On Oct 31, 12:08 pm, Jim Kelley wrote:
Owen Duffy wrote:
Jim Kelley wrote in
:

Owen Duffy wrote:

Jim Kelley wrote in news:fg8c3e$kbc$1
:

I don't think it matters where it is, or how much space is involved.
For a single source to create an interferernce pattern, there must be
a reflector somewhere. An antenna tuner for example. Interference
is the result of the overlap of waves.

Jim, could a diffractor or refractor provide the physical device that
might lead to interference?

Owen

I am almost certain that you already know the answer to that
question, so I'm left to wonder why you are asking it.

No, I am not certain, and in the interest of learning from you I am
questioning the generality of whether a reflector is the only means of
creating interference from a single source.

Owen

Fair enough, Owen. The easiest way I can think of to demonstate
interference of light is with a laser and a pair of narrow, closely
spaced slits. A diffration grating is essentially an array of
slit-like reflectors that generates a more complex type of
interference pattern. You could use one of the internal surfaces of a
prism (refractor) as a reflector. Partially reflective beam splitters
or mirrors are often used in interfereometers. And there are of
course methods by which to create sonic interference. The simplest
way is to wire a pair of stereo speakers out of phase and observe the
frequency dependent phase cancellation effect by listening to music at
different positions and speaker separations.

There are any number of possible ways to generate interference
phenomena, all of which utilize real physical objects to redirect
radiation. It is the real physical objects used to create the
interference pattern that redirect energy.

73, ac6xg

You can also use pure refraction--for example through multiple prisms
whose output face is not parallel with the input face, to bend the
light around as many total degrees as you wish (barring attenuation in
the prism). You can also bend the light away, and then back, to get a
displacement. But I suppose in all these, the effect depends on waves
coming from what appear to be different points in space.

Of course, it does not require coherent sources to see the effects of
interference. Interference is an instantaneous effect, and you can
take the average over a single cycle to see the power. So even with
sources on slightly different frequencies, it's easy to see the
pattern. However, with different frequencies, the pattern is ever-
changing, repeating when the sources are all back to the starting
phase.

As H.A.S. says, "waves of average nausea" or maybe it's becoming
intense nausea. Are we sea-sick yet? Or just sick and tired of it.

Cheers,
Tom