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 people,
i have got a few thoughts which i would like to share.
I few month ago i foundout that there are laser beams in the frequency range of of microwaves (maser beams). (http://en.wikipedia.org/wiki/Maser)
I consider the following situation: If a conducting medium (lets think...
Homework Statement
Im working on a lab experiment in my undergraduate physics degree requiring the use of a class 4 laser, i need to characterize this in terms of its power, coherence, pulse duration, wavelength and irradiance. This is a pulsed laser with rough parameters of 1-2J pulse energy...
Homework Statement
You're helping with an experiment in which a vertical cylinder will rotate about its axis by a very small angle. You need to devise a way to measure this angle. You decide to use what is called an optical lever. You begin by mounting a small mirror on top of the cylinder. A...
This is a question for knowledge not for any assignment, but I was wondering what type of equation describes the damping or extinction that the light beam coming from a laser endures. I googled and couldn't find much although I may be using the wrong terminology. Could someone point me toward a...
Hello, I didn't got an answer in the thread I posted this, so here I go with my own thread..:)
I got informed and read that the ionization of the air highly depends on the different wavelengths of the beam. About the short wavelengths was said that they are 'ionizing' and about the long...
Hello everyone!
I have a system with 2 lasers and a single camera. I have two trigger inputs going to each laser, they have a delay of minimum 350ms. These triggers are split and need to be connected to the camera to open it whenever the lasers fire. So i thought of a Tee junction where i...
Homework Statement
In the X-ray Free Electron Laser XFEL which is built at DESY in Hamburg a periodic magnetic structure (undulator) with a period λu = 5 cm forces electrons with an energy of 25 GeV to emit photons. This period determines the wave length of the photons emitted in the rest...
Homework Statement
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
Homework Equations
Sin Theta(m) = (m + 0.5) Lambda/w
The Attempt at a Solution...
I was wondering why laser on a hair makes the hair act like a single slit. I already know about Huygen's Principle behind it and all that. But what is it that can convince you that it actually is a SINGLE slit and not a double, other than just seeing it by measuring min. and using mλ = d * sinα...
Hi guys, I'm new to the forum, I'm a mechanical engineer but running a project a little outside my comfort zone which is to do with optics.
I am trying to calculate the power density of a pulsed Nd:YAG laser but am getting in a muddle with the Average and Peak powers. The project is to model...
Homework Statement
Consider a 3-level laser. Give the occupation numbers N1(R), N2(R), the inversion \DeltaN(R)/N = [N2(R) - N1(R)]/N and the flux below and above the threshold as a function of pump rate R.
F - the photon flux
Homework Equations
The Attempt at a Solution
I have...
We have a 532 nm laser that we use with our Raman tool. The only power indicator on the control is in the form of a percentage. I know that at 100%, the laser has a power of 25 mW. Does this scale linearly with power percentage? In other words, does 50% power translate to 12.5 mW?
so I am testing out different designs on a nitrogen laser, and wanted a quick way to test whether or not one design had a more intense output than the other. without having to buy a sensor, my idea was to direct the beam onto a solar cell, then measure the output current. higher current wud mean...
Hi. This has been destroying my mind all day.
Take, for example, a semiconductor laser with no internal photons initially. By spontaneous emission, one electron falls from the conduction band to the valance band and emits a photon with the bandgap frequency and a random phase. As this photon...
Hello,
This is my first post to the forum. I'm an ex-physicist who had a short career with some universities and NASA in my early life, then went on to follow the dollars in the computer industry. Now, I work at sea for a living.
Recently, I was reviewing laws pertaining to shipboard...
Hello, I am interested in modulating a laser beam with a radio frequency. Can I input the signal to the laser, or do I need to modify the beam with something like a heterodyne interferometer. If both approaches would work, would the resulting beam be the same?
Thanks, Bill
Homework Statement
Problems and information is as attached.
Homework Equations
As attached.
The Attempt at a Solution
As attached, I can solve part b (although I do not know whether it is correct or not). For part c, I cannot simplify reach the given equation. For part d, I not...
Alright, I have sources (Wikipedia) that say that when a Laser hits a certain intensity it "blooms" and creates a plasma (around a megajoule). How does a Laser achieve this and how big is the laser? Can anyone help me?
I recently bought a laser pointer offline, it claims to be able to reach up to 12 miles, and from what I can tell it is pretty strong. It says the max output power is < 5mW, and the wavelenght is 532nm. Its just a regular laser pointer, and I was wondering if there are lasers that you can buy...
i am doing a research on optoelectronic components for communication.
Can anybody explained me what a laser and modulator driver is and how it work?
Regards
For these LFR's
http://www.active-robots.com/products/sensors/hokuyo.shtml
Where exactly is the laser being shot from and recieved? The circular top? or is there something we cannot see under neath/behind?
Thanks
Hi everyone,
I've been looking at the data sheet for a pulsed laser diode driver that I've been using, and I've managed to convince myself that there's a mistake. I was hoping that if I post my explanation of how the circuit shown in the data sheet works, that you guys can either confirm that...
Homework Statement
I have a question to calculate the spectrum of an infinite pulse train from a mode locked laser with each pulse having I(t) proportional to exp(t^2 / tau^2) where tau is the pulse width. tau is 50 fs, repetition rate is 100Mhz, wavelength of operation is 800nm.
Please...
Homework Statement
Determine the amount of energy carried in 1 m of a 3.5 mW He-Ne laser beam if the cross-sectional area of the beam is 5x10^-6 m^2.
Homework Equations
J/s = Watt
The Attempt at a Solution
I converted the mW to W. I feel like I should put .0035W over 5x10^-6 m^2 to...
so I was playing with my 532 nm (green) laser pointer when I noticed something strange. You can shine it at virtually any surface it will appear as a bright green dot - nothing unexpected there. However by chance, I noticed that when I pointed it at this red bottle of laundry detergent i have...
Homework Statement
A continuous wave laser beam in free space carries a power of 15w and has a circular cross section with diameter 1mm. Calculate peak values of the oscillatory electric and magnetic fields Eo and Ho repectively.
Homework Equations
Eox = (\mu/\epsilon)^1/2 Hoy
\pir^2...
Homework Statement
Coherent light from a laser is split into two beams with intensities 16I0 and 2.25I0, respectively. What is the range of possible light intensities when the beams are recombined?
Homework Equations
A = sqrt(I)k; I = (A/k)^2
The Attempt at a Solution
A1 = sqrt(16)k = 4k...
Homework Statement
"A 1 fs pulse of laser light would be 0.3 um long. What is the range of wavelengths in a 0.3 um long pulse of (approximately) 600nm laser light?"
Homework Equations
(delta omega)(delta t) >= 1/2
c = (lambda)(frequency)
The Attempt at a Solution
I replaced (delta...
Homework Statement
Simulate the Rate Equations with Sinusoidal Signal
S: # of Photons Generated N: # of Electrons (Carriers)
Vg: Group Velocity =7.5e9 \taue: Electron relaxation time = 1e-9
\taup: Photon Lifetime = 1.7e-12 N0: 3.3e18
a: Differential Gain = 1e-15...
Hi,
This is my first post on this forum, just joined. I recently purched the S3 Spyder III Arctic portable 1W laser from wickedlasers. I bought it to try and make some cool photographs and photoshop them. After testing the device (glad I bought safety goggles with it) I was wondering how hot...
http://www.physorg.com/news/2010-11-laser-neutron-yield-energy.html
DT produces 17 MeV per fusion, so that's an output of about 800 joules; a factor of about 150X short of break even for energy applied to the target, and perhaps ~1000X short of the gain required for a practical fusion power...
Hello All,
I'm going through some lecture notes from a course on Lasers, and have come across something that is confusing me.
In homogeneously broadened media, the gain coefficient depends on (1-I/I_s)^{-1}.
where I_s is the saturation intensity.
However, in an homogeneously broadened media...
I need help with a mini communication project. I am trying to receive signals from RJ45 Ethernet (10 BASE-T), which comes in three logic levels (-2.5, 0, +2.5) and convert it into two logic levels so I can drive a laser on and off. Would anyone know of any IC's that can accept these signals to...
How to calculate the fraction of stimulated photons that escape from a laser cavity
with
alpha=0.1 cm^-1
length of cavity=1mm
refractive index of laser cavity=3.2
the photons are assumed to be escaping into air so approx refractive index is 1.
Im assuming that alpha is some sort of...
Homework Statement
Pulsed lasers used for science and medicine produce very brief bursts of electromagnetic energy. If the laser light wavelength is 532 nm, and the pulse lasts for 37 ps,
(a) how many wavelengths are found within the laser pulse?
(b) How brief would the pulse need to be to...
I am going to be pulsing a laser diode at around 2 Watt (room temperature) with a frequency of around 1-10 MHz. Right now I'm planning on using 26 AWG wire. Anyone have any thoughts on whether this is okay? Is the gauge okay? Since it's pulsed I assume I don't have to worry as much about heat...
Please refer the attached setup.
* The laser source is moving at very high speed (say, V=c/2).
* The slit is very close to laser source.
* The screen is far away from the laser source.
I would like to know,
On the 'screen', where the laser beam will fall. A or B?
-Jubair
Hello. I am am trying to find out why Hastelloy cracks during laser welding. What techniques are used to lessen the cracks etc. The main focus is to learn as much as I can about laser welding this material and what laser setting to start with . A simple google search has gotten me no where and...
Hi,I need help with this question
Assume you have a laser emitting a wavelength of 800 nm with power 20 W. You irradiate a goblet filled with water whose layer is 0.25 cm thick.
The absorption coefficient of water at this wavelength is 0.65 cm-1.
a) What is the remaining power behind the...
Hi guys,
I'm trying to make a rudimentary projector of sorts using a low power (class 1) laser diode. I'd like to shine the laser onto two mirrors: one would control the horizontal portion of the scan, and the other would control the vertical portion of the scan.
My problem is this: what...
Greetings,
I want build an interstellar probe.
Given the power of the laser beam and the mass of a mirrored object a laser is shining on, how does one calculate the thrust or acceleration?
Thanks
Homework Statement
The ionization potential of a nitrogen molecule is 15.5 eV.
How many photons from a beam of a 1054 nm high power laser must be absorbed by a nitrogen molecule simultaneously to cause multi-photon ionization?
Homework Equations
None were given.
The Attempt at...
Hi newbe here.
Can someone confirm an experiment I just made on a Meade 2x telextener (tele extender) and a Tele Vue 4x Powermate?
I placed a laser collimator into the barlow and observed a nicely formed laser point exiting the lens. Then I placed the same laser collimator into the Tele...
I am interested if current laser technology exists such that a small laser can be made that emits non-visible light, is .5cm or less (at it's largest dimension), and can detect at distances of 6ft or greater. Please feel free to direct me to other areas of the forum to direct this question if...