0
\$\begingroup\$

I'm looking to design a game where players fire a gun at a target using LASERS or IR. The target only registers a hit when a certain amount of players (say 3) are hitting the target consistantly for 5 seconds. The target has got to be around 6" square. The range will be about 3 meters.

The problem i have with this project is that I'm not sure what I can use for a target? I have looked on this site and found solar panels don't seem to work that well.

Im considering an array of photodiodes/transistors to detect the lasers/IR. But as the target is big i'll need a lot of them!

Any ideas anyone?

\$\endgroup\$
  • 1
    \$\begingroup\$ Have you tried using non-reflective glass or any material with light diffusing properties? I believe you can attach them to your sensors to make sure that the laser light scatters throughout the material, which in turn will give off enough light intensity for the sensor in question to detect it. I'll put this up as an answer if this helps. \$\endgroup\$ – Nogurenn Sep 17 '13 at 15:00
  • \$\begingroup\$ There is an obscure yahoo group Lasertag Design. There's a good deal of design information there. \$\endgroup\$ – Nick Alexeev Sep 17 '13 at 19:05
9
\$\begingroup\$

A diffuser (e.g., a piece of frosted glass) can be used to scatter light from a large target area toward a sensor mounted some distance behind it. You'll need to do the calculation (or experiment) to determine whether enough light reaches the sensor from all points on the target area, and with different incoming light angles.

As far as detecting multiple sources, I would recommend encoding each gun with a unique pattern of pulses (rather than a DC output), and having the target count how many distinct codes it is receiving at any given time. Sort of an optical CDMA.

\$\endgroup\$
  • 3
    \$\begingroup\$ +1 for noting the idea to code the individual lasers with a unique modulation pattern. \$\endgroup\$ – Michael Karas Sep 17 '13 at 15:05
  • \$\begingroup\$ To add to this answer, if you plan to place the sensor directly behind the diffuser, shaping the material in to a cone might be of big help to you. \$\endgroup\$ – Nogurenn Sep 17 '13 at 15:05
  • \$\begingroup\$ I was thinking of using ping pong balls over the photodiodes, would this do the same job as the frosted glass? \$\endgroup\$ – user29176 Sep 17 '13 at 15:22
  • \$\begingroup\$ Regarding the pattern of pulses, would a 555 timer or something do the trick? \$\endgroup\$ – user29176 Sep 17 '13 at 15:23
  • \$\begingroup\$ If you don't have any info on the diffusive property of the ping pong ball, shoot laser light at the ball from the distance that the players will shoot while recording the light intensity emitted by the ball at the presupposed position of the sensor. See if the intensity is enough for the sensor to continuously detect it. || For the pulses, you can probably have rotating wheels each with different hole distance/motor speed pattern that block the laser light, creating a pseudo-pulse effect. Note that you need to set slow motor speeds or greater hole distances. Light is too fast. \$\endgroup\$ – Nogurenn Sep 17 '13 at 15:43

Not the answer you're looking for? Browse other questions tagged or ask your own question.