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Infra red detection

Infra red detection

Infra red detection

I need some help from an optical guru – I have designed a game using a gun. The gun uses an IR diode (SFH4545) no lens, to fire a 600uS burst of 38KHz IR across a field to a retroreflective (corner cube) target. The returning IR is detected by the second barrel of the gun using a lens, focussed on a TSOP34438 ir reciever. I’ve managed to get a reasonable range by increasing the power in the IR diode but the performance is dissappointing.
If the gun and target are 27 paces apart, it works well, any further it doesn’t work at all, any nearer and the gun picks up hits from almost everything (not just the retro reflective tape). I started to think about polorising filters on the TX and RX devices, but the cost of IR polorising filters is horrendous.
I’ve thought about using visible light (650nm), so cheaper poloriser lenses could be used – I would need to choose alternative TX and RX devices to suit, but would it work ?
How can i get variable and accurate range ? anyone ? Many thanks in advance. Steve

RE: Infra red detection

Hi IRstuff, They have but.... They're usually not outdoors, they don't use retroreflective (they use LEDS fired directly at sensors) and don't need a narrow angle (accuracy). I thought about an VCSEL device, but as the signal is coming back to the person firing the gun, that might be a no no.

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