NES Light Gun Gets A Burning Laser Upgrade

September 21, 2012 by Mike Szczys 34 Comments

The Nintendo Light Gun makes a perfect burning laser. Of course it’s been gutted to make this happen. Nonetheless, the retro look can’t be beat, and the gun form factor is just what you need in a laser weapon.

This will literally burn your eye out of your head, so [Justin] and his buddies over a North Street Labs are all wearing protective goggles designed for this laser’s wavelength. But they also built a safety into the zapper itself. At the beginning of the video clip (embedded after the break) you will see there’s a key lock mounted in the butt. This lock completes the circuit between the battery and driver board. The 2W output is achieved by a 445nm M140 diode. A lot went into the heat sink and mounting cylinder to make sure the diode doesn’t just burn up after a few seconds of use.

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Variable Frequency Laser Using Shaken Ball Bearings

September 19, 2012 by Brian Benchoff 22 Comments

Lasers normally emit only one color, or frequency of light. This is true for laser pointers or the laser diodes in a DVD player. [Kevin] caught wind of state-of-the-art research into making variable wavelength lasers using shaken grains of metal and decided to build his own.

When [Kevin] read a NewScientist blog post on building variable frequency lasers built with shaken metallic grains, he knew he had to build on. He dug up the arxiv article and realized the experimental setup was fairly simple and easily achievable with a bit of home engineering.

[Kevin]’s device works by taking thousands of small ball bearings and putting them in a small vial with Rodamine B laser dye. To vibrate the particles in the dye, [Kevin] mounted his container of dye and bearings on an audio speaker and used a frequency generator to shake the ball bearings.

When a small 30mW green laser shines through the vial of ball bearings and dye, the laser changes color to a very bright yellow. By vibrating the vial at 35 to 45 Hz, [Kevin] can change the frequency, or color of the laser.

[Kevin] can only alter the frequency of the laser by about 30 nm, or about the same color change as a reddish-orange and an orangish-yellow. Still, it’s pretty amazing that [Kevin] was able to do state-of-the-art physics research at home.

Sadly, we couldn’t find any videos of [Kevin]’s variable frequency laser. If you can find one send it in to the tip line and we’ll update this post.

16×8 Pixel Laser Projector

September 14, 2012 by Mike Szczys 4 Comments

[Michiel] gave us a little shout-out by drawing the Hackaday logo with his recently completed 16×8 pixel laser projector. It uses a spinning set of mirrors mounted at slightly different angles to redirect the path of the red laser diode.

The projector is driven by an Arduino. To give it more than just a hard-coded existence [Michiel] included an Xbee module. This lets him connect to it with a computer in order to stream messages. One of the demo videos linked in his project log shows the web interface he coded which will push a message typed in the submission form out to the projector where it is scrolled like a marquee.

This type of spinning display is one of a few common methods for making laser projectors. In the image above you can see the optical sensor which is used to sync the diode with the spinning mirrors, each of which is responsible for a different row of pixels. He lists off several things that he learned when working on the project. We think the most important is the timing issues which go into something like this.

DIY Laser Cutter From Non-DIY Parts

August 31, 2012 by Mike Szczys 20 Comments

[Jerry] missed the laser cutters he had been using at the local TechShop. It closed down and after seeing some hardware in a surplus store he decided to build a laser cutter to call his own. You won’t be disappointed by his build log. It’s got a ton of hi-res images and plenty of explanation.

Often, cost is the key consideration in these types of builds. [Jerry] spent a little more than average, but look what he got back out of it. This started as a CNC machine aimed at loading silicon wafers for a company making electron microscopes. It’s barely been used, and the light-duty specs will work just fine with a laser cutter as the gantry won’t be moving much weight or fighting the rotational force of a mill motor. He tore out the stock controllers and built his own, adding a q-switched 355nm Frequency Tripled DPSS laser along the way. We’re not quite sure what that means… but in laymen’s terms it’s an ultraviolet laser source. See the finished unit cutting out some Kapton in the clip after the break.

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A Laser Audio Transmitter

August 31, 2012 by Mike Szczys 38 Comments

Here’s a way of transmitting audio that makes it virtually impossible for someone else to listen in. Instead of sending radio waves bouncing all over creation, this uses the focused light of a laser to transmit audio. In the image above you can see the silver cylinder which houses the laser diode. It is focusing the beam on a light dependent resistor to the right which looks almost like a red LED due to the intensity of the light.

The simplicity of this circuit is fascinating. On the receiving end there is no more than the LDR, a 1.5V power source, and a headphone jack. The transmitter is not much more complicated than that. It includes an audio output transformer which boosts the resistance of the audio signal. This increase in resistance ensures that the laser diode modulates enough to affect the LDR on the receiving end. The transmitter uses a 3.3V supply. Check out the video after the break to hear the high quality of audio coming through the setup.

Once you’re done playing around with the transmitter you might try turning the laser into a remote control for your stereo.

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Making Sure A Baby Is Still Breathing With Lasers And A Wiimote

August 21, 2012 by Brian Benchoff 66 Comments

[Gjoci] just became a father, and to make up for not having to carry a baby to term he decided to make himself useful in another way. He developed a sensor to detect a baby’s breathing, allaying the fears of nervous parents who are wondering why their child is so quiet.

Unlike similar builds and products that rely on microphones or capacitive sensors, [Gjoci]’s build uses the camera from a wiimote to triangulate points of light and detect motion.

The build started off with infrared LEDs, but the batteries were big and there is always the possibility of the baby swallowing electrical components. [Gjoci] finally hit upon the idea of using small 1mW laser diodes to project points of light. This worked beautifully, and since newborns don’t move much there’s no danger of shining a laser into a baby’s eye.

The rest of the build is just querying the camera every few milliseconds and seeing if the position of the reflections captured by the wiimote camera have changed. In two weeks of operation, [Gjoci] only had to respond to a few false alarms, and the hardware hasn’t crashed at all.

After the break are three videos [Gjoci] put up for us that show a test of the breathing detection system, a demo of the alarm, and an example of the build in full operation. A very awesome build, and we look forward to this post being used as evidence of prior art in a patent dispute a few years down the line.

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Femto-photography: Taking Pictures Of Bullets Made Of Light

August 17, 2012 by Mike Szczys 27 Comments

Femto-photography is a term that derives its name from the metric scale’s prefix for one-quadrillionth. When combined with photography this division of time is small enough to see groups of light photons moving. The effect is jaw-dropping. The image seen above shows a ‘light bullet’ travelling through a water-filled soda bottle. It’s part of [Ramesh Raskar’s] TED talk on imaging at 1 trillion frames per second.

The video is something of a lie. We’re not seeing one singular event, but rather a myriad of photographs of discrete events that have been stitched together into a video. But that doesn’t diminish the spectacular ability of the camera to achieve such a minuscule exposure time. In fact, that ability combined with fancy code can do another really amazing thing. It can take a photograph around a corner. A laser pulses light bullets just like the image above, but the beam is bounced off of a surface and the camera captures what light ‘echos’ back. A computer can assemble this and build a representation of what is beyond the camera’s line of sight.

You’ll find the entire talk embedded after the break.

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