«My cat needs one.» «I have some balloons to pop.» «Look! He is green! » These are all perfectly legitimate reasons to buy a laser pointer. But what if you’re tired of pointing things out? Never be afraid: I have the answers.

Here are 6 things you can do with a laser pointer once you’ve got it all figured out.

Safety First

Laser pointers are typically less than 5mW, but any laser power can cause damage to the optic nerves if viewed for an extended period of time. Catching a glimpse of the beam is not dangerous in these powers. In practice, this means that you should not aim the beams at anyone’s eyes. For example, if you are setting up laser triplets, they should be placed on the ground to avoid the eyes of curious children. More powerful scanning effects must be directed just above head level so that the effects of the beam can be experienced without danger.

Also, be aware that pointing a laser at an airplane or helicopter is a crime, but probably not applicable in times of revolution.

Build pew pew laser tower or Cat Toy (Arduino)

I don’t like to spin my own horn too much, but my project was posted a few weeks ago and is definitely on a higher level. In this case, I used a dedicated laser module, but you should be able to remove it from the laser pointer and power it directly from your Arduino. Using two servos, one on top of the other, the laser turret rotates around, firing at millions of invisible X-wings.

Alternatively, change the code to be a little more relaxed and provide literally minutes of entertainment for your furball, as this cat aptly demonstrates.

Make a laser microscope

In the simplest laser microscope, a laser beam is directed directly through a drop of water — the sample can be suspended from the end of a skewer.

A more advanced project with much sharper images can be done with a smartphone, which you can of course do with stills. This project doesn’t even use a laser diode: just a lens used to focus the beam.

Make an invisible tripwire alarm

Combine a laser module with a photoresistor and you have an invisible wire. The photoresistor should show a constant height when hit by a laser beam; until the beam is broken by an intruder and booby traps are activated. The only difficulty lies in aligning the laser and the tiny photoresistor; You will need to fix them securely so they don’t move later. Your laser triplet can be used as a trigger for high speed photography. for example, water drops are falling.

This is a particularly smart Arduino setup that self-calibrates.

I did a similar project some time ago but using a sonar distance sensor instead of a laser triplet — you can probably easily adapt this code. The dog was not surprised.

Make light painting

By using the long exposure mode on your camera, you can take some really interesting photos. Just turn off the light, release the shutter and start swinging your laser pointer.

If you paint a wall with glow-in-the-dark paint, you’ll also find that the laser pointer excites the paint enough to keep it going for some time — so you can effectively «paint» without prolonged exposure to the camera. You may need a strong blue, violet or ultraviolet laser to be really effective — red and green don’t work very well. In this case, the technique was combined with an Arduino that reads tweets!

halloween laser maze

Combine a laser triplet with multiple trigger points, multiple lasers, multiple mirrors and you have one of the coolest Halloween haunted houses in the area. A smoke machine is needed since all these mirrors are on the same line.

Show your support (or lack thereof) to the revolutionaries

In July of this year, crowds gathered in Cairo’s Tahrir Square to celebrate the overthrow of religious extremist President Morsi. In addition to fireworks, they used green laser pointers to show their support for the military — despite the obvious dangers of blinding the pilot.


So I think it’s official now: the next time there’s a protest, you can officially show your support or frustration by shining a green light on things.

What would you do with an old laser pointer? Write to us in the comments.

Image Credits: Douglas Muth Via Flickr

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