I'm no expert in night vision goggles, but "dentelé" can apply to the edges of certain kinds of leaf (elm), but also to muscles, where it is referred to as striated or striped. I would imagine that it is this which is referred to here. More prosaically, "lines".

REALLY low confidence on this one! But just possibly...

There is a scanning defect that was common in the olden days of CRT TVs, but almost completely extinct in later designs, and irrelevant with more recent display technology, in which groups of lines were displaced horizontally on a more or less regular basis, so that a vertical line looked as if it was 'crenellated' — hence preumably the idea of its looking like the teeth on a cog.

Now I don't know what technology your particualr system is using, but I know that earlier night vision systems did indeed use photomultiplier tubes, which I assume involve some kind of electromagnetic or electrostatic scanning — and as soon as scanning is involved, cogging could conceivably occur.

As I say, just a long shot in the dark!

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Note added at 2 hrs (2009-10-13 17:22:02 GMT)
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W-e-l-l — aliasing is certainly an image defect that could apply in this context; however, I have some reservations as to whether or not this FR term would be used to translate it (AFAIK, it isn't the word normally used); also, we don't usually fuss too much about niceties like aliasing in purely practical applications like military night vision, it's more relevant o high-quality TV dsipalys, computer graphics etc.

So I'm afraid I remain rather doubtful about that one...

The technology might not involved interlacing, but the description certainly sounds the same. Also called herringbone distortion.

See photo in link.