Nope, I wouldn't know where to start...
Digital camera / camcorder. Pry off the IR blocking filter, get an IR filter
for a big torch like a clulite, and bingo, you've got a nightvision camera
setup. Could be done with a very cheap camera and a car headlamp running a
100W bulb from a car battery for naff all. IR filters are about £20 from
Anchor Supplies...

Thanks for the tips, but I suspect a car battery would be a tad too
heavy to go fox / owl hunting around the local park :-} (we got within
about 8 feet of a tawny a few weeks ago - my wife spotted it, but by
the time my eyes had adjusted to the gloom it flew off)