Electronic – LED Viewing angle

If you choose synchronous detection, then you can simplify solution. Then you may want to choose LEDs as narrow angled as you can withing any part of visible spectrum.

Synchronous detection is the way to detect a signal which may be lower than background noise. Imagine taking shot with camera before LEDs are up. Then turn LEDs on and take another picture with exactly same conditions. Subtract arrays of pixel values of 2 frames from each other and look at the remainder. It will contain perfect difference of what was lit by LEDs. In your setup the DIFF picture will contain exactly retroreflectors (cataphote) only. Because the rest of the scenery got no significant increase in brightness.

While you debug the solution it will be obvious that power of LEDs can be reduced to some very low level, but only experiments will tell. I estimate that you will not need any super-powerful diodes. Some ordinary white LEDs with very acurate lens will do.

You do not specify you LEDs part number so absolute comparisons are not possible, but there will be many IR LEDs that meet your spec.

This link gets you to Digikey's IR LED page and you can then use their filter system to restrict current, radiation angle etc.

The Everlight IR25-21C - datasheet here is the widest angle IR LED that they have in stock but they don't show it as available in 1's - but they will; probably sell it few off for more $.
65 mA max, 160 degree viewing angle, 1.6mm x 3.2mm, 940 nm peak output so not all detectors will work - check camera needs.

A few of these working together should suit your viewing angle needs :-)

Substantially more powerful LEDs are available if required.