At 10:28 PM 4/26/04 +0200, Thomas Shaddack wrote:

But when I want a really bright flash on about 800-900 nm, what approach is the best?

A 1 watt IR laser diode used for burning wood. They show up on eBay for ~$100. Might start a fire though :-) Also has pointing issues.

What would be the best approach? The energies here are more in the range of rotation/vibration changes than electrons jumping up and down between the energy states. How to convert a blast of electrical energy into a shower of near-IR photons?

Regular tungsten driven to red but not bright, with a piece of low-pass filtering glass over it. You can't get rapid modulation with tungsten, of course, but a few Hz is possible. Years ago IR leds on baseball caps were posited for defeating certain (eg ATM) cameras. Don't know if they worked.