Fiber-optic laser-based system brings rifle sights into the 21st century
By Darren Quick
April 20, 2011
At long ranges, snipers must compensate not only for crosswinds and the fact that bullets travel in a curved trajectory, but also allow for even very small barrel disruptions that can cause a shooter to miss their intended target by a wide margin. Contending with such difficulties makes feats such as the 1.53 mile (2.47 km) sniper kills by British Corporal Craig Harrison even more impressive, but a new type of rifle sighting system developed at the Oak Ridge National Laboratory (ORNL) could take one of these variables out of the equation. The fiber-optic laser-based sensor system precisely measures the deflection of the barrel relative to the sight and automatically adjusts the crosshairs to match the true position of the barrel.
The ORNL technology places glass optical fibers into the exterior grooves, known as flutes, found on the barrels of modern high-powered rifles. These reduce weight and create added surface area to enable the barrel to cool faster. Such flutes are either produced by the manufacturer or can be retrofit to existing barrels. A laser diode sends a signal beam into the optical fibers which split the beam twice, sending one light beam along the top of the rifle barrel and another along the side. This allows the system to measure both the vertical and horizontal barrel deflection.
Traditional reticles are normally manually adjusted by one-fourth minutes of angle, but through the use of a combination of algorithms, optics and additional sensor inputs, the ORNL's Reticle Compensating Rifle Barrel Reference Sensor can also take into account distance and other factors affecting bullet trajectory to automatically adjust the crosshairs by 1/1,000th of a minute in real time. According to the leader of the development team, Slobodan Rajic, this makes the ONRL system 250 times better than traditional reticles.
But the ONRL team isn't done yet. Rajic and his colleagues are also working on a laser-based bullet tracking system that will provide specific information about the bullet flight path to give shooters even better odds of hitting their target.