Re: Novice question, conservation of energy


"Phil Hobbs" <pcdh@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:46C92699.4090800@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Neil Bates wrote:
"Phil Hobbs" <pcdh@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message

The impossibilities start when you're talking about thermal light. In
that case the polarization trick only works once, and you lose half the
light in each beam making it polarized in the first place. We talked
about this just recently.

Hi, I suppose by "recently" you mean the thread, "A question about the
phase difference of the beam splitter"?

No, I meant earlier discussions about the second law of thermodynamics and
the conservation of radiance. I haven't been following the beamsplitter
thread.

Cheers,

Phil Hobbs

OK, so what do you think about the problem of using symmetrical combiners,
and any transmitted-reflected phase difference other than 90° causing
problems? I mean, adding the amplitudes naively and squaring gives the wrong
total power output (no conservation of radiance.) To conserve energy, we
have to imagine an adjustment - for example, impedance in the
half-reflecting film just forces the output to be the input rate. Otherwise,
we would naively be adding two sets of around 0.707 times entering
amplitudes, for an output total of twice the input power. Or with entering
phases 180° from that, the output would "naively" be zero. Do you think
that's how it works?

Regards,

Neil Bates

http://tyrannogenius.blogspot.com


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Relevant Pages

  • Re: Novice question, conservation of energy
    ... that case the polarization trick only works once, and you lose half the light in each beam making it polarized in the first place. ... OK, so what do you think about the problem of using symmetrical combiners, and any transmitted-reflected phase difference other than 90° ... I mean, adding the amplitudes naively and squaring gives the wrong total power output (no conservation of radiance.) To conserve energy, we have to imagine an adjustment - for example, impedance in the half-reflecting film just forces the output to be the input rate. ...
    (sci.optics)
  • Re: Novice question, conservation of energy
    ... Neil Bates wrote: ... that case the polarization trick only works once, and you lose half the light in each beam making it polarized in the first place. ... Phil Hobbs ...
    (sci.optics)