Seeing Fireworks In A Different Light

If you’re worried that [Roman Dvořák]’s spectroscopic analysis of fireworks is going to ruin New Year’s Eve or the Fourth of July, relax — the science of this build only adds to the fun.

Not that there’s nothing to worry about with fireworks, of course; there are plenty of nasty chemicals in there, and we can say from first-hand experience that getting hit in the face and chest with shrapnel from a shell is an unpleasant experience. [Roman]’s goal with this experiment is pretty simple: to see if it’s possible to cobble together a spectrograph to identify the elements that light up the sky during a pyrotechnic display. The camera rig was mainly assembled from readily available gear, including a Chronos monochrome high-speed camera and a 500-mm telescopic lens. A 100 line/mm grating was attached between the lens and the camera, a finding scope was attached, and the whole thing went onto a sturdy tripod.

From a perch above Prague on New Year’s Eve, [Roman] collected a ton of images in RAW12 format. The files were converted to TIFFs by a Python script and converted to video by FFmpeg. Frames with good spectra were selected for analysis using a Jupyter Notebook project. Spectra were selected by moving the cursor across the image using slider controls, converting pixel positions into wavelengths.

There are some optical improvements [Roman] would like to make, especially in aiming and focusing the camera; as he says, the dynamic and unpredictable nature of fireworks makes them difficult to photograph. As for identifying elements in the spectra, that’s on the to-do list until he can find a library of spectra to use. Or, there’s always DIY Raman spectroscopy. Continue reading “Seeing Fireworks In A Different Light”

An acousto-optic tunable filter and laser

Acousto-Optic Filter Uses Sound To Bend Light

We all know that light and sound are wave phenomena, but of very different kinds. Light is electromechanical in nature, while sound is mechanical. Light can travel through a vacuum, while sound needs some sort of medium to transmit it. So it would seem that it might be difficult to use sound to modify light, but with the right equipment, it’s actually pretty easy.

Easy, perhaps, if you’re used to slinging lasers around and terms like “acousto-optic tunable filter” fall trippingly from your tongue, as is the case for [Les Wright]. An AOTF is a device that takes a radio frequency input and applies it to a piezoelectric transducer that’s bonded to a crystal of tellurium oxide. The RF signal excites the transducer, which vibrates the TeO2 crystal and sets up a standing wave within it. The alternating bands of compressed and expanded material within the crystal act like a diffraction grating. Change the excitation frequency, and the filter’s frequency changes too.

To explore the way sound can bend light, [Les] picked up a commercial AOTF from the surplus market. Sadly, it didn’t come with the RF driver, but no matter — a few quick eBay purchases put the needed RF generator and power amplifier on his bench. The modules went into an enclosure to make the driver more of an instrument and less of a one-off, with a nice multi-turn pot and vernier knob for precise filter adjustment. It’s really kind of cool to watch the output beam change colors at the twist of a knob, and cooler still to realize how it all works.

We’ve been seeing a lot of [Les]’ optics projects lately, from homemade TEA lasers to blasting the Bayer filter off a digital camera, each as impressive as the last! Continue reading “Acousto-Optic Filter Uses Sound To Bend Light”

RGV Laser

[Carl] sure has come a long way with laser modifications, now introducing his portable RGV Full Colour Laser. Although it feels just like yesterday when he showed us his green spiro and his Lego diffraction grating projector.

But enough of the past, the RGV laser is built using a White Fusion Mixing Kit and his own Full Colour Driver Extension. We couldn’t find any circuit diagrams or code to build your own at the moment, but it appears fairly straight forward and you can always take a look at [c4r0’s] Colour Laser.

Hackaday Links: Sunday January 24

Everyone Remembers Free day right? [The Ideanator’s] Bus Pirate came in such a nice red box – he decided to make it his permanent case.

[Chico] is in the middle of making a CNC, but decided to make some music with the steppers in the mean time.

What looks like an old wooden box is actually [Ludvig’s] super sweet retro arcade cabinet. Complete with a giant emergency stop red button.

Who says Legos are dead? [Carl] used them to create a simple and cheap diffraction grating projector. Including video!

[Torchris] used an Ethernet shield exactly as it was designed, sending data over Ethernet. Still a nice hack for those needing help working with Ethernet shields and Arduino.

Finally [Robert] let us know about a friends Arduino Binary Clock. But we think his elegant use of tape and a sand blaster to engrave glass is cooler.