Light and Entropy

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  • #51
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energia said:
this is the area of misunderstanding

you are refering to propagation
and I am refering to reflection
I think an area of misunderstanding is that you keep changing the question. But a pulsed laser can be reflected, and is, inside of the laser - the gain medium is just a small section of the overall device - and yet it seems to work just fine.
 
  • #52
Integral
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I design and build amplifiers professionally - I know the meaning of term 'amplified' better than you will ever dream of knowing it
Does this mean you are an Electrical Engineer?

If so that explains a lot right there.

Simply because you build amplifiers does not mean that you understand or even know the basics of LASER operation. The fact that you claim a laser beam is "focused" means that you do not understand laser beams. The fact that you somehow separate the the beam from the generation means that you do not understand lasers.

The fact that you seem to think that reflection is somehow different for lasers then any other source of light means that you do not understand light. It does not appear to me that you understand enough of these topics to carry on a meaningful converstion. And that explains alot right there.
 
  • #53
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my description of laser operation was given at it's most basic level
I don't need to write an essay on the operational theory of all lasers

since you work with lasers - you must understand the energy states of the electrons that make them work

lasers are possible because of the way light interacts with electrons
the photoelectric effect

(btw. Einstein was awarded the Nobel prize in 1921 for his theory on the photoelectric effect )

the electrons of each atom and molecule exist at specific energy levels
which orbit a nucleus

outer orbital electrons are at higher energy levels than inner orbital eletrons

the energy levels of electrons can be AMPLIFIED by the injection of photons

as an electron drops from an outer to an inner orbit, it loses energy in the form of light

the wavelength (colour) of the emitted light is relative to the amount of energy released. specific wavelengths of light are absorbed (exciting the electrons) causing specific wavelengths to be emitted as soon as the electrons return to their original energy level

and that's how a laser operates - any laser, whether solid state, gas, liquid, whatever

and yes I'm an electronics engineer - with a firm foundation in Maxwell equations and semiconductor physics

if physicists think they're somehow above engineers - let me remind you that it's engineers who provide the means to take physics from theory to reality
and many engineers are also physicists
 
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  • #54
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now back to the point

I'm suggesting that - at the moment of reflection, the photoelectric effect occurs between the striking photons and the electrons orbiting the nuclei of the atoms of the reflector, resulting in a net energy loss (entropy)

now do you see my point?
 
  • #55
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energia said:
the energy levels of electrons can be AMPLIFIED by the injection of photons
:confused:

The "Amplification" is the increase in the number of photons, from stimulated emission. That is, one photon induces an atom to de-excite and emit a photon (in phase), so now you have two photons. You have amplified the light signal.
 
  • #56
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Obviously you have not had even basic Quantum Theory. You need to stop lecturing about things outside of your expertise and start asking questions. Your knowledge of the fundamental functionality of lasers is woeful.

I am sorry the photoelectric effect is not the place to start.

my description of laser operation was given at it's most basic level
I don't need to write an essay on the operational theory of all lasers
In reality your description did not get anywhere near the core of the physics of a laser.
the energy levels of electrons can be AMPLIFIED by the injection of photons

as an electron drops from an outer to an inner orbit, it loses energy in the form of light

the wavelength (colour) of the emitted light is relative to the amount of energy released. specific wavelengths of light are absorbed (exciting the electrons) causing specific wavelengths to be emitted as soon as the electrons return to their original energy level
This also describes a light bulb. Or even a reflection off of a wall. What is different in a laser? You did not mention population inversion, nor did you touch the idea of stimulated emission. These are the keys to a laser, the rest is window dressing.
 
  • #57
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energia said:
now back to the point

I'm suggesting that - at the moment of reflection, the photoelectric effect occurs between the striking photons and the electrons orbiting the nuclei of the atoms of the reflector, resulting in a net energy loss (entropy)

now do you see my point?
The photoelectric effect does not enter into this. In the photoelectric effect an electron is IONIZED, simply not the case in common reflections.

Give this up, I would like you to change your approach, rather then assuming that you have a full understanding, assume that you have only a partial understanding and attempt to ask questions to help us guide you to a better understanding. As long as you maintain the delusion that you understand this field you will find it impossible to learn.
 
  • #58
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You did not mention population inversion
you want to discuss population inversion? fine

first we create two photons from one
then an amplifier must produce millions of photons
adding increasing numbers of atoms to the upper metastable state
and holding them long enough to store energy and allow the production of lorry loads of stimulated photons

the longer lifetime states allow the rate at which atoms are raised into one of these states to exceed the rate at which they leave

atoms can be excited into and held in the upper state leaving an almost empty state below them

atoms can stay in this metastable state without de-exciting while the population is being raised

a population inversion occurs when more atoms are in a higher state of excitation than in the lower state

NOTE: this violates entropy



nor did you touch the idea of stimulated emission
we must remember how a laser works

Light Amplification by Stimulated Emission of Radiation

this is not just a beam of light, it's amplified light
which requires a high energy source (an inductor coil) to drive it

here is my quote again

as you can see i've already stated the process with these terms alone

"Light Amplification by Stimulated Emission of Radiation"

notice the terms "Stimulated Emission of Radiation"


and i've had far more than basic QED (Euler-Lagrange equations) thank you
 
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  • #59
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in any case...

i've already demonstrated my point - which is that a laser beam cannot be sustained indefinately between 2 reflectors without a constant source

not using current technology - not even using emerging technology


why can't you just admit that it can't be done (?)


the whole argument is that it can't be achieved because it violates entropy
 
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  • #60
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energia said:
this topic has become tiresom

i've already demonstrated my point - which is that a laser beam cannot be sustained indefinately between 2 reflectors without a constant source

not using current technology - not even using emerging technology


why can't you just admit that it can't be done (?)


the whole argument is that it can't be achieved because it violates entropy
What the? Who has disputed this, if you use real mirrors?

What has been disputed is the notion that laser photons somehow know whether the laser is still on or not.
 
  • #61
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The photoelectric effect does not enter into this. In the photoelectric effect an electron is IONIZED, simply not the case in common reflections
this was a personal theory of mine - it has nothing to do with accepted theory

accepted theory violates entropy which is why I decided to attack it in the first place
 

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