Passcode Protected Laser Tripwire Alarm System

March 11, 2011 by Mike Nathan 13 Comments

laser_tripwire

Sometimes security doesn’t need to be overly complex to be effective. Instructables user [1234itouch] recently built a simple laser tripwire alarm that can be mounted virtually anywhere, complete with a keypad for disarming the device.

He mounted a photo cell in a project box, along with an Arduino and a 12-button key pad. A laser pointer is aimed at the photo cell from across a gap, which results in a steady voltage being read by the Arduino. When the laser beam is broken, a drop in voltage is detected, and the alarm sounds until you enter the proper pre-configured passcode. Entering the passcode triggers a 15 second grace period during which the the alarm cannot be tripped again.

It might not be built with triple-thick steel doors and thermo-sensors, but it’s a simple device for simple needs. In its current form it could be pretty useful, and with a little reworking, there are a wide range of things it could be used for.

Continue reading to see a demo video of the tripwire alarm, and be sure to check out these other tripwire-based security systems.

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Bench-top Laser Engraver Does Some Cutting Too

March 11, 2011 by Mike Szczys 25 Comments

Grab that stack of old optical drives you have in the corner and get to work building this laser engraver. [Groover] is taking a no-nonsense approach to the build and we think it is just simple enough to be accessible to a very wide audience.

The physical assembly uses sleds from two optical drives. These are mounted some angle bracket. Since lasers cut at one specific focal length, there is not need for a Z axis (simplifying the build greatly). In fact, we think the hardest part of the assembly is retrieving the laser diode from a DVD-R drive and packaging it for use with this setup.

The electronics are a combination of a couple of consumer products. Two pre-fab motor drivers are used to command the stepper motors on the optical sleds. These receive their commands from an Arduino. A package called GRBL reads in G-code ([Groover] shows how to generate this from Inkscape) and in turn sends commands to the Arduino.

The results are quite remarkable. It can engrave wood with great resolution and contrast. The video after the break even shows it cutting out shapes from construction paper. Now we still want our own full-size laser cutter, but this project is much more fiscally possible for us.

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You’ll Shoot Your Eye Out…with A 1MW Laser Pulse Pistol

March 10, 2011 by Mike Nathan 144 Comments

G.I. Joe used them to battle Cobra’s evil forces. Han solo shot his first in the Mos Eisley Cantina. For years, hand-held pulse laser guns have been something that existed only in the realm of cartoons and movies…until now.

German hacker [Patrick Priebe] recently constructed a laser pulse gun that looks so good, it could have easily come off a Hollywood movie set. Its sleek white and black exterior adds intrigue, but offers little warning as to how powerful the gun actually is.

Fitted with a Q-switched Nd:YAG laser, it fires off a 1 MW blast of infrared light once the capacitors have fully charged. The duration of the laser pulse is somewhere near 100ns, so he was unable to catch it on camera, but its effects are easily visible in whatever medium he has fired upon. The laser can burst balloons, shoot through plastic, and even blow a hole right through a razor blade.

[Patrick] says that he is more than happy to help out anyone looking to source parts and build one for their own use, so what are you waiting for?

Stick around for a quick demo video of the gun in action.

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A Different Take On A Laser Projection Microscope

March 2, 2011 by Mike Szczys 12 Comments

[Dusjagr] has another take on building a laser projection microscope. Last year we saw a laser-based microscope that shined the beam of light through a water droplet which contained the subject to be magnified. The droplet bent the focused beam of light and projected the magnified contents onto a screen. Now that’s pretty neat and [Dusjagr] has used that method himself. But most traditional microscopes use glass slides to contain the subject and this new version now makes that possible.

A bit of experimentation led [Dusjagr] to the discovery that a lens re-purposed from a webcam can achieve similar focus results as a water droplet. The video after the break shows the apparatus seen above in action. The laser shines through the lens, then through a slide that contains a water sample from a nearby pond. The image is clear, albeit completely bathed in green.

For us the most interesting part of [Dusjagr’s] writeup is his discussion of the limits of laser amplification based on the wavelength of light the diode puts out.

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Open Source Laser Cutter (v2)

March 2, 2011 by Kevin Dady 23 Comments

The Buildlog.net 2.x Laser is a second generation open source laser cutter that definitely improves the design of the first model. The 2 axis machine (optional vertical axis is manual or an upgrade is available) boasts a large 12” x 20” x 4” workspace while being smaller than its predecessor, fitting a table top design.

The older model had a goal of being self replicating, which limited the types of materials used, the new 2.x model drops that goal and uses stronger metal parts. Electronics are now modularized that allow easier and cleaner wiring, though you will still need a controller board.

There is an XMOS based controller provided on the main page of BuildLog.net, along with mechanical drawings, schematics, gerbers, instructions for both machines, and kit parts (for the first model) along with resources for the heavy items like laser tubes and power supplies.

Etching Panel Faces On The Cheap

February 17, 2011 by Mike Szczys 23 Comments

[James] came up with a way to make small numbers of high-contrast instrument panels cheaply, and without too much labor. We’ll make with the bad news right away; you’re going to need a laser cutter to use this method. Traditionally, panels that look like the one above are etched onto special composite that has one color at the surface and a contrasting color beneath. [James] started with plain old acrylic, etched his labels, then filled the voids with black wax crayon. Just scribble all over the etched face to rub wax into the grooves, go through a couple of cleaning steps using white spirit, then bake the panel to even out and harden the wax layer. He’s got several examples of his work, including medallions that are used to label LED indicators.

Long-range Laser Night-vision

February 16, 2011 by Mike Szczys 24 Comments

[Oneironaut] is back at it again, churning out yet another great hack in this long-distance night vision build. This isn’t the first time we’ve seen him build a night vision device, you may remember the monocle he put together using the view finder from an old camcorder. This time around he’ll give you look at distant object by using a laser instead of LEDs. He pulled an IR laser diode out of an old CD burner, then used a lens to spread out the dot in order to illuminate a larger area. A standard rifle scope is used as the optics, along with a security camera which can detect the infrared light. As always, he’s done a fantastic job with the images and the write-up. You’ll find his overview video embedded after the break.

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