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.
Hi all,
I'd like some help calculating laser eye safety for a 905 nm diode laser system I'm building. It's for a scanning laser rangefinder and I need to figure out if my current design (a TOF rangefinder) can be feasibly be made Class 1 eye safe. The eye safety calculations are a little...
Homework Statement
A 35mW laser produces 526nm green light.
What is the number of photons it emits each second?
1.9×1017
1.9×1018
1.0×1017
9.3×1016
Homework Equations
The Attempt at a Solution
I've been playing with E=hf and lambda = h/p ----- no success!
The...
Is there any information on the physics of the airborne laser testbed available?
Also, why is it 'airborne'? Is it referring to the laser? But aren't all lasers airborne?
Thanks x
Can you please provide some explanation for the following two questions? Or please provide some links. Thank you.
1.) How does a laser heat up a material? Does the material absorb a photon and the material's atom gets excited? - when the atom relaxes, it emit an energy equal to that of the...
Hello- On places like eBay and Amazon, one sees a lot of ultra-cheap, under $15 laser pointers in various colors. For example, my favorite green astronomy laser cost me twenty dollars from amazon last year. Contrast these prices with laser pointers from more respected brands, which seem to range...
Hello,
A few questions which i could not find complete answers online (for a physics noob). I'll try and break them down here:
// Comment: as for a good noob, i know nothing of the real calculation. //
How do i calculate the amount of energy i will need to release as a LASER beam in order...
Hi,
I wonder how to compare the power of a laser and an X-ray. For example 1mW power of a laser hitting an object is comparable to the an X-ray generating 1mW of power?
Thank you.
Greetings,
Is there a way to combine multiple lasers beams to create a more powerful beam?
If so, what optics are needed? How do they need to be arranged?
Thanks
Hi:
I'm going to buy a DFB laser for my project, when I looked for Datasheet of such kind of laser, They give dimensions and equivalent schematic, and pin connections.
For example: A 14 pin butterfly[NEC LASER DIODE NX8563LA Series], from the datasheet, pin 1 and 2 functions...
Hi guys,
I'm interested to know what would happen if you get a red laser and
combine its light with green or a blue laser.
What i would like to do is modulate the higher freq laser with a
lower frequency light source and get a different colour output.
Firstly is this possible? and...
Hi guys, look time lurker first time poster. I am simulating a simple multimode laser to analyse its output as a function of the number of modes.
Have the code for output P which i think is correct but i now need to do analyse the P spectrum in the Fourier domain.
I know my base should be...
Hi there,
This may sound like a silly question, but I'm looking at shining a high power laser onto a target material for a fixed period of time.
I have modeled Alumina in Ansys Icepak, and the temperature increase has come to 4700 degrees C. This maximum temperature is only reached for...
ok, so I've seen the movie
where they aline a HEnE laser with a photodiode to hear the modulations in the photon stream.
i been trying to re-do it, and i just can't get it to work. I am NOT using a HeNe laser, I am using a normal laser from a pen, as i was sure the concept of the laseres...
Is it possible to widen the spectral FWHM of a laser beam.
Any ideas?
I understand the lasing process leads to the monochromaticity, but such a intense light source can have other uses.
Thanks
Just curious after watching some lasers cutting 5mm thick steel sheets very fast, what is exactly cutting the steel?
Is it just a laser beam? Light only? The machines run on bottles of gas, so if not, what exactly is the beam made of?
thanks
I bought a red <5mW laser from thinkgeek.com, and it takes 2 AAA batteries. I took it apart though, took off the momentary pushbutton switch and soldered in a wire because i need to solder on a constant on/off switch at some point but I have noticed the laser is not acting how it was before...
So the US Navy has shot down a drone with a Laser... 30 second video is here:
http://www.cbsnews.com/8301-501465_162-20011041-501465.html
Can anyone identify the major obstacles in such an effort. Seems like tracking/radar type software would be very similar to conventional...
Hi guys,
I am of a Mechanical Engineering background, however my dissertation has a largely optics based focus, and I am struggling with understanding the heating effect of a Laser.
I will be using various wavelength ND:Yag lasers, and will be focussing them onto a target material, which...
Dear all
I ahev a urgent problem!
I have a bar of copper metal and I irradiated it with a Gaussian beam of NdYAG laser at 532 nm with fluence 0.4 J/cm^2 and 6 ns pulse duration.
The reflectance of the copper in this wavelength is r= 0.61
The thermal conductivity of copper is k= 4 W/cmK...
I have found a 5000 volt 20 milliamp laser at a Ham fest now logic tells me the power of the laser would be simply 5000V*0.02A= 10watt input then loses would maybe make it one watt. however I really doubt that it has that much power. I haven't been able to find a power supply capable either of...
http://www.wickedlasers.com/lasers/Spyder_III_Pro_Arctic_Series-96-0.html
The laser in this thing is an Indium Gallium Nitride multimode laser diode which is very cutting edge stuff - they have only entered the market this year, and are being used in high-brightness modern DLP projectors...
I'm working on tracing the beam path of a HeNe laser through two prisms, and I'm stuck on trying to find the incident plane in which to use Snell's law.
Basically I have the equation of the angled surface of the prism, and I have the point where the beam intersects that plane. Now I need the...
Homework Statement
A 655nm gaussian laser beam has a waist of 15mm located at a lens with focal length of 12 cm. What is the minimum beam waist and where is it located?
Homework Equations
Beam radius w = w0*sqrt(1-(z/zr)^2)
w0 = min beam waist; z = distance, zr = Rayleigh range
The...
When viewing the light coming from distant galaxies, it is my understanding that there are 2 redshifts occurring, the doppler effect from the galaxies' peculiar motions, and the cosmological redshift from space itself expanding.
For the cosmological redshift, I visualize a square of space...
Hi,
What is the equation for a E field of a single pulse of a laser?
If that laser is shined onto say a grating spectroscope (square law detector), how can I go about deriving an expression for Intensity as a function of frequency at the output of the spectroscope?
I know that the square...
my question is why oxygen lines does not appear in metal oxides spectrum taken at 532nm wavelength of Nd:YAG laser at atmospheric pressure. and what is the criteria for selecting emission lines for analysis?
I believe that the path of the photons will bend towards the center of mass, but I wonder what happens to the wavelength and the pulse shape while the photons are in the gravity well.
The photons don't undergo any real acceleration, since they are in free fall, so their wavelengths should...
LASER Problems! HELP NEEDED!
Homework Statement
1. The carbon dioxide laser usually emits at 10.6 um in the IR. Typically such a device puts out a continuous emission of from a few watts to several kilowatts. Determine the energy difference in eV between the two laser levels for this...
Hi all
I am hoping that somebody here will be able to tell me why that different types of lasers eg He-Ne or Nd:YAG have different coherence lengths and how the coherence of a laser can be improved.
I am thinking it is to do with the different gain mediums and the emission process...
Homework Statement
I have been doing an experiment using a CO2 laser. One of the procedures is the find the best gas mixture and explain why. I have found the best misture to be 8 parts co2, 1 part n2 and 1 part He, which i have researched and my sources show this is correct. However i also...
Hey Guys, first of all I apologise if this question is posted in the wrong forum section and a mod has to move it to its correct location. I am trying to find information on combining the paths of several laser beams. I have found much complex information pertaining to the combination of the...
1.Calculate the average E-Field and B-field produced by a laser with power 10W and radius 1mm
2.Not sure where to start with this one. Use equations of Flux perhaps?
3. So given the modest amount of infomation and the fact the question represents 1 mark, i assume the calculation is straight...
Hi all
Im doing work on laser interferometry for my final project,just wondering if there are any experts or experienced people in this field here,thanks much!
Homework Statement
A Ti-sapphire femtosecond laser (1fs= 10^-15s, λ≈0.8μm) has an intensity of 1022 W/cm2
when focused to a spot of 1μm radius. What is the energy of the laser pulse? What is the peak
magnetic induction B in Tesla and the electric field in V/m? What is the wave pressure in...
Homework Statement
How can you know "the difference between the two lasing energy levels?"
Homework Equations
n(lambda) = 2(pi)r
E = hf
mvr = n(h-bar)
The Attempt at a Solution
no clue
1. A monochromatic laser is exciting hydrogen atoms from the n = 2 state to the n = 5 state. What is the wavelength of the laser?
2. frequency = f = delta E / h
lambda = c/f
3. First, is the following approach valid:
I find delta E by computing E5 - E2, where En = n2h2/8mL2...
1. The maximum electric field strength in air is 3.0 MV/m. Stronger electric fields ionize the air and create a spark. What is the maximum power that can be delivered by a 1.3 cm diameter laser beam propagating through air?
2. I = P/A = c*epsilon0*E2/2
3. Using E = 3*106 for E, I...
I've never understood how diffraction is possible, which has led me to mistrust a good deal of quantum physics. I'm mystified as to how light starts spreading out in all directions after passing through an aperture. Supposedly it's because light spreads out like a wave, but then how is it...
Why did they land on the other side of the Moon?
And how did they place the Laser reflector (http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment) on the front side of the Moon?
I feel like a moron for not knowing the answer to this.
I'm looking for a laser that can deliver a single 3mJ, 10nS pulse. Most of the laser specs I've found report the laser power in watts rather than the energy in mJ. So I did the following calculation:
3mJ/10nS=3x105J/S=300kW
But...
hi, I'm working on Tm3+ fiber laser rate equation modeling using Mathematica.
The rate equations I'm using for the model are largely based on the work of Jackson and King ("Theoretical Modeling of Tm doped silica fiber lasers", 1999), albeit neglecting some factors so as to simply the model...
Hey everybody, this is not exactly a homework question, but I am writing a term paper on the topic of laser trapping and cooling, and would appreciate any good sources that anyone could provide. This is an undergraduate thermal physics class, and does not need to be extremely technical...
Homework Statement
A laser beam enters a 10.0cm thick glass window at an angle of 30 degrees from the normal. The index of refraction of the glass is 1.46. At what angle from the normal does the beam travel through the glass?
Homework Equations
sin theta 1 / sin theta 2 = n1 / n2 = v1 /...