Re: two polarized beams interfering at CCD chip


Sam Goldwasser wrote:
"Michael Koch" <astroelectronic@xxxxxxxxxxx> writes:

Mark,

No. Orthogonal polarizations cannot cancel each other.

Might it be possible that a partial de-polarization takes place inside the
CCD chip?

If the cover or filters or passivation is birefringent.....


Did a little math, and have about 95% convinced myself that orthogonal
polarizations will remain orthogonal after passing through a
birefringent plate. Even though each polarization changes,
orthogonality is maintained (if my math is correct).

So to 1st order, there should be no interference. But, if the beam
patterns have different intensity distributions, then I guess
inhomogeneities in any birefringent optics could cause a slight loss of
orthogonality.

The question now is, to Michael, are you actually seeing interference
in a CCD image from two orthogonal beams? (Or do you appear to be
seeing that?) If so:

What is the visibility of the fringes: fringe amplitude divided by
spatially-averaged intensity? (Close to 100%, 10%, less than 1%?)
How certain are you that the two beams are orthogonal?
To what degree is each beam polarized?

Regards,

Mark

.

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