Posts | Comments

Planet Arduino

Archive for the ‘laser hacks’ Category

[Electronoobs] built a coil gun and the obvious question is: how fast is the projectile? To answer it, he built a chronograph suitable for timing a bullet. The principle is straightforward. A laser and a light sensor would mark the entry and exit of the projectile over a known distance. As it turns out, there are some issues to resolve.

For one thing, a laser is too narrow and might miss the projectile. The first attempt to rectify this used mirrors, but the loss was too great — we suspect he was using a second surface mirror. The final answer was to use an array of detectors and removed the laser’s collimation lens to cover a wider area.

That worked, so all that was left was a nice mechanical design to allow changing the height of the sensors and the distance between the sensors. After that, an Arduino can take over.

We liked the mechanical design and the way he managed pushbuttons in the 3D printed case. We couldn’t help but wonder if a first surface mirror might have worked better. We also thought it would be nice to add some sort of encoder to let the device measure the distance between sensors automatically since it is adjustable. We also thought the response time and wavelength sensitivity of light-sensitive resistors might be a bit off. It seems like a photodiode or transistor would be more accurate and have better sensitivity to the laser or even just a conventional light source. But this does seem to work.

How fast was the coil gun? Well over 100 meters per second. For a point of reference, a .22 caliber round will have a muzzle velocity of well over 300 meters per second, but, still, 120 to 130 meters per second is nothing to sneeze at.

If you need a coilgun, we always liked the looks of this one. Or, you might prefer a more futuristic look.

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

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.

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.

We’ve used the copper tape writing trick ourselves and it is quite effective. The tape is often used for stained glass work and sticks to many surfaces. You can solder to it and solder overlaps where you need connections. The results are often as good as a simple single-sided PCB.

The code attached to the post is fairly straightforward and the MIDI shield does the bulk of the work. It should also make it easy to create some really impressive musical effects with a bit of extra coding.

If you want an artsy self-contained version, check out this previous Hackaday Prize entry. We’ve seen several of these at different levels of complexity.

A lighthouse beams light out to make itself and its shoreline visible. [Daniel’s] lighthouse has the opposite function, using lasers to map out the area around itself. Using an Arduino and a ToF sensor, the concept is relatively simple. However, connecting to something that rotates 360 degrees is always a challenge.

The lighthouse is inexpensive — about $40 — and small. Small enough, in fact, to mount on top of a robot, which would give you great situational awareness on a robot big enough to support it. You can see the device in action in the video below.

This lighthouse uses a common solution to the rotating connection problem: a slip ring. While these are mechanical, commercial units can be relatively reliable. To route all the signals, the slip ring needs six wire capsules meaning there are six wires that logically pass through the rotating part. The drive motor spins at 60 RPM, but there are two sensors 180 degrees apart to double the scanning rate. The 3D printed housing uses PLA and looks great.

Of course, the real trick will be using all this data meaningfully in your robot or whatever is listening to the lighthouse. That, however, is a different topic. If you think two ToF sensors are good, why not try three?

 

Ahh, midterms. Some students blow off steam between study sessions by playing video games or just zoning out. While those kids were all distracted, [Justinwong777] and his buddy [Brett] found a bunch of scrap wood and built this laser drawing machine in their school’s makerspace. You operate it as you might an Etch-a-Sketch, except your drawings are as fleeting as sparkler art on the 4th of July, if they made Tron-colored sparklers.

Though you work it like an Etch-a-Sketch, the business end operates like a laser cutter. Inside that plywood enclosure is an Arduino Uno and a pair of motors. These motors turn a series of custom gears, which move a small mirror angled at 45° in the xy-plane.  There’s a 30mW laser mounted parallel with the base, pointed at the mirror, and it reflects the beam toward a canvas panel coated with phosphorescent paint. We dig the printed ergonomic case for the joystick, which gives control of both x and y. Put on some eye protection and check it out after the break.

If you want to draw with lasers, but aren’t much of an artist, do something unexpected: build a laser turret not to kill, but to draw the weather on the wall.

The latest creation from Bengali roboticist [nabilphysics] might sound familiar. His laser-augmented glove gives users the ability to detect objects horizontally in front of them, much like a cane or pole is used by the visually impaired to navigate through a physical space.

As a stand in for the physical cane, he uses the VL53L0X time-of-flight (TOF) sensor which detects the time taken for a laser source to bounce back to the sensor. Theses are much more accurate than IR distance sensors and have a much finer focus than ultrasonic sensors for excellent directionality.

While the sensors can succumb to interferences from background light or other time-of-flight sensors, the main advantages are speed of calculation (it relies on a single shot to compute the distances within a scene) and an efficient distance algorithm that simplifies the measurement of distance data. In contrast to stereo vision, which requires complex correlation algorithms, the process for extracting information for a time-of-flight sensor is entirely direct, requiring a small amount of processing power.

The glove delivers haptic feedback to the user to determine if an object is in their way. The feedback is controlled through an Arduino Pro Mini, powered remotely by a LiPo battery. The code is uploaded to the Arduino from an FTDI adapter, and works by taking continuous readings from the time-of-flight sensor and determining if the object in front is within 450 millimeters of the glove, at which point it triggers the vibration motor to alert the user of the object’s presence.

Since the glove used for the project is a bicycle glove, the form factor is straightforward — the Arduino, motor, battery, and switch are all located inside a plastic box on the top of the glove, while the time-of-flight sensor sticks out to make continuous measurements when the glove is switched on.

In general, the setup is fairly simple, but the idea of using a time-of-flight sensor rather than an IR or sonar sensor is interesting. In the broader usage of sensors, LIDARs are already the de facto sensor used for autonomous vehicles and robotic components that rely on distance sensing. This three-dimensional data wouldn’t be much use here and this sensor works without mechanical moving parts since it doesn’t rely on the point-by-point scan from a laser beam that LIDAR systems use.

We missed [iliasam’s] laser text projector when it first appeared, perhaps because the original article was in Russian. However, he recently reposted in English and it really caught our eye. You can see a short video of it in operation, below.

The projector uses raster scanning where the beam goes over each spot in a grid pattern. The design uses one laser from a cheap laser pointer and a salvaged mirror module from an old laser printer. The laser pointer diode turned out to be a bit weak, so a DVD laser was eventually put into service. A DVD motor also provides the vertical scan which is just a slight wobble of a mirror. A Blue Pill CPU provides all the smarts. You can find the code on GitHub.

The projector is fairly limited in size with a maximum resolution of 32×14. Some displays use a vector scheme that draws with the laser. This is brighter and more capable, but also more difficult to arrange since the laser has to move rapidly in a complex motion. The raster scanning is much easier to accomplish.

A light sensor tells the CPU when the laser is about to start hitting the vertical scan mirror. Obviously, there are other ways you could arrange for the mirrors to move, but the logic would be the same.

We’ve seen [illiasam] has a lot of interest in lasers. He’s hacked rangefinders and even 3D scanners that we’ve looked at before.

There’s an interesting side effect of creating a popular piece of science fiction: if you wait long enough, say 30 or 40 years, there’s a good chance that somebody will manage to knock that pesky “fiction” bit off the end. That’s how we got flip phones that looked like the communicators from Star Trek, and rockets that come in for a landing on a tail of flame. Admittedly it’s a trick that doesn’t always work, but we’re not in the business of betting against sufficiently obsessed nerds either.

Coming in right on schedule 32 years after the release of Metroid on the Nintendo Entertainment System, we now have a functional laser arm cannon as used by the game’s protagonist Samus Aran, courtesy of [Hyper_Ion]. It’s not quite as capable as its video game counterpart, but if your particular corner of the solar system is under assault from black balloons you should be in good shape. Incidentally no word yet on a DIY Power Suit that folds the wearer up into a tiny ball, but no rush on that one.

Modeled after the version of the weapon Samus carried in 2002’s iconic Metroid Prime, [Hyper_Ion] 3D printed the cannon in a number of pieces that screw together in order to achieve the impressive final dimensions. He printed it at 0.3 mm layers to speed up the process, but as you can probably imagine, printing life-size designs like this is not for the faint of heart or short of time. While the use of printed threads does make the design a bit more complex, the fact that the cannon isn’t glued together and can be broken down for maintenance or storage is a huge advantage.

Ever popular NeoPixel strips give the cannon a bit of flash, and a speaker driven by a 2N2222 transistor on an Arduino Nano’s digital pin allows for some rudimentary sound effects with nothing more than a PWM signal. In the video after the break you can see how the lights and sounds serve as a warning system for the laser itself, as the cannon can be seen “charging up” for a few seconds before emitting a beam.

Of course, this is the part of the project that might have some readers recoiling in horror. To provide some real-world punch, [Hyper_Ion] has equipped his arm cannon with a 2.5W 450nm laser module intended for desktop engraving machines. To say this thing is dangerous is probably an understatement, so we wouldn’t blame you if you decided to leave the laser module off your own version. But it certainly looks cool, and as long as you’ve got some proper eye protection there’s (probably) more dangerous things you can do in the privacy of your own home.

Shame this kind of technology wasn’t really practical back when [Ryan Fitzpatrick] made this fantastic Power Suit helmet for a Metroid fan production.

Some people have all the luck. [MakerMan] writes in to gloat tell us about a recent trip to the junkyard where he scored a rather serious looking laser cutter. This is no desktop-sized K40 we’re talking about here; it weighs in at just under 800 pounds (350 Kg), and took a crane to deliver the beast to his house. But his luck only took him so far, as closer inspection of the machine revealed it was missing nearly all of its internal components. Still, he had the frame, working motors, and laser optics, which is a lot more than we’ve ever found in the garbage.

After a whirlwind session with his wire cutters, [MakerMan] stripped away most of the existing wiring and the original control board inside the electronics bay. Replacing the original controller is an Arduino Nano running Grbl, likely giving this revived laser cutter better compatibility with popular open source tools than it had originally. Even though the laser cutter was missing a significant amount of hardware, he did luck out that both the motor drivers were still there (and working) as well as the dual power supplies to run everything.

After a successful motion test, [MakerMan] then goes on to install a new 90W laser tube. Supporting the tube is a rigged up water cooling system using a plastic jug and a cheap bilge pump. He also added an air assist system, complete with side mounted compressor. This pushes air over the laser aperture, helping to keep smoke and debris away from the beam. Finally, a blower was installed in the bottom of the machine with flexible ducting leading outside to vent out the smoke and fumes that are produced when the laser is in operation.

This machine is a considerable upgrade from the previous laser [MakerMan] built, and as impressive as this rebuild is so far, we’re interested in seeing where it goes from here. If you ask us, this thing is begging for an embedded LaserWeb server.

A lot of the DIY laser engravers and cutters we cover here on Hackaday are made with laser diodes salvaged from Blu-ray drives and projectors, which are visible lasers in the 400 – 450nm range (appearing as violet or blue). Unfortunately there is an upper limit in terms of power on visible diode lasers, most builds max out at 5W or so. If you need more power than that, you’ll likely find yourself looking at gas laser cutters like the K40. While the K40 is a great starting point if you’re looking to get into “real” lasers, it’s a very different beast from the homebrew builds using visible lasers.

With a gas laser the beam itself is invisible, making it much more difficult to align or do test runs. One solution is to add a visible laser to the K40 which can be used to verify alignment, but making sure it’s traveling down the same path as the primary laser usually requires an expensive beam combiner. Looking to avoid this cost, [gafu] wanted to see if it was possible to simply move the visible laser into the path of the primary beam mechanically.

An adjustable microswitch detects when the lid has been opened.

In the setup that [gafu] has come up with, a cheap laser module (the type from a handheld laser pointer) is moved into the path of the primary laser on an arm that’s actuated by a simple hobby servo. To prevent the primary and visible lasers from firing at the same time, an Arduino is used to control the servo given the current state of the K40’s lid. If the lid of the K40 is open, the primary laser is shutoff and the visible laser is rotated into position so the operator can see where the primary laser’s beam would be hitting. Once the lid is closed, the visible laser rotates out of the way and the primary is powered back up.

Running the cutting or engraving job with the lid of the K40 machine open now let’s [gafu] watch a “dry run” of the entire operation with the visible laser before finally committing to blasting the target with the full power beam.

We’ve covered many hacks and modifications for everyone’s favorite entry-level CO2 laser cutter. From replacing the controller to making it bigger, K40 owners certainly seem like a creative bunch.


Filed under: Arduino Hacks, hardware, Laser Hacks


  • Newsletter

    Sign up for the PlanetArduino Newsletter, which delivers the most popular articles via e-mail to your inbox every week. Just fill in the information below and submit.

  • Like Us on Facebook