Light and LASERs

[Crash]

Originally posted by Radical Edward

I just remembered, you can do the diffraction slit thing with a CD and work out the amount of data a CD can hold

 

Can you explain please

[YT2095]

Cap'n Refsmmat said in post # :

lasers light emits all the same frequency of photons. Not a bunch of different frequencies and colors, like white light. It's pure, so it hardly scatters.

 

the scattering effect is not a function of the wavelength or frequency of the light.

 

Interestingly though, I have actualy presented an idea for a white light lazer that I beleve would work quite nicely!, as of yet all the opinions I`ve had back from various scientists in this feild are that they don`t know what would happen and that it`s certainly an interesting idea.

I lack the funds to try it, and they`re all caught up with their own projects and limited funding too

 

what Rad Ed told you is perfectly correct, and if you read my post, I mention the exact same things, and NOT just about polarity as you seem to think

 

Rad: the dye lasers aren`t just toxic but the Cuvette prices are scary too! LOL

 

 

[Radical Edward]

Crash said in post # :

 

Can you explain please

 

well for simplicity you can treat the CD itself as a diffraction grating, since the information is encoded as dips in the surface, it forms a repetitive grating like pattern. When you shine the laser on it, the reflections will interfere in the same manner as the diffraction grating. Now on the wall you will get a projection of little dots, and from that you can work out the distance between the pits on the surface. Assuming one pit to be a bit of information, you can then work out the number of bits that can be stored on the surface area of the CD.

[alt_f13]

That's radical, edward.

[Cap'n Refsmmat]

YT2095 said (confusingly, in my case)in post #27 :

 

the scattering effect is not a function of the wavelength or frequency of the light.

 

Interestingly though, I have actualy presented an idea for a white light lazer that I beleve would work quite nicely!, as of yet all the opinions I`ve had back from various scientists in this feild are that they don`t know what would happen and that it`s certainly an interesting idea.

I lack the funds to try it, and they`re all caught up with their own projects and limited funding too

I never thought that... so what is the scattering effect a function of?

Ok, I'm not going to be sleeping tonight, you got me really confused.

 

 

alt_f13 said in post #29 :

That's radical, ++++++.

Hardy har har. :lame:

[alt_f13]

YT2095 said in post # :

 

 

Interestingly though, I have actualy presented an idea for a white light lazer that I beleve would work quite nicely!, as of yet all the opinions I`ve had back from various scientists in this feild are that they don`t know what would happen and that it`s certainly an interesting idea.

I lack the funds to try it, and they`re all caught up with their own projects and limited funding too

 

 

 

 

How would the waveform look?

 

And on a related subject, does the white light coming from our computer screens have a pattern in its waveform?  Combined average per pixel I mean.  I would assume it does.

[YT2095]

that`s exactly the principal I was working on, imagine a cross section of a Ruby laser being circular like a pie, then divide that pie into 3 equal peices, Red, Green and Blue then fusing a junction between them. then treat as the standard crystal in a Ruby laser. the idea behind it was that no surface would be able to reflect ALL of the light (except a mirror) and so you`de have a laser that would be effective on any color not just those matched to a single frequency

[Cap'n Refsmmat]

oooooooooooohhhhhhhh! That's how! So you have a green crystal/dye/whatever, a blue one, and a red one, and it becomes white!!!

You still didn't answer my question, though.

[YT2095]

and what PARTICULAR question was that?

the scattering effect? well I answered that in post #2

 

what you said in post #15 is not wrong.

 

so I`m more than sure you can put 2 and 2 together here

 

think "Coherant" and then WHY it wouldn`t scatter

[ski_power]

I was taught that light travelled in electromagnetic waves, and hence it could travel in vacuum. Not because that photons were the medium.

And one small doubt. How does light "know" when to behave like a particle(Photo Electric Emission, Polarization) and when to behave like a wave(Simultaneous reflection/refraction, Interference of Light etc)? This question has been puzzling me for a long time.

[swansont]

I was taught that light travelled in electromagnetic waves' date=' and hence it could travel in vacuum. Not because that photons were the medium.

And one small doubt. How does light "know" when to behave like a particle(Photo Electric Emission, Polarization) and when to behave like a wave(Simultaneous reflection/refraction, Interference of Light etc)? This question has been puzzling me for a long time.[/quote']

 

Light IS an electromagnetic wave. It's an oscillating electric and magnetic field.

 

One hurdle in this understanding is that we think of particles and waves as separate entities. So perhaps it would be easier to think of a light as a "wavicle," which has both particle and wave properties. We just can't do an experiment that measures both properties at the same time.

 

(Also - polarization would be a wave property - it's the orientation of the electric field oscillation.)

[ski_power]

Oh ok, polarization is wave property, got it.

(I guess "wavicle" is a radical new way of thinking)

So, nature of light still remains mysteriously to us?

But assume that we know the nature of light, then what will we benefit from it?

[swansont]

Oh ok' date=' polarization is wave property, got it.

(I guess "wavicle" is a radical new way of thinking)

So, nature of light still remains mysteriously to us?

But assume that we know the nature of light, then what will we benefit from it?[/quote']

 

The nature of light becomes less mysterious if you study QM, optics and atomic physics for a number of years.

 

The benfits we have today are numerous. The benefits of tomorrow probably haven't been discovered (or at least exploited) yet. "It's really hard to predict what will or won't be invented in the future," he said, as he boarded the maglev train to take him through the undersea tunnel to the city of New Atlantis on the ocean floor.

[5614]

whats the difference between class 2 lasers and class 3a lasers? i was thinking of buying both, but the 3a is very expensive and i dont think its worth buying.... what do you think?

[Scott]

Brief history of time?

 

Hmm... sorry' date=' sounds like an oxymoron, since time's been around for billions of years. [/quote']

 

Acutally, time actually could only have been around since your moment of first conciousness. Nothing exists unless you are there to perceive it (theoretically), because your existance makes the universe exist (hmmm, kind of a deep thought ). So, in conclusion, if you dont exist then you cant perceive the world, which doesnt exist because you cant perceive it and you are the only one who actually KNOWS things exist because you cant trust anything anyone else says unless you are them.

 

Time is just an abstract concept made by humans. If you dont exist then time itself doesnt exist.

 

Hmmm..... Not sure if this all makes since, as im quite tired.

 

Sorry i ranted so much, i didnt mean to offend anyone if anyone finds this to be offensive .

 

But my main point of this post is, where can i find that book, my library doesnt carry anything of this sort.

 

EDIT: ahh, amazing what a little googling will do.

 

If anyone wants to know, you can find a (short im guessing) version of a brief history of time here: http://www.generationterrorists.com/quotes/abhotswh.html

 

I even found this quote from the page that kinda reinforces what i said above: "We see the universe the way it is because we exist."

[5614]

i think this is in the wrong thread! mod, can you help?

[swansont]

whats the difference between class 2 lasers and class 3a lasers? i was thinking of buying both, but the 3a is very expensive and i dont think its worth buying.... what do you think?

 

The output power.

 

Laser Class definitions

 

Many laser pointers are class IIIa, so not all of that type are expensive.

 

Also note that proper containment of a higher power laser turns it into a class I laser, so don't assume that the laser from e.g. that old CD player is safe because it's class I. Once it's out of the box or you defeat the interlock (or whatever) it's potentially dangerous.

[AzurePhoenix]

Hi. Quick Q, what is the most powerful theoretical non-pulse emission laser (one sustained over long periods of time at a stable output of energy), and what are the mechanisms used, theoretically.

Oh yeah, TY2095, that idea for a white laser is really cool, but I doubt the applications would be terribly valuable. Of course, I haven't had a lot of time to think about it. Any ideas?

[5614]

is there any way to take a class 2 or 3a laser and increase its anything? wavelength, frequency, power.... are there any variables?