Using a fresnel lens to disperse laser light (and some other laser questions)

I'm not great at Googling stuff, and looking at a wall of words written by a man in California three years ago just isn't the same as talking to people.

I think what I'm going to do is grab a bunch of TSOP38238 modules or something similar and mount like forty of them to a custom PCB at a distance of half an inch away from each other. They will all share an output, power, and ground pin. I will then put some frosted acrylic or glass in front of them at a distance of 2cm or so to diffuse the laser light just a bit, so that the diffused beam will hit one or more of the receivers. Mirrors will be mounted inside this frosted acrylic/glass box so that even if the laser comes in at a massive angle, it will diffuse, reflect off the mirror, and make contact with an IR receiver.

The problem is that the laser might hit two IR modules at once. What happens then? Will it read twice? I'll have to do some testing.

There you go.

You'll also have to learn to read. And by that, I mean: learn to distill the useful information from the wall of words from the Californian guy, and learn to use systems to locate relevant information.

The willingness of other people to help you out is only going to take you so far. At some point you'll have to put in (the majority of the) effort.

Found a laser diode. Looks like it'll need a voltage regulator before I connect it to an IR transmitter breakout because it runs at 3V.

You need to learn. It's not impossible, Google is really simple to use. Your example is quite dismissive and contrived. If you really want to progress in your hobby you need to get over your own preconceptions and supposed limitations. You will never be able to get the information you need to even begin on your projects if you have to depend on random people in forums. It may sound harsh, but it's the truth. All of the people who are giving you advice have advice to give, not because they listened to people (although they certainly did), but because they learned to research and build actual working things.

Acting helpless will bring more hostility to you, not just here but on almost any technical forum.

Sorry. I just assume everyone has the same attitude towards helping people as I do, which is a really dumb assumption.

Also I can't find many sources. Ever. I think I'm going to start documenting my projects so others can refer to it later.

That said, you guys have been infinitely helpful. I have an idea of what to do now, so thanks so much.

Don't forget to come back with updates on what you've done. People would like to see some results of the "seeds they planted".

Of course.

By the way, I was dubious about putting the IR receiver outputs in parallel. But I checked the data sheet and each one has an internal 30k pull up resistor. That means you can parallel the outputs, within limits on how many units. If the parallel resistance gets too low, an individual receiver output can't pull it down far enough to make it a logic LOW. IDK about 40 of them, but you can definitely multiple them.

40 does seem like a lot. I'll look into ways of using less.

So I tested this in TinkerCAD circuits and it didn't actually read twice. But who knows how accurate TinkerCAD is.

Time to gather all the info again.

Criteria, constraints, and concepts:

  • An 850nm 1mw laser diode will fire a beam controlled by the IRremote library.
  • The receiver will catch the laser, diffuse the beam slightly, and receive the signal using an array of IR receivers.
  • Players will wear these laser glasses while playing, which will be modified with a strap.
  • The gun and receivers will not be connected in any way.
  • Everything will be battery powered.
  • The system will be lit using green LED lights to signify the sensors players need to aim for, and to prevent accidental shots at the face.
  • The receivers will beep and flash red when a player takes damage.
  • There will be multiple receivers. Two 4x4 inch pads on the chest and back, one 2x2 pad on each shoulder, and a 2x2 pad on the blaster.
  • Shooting the receiver on the blaster disables it for a few seconds and causes the blaster to beep twice and flash red.
  • The blasters will beep when they fire and flash a green light as an indication.
  • You will not have to "reload" the blaster in any way.
  • There will be different types of blasters which send different signals and do different amounts of damage.
  • The laser beam will not be collimated unless the blaster is intended for long-range use.
  • The blasters will have physical or optical sights.
  • There will not be a "team" system.

Player rules:

  • A player begins with 100 health. When all of that health is taken away, the receivers will cease to function and the LEDs on the player's vest will turn blue.
  • Taking off your laser glasses is not allowed for the player's own safety.
  • Players are not allowed to tamper with or reprogram the blasters for an unfair advantage.
  • Players will not cover their own receivers to block the laser at any time.
  • If there is a malfunction or short circuit, players must stop the game immediately and resolve the issue.
  • Players cannot continue shooting after they are eliminated. They must turn off their blaster and spectate.
  • Players can only use one weapon at a time.

Not sure how a target is supposed to prevent accidental shots at not-the-target.

At best it looks like you mean “somewhat reduce the probability of a face shot after everyone is ‘splained and advised not to shoot at faces”.


The game is intended to be played in a dark environment. That's why I need lights.

So same cabbage chewed some more


People will be wearing laser glasses, the laser is only 1mw, and the pulses from the IRremote library are very short.

I think even if there is an accidental direct hit to the eye, it shouldn't damage the retina or even get through the glasses. I'll have to test by putting an IR receiver behind a pair of laser glasses and testing if the laser can give an output.

Huh? What makes you think glasses are going to block 800-900nm wavelengths? What kind of glasses?

You forgot a constraint: lack of fundamental knowledge in the relevant areas of physics. I think at this point your best bet would be to team up with someone(s) who has the knowledge to make this kind of thing happen. For me, it's clear by now that you're not going to do this in any foreseeable timeframe.

Laser glasses rated for 800-1000nm or so.

This is probably going to be my next major project. After I finish asking the forum questions, I'll venture off to the internet to gather information and learn about optics.


all photodiodes in parallel


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