I'm trying to find a 940nm SMD infrared led with minimal red glow at night. The TSAL6400 gets close to it, but it's still not completely invisible and not SMD.
I've tried covering them up with an infrared transmitting acrylic sheet but it's completely transparent to the red glow.
My guess it that the radiance on the lower end of the spectrum goes to close to the RED range. Although it's still infrared, the eye is still slightly sensitive to it.
How do I eliminate the red glow visible to the human eye from an IR led?