We’ve all tangled with unwelcome plant life at one point or another. Whether crabgrass infested your lawn, or you were put on weeding duty in your grandfather’s rose patch, you’ll know they’re a pain to remove, and a pain to prevent. For farmers, just imagine the same problem, but scaled up to cover thousands of acres.
Dealing with weeds typically involves harsh chemicals or excessive manual labor. Lasers could prove to be a new tool in the fight against this scourge, however, as covered by the BBC.
[Jeshua Lacock] from 3DTOPO owns a large-format CNC (4’x8′, or 1.2×2.4 m), that he strongly feels is lacking laser-cutting capabilities. The frame is there, and a 150 W CO2 laser tube has been sitting in a box for ages – what else could you need? Sadly, at such a scale, aligning the mirrors is a tough and finicky job – and misalignment can be literally blinding. After reading tales about cutters of such size going out of alignment when someone as much as walked nearby, he dropped the idea – and equipped the CNC head with a high-power laser diode module instead. Having done mirror adjustment on a few CO2 tube-equipped lasers, we can see where he’s coming from.
Typically, the laser modules you see bolted onto CNC heads are firmly under three watts, which is usually only enough for engraving. With a module that provides 5 watts of optical power, [Jeshua] can cut cardboard and thin plywood as well he tells us even 10 W optical power modules are available, just that he didn’t go for one. We reckon that 20 W effective power diodes are not that far into our future, which is getting very close to the potential of the blue box “40 W but actually 35 W but actually way less” K40 laser cutters we cherish. [Jeshua]’s cutter is not breaking speed limits, but it’s built on what’s already there, and the diode is comparatively inexpensive. Equipped with a small honeycomb surface and what seems to be air assist, it’s shown in the video cutting an ornamental piece out of cardboard!
We hackers have been equipping CNCs with laser diodes for a while, but on a way smaller scale and with less powerful diodes – this is definitely a step up! As a hacker, you should have at least some laser cutting options at your disposal, and this overview of CO2 cutters and their availability can get you started. We’ve also given you detailed breakdowns about different sides of laser cutting, be it the must-have of safety, or the nice-to-have of air assist.
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!
What do potato chips and lost car keys have in common? On the surface, it would seem not much, unless you somehow managed to lose your keys in a bag of chips, which would be embarrassing enough that you’d likely never speak of it. But there is a surprising link between the two, and Samy Kamkar makes the association in his newly published 2019 Superconference talk, which he called “FPGA Glitching and Side-Channel Attacks.”
In one of the cooler hacks we’ve seen recently, a bunch of hacking academics at the University of Michigan researched the ability to flicker a laser at audible sound frequencies to see if they could remotely operate microphones simply by shining a light on them. The results are outstanding.
While most Hackers will have heard about ‘The Thing’ – a famous hack where Russian KGB agents would aim a radio transmitter at the great seal in the US embassy, almost none of us will have thought of using lasers shined in from distant locations to hack modern audio devices such as Alexa or Google Assistant. In the name of due diligence, we checked it out on Wikipedia: ‘The Photoacoustic Effect’ , and indeed it is real – first discovered in 1880 by Alexander Bell! The pulsing light is heating the microphone element and causing it to vibrate along with the beam’s intensity. Getting long range out of such a system is a non-trivial product of telescopes, lasers, and careful alignment, but it can be made to work.
Digging deeper into the hack, we find that the actual microphone that is vulnerable is the MEMS type, such as the Knowles SPV0842LR5H. This attack is relatively easy to prevent; manufacturers would simply need to install screens to prevent light from hitting the microphones. For devices already installed in our homes, we recommend either putting a cardboard box over them or moving them away from windows where unscrupulous neighbors or KGB agents could gain access. This does make us wonder if MEMS mics are also vulnerable to radio waves.
As far as mobile phones are concerned, the researchers were able to talk into an iPhone XR at 10 metres, which means that, very possibly, anybody with a hand held ultra violet / infra red equipped flashlight could hack our phones at close range in a bar, for example. The counter-measures are simple – just stick some black electrical tape over the microphone port at the bottom of the phone. Or stay out of those dodgy bars. Continue reading “Laser-Based Audio Injection On Voice-Controllable Systems”→
If you’ve worked with a laser cutter before, you might not find much new in [Maker Design Lab’s] recent post about getting started. But if you haven’t, you’ll find a lot of practical advice and clean clear figures. The write up focuses on a tube-style laser cutter that uses a gas-filled tube and mirrors. Some cheap cutters use a diode, and many of the same tips will apply to those cutters.
You can probably guess that a laser cutter can cut like a CNC and also engrave where the cut doesn’t go all the way through. But it can also mark metals and other surfaces by using a marking solution. If you’ve done CNC or 3D printing, the process is similar, but there are a few unique things to know, like the use of the marking solution.
Attention: No pirates maritime wealth redistribution agents were harmed in the making of the video below.
Some projects are for work, some are for fun, and some, like this entirely 3D-printed camera pan-tilt gimbal, start out as work and then turn into fun. As professional digital FX artist [FlorianH] tells the tale, he was in need of such a rig for some motion-control work. Buying off the shelf is always an option, except when it’s boring, so [Florian] invested an untold number of hours in front of Fusion 360 meticulously designing every last part, except for some bearings, the NEMA 17 steppers, and some fasteners. Ten One hundred hours of printing later and the device was ready for assembly and a quick test, which showed that this thing is smooth as silk.
And the pirate snuff-vid? That was just for fun, and we enjoyed it immensely. [Florian] assures us that none of the explosions were added in post; all are practical effects, done with flash cotton and a bit of powdered charcoal. We asked – you know, for reference.
We’ve featured lots of pan-tilt rigs before, using everything from hobby servos to purely mechanical linkages. But this one has a certain flair to it that we really like.
In one of the cooler hacks we’ve seen recently, a bunch of hacking academics at the University of Michigan researched the ability to flicker a laser at audible sound frequencies to see if they could remotely operate microphones simply by shining a light on them. 
Knowles SPV0842LR5H. This attack is relatively easy to prevent; manufacturers would simply need to install screens to prevent light from hitting the microphones. For devices already installed in our homes, we recommend either putting a cardboard box over them or moving them away from windows where unscrupulous neighbors or KGB agents could gain access. This does make us wonder if MEMS mics are also vulnerable to radio waves.
