ORNL Builds Reticle-Compensating Sight with Laser Barrel Sensor
Scientists at the Oak Ridge National Laboratory (ORNL) have developed a system that uses lasers and fiber optics to measure very small changes (deflections) in a rifle barrel. These deflections are recorded with laser sensors, and then algorithms are used to compute the resultant changes in bullet trajectory. Using computer-calculated trajectories, the digital sighting system’s “virtual” reticle automatically adjusts to compensate for barrel deflection, as well as changing environmental conditions. The microprocessor-controlled digital reticle can adjust to 1/1000th of a Minute of Angle (MOA). That makes it far more precise than any conventional riflescope reticle.
ORNL Barrel Sensor with Compensating Reticle
Shown below is a laboratory prototype of Oak Ridge National Laboratory’s Reticle Compensating Rifle Barrel Reference Sensor. This system precisely measures the deflection of the barrel relative to the sight and then electronically makes the necessary corrections. The system was developed by a team led by Oak Ridge National Laboratory’s Slobodan Rajic, shown in the photo.
The Reticle Compensating Rifle Barrel Reference Sensor takes the guesswork out of shooting by shifting the burden of knowing the relative position between the barrel and the weapon sight axes from the shooter to an electronic sensor. The system precisely measures the deflection of the barrel relative to the sight and then electronically realigns the moving reticle, or crosshairs, with the true position of the barrel, or bore axis.
“When a weapon is sighted in, the aim point and bullet point of impact coincide,” Rajic said. “However, in the field, anything that comes into contact with the barrel can cause perturbation of the barrel and induce errors.”
With modern high-caliber rifles boasting ranges of up to two miles, even very small barrel disruptions can cause a shooter to miss by a wide margin. That makes this technology indispensable from a marksman’s perspective, Rajic said.
From a technological standpoint, the approach is straightforward. ORNL starts with fluted barrels (the flutes play a key role). With the ORNL technology, glass optical fibers are placed into the flutes. The sensor system contains a laser diode that sends a signal beam into the optical fibers parallel to the bore axis of the barrel.
“The optical fibers are designed to split the laser beam twice, sending one beam along the top of the rifle barrel and another light beam along the side of the barrel,” Rajic said. “Thus, we can measure both the vertical and horizontal barrel deflection.”
Through a combination of algorithms, optics and additional sensor inputs, the system can take into account distance and other factors affecting the bullet trajectory. Ultimately, the whole optical/laser/digital system provides the shooter with crosshairs that automatically adjust for conditions in real time.
A Compensating Reticle with 1/1000 MOA Precision
Skeptics of electronic sighting systems have complained that the resolution of a digital rifle-sight is too crude to allow precise aiming. There simply aren’t enough pixels on a viewscreen to allow ultra-precise aiming at long-range targets, shooters have said. In fairness, the existing commercially-available digital rifle sighting systems HAVE been crude — with a lo-rez screens like you might find in a portable GPS.
Well you can forget all that. ORCL has achieved a break-through in digital sighting. The bar has been raised — by an order of magnitude. The resolution of ORNL’s digital, sensor-informed Compensating Reticle is 125 times better than that of traditional target reticles, which can normally be adjusted by one-eighth Minute of Angle (MOA) (at best). Now get this — the ORNL sensor can sense angular displacement and shift the reticle by 1/1,000th of a minute of angle. While this system is expensive, and designed (at this point) for the military, this technology could eventually benefit sport shooters. A decade from now, we would not be surprised if long-range civilian shooters commonly use electronically-enhanced optics, with digital reticles that automatically compensate for bullet drop (and maybe even windage).
ORNL scientists are also working on technology that could yield much more precise and accurate plots of bullet trajectories. We will no longer have to rely on “guesstimated” data inputs, and certain assumptions about bullet drag factors. Rajic and colleagues are developing a laser-based, bullet tracking system that would record plot the bullet’s actual flight path while the bullet is in the air. In other words, this tracking system would be able to plot the bullet’s true trajectory from muzzle to target. That is much differerent than current ballistic “solvers” which merely draw a predicted arc based on muzzle velocity, wind and temp inputs, and a reference BC value.
Oak Ridge National Laboratory is a multi-program science and technology laboratory managed for the U.S. Department of Energy by UT-Battelle, LLC. Over 3000 scientists and engineers at ORNL conduct basic and applied research and development to create scientific knowledge and new technology in key areas of science, energy, the environment, and national security.
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Tags: ballistics, Barrel, Compensating Reticle, Digital Sight, Fluted Barrel, Laser, Oak Ridge, ORNL
What is the point?
Are they assuming the shooter can re-aim for the new crosshair zero while the bullet is moving down the barrel?
Fat chance.
can’t see how this works. The effect of barrel vibrations cannot be corrected by an aiming device. You will be chasing the bullet hole since the vibrations are random. The only useful technology out this effort is the high resolution digital scope reticle.
STEVE: I agree 100% that the exciting technology for sport shooters is the high-resolution digital sighting system — something we’ve been waiting for. As for real-time compensation for barrel deflections, the jury is out. Maybe ORCL knows something we don’t about cyclical barrel modulations over the course of a firing string. Hopefully ORNL will do a demo with a real rifle that can show some real world benefits.
Big Guns
I suspect that this system was originally developed to aid long-range accuracy with big guns: Naval canons, artillery, and tank main guns. These long tubes obviously shake, flex, and droop as they are cycled. The ORNL system could help correct for trajectory variances caused by barrel “perturbations” that may be much more dramatic than what is seen on a rifle barrel. That’s my guess. I know the Abrahms has a sighting system that allows the tankers to shoot “on the move”. I suspect the ORNL system would add additional refinement to the military’s ability to accurize its big guns — particularly on a moving ship, moving tank, rolling vehicle, or even a howitzer-equipped flying gunship.
I agree with John and Steve. All this high tech is very interesting, however, how is this going influence the behaviour of dumb bullets in external ballistics with a human trigger puller?
This is just miniaturisation tanks have had this kind of equipment for at least a decade. You have and mirror on the end of the barrel and a laser on top of the barrel and laser light reflets ont to a an optic with a grid patern where . Look at small arms colimator that is basicaly how it works and determines deflection after that its just question of software that works out a firng solution ,as the barrel heats up it deflects a small amount if any tensions are present in material it can bend in random direction not just down POI shifts differently in every barrel if you are able to measure it prior the shoot and correct the reticle then when shooting you avoid any POI shift altogether ,same in regards to evironmental conditions you have slightly diffenrent POI in winter subzero than in sommer heat ,very advanced big guns also measure muzzle velocity in real time to adjust for changes in ammo.
like anything in that comes out of Oak Ridge is practical
I think we’ve only scratched the surface of where the government really is so far ahead of what the public knows.
As previously mentioned this is just a miniaturised Muzzle Referencing System (MRS), as used for years with tank guns. The high accuracy needed for tanks guns firing with APDS and later APDSFS rounds necessitated the use of such systems.
The MRS measures any change in the muzzle’s point of aim from the initial recorded reference before the next round is fired, not during firing. The changes could be be due to uneven heating of the barrel (no thermal jacket), droop (gravity and heat related), barrel stresses (heating and prior round fired, aka barrel memory), etc, etc.
When using MRS, laser range finders, a gyro-stabilised gun, met station, various other sensors and a ballistic computer, modern tankguns can achieve accuracy in the order of 0.3 by 0.3 meters at 2,000 meters (about 0.5 MOA).
I have also seen them mounted on some artillery pieces, mainly self-propelled Western systems.
For more info, just do a search for muzzle referencing system.