13
votes
Accepted
Does color temperature limit how much a laser of a given wavelength can heat a target?
The argument for heating by the Sun is that if the target object is hotter than the Sun it would heat the Sun rather than the Sun heating it. We could try to apply this argument to a laser, but how ...
- 358k
7
votes
Accepted
In hetero- homodyne detection, what does it mean to operate at the Quantum Shot Noise limit?
There are good questions here. I don't have time to thoroughly answer all of them.
What does it mean for a hetero- or homodyne receiver to be operating in the Quantum Shot Noise limit?
In general ...
- 14.4k
6
votes
Does color temperature limit how much a laser of a given wavelength can heat a target?
Neither the Sun nor a laser are objects in thermodynamic equilibrium
The second law of thermodynamics, which prohibits the flow of heat from a colder to a warmer object, applies to objects that have ...
- 60.3k
6
votes
Does color temperature limit how much a laser of a given wavelength can heat a target?
Assuming that the target is a black body. The real critical factor affecting heat transfer is emit energy per unit area described by Stefan–Boltzmann law $M=\sigma T^4$. The temperature increase ...
- 151
4
votes
Does color temperature limit how much a laser of a given wavelength can heat a target?
No, your reasoning does not apply to a laser. You can use Wien’s law to relate the peak emission wavelength to the temperature of a black body emitter (a perfect absorber/emitter across all ...
- 1,665
4
votes
Does color temperature limit how much a laser of a given wavelength can heat a target?
No, it is totally unrelated. Look at the National Ignition Facility (at LLNL). It has a laser, I do not know what its frequency is (probably a small multiple of $c/1064\,$nm, but it heats a pellet to ...
- 35.4k
3
votes
Accepted
Dipole term in light-matter interaction
These are not distinct things, but rather different side of the same notion.
More systematically dipole, quadrupole and other moments arise when performing Multipole expansion of a charge distribution....
- 60.3k
2
votes
Accepted
What is a simple model of telescope sensitivity?
This question seems to be about photodetectors, not telescopes.
If $N$ photons fall on the active area of a pixel then $\epsilon_Q N$ photoelectrons will be produced. where $\epsilon_Q$ is the quantum ...
- 14.4k
1
vote
Besides the 2nd law of thermodynamics, what laws of optics prevent the temperature of the focal point of lens from being hotter than the light source?
My easiest argument was that the 2nd law of thermodynamics prevents this from happening because heat can't flow passively from a place of lower energy/entropy to a place of higher energy/entropy. He ...
- 39k
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