A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow.
A laser differs from other sources of light in that it emits light which is coherent. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar. Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum. Alternatively, temporal coherence can be used to produce ultrashort pulses of light with a broad spectrum but durations as short as a femtosecond.
Lasers are used in optical disc drives, laser printers, barcode scanners, DNA sequencing instruments, fiber-optic, semiconducting chip manufacturing (photolithography), and free-space optical communication, laser surgery and skin treatments, cutting and welding materials, military and law enforcement devices for marking targets and measuring range and speed, and in laser lighting displays for entertainment. Semiconductor lasers in the blue to near-UV have also been used in place of light-emitting diodes (LED's) to excite fluorescence as a white light source. This permits a much smaller emitting area due to the much greater radiance of a laser and avoids the droop suffered by LED's; such devices are already used in some car headlamps.
hello forum.
a question about light and uncertainty:
If a laser beam has a 2 cm diameter when it passes through an aperture that is 6 cm wide, the beam is not affected by the aperture.
Why? What happens to the uncertainty principle there?
Isn't the probability wavefunction affected by...
I am struggling with the following question:
My attempt so far is:
(in the diagram h is supposed to be A)
(i have also assumed the pulse time is negligible, so the mass starts at the resultant velocity)
The set of homework questions this has come from is supposed to be related to...
Homework Statement
Light in the near-infrared (close to visible red) can penetrate surprisingly far through human tissue, a fact that is being used to "illuminate" the interior of the brain in a noninvasve technique known as near-infrared spectroscopy (NIRS). In this procedure an optical...
Is it possible to detonate or to ignite a fuel and air mixture using lasers, or a laser pulse, any type of laser, CO2 or other wise ?
or is there any possible way of using Lasers for the propulsion of an aircraft, i am already aware of several methods, but they do not include ignite fuel, any...
How does the laser cooling work? I have read that it is used to cool ions in vacuum, by absorbing their kinetic energy with a laser beam; but I don't understand why the laser cool the ions and not raise their energy by moment transfer
I'm a physics students and I'm in my Final Year now. The title of my final year project is phase-locked laser system. I have quite some fun playing around with the mirrors, lens and laser stuff.
I'm interested in doing my phd in photonics related area. I'm not sure whether I should go for...
So here's a crazy question...I was trying to think it through and have come up with nothing.
Is it possible to bend a laser beam's cross section? For instance, if you are using a diode bar (which has a beam cross section resembling a line) is there a simple way to bend it into a...
I came up with this idea purely because I had some free time over the weekend. Basically, I want to transmit audio signals (i.e. from a standard 1/8" audio jack) by laser (in essence, streaming it by laser to a speaker setup somewhere else). Most of my interest are not on the circuitry side of...
Hi,
I've decided to make my own meter for measuring laser power to around 10% accuracy if possible. Optical power meters are way too expensive for me though.
One building block I've decided to use is a phototransistor, because I've found one which has very good linear response - when measuring...
I have a rack mount quad lab laser it has 4 series wired SMA905 connectorized diodes.I am wanting to use two of the to pump a Spectra Physic Millenia 1st generation 1064nm laser cavity which has 2 FC female connectorized collimation lenses. They pump a 4x4x7mm water cooled YVO4 crystal from two...
Hiya,
Question 1: (Main question)
I bought a lux meter while understanding very little about how light is measured. I'm hoping to measure the output of a laser in mW. I assume it's possible to do this at least to an accuracy of about 10-20% which is all I need? If so, please could someone help...
Hi all,
I would like to ask a question.
Some people tell me that the red light emitted from the ball pen (I don't know the exact word in English, I mean the pen that lecturer uses to focus light on the slides when conducting presentation, in Power point eg) is the laser light. Is it true...
I want to superpose two laser beams to create the beat frequency.
I design the system to be like this .
Two laser beams come from A and B meet at the center of the PBS, so that two laser beams going out to C and D. I tune the laser beams A and B such that the laser output at C and D...
The Earth moon distance = 3.8 * 10^8 meters
Time for light to reach moon = 1.266 sec.
A laser at the origin on Earth pointed at moon rotates .001 radian
with angular speed w = 10 radians/sec.
The arc length distance described on moon ,s= (radians) (radius) =3.8*10^5 meters
The velocity of...
I would like to understand , how a beam laser changes its trajectory near of a supermassive body? Is there any relation with Einstein's equivalence equation between mass and energy?
i am not able to understand this line..
in semiconductor laser the transition probablity for a radiative transition across the conduction and valence gap must be high and must exceed the probablity for non -radiative transfer of energy to the lattice.
please explain this theory.
solar "laser" (for the lack of abetter word)
Im new here so I am sorry if this is in the wrong spot. but i was wondering if it would possible to take a sun tunnel and like a laser have a partial mirror at one end and a mirror at one end reflecting light back and forth then take fiber optic...
My next project is to build a simple TEA nitrogen laser, as seen here: http://photonics.tfp.uni-karlsruhe.de/1/a-homemade-uv-laser.html
Would it be acceptable to substitute two strontium titanate ceramic caps, each rated 50KVDC @ 910pf, in place of the suggested aluminum foil / plastic...
you are on the millenium falcon, going at the speed of light, and you fire a laser. does the laser go anywhere?
if you were on a truck moving at 50m/s and threw a ball forward at 20m/s, then the ball would go at 70m/s. not the same when dealing with c, right?
so then how can the laser go...
Does anyone know how to simulate the pulse laser drilling?
I am trying to use Comsol or MATLAB to simulate the laser interaction with a specified piece of material.
Following, plot the time (X axis) versus temperature (Y axis) diagram
to see the temperature distribution.
Any help in...
I'm looking for topic ideas for my Advanced Photonics class. We have to do a 5 - 10 page research paper, considering engineering feasibility and economics, of a project that somehow uses photonics or lasers to help the alternative energy cause. However, it needs to be new and innovative, not...
This is probably just nuts but let's say you switch on a laser, point it to the sky and leave it on for billions of years until the beam has traveled billions of light years. Then you rotate the laser 360 degrees in let's say 1 RPM. Does the laser spot that is now billions of light years away...
"Laser Flashlight" possibility
Maybe some of you have seen the video, where they make a match-lighting capable laser pointer out of a DVD burner laser, like the youtube's video CgJ0EpxjZBU.
Now, it's well known that youtube's bogon emissions are off the charts, nevertheless, having an ample...
1) When you excite amolecue and it releases photons off a given frequency, is that frequency the the very frequency which would best excite an identical molecue?
2) or are the release frequency(ies) and absorption frequency(ies) different?
3) If you excite a hydrogen atom with a certain...
have absolutly no idea where to put this but ill put it here
My eyesight is something like +6.25/+6.50
Now the eye man (optomotrist?) said that they only make contact lenses that go up to +6. I was wondering why this is?
Also why can't long sighted people have laser eye sugery? Is there...
http://optics.ph.unimelb.edu.au/atomopt/publications/littrow_rsi_vol72_p4477_2001.pdf
The picture of the ECDL I explain can be found from the above web site.
The purpose of piezo is to change the cavity length of the diode laser, so that the wavelength can be varied.
From the picture...
Has anybody ever tried adding mirrors around a laser tube cavity where a lot of spontaneous emission can be reflected back into the tube? The idea is like this - if there is a low probablitity of absorption, perhaps the emissions will be induced to occur down the main laser tube where the...
Hi
Knowing that i live in France (40 USD to import from USA which is expensive)
I am currently looking for :
1) A Laser mouse (around 25 - 50 euros)
is this one good :
Mouse : http://www.amazon.com/dp/B000U75V02/?tag=pfamazon01-20
Mouse pad ...
Information is stored in a series of pits on the disc. These pits are scanned by a laser beam. An significant limitation on amount of information that can be stored on a disc is width of laser beam.
I knew why the width of laser beam is important coz diffraction effect of loght.
How...
Information is stored in a series of pits on the disc. These pits are scanned by a laser beam. An significant limitation on amount of information that can be stored on a disc is width of laser beam.
I knew why the width of laser beam is important coz diffraction effect of loght.
But, i...
have a wave equation:
(∂^2 p)/〖∂z〗^2 -1/c^2 (∂^2 p)/〖∂t〗^2
In my case, (fields propagation within a semiconductor laser)
Which can be factored into forward propagating photon density:
(∂p^+)/∂t+C_g (∂p^+)/∂z=C_g Gp^++〖1/2 βR〗_sp
And backward propagation wave (photon density)...
Okay, I have been reading the article Laser Deceleration of an Atomic Beam by William D. Phillips see attachment.
But I have a few problems:
1. Optical Pumping.
On page 1, 2. column they write:
I don't quite get the last part. How can the Zeeman effect change the selection rules?
2...
Hi:
Is it possible to make a free-electron laser that emit coherent gamma
rays? If so, could this laser be used to ignite Hydrogen-Boron fusion?
Thanks,
Radium
For my senior thesis I'll be spending some time in the laser lab, though I am not familiar with practical considerations of lasers. Does anyone have any good reads on equipment and procedures for experimental optics?
Thanks
I know that Bragg cell used in laser doppler vibrometer (LDV) is used to give information about the direction of the velocity of the object that we measure. I also know that Bragg cell will shift the frequency of the laser beam(modulation frequency is reduced) when the object is moving towards...
Currently, most CD players use laser light in the red portion of the spectrum. What changes would be rquired in the manufacturing of CDs if blue laser light were to be used?
I don't really get this question...CD players have to do with polarization and thin films... right? I don't know much...
Hey!
What would happen if you were orbiting a neutron star and shot a powerful laserbeam at the surface, at some angle?
Would it reflect? Would it be absorbed?
Thinking (if you picture the star as a perfect neutron star) that the surface is absolutley smooth, it would reflect light...
I'm working with a couple different diode lasers, attempting to automate control of them (on and off mainly) by modulating the source currents externally. One of them is a green laser that draws ~1.4A, 3.3V but has no modulating chip in the power line.
I've got another smaller red laser module...
If you zap a n-type semicond. with a laser with energy at, say, the band gap, what happens to the donor electrons? For sake of argument, let's say we're at low temp. where the occupation of electrons on donors is high. I know technically, you should only get transitions at the energy of the...
I am slightly unsure about how the divergence can be increased by the use of either bi-concave or plano-concave lenses. I understand the general theory behind it but am having trouble putting numbers to it. e.g. if you have a laser beam with a diameter of 2mm and a divergence of 2mrad what...
1. The problem
A HeNe laser (wavelength = 633nm) is used to illuminate an opaque plate containing a a specified aperture. The light which passes through the aperture falls on a screen at a distance of 4 m from the aperture plate.
c) The aperture is replaced by two long rectangular slits...
Hello!
My textbook quotes the probability W of a transition between the levels 1 and 2 of a laser that appears in the rate equations. For
E_2 = E_1 +h\nu
it is supposed to be given by:
W = \frac{1}{\tau VD(\nu)\Delta\nu}
where \tau is the lifetime of the level 2 (probably for...
I am doing some basic heat calculations about a CW laser illuminated tungsten tip (which should be used for photoemission) - I started to play with the tip geometry to try and find a way to get more flux Watts/metre^2 onto the tip without it melting. I found that after solving the 1d heat...
Does anyone know where I can find a derivation how/why a light beam disperses? I'd like to see some sort of solution to Maxwell's equations for a finite width EM wave in free space.
If the beam is a linear superposition of frequencies and Maxwell's equations are linear, does a laser beam...
In 1975 I've got the job in lab constructing middle power one mode CO2 lasers for outer space object location (they used C and O isotopes for reducing losses in atmosfere).
The main joke for newbies of our lab's boss (Yuri Vasilievich Pechenin) was to breathe sigarette smoke from mouth into...