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Occupied Christmas: Lasers in the Loo

What happens when a bunch of physicists and science writers compete in the annual holiday office decoration contest? Apparently, they decide to decorate the bathroom.

The Physics Buzz team and a few of our cubicle neighbors did just that during our off-duty time over the past few weeks. The tiny bathroom at the end of our hall was nearly unrecognizable (in a good way) after our flurry of interior designing.

Aptly named the Can of Cheer, our re-designed water closet comes equipped with wallpaper, lights, a Christmas tree, cookies for Santa, and a few physics goodies as well.

The judges took notice, awarding our department the Grand Prize for Best Overall Concept in our society's annual decorating contest. Santa would be proud.

We've got a video tour for you below, and I'll guide you through what makes this physics-themed restroom so festive.

Lasers in the Lavatory

Most of the decorations in our bathroom, albeit awesome, don't have a physics connection. Nonetheless, one of the main features in the bathroom combines lasers and music for maximum holiday enjoyment.

A little over midway through the video, you'll notice that the music stops for a quick demonstration. On display is Spectra Sound: our device that sends music across the (bath)room to a speaker via a laser pointer.

By modulating the strength of the laser signal, you can transfer the information needed to play back audio from a speaker. A photocell picks up the changing voltages sent by the laser beam, and that can be converted back into sound waves in an amplifier.

In the Can of Cheer, we hooked up our laser pointer to an iPad and pointed it at the door lock. In the unlocked position, the lock reflected the laser. When locked, however, the laser beam could pass through and hit the photocell on the other end of the door. This signal, in turn, is passed to the speaker taped next to the door, spreading holiday cheer to the occupant.

For more information on laser modulation to transmit audio signals, check out this video below.

You can purchase Spectra Sound kits from the American Physical Society's store and put together your own laser sound system — just in time for the holidays. Alternatively, you can gather the supplies yourself and make your own system (check YouTube for tutorials).

So what did our lavish loo garner? A certification of its awesomeness. Proof is below; it was definitely worth it.

In the immortal words of Physics Buzz team member Mathlete: "We decorated the cr*p out of it."


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