# Fun Stuff to do With a Laser Pointer **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [July 24, 2010, 8:41pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877 "2010-07-24T20:41:14Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [July 27, 2010, 9:05pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/41 "2010-07-27T21:05:57Z")
> [@Bookkeeper](#): > > Two of our three cats go nuts over the laser pointer (the other just looks at you and goes “Meh”). I have one I got as a freebie at a conference (combination pen, USB key, and laser pointer) that is easily visible on the side of the apartment building 3 blocks away. I can see why these are dangerous to airplane pilots at night! It’s all those things? :eek: One of those and an iPad and you never need anything else ever again. ---
**Author:** ![Swallowed\_My\_Cellphone](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@Swallowed\_My\_Cellphone](https://boards.straightdope.com/u/Swallowed_My_Cellphone)\ **Post date:** [July 27, 2010, 9:14pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/42 "2010-07-27T21:14:30Z")
> [@Ale](#): > > Now I wonder, if I could do something similar if I ever stumble across a tiger while trekking… Tigers ignore laser pointers, you’d need a laser flashlight. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [July 27, 2010, 9:18pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/43 "2010-07-27T21:18:26Z")
> [@Babale](#): > > > [@Bookkeeper](#): > > > > Two of our three cats go nuts over the laser pointer (the other just looks at you and goes “Meh”). I have one I got as a freebie at a conference (combination pen, USB key, and laser pointer) that is easily visible on the side of the apartment building 3 blocks away. I can see why these are dangerous to airplane pilots at night! > > It’s all those things? :eek: > > One of those and an iPad and you never need anything else ever again. You also need a knife. [Unless that’s built in as well.](http://www.swissarmy.com/MultiTools/Pages/Product.aspx?category=victorinox+flash&product=5301LG4&) ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [September 16, 2010, 12:47pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/45 "2010-09-16T12:47:07Z")
> [@cardinal\_fang](#): > > [Dogs](http://www.youtube.com/watch?v=plpNE9YSCSQ) too. I’d like to point out that the current thinking I’ve been seeing on dog-themed message boards is that use of laser pointers – or any moving light – as a dog toy is counterindicated. The risk is habituating the dog to chasing moving light. Other moving lights, including headlights from passing cars, streetlights shining through moving tree branches, and so on, can not only cause the dog to actively make noise in the middle of the night, but, since they go on all night, can induce a lot of tension and strain in dogs who are used to getting all keyed up for a moving light. Some dogs have become nervous wrecks after getting obsessed with lasers. Some people have reported their dogs now bark in frustration at every moving light. IMHO it’s not worth it. ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [September 16, 2010, 2:22pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/46 "2010-09-16T14:22:15Z")
I discovered that my green laser pointer makes some funky patterns if I shine it at my wife’s crystal knickknacks. She has this little village made of Waterford crystal, and the crystal breaks the laser up into some crazy scatter-patterns, especially in a darkened room. The crystal candy jar makes even crazier patterns. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [September 16, 2010, 4:05pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/47 "2010-09-16T16:05:10Z")
Wet blanket here. I’ve been reading that the infrared scatter from cheap green laser pointers can damage your eyes: [http://www.technewsdaily.com/dangerous-infrared-light-leaks-from-cheap-green-laser-pointers-1036/](http://www.technewsdaily.com/dangerous-infrared-light-leaks-from-cheap-green-laser-pointers-1036/) Of course any laser pointer can damage eyes, kids playing with them tend to make me nervous. ---
**Author:** ![cjepson](https://avatars.discourse-cdn.com/v4/letter/c/a9adbd/32.png) [@cjepson](https://boards.straightdope.com/u/cjepson)\ **Post date:** [September 16, 2010, 6:04pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/48 "2010-09-16T18:04:47Z")
> [@Max\_Torque](#): > > I discovered that my green laser pointer makes some funky patterns if I shine it at my wife’s crystal knickknacks. She has this little village made of Waterford crystal, and the crystal breaks the laser up into some crazy scatter-patterns, especially in a darkened room. The crystal candy jar makes even crazier patterns. All kinds of glass objects do this. Try empty jars (especially those with rough sections around the bottom). Or drinking glasses with some sort of texture to them. ---
**Author:** ![Jimeeb](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@Jimeeb](https://boards.straightdope.com/u/Jimeeb)\ **Post date:** [September 28, 2012, 5:34pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/50 "2012-09-28T17:34:28Z")
> [@Raguleader](#): > > One of the EOD guys in our squadron has a green laser light pen, and mostly he used it to demonstrate how it could make an intense bright green dot on the wall in the secretary’s office at the other end of our building (maybe a couple hundred feet long, with one long hallway) > > From what I understand, combat controllers in the Air Force use laser pointers to guide laser-guided bombs down to their targets. They can even move the pointer around and the bomb will re-aim itself in mid-fall. You can get those bombs to do some neat tricks if you move the laser at the last second. > > I don’t know if you have any laser-guided bombs handy, but if you do, I’d check with your landlord or your HOA before you started playing with it and a laser pointer. I would imagine that if you have bombs laying around that Homeland Security would be interested in this also. ---
**Author:** ![Seanette](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/seanette/32/9139_2.png) [@Seanette](https://boards.straightdope.com/u/Seanette)\ **Post date:** [September 28, 2012, 7:16pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/51 "2012-09-28T19:16:59Z")
> [@Babale](#): > > Red. > > And yeah, I was thinking about the photography thing earlier since when I move it really fast it leaves trails on the floor. > > EDIT: ha, on the way home I ran into a stray cat and shined it at him but he ignored me. ☹ I need to find a house cat My previous cat was indifferent at best to laser pointers. The current cat will chase the dot, at least until her attention span gives out :). They’re also useful with small children. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [September 28, 2012, 8:10pm UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/52 "2012-09-28T20:10:09Z")
> [@Max\_Torque](#): > > I discovered that my green laser pointer makes some funky patterns if I shine it at my wife’s crystal knickknacks. She has this little village made of Waterford crystal, and the crystal breaks the laser up into some crazy scatter-patterns, especially in a darkened room. The crystal candy jar makes even crazier patterns. You can also demonstrate principles of optics. Shine the light upwards through the bottom of a glass of water and demonstrate total internal reflection when you hit the critical angle. Show refraction of light at an interface by watching the beam bend as it passes into water from above. Put sugar at the bottom of a glass of water and let it dissolve quietly to form a sugar concentration gradient, then show gradient index variation when the laser beam gradually bends pasing through it. Use a glass ball or a spherical container of water (or us the circular cross-section of a round glass filled with water) to demonstrate how light passes through a raindrop and forms a rainbow. Bounce it off a CD or DVD and observe diffraction grating effects. Bounce light off a reflecting surface onto a wall to show Laser Speckle. Shine the light through fine weave silk (as Hopkinson did, with ordinary light, back in the 18th century) and project diffraction patterns on the wall. If you do siome of these experiments with both a red and a green laser pointer, you can show how the effects are wavelength-dependent. You can even measure the wavelength of the light by measuring the diffraction patterns and knowing the spacing of lines in your silk/CD/DVD. Actually, the biggest use our laser pointers get in our house is as a cat toy. All three of them go nuts over the dot, but Hestia goes the most insane over chasing it. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [September 29, 2012, 12:18am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/53 "2012-09-29T00:18:36Z")
> [@longPath](#): > > I once read that it was possible to eavesdrop on conversations at a distance by demodulating a laser beam bounced off a subjects windows. This was an experiment to see if it was possible using resouces at-hand. We never got to the demodulation phase. This was invented (at least in an early form) by [Léon Theremin](http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#Espionage) in the 1940’s or so. Yes, same guy who invented the electronic musical device. (ETA: Not sure if that link is working quite right. Seems like you have to scroll UP a page to get to the start of the relevant Wiki paragraph.) ---
**Author:** ![Raguleader](https://avatars.discourse-cdn.com/v4/letter/r/258eb7/32.png) [@Raguleader](https://boards.straightdope.com/u/Raguleader)\ **Post date:** [September 29, 2012, 2:49am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/54 "2012-09-29T02:49:25Z")
I hear you can also use them to distract zombie cats. So, my wife and I got a cat recently. Not only does he love chasing the dot, but he seems to know what it comes from. Whenever I pick up the laser pointer, before I turn it on, he gets all excited, like a dog seeing his owner grab a tennis ball. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [September 29, 2012, 5:52am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/55 "2012-09-29T05:52:48Z")
> [@CalMeacham](#): > > Use a glass ball or a spherical container of water (or us the circular cross-section of a round glass filled with water) to demonstrate how light passes through a raindrop and forms a rainbow. Using a laser? ---
**Author:** ![\_Olive](https://avatars.discourse-cdn.com/v4/letter/_/4af34b/32.png) [@\_Olive](https://boards.straightdope.com/u/_Olive)\ **Post date:** [September 29, 2012, 6:16am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/56 "2012-09-29T06:16:57Z")
Star gazing with friends with the green lazer. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [September 29, 2012, 11:15am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/57 "2012-09-29T11:15:03Z")
Stay the Hell away from the airport! > **[Lasers and aviation safety](https://en.wikipedia.org/wiki/Lasers_and_aviation_safety)** > > Under certain conditions, laser light or other bright lights (spotlights, searchlights) directed at aircraft can be a hazard. The most likely scenario is when a bright visible laser light causes distraction or temporary flash blindness to a pilot, during a critical phase of flight such as landing or takeoff. It is far less likely, though still possible, that a visible or invisible beam could cause permanent harm to a pilot's eyes. Although laser weapons are under development by armed forces, th... BTW–I work at an airport. I don’t want a Cessna in my lap. ---
**Author:** ![Icerigger](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/icerigger/32/432_2.png) [@Icerigger](https://boards.straightdope.com/u/Icerigger)\ **Post date:** [September 29, 2012, 11:35am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/58 "2012-09-29T11:35:49Z")
Using one to build a really cool Star Trek laser gun from The Cage. [![](https://img.youtube.com/vi/dZdPC7ByN-c/hqdefault.jpg "Star Trek "The Cage" Laser") ](https://www.youtube.com/watch?v=dZdPC7ByN-c) ---
**Author:** ![Spiderman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiderman/32/230_2.png) [@Spiderman](https://boards.straightdope.com/u/Spiderman)\ **Post date:** [September 30, 2012, 12:23am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/59 "2012-09-30T00:23:42Z")
Shine it back & forth across the ceiling & walls & you don’t need to take the dog for a walk in the rain. Bonus: it’ll take him 5-10 mins after you stop to finally give up & realize it’s not coming back so I can exercise him while doing something else in another room. ---
**Author:** ![Anamorphic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/anamorphic/32/3057_2.png) [@Anamorphic](https://boards.straightdope.com/u/Anamorphic)\ **Post date:** [September 30, 2012, 12:35am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/60 "2012-09-30T00:35:10Z")
Take it apart to make a macro lens for your smartphone! > **[Turn a Cheap Laser Pointer Into a Removable Macro Photography Lens for Your...](https://lifehacker.com/turn-a-cheap-laser-pointer-into-a-removable-macro-photo-5943363)** > > Smartphone cameras are better than ever, and while they can take some pretty solid pictures, you can really get some fun shots with a DIY macro lens. Here's how to put a macro lens on your phone without having to open up your hardware. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [September 30, 2012, 1:02am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/61 "2012-09-30T01:02:27Z")
> [@AaronX](#): > > Using a laser? Yep. You won’t see color separation, but you can clearly see how the rainbow occurs at a minimum. And with a coherent surce like a laser you’ll see the supernumerary bands really well. ---
**Author:** ![Digital\_is\_the\_new\_Analog](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)\ **Post date:** [September 30, 2012, 3:00am UTC](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877/62 "2012-09-30T03:00:52Z")
> [@Senegoid](#): > > This was invented (at least in an early form) by [Léon Theremin](http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#Espionage) in the 1940’s or so. Yes, same guy who invented the electronic musical device. > > (ETA: Not sure if that link is working quite right. Seems like you have to scroll UP a page to get to the start of the relevant Wiki paragraph.) Your link has an additional #Espionage on it, which says to scroll to a section of the page. You probably wanted it to show [http://en.wikipedia.org/wiki/L%C3%A9on\_Theremin](http://en.wikipedia.org/wiki/L%C3%A9on_Theremin) instead of [http://en.wikipedia.org/wiki/L%C3%A9on\_Theremin#Espionage](http://en.wikipedia.org/wiki/L%C3%A9on_Theremin#Espionage) -D/a [Previous page](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877.md?page=2) [Next page](https://boards.straightdope.com/t/fun-stuff-to-do-with-a-laser-pointer/547877.md?page=4)