Laser Tracker Replays Competitive Rock Wall Climbs

April 19, 2011 by Mike Nathan 17 Comments

Instructables user [PenfoldPlant] is a big fan of indoor rock climbing, and while watching others make difficult climbs, he has often wondered if he could follow the same route up the wall. Unfortunately, aside from watching the other climbers and hoping to remember the path they have taken, he found there isn’t much you can do to ensure that you have precisely replicated the climb.

He thought awhile and came up with a laser tracking system that can be used to record a climber’s ascent, then replay it any number of times. This allows climbers to be able to replicate other climbers’ paths as well as compete against one another in timed races.

This works much like the “ghost” feature found in most racing games, though the process is half manual/half automated. The initial ascent is recorded by manually tracing the climber’s route with a laser pointer as they climb. The path is recorded and then can be replayed, courtesy of the onboard Arduino.

It really is a neat system, and while it works pretty well already, we think there is still room for enhancement. It wouldn’t be extremely difficult to have the climber wear some sort of light beacon that could be tracked using a web cam or other recording device, taking the manual labor out of the equation. In that case however, we imagine the Arduino would need to be swapped out for something a touch more powerful.

Stick around for a quick video of the tracking system in action.

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Laser Trip Wire – The Bare Essentials

April 19, 2011 by Mike Szczys 12 Comments

[Gordon] sent us a tip about this simple laser trip wire system after reading yesterday’s post on a more complicated laser security unit. That build did a lot to provide functionality, such as a system to disarm the trip wire, and a robust light detection circuit. This time around there’s more happening with smoke and mirrors than with electronics.

[The Timmy] built this simpler version based on a laser trip system from Afrotechmods (video of that one is embedded after the break). He had a bag full of small square mirrors which he attached to a wall with some poster putty. A laser module shines a beam of light onto a cadmium sulfide sensor after it bounces around the optical network for a while. That CdS sensor controls an N-channel MOSFET, switching it off when light is detected and on when the intensity of the laser is absent. This example just turns an LED on and off, but since it uses logic-level voltages you can choose to add a microcontroller to the mix if you have other plans in mind.

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Laser Tripwire Alarm System Uses Mirrors To Increase Coverage

April 18, 2011 by Mike Nathan 15 Comments

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Instructables user [EngineeringShock] has been hard at work building a laser trip wire security system, complete with a combination lock. The security system works just like you see in the movies, employing an array of mirrors to bounce the laser across an opening several times in order to secure the space.

A PIC18F1220 micro controller sits at the center of the alarm and handles the majority of its functions. It takes input from the laser detection circuit, triggers the buzzer, as well as arms and disarms the entire alarm system. An LS7222 digital lock handles the passcode verification side of things, taking input from a 16-button matrix keypad, and telling the PIC when the proper code has been entered.

As you can see in the video below, the alarm system works and the buzzer is quite loud. There is one small problem however – the alarm only arms itself after the proper code has been entered and the lights have been turned off. The light sensing circuit he uses is too sensitive and can only operate in darkness, though he discusses the ability to add a more accurate sensing solution.

If you are interested in reading more about laser tripwire security systems, check out this similar passcode-based system, this alarm system built into a toy, and this Arduino-based alarm system.

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Laser Camera Sees Around Corners

April 18, 2011 by Brian Benchoff 18 Comments

After reading over the proceedings of the 2005 SIGGRAPH, [Dan] realized he could reproduce one of the projects with $50 worth of equipment and some extreme cleverness.

[Dan]’s dual scanning laser camera operates by scanning a laser across an object. The light reflected from the object illuminates a flat surface, and this light is measured by a photocell. After measuring the resistance of the photocell, an image can be reconstructed from the light reflected off the flat surface. The result is quite ingenious, and we’re very grateful [Dan] gave us a great walkthrough with the code and theory of operation.

The project was covered in this Slashdot story a from a few years ago, and we’re surprise no one has bothered to cobble this project together. It’s a very simple build – two servos to control the x and y axes of the laser scanner, a photocell, and an ATMega board. Dan says the microcontroller isn’t even necessary, and this ‘remote imaging’ could be done with an ADC hooked up to a parallel port.

[Dan] was kind enough to to give us a video of his contraption in action. A very nice build from a very accomplished guy.

Save Boatloads Of Cash By Building Your Own Laser Cutter

April 14, 2011 by Mike Nathan 26 Comments

diy_laser_build

Have a bunch of time on your hands, and about $2,500 sitting around? Why not settle in and build yourself a laser cutter?

That’s exactly what Buildlog forum member [r691175002] did, and he told us about it in our comments just a few moments ago. Laser cutters can be pretty cost prohibitive depending on what you are thinking of picking up. The cheapest Epilog laser we could find costs $8,000, and you know what can happen when you try buying a cheap laser online.

Instead of going for a ready-made cutter, he purchased an open-source kit from Buildlog, documenting the highlights of the build process online. The build log walks through a good portion of the construction starting with the frame and motor mounts, continuing through wiring up the electronics as well as some of the finishing touches. If you happen to head over to take a look around, you will find that there are plenty of pictures from various stages of the construction process to keep you busy for awhile.

With everything said and done, [Ryan] is quite happy with his laser. After going through the build process, he offers up some useful construction advice, as well as tips on sourcing cheaper hardware. He estimates that if he built the laser today, he could probably cut the costs nearly in half.

There’s no doubt about it – a $1300 laser cutter sounds pretty darn good to us.

Analog Scope Stands In To For Laser Light Show

April 14, 2011 by Mike Szczys 6 Comments

[Joey] likes to dabble in laser projection, building his own hardware and writing the software that drives it. One way that he tests his setup is by replacing the laser assembly with an analog oscilloscope. This allows him to ensure that the driver board is receiving data from the software, and translating it into the correct electrical signals to drive the motors controlling the mirrored redirection of the laser beam.

In the video linked above [Joey] walks us through this process. It starts by connecting scope probes to the digital-analog-converter card that outputs image data for the projector. From there the XY mode is used to map the two channels perpendicular to each other; the motors that these signals are meant to control have mirrors that also move perpendicular to one another. After adjusting the scale and the timebase you will see the pattern the laser dot is meant to trace.

[Joey] entered this in a Tectronix contest. There’s plenty of other interesting entries to browse though. If have an entry that you’d like to see featured, or if you come across any other interesting stuff, don’t forget to tip us off.

Blu-ray Laser Plotter Writes On Glow-in-the-dark Screen

April 6, 2011 by Mike Szczys 17 Comments

This laser display is persistent thanks to a glow-in-the-dark screen. [Daniel] built it using a Blu-ray laser diode. As the laser dot traverses the screen, it charges the phosphors in the glow material, which stay charged long enough to show a full image.

The laser head is simple enough, two servo motors allow for X and Y axis control. A Micro Maestro 6-channel USB servo controller from Pololu drives the motors, and switches the diode on and off. This board offers .NET control, which [Daniel] uses to feed the graphics data to the unit. Check out the video demonstration below the fold to see a few different images being plotted. It’s shot using a night-vision camera so that you can really see where the laser dot is on the display. It takes time to charge the glow material so speeding up the plotting process could actually reduce the persistent image quality.

This is yet another project that makes you use those geometry and trigonometry skills.

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