Reducing the pulse length from 10ms to 10us means 1/1000 of the light output all other things staying the same. Or with other words: 100W for 10ms is 1J while 100W for 10us is only 1mJ. If you want to get 1J during 10us this translates to 100kW. This is the reason why high speed photography is usually not approached with LEDs.
You might want to consider some focusing lenses to compensate for that. Or consider xenon flashes.