Building A 1.4W Laser Pointer In A Tiny Housing

Laser pointers were cool for about 30 seconds when they first came out, before becoming immediately passé and doing absolutely nothing to improve the boss’s quarterly reports presentation. However, just as with boom boxes and sports cars, more power can always make things better. [Styropyro] was unimpressed with the weak and unreliable laser pointers he’d sourced from eBay, so gutted one and began a fresh build.

After fiddling with some basic 1mW eBay green lasers, [styropyro] had some fun turning up the wick by fiddling with the internal trimpots. This led to the quick and untimely death of the cheap laser diodes, leaving a compact laser pointer shell ripe for the hacking.

To replace the underwhelming stock components, [styropyro] chose a Nichia NDG7475 high-powered laser diode, fitting it into a small heatsink for thermal management. Current draw was far too high to use the original switch, so the stock housing’s button is instead used to switch a MOSFET which delivers the full current to the laser driver. To reach the higher output power of 1.4W, the laser diode is being run over specification at 2.3 amps. All this current draw would quickly overwhelm standard AAA batteries, so a pair of lithium polymer 10440 batteries are substituted in to do the job.

The build shows that with clever parts selection and some easy hand soldering, you too can build an incredibly dangerous laser pointer at home, that fits neatly in your shirt pocket. Alternatively, you might prefer something on the larger scale. Video after the break.

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[Ben Krasnow] Builds a One-Component Interferometer

When we think of physics experiments, we tend to envision cavernous rooms filled with things like optical benches, huge coils in vacuum chambers, and rack after rack of amplifiers and data acquisition hardware. But it doesn’t have to be that way – you can actually perform laser interferometry with a single component and measure sub-micron displacements and more.

The astute viewer of [Ben Krasnow]’s video below will note that in order to use the one component, a laser diode, as an interferometer, he needed a whole bunch of support gear, like power supplies, a signal generator, and a really, really nice mixed-signal oscilloscope. But the principle of the experiment is the important bit, which uses a laser diode with a built-in monitoring photodiode. Brought out to a third lead, older laser diodes often used these photodiodes to control the light emitted by the laser junction. But they also respond to light reflected back into the laser diode, and thanks to constructive and destructive interference, can actually generate a signal that corresponds to very slight displacements of a reflector. [Ben] used it to measure the vibrations of a small speaker, the rotation of a motor shaft, and with a slight change in setup, to measure the range to a fixed target with sub-micron precision. It’s fascinating stuff, and the fact you can extract so much information from a single component is pretty cool.

We really like [Ben]’s style of presentation, and the interesting little nooks and crannies of physics that he finds a way to explore. He recently looked at how helium can kill a MEMS sensor, an equally fascinating topic.

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Robotic Laser Keeps Cat Entertained While You Hack

Whether it’s our own cat or a neighbor’s, many of us have experienced the friendly feline keeping us company while we work, often contributing on the keyboard, sticking its head where our hands are for a closer look, or sitting on needed parts. So how to keep the crafty kitty busy elsewhere? This roboticized laser on a pan-tilt mechanism from the [ team] should do the trick.

The laser is a 650 nm laser diode mounted on a 3D printed pan-tilt system which they found on Thingiverse and modified for attaching the diode’s housing. It’s all pretty lightweight so two 9G Micro Servos do the grunt work just fine. The brain is an Arduino UNO running an open-source VarSpeedServo library for smooth movements. Also included are an HC-05 Bluetooth receiver and an Android app for controlling the laser from your phone. Set it to Autoplay or take a break and use the buttons to direct the laser yourself. See the video below for build instructions and of course their cat, [Pepper], looking like a Flamenco dancer chasing the light.

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Metal 3D Printing: Insta-Layers

Selective Metal Sintering is cool but slow. Fear not, a technology that was initially developed to smooth and pattern laser beams is here to save the day, according to a new paper by Lawrence Livermore researchers.

In a paper titled “Diode-based additive manufacturing of metals using an optically-addressable light valve,” the researchers lay out a procedure for using an array of high-powered laser diodes among other things to print a whole layer of metal from powdered metal at one time. No more forward and backward, left and right. Just one bright flash and you’re done. Naturally, the technology is still in its infancy, but huge 3D printed metallic parts are something we’ve always hoped for.

According to [Matthews], the first author of the paper, the mojo of the process comes from a customized laser modulator: the Optically Addressable Light Valve which functions similarly to liquid crystal-based projectors but can handle the high energies associated with powerful lasers. There’s more information straight from the paper’s authors in this interview.

While it’s true that now is the time for direct metal 3D printing, it appears that for the time being the average hacker is stuck with alternative methods for printing metal. While it’s not the same, pewter casting with PLA might suffice.

Thanks to [Kevin] for sending this in!

Sending Music Long Distance Using A Laser

This isn’t the first time we’ve seen DIYers sending music over a laser beam but the brothers [Armand] and [Victor] are certainly in contention for sending the music the longest distance, 452 meter/1480 feet from their building, over the tops of a few houses, through a treetop and into a friend’s apartment. The received sound quality is pretty amazing too.

In case you’ve never encountered this before, the light of the laser is modulated with a signal directly from the audio source, making it an analog transmission. The laser is a 250mW diode laser bought from eBay. It’s powered through a 5 volt 7805 voltage regulator fed by a 12V battery. The signal from the sound source enters the circuit through a step-up transformer, isolating it so that no DC from the source enters. The laser’s side of the transformer feeds the base of a transistor. They included a switch so that the current from the regulator can either go through the collector and emitter of the transistor that’s controlled by the sound source, giving a strong modulation, or the current can go directly to the laser while modulation is provided through just the transistor’s base and emitter. The schematic for the circuit is given at the end of their video, which you can see after the break.

They receive the beam in their friend’s apartment using solar cells, which then feed a fairly big amplifier and speakers. From the video you can hear the surprisingly high quality sounds that results. So check it out. It also includes a little Benny Hill humor.

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RC Drag Racing Christmas Tree and Speed Trap

In the drag racing world, a Christmas tree is the post at the start line that sequentially lights up a set of yellow lights followed shortly after by a green light to tell the drivers to go, the lights obviously giving it its seasonal name. Included at the base of the tree are lasers to detect the presence of the cars.

[Mike] not only made his own Christmas tree for his RC cars, but he even made an end-of-track circuit with LED displays telling the cars how long they took. Both start and finish hardware are controlled by Pololu Wixel boards which has TI CC2511F32 microcontrollers with built-in 2.4 GHz radios for wireless communications.

In addition to the LEDs, the Christmas tree has a laser beam using a 650nm red laser diode for each car at the start line that’s aimed at a TEPT5600 phototransistor. If a car crosses its beam before the green light then a red light signals the car’s disqualification.

The end-of-track circuit has 7-segment displays for each car’s time. [Mike] designed the system so that the Christmas tree’s microcontroller tells the end-of-track circuit’s microcontroller when to reset the times, start the times, and clear the times should there be a disqualification. The finish line controller has lasers and phototransistors just like the starting line to stop the timers.

Oh, and did we mention that he also included 1980’s car racing game sounds? To see and hear it all in action check out the video after the break. If the cars seem a little drunk it’s because pushing left or right on the controller turns the wheel’s fully left or right.

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Etching PCBs With A 3D Printer

With the coming of very cheap blue laser diodes, PCB fabrication has become increasingly interesting. Instead of making a photoresist, placing it over a piece of pre-sensitized copper clad board, and putting the whole assemblage under a blacklight, it’s possible to put a photomask on a board with a tiny bit of very blue light. All you need is a CNC machine. A 3D printer can be a very precise CNC machine, and when you combine these two ideas together, you can make printed circuit boards with an Ultimaker.

[Geggo] had the idea of attaching a blue laser diode to his Ultimaker to burn a few traces into presensitized copper board. With a 3D printed adapter, he was able to mount the diode and associated electronics right on the extruder body. With a small ring to tighten up the aperture, [geggo] was able to put a 50 micrometer wide dot of light on a piece of copper. The laser is powered directly from the PWM fan output on the printer controller board, allowing this entire mish-mash of cheap electronics to be controlled via G-code.

A few experiments were necessary to determine the correct speeds and power settings, with the best results being 1000 mm per minute at 40 mA. The finished board looks fantastic, and a few minutes after [geggo] was done etching a board, he started using his 3D printer as a printer. It’s a result that is so good, so easy to accomplish, and requires so little effort it makes us wonder why we don’t see more of this.