. i searched but could not find the right keywords..

Homework Statement I would like to learn how to calculate whether a laser can burn through a material, or not. For example right now I need to calculate whether a laser from a DVD burner (which supposedly is max. 400 mW strong) can burn through steel. Homework Equations I can imagine...

Hi everyone, I'm attempting the laser audio transmitter project. And example of it is found here: http://www.freeinfosociety.com/site.php?postnum=2310 I'm quite new to electrical engineering type work, and am a little confused by why the circuit works the way it does. The diagram is this...

Hi, i wanted to make a laser cutting device, not the big one but a small device just to cut a few mm thick paper. I just learned from a site(www.ehow.com/m/how_6692865_make-homemade-cutting-laser.html) that you can actually convert a laser pointer to a laser cutting device by rotating the...

Hello everyone, I am an undergraduate student studying lasers. I have hard time to comprehend why does the beam diffract upon leaving the laser, does it have something to do with the wavefront being limited in size? Can you explain why does the following formula exists and how is it derived...

Homework Statement I need to be able to widen the beam of a laser for an experiment I am doing. I want to increase the area the beam takes up while preserving the total amount of light passing through a plane. I provided a diagram of a way I think I can do this, but I would appreciate any...

***Note: I am not trying to make a laser that I can sell or profit from (well at least not now anyways :biggrin:); I'm just focusing on trying to make a laser that is crude and simple, but also one that I can be proud of; thanks.*** I have done a decent amount of research on lasers, and...

If I understand things correctly, the coherent state of a laser beam implies that the photon quantum field is a superposition of states with different particle numbers. This also implies that a laser beam is not in an energy eigenstate. To get energy conservation, I assume that this...

Hey guys, A simplified diagram for the energy levels involved in Nd:YAG laser can be found here: http://upload.wikimedia.org/wikipedia/commons/6/69/YAG2.svg Two (short) questions: 1. Selection Rules The lasing transition happens between ^{4}F_{3/2} and ^{4}I_{11/2}. In the process J (of the...

It occurred to me today that I really don't know much about lasers. When dealing with electromagnetic waves, we always talk about plane waves, which are infinite in extent, or spherical waves, which spread out as they travel. What then is laser light? A finite plane wave? How do you treat...

Hi I have read the following online (http://tf.nist.gov/general/pdf/1819.pdf): "Regardless of the application, the basic goal of locking the frequency of a laser to a cavity is to reduce the frequency fluctuations between the laser and cavity. The noise spectrum of the laser’s frequency...

Hi I am confused about the concept of Power Spectral Density (PSD) of a laser. Say I hook up my laser error signal to a PSD: Is it correct to say that the PSD basically gives me the Fourier transform of the signal? Niles.

Hi all, Does anyone know of any references on how much a laser would spread out in space? I'm not sure if this is the right place for this, but I know there are various experiments planned in the future for space that rely on lasers going back and forth between satellites. Just looking for...

So my brother had a birthday party the other day where this company that rents laser tag guns comes over and all his friends played a big game of laser tag outside. the guns worked surprisingly well, and there was even a "grenade" that would shoot lasers out in all directions once a pin was...

I was watching a show on the science channel called "Alien Encounters". Well in one of them they showed a ship that looked as if it was propelling itself by firing a laser at it's solar sail. Now I am pretty sure that from what I understand about physics, that would not be possible. Correct if...

I'm working with a setup involving a collimated laser (Thorlabs model CPS180), two polarizers, a beam splitter, and 2 photo-diodes. While measuring the intensity of the laser via LabView, without changing any of the components, I find the intensity varies by 0.2mV for the first hour of...

from online descriptions of laser mouse operating principle it's unclear to me that the mouse would need to be particularly big. Is the size of the mouse really based on ergonomics considerations and it could in practice be fit into much smaller case if we wanted to? Is the mouse actually mostly...

Hi all, I'm a total NEWB to this forum, so Hi! I need help deciding which laser to go with, and choosing optics (I'm almost a complete optics NEWB, I don't know any of the simple equations by heart) I'm working on microfluidics, and am building a custom CNC laser etcher that has a step...

Hi to you all, I have a quick question about laser pulse energy. For Q-switching solid state laser source, can you change the energy of a laser pulse without changing the wavelength? If so, how? Thanks so much...

Hi, I'm doing a experiment/report on this topic, I'm trying to get a better understanding of the equation "nλ = dsinθ" ALL length measurements are in meters for simplicity's sake. n = bright spot number from the central bright spot (n0) d = distance between slits The angle "θ" and distance...

Would a nuetrino laser cause any damage if aimed at a target and the nuetrinos had sufficiently high, ultra-relavisitic energy? Obviously, photons, and relativistic collimated beams of protons, electrons, etc. would do damage, but all such "lasers" interact with electromagnetism. They destroy a...

Dear, I am reading a paper on Bose Einstein condensate and an atom laser. I have two questions which are bothering me for a time. - When you are going to make do all the atoms start with the same the Broglie wavelenghts or do they start with different wavelenghts due to different...

Homework Statement I've conducted two laser experiments. One with single slit, and one with a double slit. I've produced two graphs which look something like these...

Hi, I am creating a laser microphone in labs at the moment, and was wondering if anyone could help explain how/ why it works. We are shining a laser a a reflective surface and using a photo-diode and some basic op amp electronics to detect the reflected beam and produce a voltage output...

I've been mulling over whether or not to undergo laser surgery to correct my vision. Myopia set in when I was 12 and has gradually become worse (~ -3.75, 4 now). Being rather active, I find glasses to be a big pain because they get in the way often, sometimes even leading to injury. I was...

I have a keychain-type red laser pointer (5mW typical type) and I was using it for something when all of the sudden it is really dim. Even if I bump up the voltage it is still dim and I'm suspecting it is fried. I overvolted it for about 2 sec with a weak 5v source off an arduino but it worked...

hey everyone.. I am looking to generate a laser induced plasma channel along the majority of the length of the laser beam and was looking for some advice and input... i was wondering if anyones done any experimentation with laser induced plasma channels and may have some information as to...

Ultrafast laser spectroscopy, as I know, is used for the determination of femtosecond events in condensed phases. My question is, what applications do these discoveries have, or are they just for "research"?

Hi! I am having a bit of a problem comprehending the physics of the Haynes-Shockley experiment; specifically the one where the excess carriers are generated with a laser. In the ordinary experiment, some electrons or holes are physically injected through a contact, right? Thus, there will be...

Hello Forum, I understand the difference between LEDs and lasers: both operate at optical frequencies, but the LEd has a larger beam divergence and a higher spectral content, less temporal coherence... Assuming we are able create the same beam divergence for a laser as for a LED (using...

Does anybody have any tips for doing this well? Frankly, I'm pretty terrible at it. I mean, once I get a small amount going through, I can do a little bit of optimisation by adjusting the angle of the fibre in one direction, and then adjusting the angle of the incident beam along the same plane...

What would happen if I bought highly sensitive photographic film such as ASA 800 and shined a laser pointer on it? When I get it developed will the photons that the laser emitted show up on the film?

Homework Statement A ship is traveling at a speed of .8c. When the ship is 90 degrees from the target, it shoots a laser downwards. What angle must it shoot the laser to hit the target? Homework Equations \mu_{x}=0 \mu_{y}=-c \mu_{x}'=\frac{mu_{x}-v}{1-\frac{v*mu_{x}}{c^{2}}}=-v...

I know that lasers will always have divergence due to diffraction. With that said, they don't diverge until after the point of focus, correct? Is there a limit to how far a laser can be focused?

I am using a laser diode to count aerosol particles flowing through a gas stream. The refracted light is being funneled to a photo-multiplier via fiber optics. When there is no gas flowing (and therefore no particles) we are seeing some strange results from the output signal of the...