Designing A Laser Tag System : IR Problems

Hello,
I've decided to attempt to make a laser tag setup with Arduino. There'll be 6 vests and guns, each vest will have target areas. What I'm stuck on is actually shooting, more specifically, how to send the signal. For the longest time, I was planning for IR beams and receivers, but after further research, I became disinterested in using IR. From the beginning, I planned to have a laser in the front of the gun, primarily I figured it'd be detected by sensors, but that was before I did research and originally found out that there was no "laser sensor diode" (except for some fiber optic sensor, which I couldn't find anything about). After deciding it couldn't easily be detected, I figured I'd just mount it so a user knows where they're shooting at when the shoot. After this was when I did research on IR and realized it was far to inaccurate.

To summarize the above, I basically need some guidance as to what to use for transmitting and receiving signals for laser tag. My current thinking is that I should use a laser to send signals, and use a photoresistor to receive them (by checking for a high lux value on the Arduino). The only problem is, there is no huge photoresistor that could take up a 25 inch diameter half sphere.
Of course, another option I'm considering is using a IR Receiver that picks up the wavelength type of the laser I'll be using which is this: 5V Red Laser Diodes for Toys / Instruments - Golden + Red + Blue (2 PCS) - Free shipping - DealExtreme

The basic problem is, there needs to be an emitter and a receiver of some sort. The emitter must be direct and not expand very much so you can't tag multiple people, and the receiver needs to have a range of 30+ meters and be able to pick up signals that are a few inches away from it, but not those of greater distance (or just be a huge circle sensor).

If anyone has any suggestions, products, or tips, please, at this rate, anything is helpful.

Sincerely,
Chris

Use ATtiny85 chips.

Another thing to cconsider is eye damage. I would think you'd want a laser bandwidth that is not going to cause accidental eye damage, or dial the power way back - but then makes it harder for the receiver.

@CrossRoads

I don't think that'll be a huge problem, this won't be used publicly, and I may end up adding helmets with a shaded visor.

raschemmel,

I've been considering using An Arduino Pro Mini in the gun and several small Atmel chips linked to it in the suit.

I agree, also the laser has a very small spot, so a target would need to have a large area, i know of no detector that would do that without expensive optics.

I would probably use a standard pin diode as a detector and use a colminated beam from an ir led.

I would pulse modulate it like a remote rather than just detect a luminance level, more reliable better range.

Try looking at some of these photodiodes as laser detectors. Many respond to infrared and visible light, and laser is certainly visible.

Colmination can be acomplished by mounting the led at the back of a short tube although the better commercial devices use lenses.

At a police trade show, I once saw a "live fire" training laser tag system, where the laser was in a barrel insert, triggered by firing a blank.
The target vest was woven with notched optical fibre - a sort of optical leaky feeder - and with an array of photo diodes could locate a hit very accurately.
You could try the sort of light guide used on the back of LCDs as a target to increase the hit area.

Maybe a small fresnel lens over each sensor diode to broaden the light sensitive area?

They are rather expensive.

This is the normal method

Modulation is essential to identify who shot who.

I would add that some use a laser for sighting only, it is essential that proper filter glasses are worn though not just dark glasses.

Alright, so at this point, I guess I could mount a laser above an IR emitter for effect, even though it'd be a bit off. The IR emitter can go far back in the barrel of the gun, and a lense will be at the tip. I guess that covers the emitter. Now what about the receiver?

If anyone has any suggestions on receivers, let me know. It'd have to be able to pick up shots that are hit like right next to it, because I am not covering each sensor pad on the suit with photoresistors or IR receivers. If it has a large field of view it could accidently pick up other shots not aimed at it. Anyone know of a happy medium receiver?

Also, where could I find a lense that would work for the emitter? It's not exactly my field of expertise.

Thanks,
Chris

Also, please note that I'll end up needing 18 of these receivers, so no more than $5 each would be perfect. Around or below $3 is best. If anyone knows of a good receiver that has a medium field of view so it doesn't catch stray signals but does catch ones that hit like right next to it, please, drop a comment.

Thanks!

Use a pin diode as a detector.

The hit area is dictated by the degree of colmination of the emitter.

An understanding of optics is needed, edwards scientific used to have a good primer in their catalogue, they also sell lenses.

The better "toys" with long range use a ir laser with beam expanders, just because ir is invisible does not make it eye safe..

The reciever circuit you can find by googling for ir remote reciever circuits.

Modulation and demod is well within arduino capability.

3 dollars , no problem, reciever is just the diode and an amplifier, send all the signals to arduino for decoding.

Look for arduino ir remote circuits for guidance.

Basically what you are building is an ir remote.

The secret to the aiming accuracy lies in the optics.

I get the optics accuracy part. I don't want to send a signal, I just want to send IR waves from the gun to another sensor. The sensor is constantly being checked by the microcontroller. When the microcontroller gets the value from the sensor that a beam has hit it, it'll transmit another signal (via RF) to another Arduino that controls the entire game saying that the suit #whatever has been hit. Eventually, I might make it so guns send a signal via RF to the Arduino saying "suit #whatever shot" and when a suit is hit it takes the last gun that shot and gives that one a point. Otherwise it'll be just team scoring, which I'm fine with.

All in all...

I don't want to send a signal, I just want to send IR waves from the gun to another sensor. The sensor is constantly being checked by the microcontroller. When the microcontroller gets the value from the sensor that a beam has hit it, it'll transmit another signal (via RF) to another Arduino that controls the entire game...

That will not work.

Thwhole point of modulation is it allows short very bright pulses of light to be emitted.

If you run the led continuously its much lower power, you will be lucky to get a range of a few cm that way

Also the detector will pick up ir from the sun, lights , passing fireflies etc.

I don't plan to run it continuously. If the Arduino checks every 0.25sec, then I'll have the laser on for 0.50sec after the trigger is pulled. There's a 1.5 second cooldown between shooting.

Oops, Infrared LED I mean. Same thing applies for the laser though.