Microwave Ovens: Need More Power? Use Lasers Instead!

September 28, 2021 by Dave Rowntree 15 Comments

You know how it is, you get in late from work, you’ve been stuck in traffic for what seems like an eternity, and you’re hungry. You reach for the microwave meal, and think, if only I didn’t have to wait that three-and-a-half minutes, 900 watts just isn’t enough power. What you need is a laser microwave, and as luck would have it, [Styropyro] has built one, so you don’t have to. No, really, don’t.

After he observed a microwave only operating on a half-wave basis, and delivering power 50% of the time, he attempted to convert it to full-wave by doubling up the high voltage transformer and rectification diodes. While this worked, the poor suffering magnetron didn’t go the full mile, and died somewhat prematurely.

Not to be disheartened, the obvious thing was to ditch the whole concept of cooking with boring old radio waves, and just use a pile of frickin’ lasers instead. Now we’re not sure how he manages to get hold of some of the parts he uses, and the laser array modules look sketchy to say the least, and to be frank, we don’t think they should be easy to get given the ridiculous beam power they can muster.

With the build completed to the usual [Styropryo] level of excellent build quality, he goes on to produce some mouthwatering delicacies such as laser-charred poptart, incinerated steak with not-really-caramelised onions and our favourite laser-popcorn. OK, he admits the beam has way too much power, really should be infrared, and way more diffuse to be even vaguely practical, but we don’t care about practicality round these parts. Who wouldn’t want the excitement of going instantly blind by merely walking into the kitchen at the wrong time?

We’ve covered a fair few microwave oven related hacks before, including a neat microwave kiln, and hacks using microwave parts, such as a janky Jacob’s ladder, but this is probably the first laser microwave we’ve come across. Hopefully the last :)

And remember kids, as [Styropyro] says in pretty much every video on his channel:

All the crazy stuff I’m about to do was done for educational purposes, in fact if you were to try any of this stuff at home, you’d probably die…

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DIY Laser Speckle Imaging Uncovers Hidden Details

September 17, 2021 by Tom Nardi 31 Comments

It sure sounds like “laser speckle imaging” is the sort of thing you’d need grant money to experiment with, but as [anfractuosity] recently demonstrated, you can get some very impressive results with a relatively simple hardware setup and some common open source software packages. In fact, you might already have all the components required to pull this off in your own workshop right now and just not know it.

Anyone who’s ever played with a laser pointer is familiar with the sparkle effect observed when the beam shines on certain objects. That’s laser speckle, and it’s created by the beam reflecting off of microscopic variations in the surface texture and producing optical interference. While this phenomenon largely prevents laser beams from being effective direct lighting sources, it can be used as a way to measure extremely minute perturbations in what would appear to be an otherwise flat surface.

In this demonstration, [anfractuosity] has combined a simple red laser pointer with a microscope’s 25X objective lens to produce a wider and less intense beam. When this diffused beam is cast onto a wall, the speckle pattern generated by the surface texture can plainly be seen. What’s not obvious to the naked eye is that touching the wall with your hand actually produces a change in the speckle pattern. But if you take high-resolution before and after shots, the images can be run through OpenCV to highlight the differences and reveal a ghostly hand-print.

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Harp Uses Frikin’ Lasers

September 14, 2021 by Al Williams 12 Comments

We aren’t sure if you really need lasers to build [HoPE’s] laser harp. It is little more than some photocells and has an Arduino generate tones based on the signals. Still, you need to excite the photocells somehow, and lasers are cheap enough these days.

Mechanically, the device is a pretty large wooden structure. There are six lasers aligned to six light sensors. Each sensor is read by an analog input pin on an Arduino armed with a music-generation shield. We’ve seen plenty of these in the past, but the simplicity of this one is engaging.

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An acousto-optic tunable filter and laser

Acousto-Optic Filter Uses Sound To Bend Light

September 10, 2021 by Dan Maloney 17 Comments

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” →

Squares of sample materials placed on the laser bed awaiting the sensing head

Smart Laser Cutter Ad-on Detects Material Optically

September 6, 2021 by Dave Rowntree 9 Comments

Come on now, admit it. You’ve done it. We’ve done it. You know — you were really sure that sheet of plastic stock you found lying around the hackerspace was acrylic right? You dialled in the settings, loaded the design, set the focus and pushed the little green ‘start’ button. Lots of black smoke, fire, and general badness ensued as you lunged for the red ‘stop’ button, before lifting the lid to work out how you’re going to clean this one up.

That was not acrylic. That was polycarbonate.

What you need is the latest gadget from MIT: SensiCut: A smart laser cutter system that detects different materials automatically.

The technique makes use of so-called ‘speckle imaging’ where a material illuminated by a laser will produce a unique pattern of reflected spots, or speckles into a camera. By training a deep neural model with a large set of samples, it was found possible to detect up to 30 types of material with 98% accuracy.

The pre-baked model runs on a Raspberry PI zero with an off-the-shelf camera all powered from a power bank. This allows the whole assembly to simply drop onto an existing laser cutter head, with no wiring needed.

Even if you’re a seasoned laser cutter user, with a well-controlled stock pile, the peace-of-mind this could give would definitely be worth the effort. A more detailed description and more videos may be found by reading the full paper. Here’s hoping they release the system as open source, one day in the not-to-distant future. If not, then, you know what to do :)

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Thor does battle with a man shooting lasers from his hands

Of Lasers And Lightning: Thwarting Thor With Technology

August 17, 2021 by Adam Zeloof 45 Comments

Most of us don’t spend that much time thinking about lightning. Every now and then we hear some miraculous news story about the man who just survived his fourth lightning strike, but aside from that lightning probably doesn’t play that large a role in your day-to-day life. Unless, that is, you work in aerospace, radio, or a surprisingly long list of other industries that have to deal with its devastating effects.

Humans have been trying to protect things from lightning since the mid-1700s, when Ben Franklin conducted his fabled kite experiment. He created the first lightning rod, an iron pole with a brass tip. He had speculated that the conductor would draw the charge out of thunderclouds, and he was correct. Since then, there haven’t exactly been leaps and bounds in the field of lightning rod design. They are still, essentially, a metal rods that attract lightning strikes and shunt the energy safely into the earth. Just as Ben Franklin first did in the 1700s, they are still installed on buildings today to protect from lightning and do a fine job of it. While this works great for most structures, like your house for example, there are certain situations where a tall metal pole just won’t cut it.

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Using A Laser To Blast Away A Bayer Array

August 9, 2021 by Stephen Ogier 47 Comments

A Bayer array, or Bayer filter, is what lets a digital camera take color photos. It’s an array of tiny color filters that sit on top of a camera’s CCD. The filter makes it so that each sub-pixel in the image sensor only sees red, green, or blue light. The Bayer filter is an elegant tool that gives us color digital photos, but what would you do if you wanted to remove one?

[Les Wright] has devised a way to remove the Bayer filter from the Raspberry Pi Camera. Along with filtering red, green, and blue light for their respective sensors, Bayer filters also greatly reduce the amount of UV and IR light that make it to the CCD sensor. [Les] uses the Raspberry Pi camera in his Pi-based Spectrometer, and he wants to remove the Bayer filter to improve and expand its sensitivity.

Of course, [Les] isn’t the first one to want to do this. Some have succeeded in physically scratching the filter off of the CCD, but because the Pi Camera has vital circuitry around the outside of the sensor, scratching the filter off would likely destroy the circuitry. Others have stripped it off using chemical means, so [Les] gave this a go and destroyed no small number of cameras in his attempt to strip the filter off with solvents like DMSO, brake fluid, and industrial paint stripper.

A look at the CCD, halfway through the process.

Inspired by techniques used in industry, [Les] eventually tried to use a several-kW nitrogen laser to burn off the filter (which seems appropriate given his experience with lasers). He built a rig that raster scans the laser across the sensor using stepper motors to drive micrometer bases. A USB microscope was included to allow progress to be monitored, and you can see a change in the sensor’s appearance as the filter is removed.

After blasting off the Bayer filter, [Les] plugged his improved camera into his home-built spectrometer and pointed it outside. The new camera gives the spectrometer much more uniform sensitivity and allows [Les] to see further into the IR and UV bands. The spectrometer can even detect the Fraunhofer lines—subtle dips in the sun’s spectrum from absorption by molecules in the atmosphere.

This is incredible for a DIY setup and instrument, and we can’t wait to see what [Les] does next to improve his measurements. If your spectrometry needs are more mass than visual, take a look at this home-built mass spectrometer. Home spectrometers aren’t just for examining light spectra—they can also be used to judge the ripeness of fruit!

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