Tagged Questions
1
vote
2answers
50 views
Selectively visible laser beam with a controllable means
How can parts of a laser beam be made visible while others left invisible using something electronically controllable (for example, another laser beam crossing it, or a magnetic field, or heat, etc).
3
votes
1answer
68 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 ...
2
votes
2answers
57 views
Optical trapping problem
Can we make light slower by applying optical trapping (I mean applying laser beam to lower the speed of light)?
2
votes
1answer
81 views
Factors that make beam divergence worse after refocusing
A beam of light of width $W$ and wavelength $\lambda$ with divergence that is diffraction-limited is refocused with an optical element placed at a distance $D$ from the beam source. Will the refocused ...
2
votes
1answer
104 views
How would one generate Brownian light? What would it look like?
When light is an equal mix of all visible frequencies, we call it white light.
By analogy, sound that is a mix of all audible frequencies is called white noise.
For sound, there is an additional ...
4
votes
3answers
166 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 ...
5
votes
3answers
313 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 ...
6
votes
2answers
464 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 ...
1
vote
1answer
76 views
Ideal four-level Gain Medium (or just any old gain medium)
What exactly is happening in a laser's gain cell when the irradiance is greater than the saturation irradiance?
Also can someone offer a clear conceptual treatment of the gain-coefficient and its ...
3
votes
1answer
249 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, ...
0
votes
2answers
2k views
Free Optics Simulation Programs
I'm having an extremely difficult time finding an optics program that is easy to use and offers accurate physics simulations. I'm not asking for much, I just want to be able to simulate a laser going ...
3
votes
2answers
165 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 ...
1
vote
1answer
112 views
Why does heterodyne laser Doppler vibrometry require a modulating frequency shift?
On the wikipedia article (and other texts such as Optical Inspections of Microsystems) for laser Doppler vibrometry, it states that a modulating frequency must be added such that the detector can ...
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?
1
vote
1answer
125 views
What is the optical power level of common fiber optics lasers?
In the book Nonlinear Optics, it is stated that the nonlinear effects start to become a problem in WDM systems (around 1550 nm) after about 1 mW of optical power. However, I measured the optical power ...
5
votes
2answers
267 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 ...
1
vote
3answers
5k views
What makes some laser beams visible and other laser beams invisible?
What makes the beam of some lasers:
1-visible?
such as the ones used in clubs or such as the laser pointers sold at amazon which if pointed to the sky look like a solid visible beam of light ...
3
votes
1answer
298 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 ...
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 ...
0
votes
0answers
51 views
on interference [closed]
A laser is oscillating at two frequencies v1 and v2 such that v2-v1=c/2l where resonator length. If the laser is used in an interference experiment,what is the minimum path difference between ...
3
votes
2answers
532 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 ...
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 ...
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
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?
2
votes
3answers
3k views
How do laser rangefinders work when the object surface is not perpendicular to the laser beam?
I find the functioning of a laser rangefinder confusing.
The explanation usually goes like this: "you shine a laser beam onto the object, the laser beam gets reflected and gets back to the device and ...
2
votes
3answers
484 views
Recently publicized experiment on destructive interference between two laser beams
Recently I've had several non-physicist friends ask me, independently of each other, about an experiment where two collinear laser beams destructively interfere along a certain length. Everybody wants ...
6
votes
4answers
424 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 ...
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). ...
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
953 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 ...
2
votes
3answers
192 views
Material resistency to lasers beam
Keeping the average power constant, why some materials are more eager to be damaged by pulsed laser with respect of C.W. lasers, or viceversa?
When i talk about pulsed lasers i think for examples of ...
9
votes
4answers
711 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
752 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 ...
