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.
Homework Statement
Thought Project 7 Skill Level III Problem
Laser, which use light rays of set wavelengths (colors), are in constant use in our world, in everything from surgery to supermarket checkout scanners.
Execute the necessary research to determine whether the color of a laser...
I am designing a laser targeting system on which various control methods will be implemented and compared. The system consists of a laser pointer mounted on a two axis gimbal. The laser shines on a 30 cm x 30 cm white screen, behind which is a digital camera. The camera sends all information...
Hi guys, so I'm at my wit's end. I'm trying to measure fluorescence/phosphorescence lifetime. I have a laser pumping at 532nm and it's pulsed at 25 picoseconds. I also have a ICCD/spectrometer.
Here's the problem: Currently I'm using the spectrometer triggered internally with a gate pulse width...
I took a cube polycarbonate sample and put a laser through it (perpendicular to a face). When light crosses both faces (front and back), some of the light will reflect while some goes through. My questions are:
1) For the light that reflects off the first face and goes straight back into the...
If a TEM00 output laser source (regarding both cases of single frequency vs multifrequency) is used as input into a multimode optical fiber, is it possible for the output of the optical fiber to be multimode?
Hey guys, I'm wondering.. If I were to reflect a green laser pointer to the mirror, will the reflected laser be hot too? Or will I be heating the mirror?
I'm sure most of you on this board know what the VASIMR plasma rocket engine that is being prepared to be tested on the ISS. I read that high-powered radio waves are used to heat the argon gas to the plasma state of matter and then the superconducting magnets eject the superheated gas out of the...
I have a question, I used pulsed Nd:YAG laser to weld a steel part but I didn’t measure the pulse energy during the experiment. I was wondering if there is a way to calculate it somehow?
I have laser pulse duration, frequency (repetition rate), and laser (mean) power.
Thanks
Hi
I keep reading that an atom cannot be cooled to v=0 because of random recoil from spontaneous emission, i.e. a random walk in momentum space.
If it is a random walk, then - on average - we don't have any net motion, i.e. we stay at the initial position. This also holds in momentum...
I just purchased a HeNe laser with a power supply that came with it. I am not sure how to wire the powersupply to test the laser. There are 4 input wires, Brown, Blue, Green and white. The output is already plugged in correctly. I can take pictures if needed.
Hi,
Is there a such mirror which can reflects a UV laser (~190nm wavelength) with Reflectance greater than 95% and also invisible laser (not necessarily in a high Reflectance)?
Thanks
Hello all,
I'm new to the forum, and probably i post in the wrong place, but i will appreciate your help.
I do my PhD in Chemical Physics on the topic of nano materials, we do all kind of optical experiments (PL, LT, Confocal microscopy and so on), and till now used a very old laser Ar ion...
Homework Statement
You are making a laser with light of wavelength 310 nanometers using a MgF2 window (which will transmit the UV). The mirrors will be external so each end of the 'pumping' gas discharge tube must be cut at Brewster's angle so that there is no reflection from the surface as...
Hi, I'm new to this forum so please don't get mad if this post is in the wrong place.
I have a laser beam pointed at a solar panel (regular PV cells) and the current comes out as expected on my oscilloscope (small waves varying like pulses between 0.45 and 0.50 V regularly). I tried...
I wanted to make tiny movements of the Earth visible by reflecting laser light off liquid gallium metal. It did produce nice reflections on my wall, showing dramatic wobbles of very tiny movements of the liquid gallium. It did however produce light interference patterns which I cannot explain...
Question: If you were to theoretically shine a laser into the intersection of two mirrors, what would happen to the reflected beam? When I say 'theoretically' I mean that the beam would hit the corner perfectly.
I'm confused by this because the derivative of a sharp point on a graph is...
Hi,
I have a problem with an optics experiment, the experiment involves measuring the interference patterns created by the tracks of a CD.
But as soon as I put a lense in between we get an really odd pattern, this pattern seems to not move along with the laser as the beam is being shifted...
I have a cheap $8 USD 5mW green laser for pointing out stars to my daughters and neighbours. This laser does not have a safety rating on it, so I treat it as a class 3. It is getting weak and I need to replace it.
My first thought was to order from Wicked Lasers [1], who had been recommended...
What is the pattern made of balls?
https://www.youtube.com/watch?v=KrUhKQxOPx0
I have some hypotesis: Something related to the CCD, a diffraction pattern caused by some dirt on the lens, or, but i think it's absurd, the Bravais lattice of the lens?
I'm very curious!
A laser beam whose intensity is modulated (at frequency, f) is falling on a black absorber. For the surface temperature, there will be two components: (1) modulated temperature or photothermal wave and (2) a static dc temperature component.
The photothermal signal properties are well known...
http://nerdapproved.com/misc-gadgets/dolphin-laser-pointer-keychain/"
So in the above image they have little attachments for laser pointers that can make different designs. I've played around with similar types of attachments for laser pointers and have never thought about the physics...
Homework Statement
A CD stores data in digital form by encoding it into a grooves as a series of bumps of height 160 nm above the base of the groove. Explain how infromation is picked up from the CD using a laser and calculate its wavelength.
Can someone please explain how to do this...
Hi,
I have the book by Peter Milonni, Laser Physics. Does anyone who has this know what the p(z) and q(z) represent in the equation on gaussian beam solution to a 'beamlike' wave on page 282, under the chapter 7.5 "Gaussian beams"?
\epsilon(\bar{r})=Ae^{ik(x^{2}+y^{2})/{2q(z)}}e^{ip(z)}...
See what I mean http://www.lanl.gov/orgs/tt/pdf/techs/3dlaser_pointer.pdf". Actually, coming to the point, how is this laser pointer at the Los Alamos National Laboratory able to control the z-axis with the slider?
There was a previous thread by someone else which was replied with something...
We're trying to build a circuit that will detect when a laser crosses a photoresistor and light an LED. What we're trying to do is have three different photoresistors, and three diffferent LED's, each of which correspond to one photoresistor. The idea is that when one photoresistor is struck...
Homework Statement
Reflection at a surface takes place under the condition that the field amplitude is zero at the reflecting surface. As a result, the axial modes i of wavelength λi inside a laser cavity can be defined by their number ni of sine-wave half cycles that fit exactly into the...
I currently have a laser set up that sends three lasers (red, yellow, green) into an optical fiber. On the other end of the fiber, the emitting light is shooting in essentially one forward direction. Does anyone have any suggestions or a suggestion on a certain material that if put on the end...
When we are considering the how much optical power a component/pin detector can withstand, are we more concerned about keeping an eye on the peak power or can we ignore the peak power so long as the average power is below some threshold value?
A beam of light from a laser projected on a screen with a very small hole in it will spread after it traverses the pin hole because of the HUP: Measuring position so accurately causes loss of information about the momentum. I believe that in the case of laser light, only information about the...
Hi
I would like to understand the statement that "there cannot be a two-level laser" in a bit more detail.
I understand that given an active medium consisting of two-level systems, one cannot pump it using photons with an energy equal to the energy gap to reach population inversion, because...
So this is the case - I've bought some shocking laser tag guns to play with my friends, though I am unsatisfied with their range which is merely 5 meters. I was wondering if I could add some convex lenses in front of the laser gun in order to increase the range of the laser, would that work...
Hello I have a question regarding reflected light from a surface of higher index of refraction.
Suppose I have a ideal laser, and an ideal surface with reflection coefficient 0.7 or something like that.
Say I shine my laser directly perpendicular to the surface (at 90 degrees).
I...
Hi guys,
I am currently doing a project which involves firing a class 4 laser into a small enclosure (200mmx200mm) and onto a target, which is to emit IR. I am trying to theoretically prove that there will be no ionization of the air (i.e. turn the air into plasma) inside the enclosure...
I have a question about Ring Laser Interferometry.
A couple of years ago I contributed some text and several pictures to the http://en.wikipedia.org/wiki/Sagnac_effect" . Ever since I have been curious about the quantum interpretation of Ring laser interferometry.
The special thing about...
Hello everyone, hope you can help me! I am doing research involving illumination of an object in a cylindrical acrylin tube filled with water using a Nd:Yag laser.
Homework Statement
I am trying to figure out the refraction of the laser as it passes from air through the curved acrylic then...
I am working on a project and am combining three laser beams in an effort to make artificial white light out of the end of the fiber. It is currently producing about 1 mw of power. How could I increase the power out of the end of the optical fiber?
Homework Statement
(1) A Physics lecturer, on a dark night, shines his laser pointer towards the star Vega.
(a) Roughly, how many optical photons from the Sun per second enter the eye of an
astronomer standing on a planet orbiting Vega ? Assume that 50 % of the light
from the Sun is...
Hi,
I'm currently recalibrating an optical tweezer for my undergraduate thesis. The alignment did turn out well so far but I'm a little bit concerned about the power loss within the microscope (here's a picture of the relevant part, without prisms).
I read in a paper that 20 to 100mW are...
Why is a laser monochromatic? I read somewhere that the reason is because of a Fabry-Perot cavity, and not necessarily because of stimulated emission, so that if you have an ordinary light bulb in such a cavity, it would produce monochromatic waves.
Can you just send the stimulated light...
I was setting up a 2.0 mW, unpolarized 543 nm (green) He-Ne laser today when I discovered something odd. I was using an iris diaphragm (like these: http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=206) to align the beam parallel to the laser table. I found that if I placed a white...
There seems to be some debate as to whether laser light is an example of quantum coherence (as posted in this thread: link). I think it deserves its own discussion. I'm no expert in this field, so I mainly go by what I read; I found this interesting Wikipedia reference here:
Comments?
I'm not sure if this is the best place to post this, if not please point me in the direction I should go.
I'm doing robotics research with a professor who told me to study a few different things. One was to find some papers on plane extraction from 3d laser data. Can anyone give me the name...
i want to create laser expander, that scan the wall; with 3m x 3m dimension and 50m distance from this expander. and using with two Rotary Prism mirrors; one for "x" movement and another for "y" move.
is there anyone help me.
Homework Statement
I did the single slit light diffraction lab. The diode laser we used was 630-680 nm. It produced an image very much like the one on this page:
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/fraungeo.html#c1
How does having multiple wavelengths in the laser change...
Homework Statement
High power lasers in factories are used to cut through cloth and metal. One such laser has a beam diameter of 1.5mm and generates an electric field at the target having an amplitude of .854MV/m.
speed of light= 3.0e8 m/s
permeability of free space is 4pi x 10-7 TN/A
What...
fastest modulation: laser diode vs LED...
Hello Forum,
in the telecomm industry, the most common and economical form of modulation is direct modulation, acting on the current operating LEDs or diode lasers.
Using an external intensity modulator (OOK), like a super fast chopper, the...