Light Amplification by Stimulated Emission of Radiation. A means of creating coherent light by either driving an atomic or molecular transition in an optical cavity or firing a beam of electrons through an undulator.
21
votes
2answers
418 views
Why does laser light not affect glowing materials?
I have this childrens rubber ball which glows in the dark after it's exposed to light. I "charge" it with a flash light then play with my dogs at night. I thought to try a very intense green laser, ...
11
votes
6answers
1k views
Tried to do the double slit experiment, failed. Why?
I tried, and failed, to do the double-slit experiment. I thought I had a good experiment setup, but obviously I was wrong. Can anyone offer some insight in what I might have done wrong? Most of ...
10
votes
4answers
427 views
When lasers are used to cool atoms or ions, etc where does the heat go?
According to the first law of thermodynamics, sourced from wikipedia
"In any process in an isolated system, the total energy remains the same."
So when lasers are used for cooling in traps, similar ...
10
votes
3answers
2k views
Physics of Focusing a Laser
The temperature that a solar death ray can produce is limited due to the solid angle of the sun itself. Entropic arguments dictate that you can't focus the sun's light to create temperatures higher ...
9
votes
2answers
706 views
Is the “How to break the speed of light” minute physics video wrong?
I am referring to this video, on YouTube, by minutephysics, which has quite a lot of views.
In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the ...
9
votes
7answers
3k views
Why is a 1mW laser dangerous?
In our Physics lab we have a 1 milliwatt (0.001W) helium neon laser. Despite the low power, we were cautioned not to even look at reflections of the beam as it could cause permanent eye damage - why ...
9
votes
4answers
954 views
Is it possible to observe interference from 2 independent optical lasers?
It seems that if the coherence length of a laser is big enough, it is possible to observe a (moving) interference picture by combining them. Is it true? How fast should photo-detectors be for ...
9
votes
4answers
719 views
What ways are there to measure the local polarization of a laser beam?
Measuring the polarization of a laser beam is a simple enough task if the polarization is the same everywhere. You can even buy commercial polarimeters.
How do you go about it if the light beam has ...
9
votes
2answers
753 views
What is an intuitive explanation of Gouy phase?
In laser resonators, higher order modes (i.e. TEM01, etc) accumulate phase faster than the fundamental TEM00 mode. This extra phase is called Gouy phase. What is an intuitive explanation of this ...
8
votes
5answers
602 views
How to build a laser in the garage?
So I wonder if it is any how possible to build laser at home. A powerful one to melt brick.
7
votes
3answers
730 views
Can radio waves be formed into a pencil beam?
Laser beams are said to have high "spacial coherence". This means that the beam is highly concentrated even at long distances (low spread).
Can this be achieved with radio waves (much longer waves) ...
7
votes
2answers
151 views
What exactly is the difference between a sychrotron light source and a free electron laser?
Cyclotron radiation is radiation emitted by a charged particle being bent by a magnetic field. The only difference between cyclotron and synchrotron radiation is that the latter occurs at relativistic ...
7
votes
2answers
298 views
Fairly Broad Spectrum Light Source Options
I tried this sight before to find filtering options and got fantastic results, so let's try again!
I am setting up an experiment that requires light of two different frequencies (445nm and 350nm). ...
6
votes
2answers
474 views
Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
6
votes
4answers
426 views
Far-field intensity from scattering of small particles
Howdy, I'm building a simulation for looking at the light field underwater. In order to verify my simulation, I'm looking for some data showing the far-field intensity that comes from single ...
6
votes
2answers
105 views
PSF Measurements In Fluorescence Imaging
Quite a technical question!
I have measured the Point Spread Function of 100nm fluorescent breads with my Olympus scanning head. I'm two-photon exciting the beads with a wavelength of 800nm and ...
6
votes
1answer
330 views
Is the time reversed laser really a laser?
I'm looking at the time reversed laser and I was having trouble understanding why we call this device a laser. To me this device is more like the absorbers found in FDTD codes, something like a CPML.
...
5
votes
2answers
268 views
How does infrared light 'erase' phosphorescence on zinc sulfide?
I found some sheets of zinc sulfide in my basement that phosphoresce green for up to 24 hours or so after exposure to bright light in the violet range or shorter. One of the first things I tried was ...
5
votes
3answers
316 views
How do “holographic plates” work?
I asked a question about laser stage lighting over at Audio Video Production, and received an excellent answer that explained that laser clusters are generated from a single beam via something called ...
5
votes
2answers
241 views
Did anyone claim that quantum theory meant lasers would never work
I've been reading 'How the Hippies saved Physics', which describes a design for a superluminal communication device, of which the crucial part was a laser which duplicated an incoming photon many ...
5
votes
1answer
708 views
Laser cutting/drilling of copper
In industry, it's common to cut steel using 50-200 W $\mathrm{CO}_2$ laser.
Meanwhile, for making holes in PCB (35 $\mu$m of Cu), DPSS 355 nm laser is usually used and secondary $\mathrm{CO}_2$ to ...
5
votes
1answer
77 views
Free Electron Lasers (FEL) and limits on laser wavelength
Free Electron Lasers are based on Synchroton coherent radiation when a collimated electron beam suffers trajectory curvature due to a strong bouncing magnetic field inside an undulator.
Free Electron ...
5
votes
2answers
219 views
What reflective media do laser shows use?
I am having a hard time in finding out what exact light media laser shows use. I am trying to build a laser show myself. I know that the laser light is reflected off these particles in such a way that ...
4
votes
1answer
1k views
Why are lasers inefficient?
Why are lasers inefficient? Is it because of the heat lost during lasing? Why couldn't there be thermocouples or turbines in parts of the cooling circuits to extract something out of that heat?
4
votes
3answers
506 views
Does there exist a laser that is tunable over the whole visible spectrum?
Does there exist a laser that is tunable over the whole visible spectrum?
If so does there exist one that is solid state?
This is to settle a score with my dumb workmates.
4
votes
2answers
204 views
Laser beam shaping
Hi I like to build a laser pointer that reflects different shapes for a project I am working on. I know this can be done with Diffractive Optical Elements. Are there other options? DOEs are expensive. ...
4
votes
2answers
390 views
Line width of green DPSS laser
Could someone suggest what is the line width/mode stability/coherence length of generic cheapo green (532nm) DPSS laser?
I've found lots of nice info here: ...
4
votes
2answers
262 views
What is a good reference for the quantum mechanical description of lasers?
I am currently taking a graduate level class on lasers. The primary focus of the class is on the design and engineering aspects of lasers, e.g. resonator design. However the first portion of the class ...
4
votes
3answers
167 views
Counterpropagating beams in a ring cavity lasers
Ring cavity lasers usually has a intracavity element like a optical diode to forbid standing wave pattern and, consequently, spacial hole burning and related instabilities. So, my question is: why to ...
4
votes
2answers
200 views
Optical Drive Physics
I have been recently wondering how is data stored on and retrieved from optical devices like CDs, DVDs, and Bluray. What makes these different storage types different from each other?
4
votes
3answers
284 views
Good (citable) paper on Laser Physics
I am looking for reference papers and/or books on the principles of LASER. I've understood that
Gould, R. Gordon (1959). "The LASER, Light Amplification by Stimulated Emission of Radiation"
...
4
votes
1answer
122 views
What theories allow for “Tractor Beams”?
NASA recently announced $100k grant to study the possibility of using laser tractor beams. What tractor beam concepts have been published but not been dis-proven?
4
votes
2answers
215 views
Why isn't V. A. Fabricant given the credit for the discovery of the laser?
In another question here I asked for help in finding old Russian papers in physics and as an example I gave the founding papers on the laser by Basov and Prokhorov (from 1945 and 1954). In an answer ...
4
votes
1answer
95 views
Optical laser pumping and reflectors
Let's say we are building Nd:YAG laser.
It is optically pumped by some linear xenon flash lamps, it absorbs light around 750nm and 800nm, and emitted light is at 1064nm.
The question is why doesn't ...
4
votes
1answer
51 views
what general physical arguments discredit induced emission of nuclei?
trying to read a bit about "quantum nucleonics", i've encountered this rebuttal from people at Livermore that induced radiation stimulation of Hafnium nuclei is possible. Something that catches my eye ...
4
votes
1answer
161 views
what is the probability distribution for the angle of an approximate laserbeam
I'm trying to simulate the light distribution characteristics from a Gaussian laser beam, but having difficulty with the angular distribution.
I need to generate a large number of points on an x/y ...
3
votes
4answers
179 views
Water Jet Cutter and Laser
I watched a video of "Glass cutting" which uses a Water Jet Cutter. It was said that Cutting glass simply by machines would eventually crack it... So, They're using grains of sand (by placing a sand ...
3
votes
2answers
71 views
Why is the photon emitted in the same direction as incoming radiation in Laser?
When an atom “lases” it always gives up its energy in the same direction and phase as the incoming light. Why does this happen? How can this be explained?
How does the photon generated because of ...
3
votes
3answers
102 views
Do laser beams interfere noticeably with each other?
I want to arrange some red lasers along a 90 degree arc of a circle, aimed towards the center of the circle. When their beams hit the opposite side of the circle, will I notice any interference ...
3
votes
2answers
303 views
The most price-efficient experimental setup involving SPDC, single-photon counting etc
I would like a suggestion on a price-efficient way of experimenting with spontaneous down-conversion and single-photon counting. The simple dual-slit experiment could be one part of an application ...
3
votes
1answer
258 views
Beam splitters- Direction of use
There are two cases I'm asking about. The square in the middle is a cube beam splitter in the same orientation for both cases. We are looking at the beam splitter from the top. In the first case, ...
3
votes
2answers
166 views
Redirecting light beams from beam splitters
I'm doing a project where I am taking a laser beam and sending it through a beam splitter. As I understand, approximately 50% of the light will go pass through and 50% will be reflected. So this means ...
3
votes
1answer
300 views
Focusing laser & off-axis illumination & diffraction limit
I've thought I had a good understanding how resolution enhancement tricks works for projection lithography, until I tried to understand if it's possible to get sub-diffraction performance for focused ...
3
votes
2answers
296 views
What makes excimer lasers so complex, rare and expensive?
We all can agree that UV lasers are extremely useful, but we (poor majority) are still struggling with 355nm DPSS ones, while excimer lasers being prohibitively expensive (let's say at 1-10W average ...
3
votes
2answers
534 views
Propagation of light in transparent media: absorption and reemission or scattering?
In the two Phys.SE questions What is the mechanism behind the slowdown of light/photons in a transparent medium? and Why glass is transparent? transparent media were discussed. But I'd like to clarify ...
3
votes
1answer
69 views
Three polarizers, 45° apart
If light is passed through two polarizing filters before arriving at a target, and both of the filters are oriented at 90° to each other, then no light will be received at the target. If a third ...
3
votes
1answer
266 views
Doppler cooling limit vs recoil limit
I was discussing laser cooling in class today and I understood that the main principle of the process is to tune a laser to a frequency lower than the absorbtion frequency of the atom and so only the ...
3
votes
2answers
686 views
Can 2 beams of ultraviolet light intersect and be visible where they intersect?
Is it possible that if you have 2 ultraviolet lasers, that are invisible to the human eye, and if you aim their beams to intersect at some point, that the place of intersection will show a lower ...
3
votes
1answer
143 views
Laser frequency tripling
I've heard that common way to get 354nm laser is to triple 1064nm Nd:YAG one.
But how to make non-linear crystal to do tripling instead of doubling?
What are the best crystals for tripling and what's ...
3
votes
1answer
108 views
Gamma Ray LASER Theory and Technology
I am aware that a similar question has been asked by someone else in the past, but in a very general form. Due to the physics interest and technology, in this question I put emphasis on the detail of ...
