The green laser pointer that Santa left me has proved to be the coherent light source of Satan. At various points during the holiday, its hypnotic 532-nanometre glow led otherwise respectable people to suggest badness. Yes, you can make a very distant policeman in a green high-visibility jacket light up like an angel. You can scare pigeons in the trees outside without leaving your armchair. But you do not -- no, not even when encouraged to by men of the cloth -- point the darn thing at nearby aircraft.
Some people have been doing just this, though. Reports from the States say that there's been a rash of pilots reporting laser light from the ground shone into the cockpit, sometimes dazzling the guy in charge. Not what you want on final approach: this being the States there are dark implications of some terrorist plot to disrupt air travel. Call me old-fashioned, but after a few years of being warned about dirty bombs, anthrax, thermonuclear devices in beefburgers or whatever it seems to me that the preferred terrorist modus operandi involves a hunk of high explosives. The idea of the bad guys putting in a bulk order to www.wickedlasers.com and then standing around in a field squinting at passing planes and waving pens in the air just doesn't gel. But it's probably enough to get me on the no-fly list.
Another common understandable reaction to seeing the pointer is fear. It looks very bright, not because it's any more powerful than the red ones which caused so much panic a couple of years ago but because it produces the colour to which the eye is most sensitive. It looks scary. It isn't -- after much hunting, I found lots of vague but chilling warnings of fried retinas but only a couple of actual scientific studies. The most convincing of these was of a mildly gruesome study where owners of cancerous retinas that were due to be removed volunteered to get their eyeballs zapped by laser pointers. Despite some of these exposures being hundreds of times more fearsome than anything that can happen by accident, the medical team behind the study found no evidence of anything untoward.
So I shall continue to lase. If you're passing through Holloway of an evening and see some strange flashing lights in the sky, you'll know what's going on.