Cardboard Vs. Laser Shootout: A Tale Of Speed And Power Settings

You probably already know that cardboard is versatile, but that goes far beyond the corrugated stuff. There are many types of cardboard out there, some of which you may not even be aware of. In the video after the break, [Eric Strebel] goes through them all and pits each one against his 50 W water-cooled laser with air assist, making a nice reference for himself in the process.

The point of this shootout is to find the optimum speed and power settings for each of these materials using a free power versus speed file. [Eric] almost always runs the thing somewhere between 10% and 50% power, so that’s the range represented here. He’s looking for two things: the settings that leave the least amount of kerf (make the thinnest cut line) and make the cleanest cuts without producing a lot of residue.

[Eric] divided his contestants into three weight classes, the heavyweights being butter board, chip board, mat board, and illustration board All of these are thicker than 1mm. On the middleweight roster, you have railroad board, 4-ply Bristol board, and stencil board, and all of these are under 1mm thickness. Finally, we have the lightweights — yupo paper and 300 series Bristol board, both of which are less than ½ mm thick.

To test their model-making capabilities, [Eric] made a cube out of each material. Once the glue is dry, he peels off the painter’s tape and goes through the various pros and cons of them all. Be sure to check it out after the break.

Of course, you don’t have to hit up the art store to have fun with cardboard — just visit your recycling bin and mix up some cardboard pulp for sculpting and molding.

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A 3D-printed mini laser engraver made from DVD-RW drive motors.

Mini Laser Engraver Could Carve Out A Place On Your Desk

Got a couple of old DVD-RW drives lying around, just collecting dust? Of course you do. If not, you likely know where to find a pair so you can build this totally adorable and fully dangerous laser engraver for your desk. Check out the complete build video after the break.

[Smart Tronix] doesn’t just tell you to salvage the stepper motors out of the drives — they show you how it’s done and even take the time to explain in writing what stepper motors are and why you would want to use them in this project, which is a remix of [maggie_shah]’s design over on Thingiverse. As you might expect, the two steppers are wired up to an Arduino Uno through a CNC shield with a pair of A4988 motor drivers. These form the two axes of movement — the 250mW laser is attached to x, and the platform moves back and forth on the y axis. We’d love to have one of these to mess around with. Nothing that fits on that platform would be safe! Just don’t forget the proper laser blocking safety glasses!

Need something much bigger that won’t take up a lot of space? Roll up your sleeves and build a SCARA arm to hold your laser.

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CO2 laser cutting ceramic sheet under water film

Water Is The Secret Ingredient When Laser Cutting Ceramics To Make Circuits

[Ben Krasnow] over at Applied Science was experimenting with cutting inexpensive ceramic sheets with his cheap CO2 laser cutter when he found that (just as expected) the thermal shock of the CO2 beam would cause cracking and breaking of the workpiece. After much experimentation, he stumbled upon a simple solution: submersion under a thin layer of water was sufficient to remove excess heat, keeping thermal shock at bay, and eventually cutting the material. Some prior art was uncovered, which we believe is this PHD thesis (PDF) from Manchester University in the UK. This is a great read for anyone wanting to dig into this technique a little deeper.

The CO2 laser cutter is a very versatile tool, capable of cutting and etching a wide range of materials, many of natural origin, such as cardboard, leather and wood, as well as certain plastics and other synthetic materials. But, there are also materials that are generally a no-go, such as metals, ceramics and anything that does not absorb the laser wavelength adequately or is too reflective, so having another string in one’s bow is a good thing. After all, not everyone has access to a fibre laser.

After dispensing with the problem of how to cut ceramic, it got even more interesting. He proceeded to deposit conductive traces sufficiently robust to solder to. A mask was made from vinyl sheet and a squeegee used to deposit a thick layer of silver and glass particles 1 um or less in size. This was then sintered in a small kiln, which was controlled with a Raspberry Pi running PicoReFlow, and after a little bit of scrubbing, the surface resistance was a very usable 2 mΩ/square. Holes cut with the laser, together with some silver material being pushed through with the squeegee formed through holes with no additional effort. That’s pretty neat!

Some solder paste and parts were added to the demo board, and with an added flare for no real reason other than he could, reflowed by simply applying power direct to the board. A heater trace had been applied to the bottom surface, rendering the board capable of self-reflowing. Now that is cool!

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Microwave Ovens: Need More Power? Use Lasers Instead!

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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Lasers used to detect handprint.

DIY Laser Speckle Imaging Uncovers Hidden Details

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

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

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”