From: diveboss@xmission.com How far apart will you be?
Guy, a separation estimate would be about nine miles, as the crow flies. I'll check it more precisely soon and let you know. I believe Ann will agree with me in saying that our first attempt was a great success. The laser light was easily the brightest light seen from my point of view when directly targeted. I could see Ann's location through the small refractor I used for aiming purposes. She flashed a regular flashlight that let me place my dot just about on-target. She can describe for herself what she saw from her location.
From my vantage point, I saw her laser easily- you couldn't help but see it! In the telescope, the diverging beam itself could be easily detected sweeping around-an eerie effect reminiscent of "War of the Worlds". I couldn't see the beam with the naked eye, just the source. When it was just off-target it was still visible but not brilliantly bright, as when we were inside the beam itself.
I used a remote switch to keep from moving the telescope when I was flashing the laser. I only kept it on for less-than-30-second intervals and usually flashed it slowly but regularly. I used my Beta Electronics optimized 5mw unit on a vee-block mounting arraingement on a small refractor. Prior to the test, I mounted the laser on the telescope and projected the dot on a fence about a block away, then shimmed the laser until the dot was dead-center in the field-of-view of a crosshair eyepiece. I left it undisturbed until the test tonight. It was then just a matter of finding Ann's flashlight in the eyepiece, then superimposing the crosshairs on her location and turning-on the laser. Of course it wasn't that simple- the cold made the tripod pan/tilt head I was using a bit sticky so precise adjustments were more difficult to make than in my living room hours earlier. But it was adequate for a first try. I also flashed my "3-5mw", $42 Computer Geeks unit at her, hand-held. Her remarks to me on the cell phone were to the effect that it seemed as bright as the high-dollar unit, but she'll have to elaborate there. Of course it was impossible to keep the hand-held unit on-target steadily. I also discovered that the batteries in my Beta unit were dying near the end of the approximately 20-minute test. They were the original cells that came with the laser and there is no telling how long they were sitting on a shelf before being sold. They were also an off-brand (Toshiba) labeled for the Asian market. Next time I take fresh spares. I exposed two frames of ASA400 with a 50mm lens, if one of them turns out I'll scan it and post it to my Gallery page.
From this experience I can say that a 5mw laser pointer is no hazard to an aircraft flying at 30,000 feet. Just keeping it on-target while hand-holding it would be a remarkable task in itself. The only way I could keep Ann targeted tonight was because we were in cell-phone contact and she told me when I was pointed at her. And she was stationary- staying on a moving target would be incredibly difficult if not impossible. And even on-target, it was not too bright to look at. It was very bright, brilliant, even, but not uncomfortably so. Entrancing, attention-getting is more like it. I think the only hazard to aircraft would be those on-approach, at much lower altitudes. Say two miles instead of nine or ten. Read Kurt's paper for more information on the effect of lasers at close range.
For future attempts I'm going to improve on the laser/telescope interface itself, and use my equatorial mount with precision slow-motion controls, for more precise micro-adjustments. I'd also like to try it the full length of the valley- say from Steve Dodd's neighborhood to Ann's, more like about 30 miles. Did anyone else happen to notice the laser light flashes tonight? If so, what did you see and what was your location? All in all this was an interesting, FUN activity on an otherwise cold, cloudy night. __________________________________ Yahoo! FareChase: Search multiple travel sites in one click. http://farechase.yahoo.com