Originally Posted By: hunter4funFor a laser I would narrow bandpass +/-2nm. But for LED the spectrum is given which shows from 825 to 1000nm so a 850nm side pass should give you 90% of all usable light and block the red you don't want. Yes you will lose 10% but it's not that bad esp while suppressing the red down to 0.001%
Unless the camera really isn't picking up 940nm and only the red light is what's actually illuminating it then I don't see how this won't work.
Science of the output spectrum from the led and the filter's transmission/suppression easily give the correct result...
Unfortunately, the IR output from an IR LED looks more like a normal curve, with a 95% confidence interval that you will not be able to use it with a band pass filter on it....
Like I mentioned previously, band pass filter works great dimming the output of a monochromatic pure beam IR laser but doesn't work as you are planning with an IR LED.