I’m pretty sure I’m not the only one who did this, but the first thing I did when I got my first laser pointer was go outside and point it at the moon. I’d stare and wonder if someone was up there, would they be able to see the little red light shining from the Earth?
Takayuki Ohira, creator of the MEGASTAR planetarium projector, recently conducted an experiment to test the limits of your generic laser pointer and posted the results on Twitter. He attached a class 1mW laser pointer to a telescope and pointed it at a building roughly 20km away to see if the light could be seen by the naked eye.
Check it out! It can!
Ohira was aided by Japanese astronaut Soichi Noguchi, who snapped a picture with his phone from the receiving end of the laser.
こんなに明るく！！凄いです＼(^o^)／ pic.twitter.com/H7cl7LNxNr
— 宇宙ニュース (@tx_spacenews) November 11, 2013
Ohira has warned that this is not something that people should be trying willy nilly. He specifically chose to conduct his experiment at night based on weather patterns and the air condition, and only did it after calculating the safe distance that the laser he was using could be viewed without harm to the retina, also taking time to properly calibrate his telescope.
At this point, it’s also probably worth noting that last year alone, there have been over 3000 reported incidents of aeroplane pilots being disoriented by lasers being flashed into the cockpit — a crime punishable by prison time.
Ohira tweeted, “If it can be seen by the naked eye, it can be picked up by a sensor, so if you were to embed a signal in it, you could use it to communicate. It’s optical communication so gigabit levels should be easy.” After this success, Ohira is hoping to try from even further away.
This experiment was done with a 1mW laser. Think of how far one of those match-lighting 1500mW lasers can reach. My pointing-at-the-moon thing might not have been that crazy after all. Imagine that… Using a laser pointer to annoy cats from the moon…
大平貴之 [Twitter]
レーザーポインターの光はどこまで見えるのか？ [Togetter]
Laser pointer attacks on aeroplane pilots have jumped 1100% since 2005 [Quartz]
Comments
20 responses to “One Man’s Quest To Prove How Far Laser Pointers Reach”
Lazer beam towers for internet now please!
Well that *was* the plan…
Storms… pollution… birds… horrible idea for internet.
Well, Fiber optic uses lasers
That’s not a laser, it’s Professor Frink’s death ray
Good news everyone! My laser is visible from at least 20km away.
That’s professor Farnsworth, but that’s ok because it’s Monday.
Thank you for understanding. Headache + Monday Monkey (who lives for the weekend, sir) will do that. In such case:
Laser, Beginulate! With the visible light and the precision and the retina BURNING!
He should put one on the frikkin’ moon
They’ve already done it anyway. There are actually retroreflectors on the moon which they used to accurately calculate the distance of the moon from the earth by aiming lasers on the earth at the retroreflectors and measuring the time taken for light to reflect back. They got a whole load of other data from it as well.
Oh.. well.. carry on, then…
Yes, but do they usefully reflect a 1mW laser? The moon experiments used lasers around 2-5 watts, over a thousand times more powerful than used in this test.
Of course a signal to the moon and back goes much further, but by my figuring passes through *less* air on its way up than a 20km laser that stays close to sea level.
My own experiments when I first got my hands on a laser pointer had it visible with the (short-sighted) naked eye when shone at a building a hundred metres or so away. As the “return” signal is no longer concentrated in a coherent beam that’s fairly impressive in itself.
They already did. They called it the Alan Parson Project
Use the 1500mW one to sign your name on the moon. Ultimate Graffiti.
Somehow laser the Moon’s face from Majora’s Mask onto our own moon.
Now, if you’ll just look at this diagram *points with laser pointer* on my next slide on the building 20 km over that way, you’ll see some very interesting data on people with incredibly good vision.
Ohira tweeted, “If it can be seen by the naked eye, it can be picked up by a sensor, so if you were to embed a signal in it, you could use it to communicate. It’s optical communication so gigabit levels should be easy.”
Brilliant. You could modulate the signal. Thus transmit it really fast. And if you had a medium, like, for example, a light guide cable (Which I’ll call Fibre Optic) you could have high speed communications.
However, 20km is impressive. Was he using optics on his 1mW laser?
I think he means a non cable communication. For example, communicating with the ISS, not that it is any type of issue currently.
Maybe one day they could use lasers to communicate ship to ship in space.
They kinda already do actually http://en.wikipedia.org/wiki/Free-space_optical_communication
Cool, but not that surprising… you can technically see a candle flame from nearly 50km with the naked eye in the right conditions.
http://www.livescience.com/33895-human-eye.html
I bet even a shitty $2 laser would go a lot further if it were tested properly.