Physics and Technology to Record Explosive Ordinance
The explosion of military ordnance is a violent and fast moving event. At the point of detonation, fragments are flying off faster than the speed of sound. Personnel cannot be in the same proximity as the ordnance and neither the human eye nor standard cameras can track the motion of the particles and effects from the explosion.
All ordnance is created to have a particular effect when it is detonated. Shape explosives, for example, are made to project the power of the weapon in one particular direction in order to penetrate a wall or a bunker and not harm the friendly troops that are massed to the rear of the explosion. The only way to measure the effectiveness of the munitions is to set up a high speed imaging solution using high speed cameras that can capture the effects of speed, velocity, shrapnel effects, and shock wave and freeze them in time. In that manner, the direction and dispersal patterns from the ordnance are evaluated.
In the case of military ordnance, the requirements of the high speed imaging setup and associated speed cameras requires equipment that can achieve up 7500 frames per second (fps) at a full 1280 by 800 resolution. As the need for the higher resolutions can be reduced, and frame rates of 1,400,000 fps are achievable which increases the number of images significantly for analysis. The shrapnel tracking requires the higher frame rates due to the small size and high speed of the particles whereas the blast wave can be tracked at a lower resolution rate. It is also necessary to go to CMOS sensors for shrapnel tracking due to the inability to light the test area. CMOS operates well in low light conditions and will pick up the shrapnel fragments without additional lighting. Any attempt to light the area would just result in the damage of those fixtures so the added cost of the CMOS sensors is justified.