Normally, you think of things casting a shadow as being opaque. However, new research shows that under certain conditions, a laser beam can cast a shadow. This may sound like nothing more than a novelty, but it may have applications in using one laser beam to control another. If you want more details, you can read the actual paper online.
Typically, light passes through light without having an effect. But using a ruby crystal and specific laser wavelengths. In particular, a green laser has a non-linear response in the crystal that causes a shadow in a blue laser passing through the same crystal.
You might think that visualizing music with lasers would be a complicated and difficult affair. In fact, it’s remarkably simple if you want it to be, and [byte_thrasher] shows us just how easy it can be.
At heart, what you’re trying to do is make a laser trace out waveforms of the music you’re listening to, right? So you just need a way to move the laser’s beam along with the sound waves from whatever you’re listening to. You might be thinking about putting a laser on the head of a servo-operated platform fed movement instructions from a digital music file, but you’d be way over-complicating things. You already have something that moves with the music you play — a speaker!
[byte_thrasher’s] concept is simple. Get a Bluetooth speaker, and stick it in a bowl. Cover the bowl with a flexible membrane, like plastic wrap. Stick a small piece of mirror on the plastic. When you play music with the speaker, the mirror will vibrate and move in turn. All you then have to do is aim a safe laser in a safe direction such that it bounces off the mirror and projects on to a surface. Then, the laser will dance with your tunes, and it’ll probably look pretty cool!
If you get an inexpensive diode laser cutter, you might have been disappointed to find it won’t work well with transparent acrylic. The material just passes most of the light at that wavelength, so there’s not much you can do with it. So how did [Rich] make a good-looking sign using a cheap laser? He used a simple paint and mask technique that will work with nearly any clear material, and it produces great-looking results, as you can see in the video below.
[Rich] starts with a piece of Acrylic covered with paper and removes the paper to form a mask. Of course, even a relatively anemic laser can slice through the paper covering with no trouble at all. He also cuts an outline, which requires a laser to cut the acrylic. However, you could easily apply this to a rectangular hand-cut blank. Also, most diode lasers can cut thin acrylic, but it doesn’t always come out as cleanly as you’d like.
Many hobbies seem to have a subset of participants who just can’t leave well enough alone. Think about hot rodders, who squeeze every bit of power out of engines they can, or PC overclockers, who often go to ridiculous ends to milk the maximum performance from a CPU. And so it goes in the world of lasers, where this avalanche driver module turns Nichia laser diodes into fire-breathing beasts.
OK, that last bit might be a little overstated, but there’s no denying the coolness of what laser jock [Les Wright] has accomplished here. In his endless quest for more optical power, [Les] happened upon a paper describing a simple driver circuit that can dump massive amounts of current into a laser diode to produce far more optical power than they’re designed for. [Les] ran with what few details the paper had and came up with a modified avalanche driver circuit, with a few niceties for easier testing, like accommodation for different avalanche transistors and a way to test laser diodes in addition to the Nichia. He also included an onboard current sensing network, making it easy to hook up a high-speed oscilloscope to monitor the performance of the driver.
For testing, [Les] used a high-voltage supply homebrewed from a Nixie inverter module along with a function generator to provide the pulses. The driver was able to push 80 amps into a Nichia NUBM47 diode for just a few nanoseconds, and when all the numbers were plugged in, the setup produced about 67 watts of optical power. Not one to let such power go to waste, [Les] followed up with some cool experiments in laser range finding and dye laser pumping, which you can check out in the video below. And check out our back catalog of [Les]’ many laser projects, from a sketchy tattoo-removal laser teardown to his acousto-optical filter experiments. Continue reading “Most Powerful Laser Diodes, Now More Powerful”→
Whether the goal is reverse engineering, black hat exploitation, or just simple curiosity, getting inside the packages that protect integrated circuits has long been the Holy Grail of hacking. It isn’t easy, though; those inscrutable black epoxy blobs don’t give up their secrets easily, with most decapping methods being some combination of toxic and dangerous. Isn’t there something better than acid baths and spinning bits of tungsten carbide?
[Janne] over at Fraktal thinks so, and the answer he came up with is laser decapping. Specifically, this is an extension of the laser fault injection setup we recently covered, which uses a galvanometer-scanned IR laser to induce glitches in decapped microcontrollers to get past whatever security may be baked into the silicon. The current article continues that work and begins with a long and thorough review of various IC packaging technologies, including the important anatomical differences. There’s also a great review of the pros and cons of many decapping methods, covering everything from the chemical decomposition of epoxy resins to thermal methods. That’s followed by specific instructions on using the LFI rig to gradually ablate the epoxy and expose the die, which is then ready to reveal its secrets.
The benefit of leveraging the LFI rig for decapping is obvious — it’s an all-in-one tool for gaining access and executing fault injection. The usual caveats apply, of course, especially concerning safety; you’ll obviously want to avoid breathing the vaporized epoxy and remember that lasers and retinas don’t mix. But with due diligence, having a single low-cost tool to explore the innards of chips seems like a big win to us.
While many of us now have laser cutters — either a K40-style machine or one of the newer high-output diodes — you probably don’t have one that cuts metal. True, some hobby lasers now offer IR laser heads with modest power to engrave metal. The xTool S1, for example, accepts a 2 W IR laser as an option, but we doubt it would cut through anything thicker than foil. However, there are a growing number of fiber and carbon dioxide lasers that can cut metal at semi-reasonable prices, and [All3DP] has a primer on the technology that is worth a read.
According to the post, CO2 lasers are less expensive but require gas assist, can’t work with shiny metals well, and are finicky because of the mirrors and glass tube inside. Fiber lasers cost more, but don’t need gas, work on more materials, and have fewer parts that need maintenance or may be prone to damage. There are other kinds of lasers, but the post focuses on these, the most common ones.
Machines that can cut metal aren’t cheap. They start at about $10,000. However, prices are dropping and we remember when $10,000 would buy you what would today be a terrible oscilloscope, so maybe there’s hope for an impulse-buy metal-cutting laser one day.
It isn’t that diode lasers can’t cut metal at all, but the results are not terribly useful. What would you rather have? A metal cutter or a metal 3D printer?
We’ve covered a scanning laser project by Ben Make’s Everything last year, and now he’s back with a significant update. [Ben]’s latest project now offers a higher resolution and RGB lasers. A couple of previous versions of the device used the same concept of a rotating segmented mirror synchronised to a pulsed laser diode to create scanlines. When projected onto a suitable surface, the distorted, pixelated characters looked quite funky, but there was clearly room for improvement.
More scanlines and a faster horizontal pixel rate
The previous device used slightly inclined mirrors to deflect the beam into scanlines, with one mirror per scanline limiting the vertical resolution. To improve resolution, the mirrors were replaced with identically aligned mirrors of the type used in laser printers for horizontal scanning. An off-the-shelf laser galvo was used for vertical scanning, allowing faster scanning due to its small deflection angle. This setup is quicker than then usual vector galvo application, as the smaller movements require less time to complete. Once the resolution improvement was in hand, the controller upgrade to a Teensy 4 gave more processing bandwidth than the previous Arduino and a consequent massive improvement in image clarity.
Finally, monochrome displays don’t look anywhere near as good as an RGB setup. [Ben] utilised a dedicated RGB laser setup since he had trouble sourcing the appropriate dichroic mirrors to match available lasers. This used four lasers (with two red ones) and the correct dichroic mirrors to combine each laser source into a single beam path, which was then sent to the galvo. [Ben] tried to find a DAC solution fast enough to drive the lasers for a proper colour-mixing input but ended up shelving that idea for now and sticking with direct on-off control. This resulted in a palette of just seven colours, but that’s still a lot better than monochrome.
The project’s execution is excellent, and care was taken to make it operate outdoors with a battery. Even with appropriate safety measures, you don’t really want to play with high-intensity lasers around the house!
