1) How can laser be used for windage measurements?
2) What kind of invisible-to-naked eye, non-IR laser would continue to be effective over ranges longer than a mile (1.6kms)?
http://blogs.discovermagazine.com/80bea ... MQEu5_hXqA“Don’t shoot until you see the whites of their eyes,” American revolutionaries supposedly yelled at the Battle of Bunker Hill. Legend has it that the rebels were trying to conserve ammunition, given the inaccuracy of their 18th century guns.
But things have come a long way since 1775. With DARPA‘s new “One Shot” sniper system, scheduled to be in soldier’s hands by the fall of 2011, the U.S. military will give snipers the ability to take out an enemy at a distance of .7 miles in winds around 10 to 20 miles per hour. Military brass hopes the system will give snipers a perfect shot at least six times out of ten.
The One Shot system still wouldn’t come close to matching the record for shooting accuracy: In November of last year, British Army sniper Corporal Craig Harrison made two shots at a distance of 1.53 miles in Helmand Province, Afghanistan. But Harrison modestly thanked perfect shooting conditions: no wind, great visibility, and mild weather. The DARPA program aims to give soldiers the technology to hit a target despite adverse conditions.
To meet that goal, engineers first had to figure out what to do about wind. The prototype gun can’t get rid of the wind, but it needs to correct for it. Otherwise, over long distances, the bullets will veer off course; DARPA notes that a 10 mph crosswind can produce a miss even at a distance of a quarter of a mile.
The One Shot sniper scope has a computer system that uses lasers to track not only distance, but also the wind turbulence in the path of the bullet. A set of crosshairs appears not in direct line with the gun’s barrel, but instead where the bullet will actually hit, and also displays the confidence of that shot.
US military trials have found that a laser beam shone on the target can do more than just determine the range: it can also be used to “measure the average down range crosswind profile”. The laser information can be combined with automatic readings of temperature, humidity etc and a “ballistic solution” computed.
But there’s more work to be done on the One Shot system before it arrives in combat zones. These high-tech systems can’t require a lot of training or give off a lot of heat.
What the agency really wants is a battle-ready system that doesn’t require tricky in-field optical alignment and fiddling with lasers. Night and day accuracy also means that the laser, which is used to help calculate and subtract wind turbulence between the predator and his prey, can’t be infrared. Enemies with night-vision goggles would see that from a mile away.
DARPA has just finished its first phases of the project, developing and testing the computer targeting system. Among other things, the next steps include making the system the right size and weight for battle, and completing some tweaks to the target crosshairs. With these improvements, according to a DARPA announcement this month, the Agency will ask for 15 “fully operational and field hardened systems” for field testing.
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Got it! THIS is how it might be done - another post on a similar system already in place by the Israelis...
http://www.accurateshooter.com/optics/n ... aserscope/Imagine a “smart scope” that can range your target AND calculate windage correction. Such technology may appear in riflescopes fairly soon. The Israeli Government’s Soreq Nuclear Research Center has received a U.S. patent for a new laser-based technology that can gauge wind vectors as well as target distance, using a laser rangefinder coupled to a rifle-scope. The Israeli system is called LIDAR, an acronym for Laser Identification Detection And Ranging. This new technology could, potentially, be a major boon for long-range shooters, both military and civilian. Ironically LIDAR was first developed for environmental monitoring (not for use with weapons). A LIDAR system was used for 3-D mapping and modeling of wind-driven plumes from the Israel Electric Company’s Rabin power plant.
The new Israeli LIDAR unit gauges wind speed by detecting fluctations in laser signals sent out from the integrated scope/LRF, reflected back from the target, and then received by photodiodes in the scope/LRF. Other scopes have used built-in LRFs to measure distance-to-target, but Israel’s patented LIDAR goes one step further, using the laser to gauge BOTH target distance AND wind vectors (i.e. velocity + direction). This information is entered automatically into software. The software then calculates a ballistic solution compensating for distance, wind angle, and wind velocity. If it really works, LIDAR represents a remarkable technological achievement. The Israelis claim LIDAR works for targets at distances of 500m or greater. Why won’t it work at closer ranges? Presumably the wind-induced laser fluctuations are too small to register at closer distances.
Current Integrated LaserScopes for Hunters
While the Israeli LIDAR system may seem like science fiction, it’s not that far removed from the lastest commercial optics. Engineers on both sides of the Atlantic have already integrated laser rangefinders (LRFs) into rifle-mounted “consumer” optics. Just this year, Burris introduced an affordable “consumer” scope, the Eliminator, that ranges the distance to target and then displays the ballistically correct aiming point on the vertical crosshair. The amount of hold-over is automatically calculated with reference to ballistics formulas. At right is a view through the Burris Eliminator; the illuminated dot shows the calculated aiming point.
While such technology can help a shooter compensate for bullet drop, windage compensation is another matter. A shooter must still gauge crosswind angle and velocity, and then hold left or right accordingly. If the LIDAR system can perform this task reliably, that is a major advancement.
Meanwhile, in the United States, the Defense Advanced Research Projects Agency (DARPA) is proceeding forward with a One-Shot Sniper System, another “Super-Scope” that will have day/night capability, and calculate both elevation AND windage correction automatically. Prototypes have already been tested, demonstrating that a laser beam can be used to “measure the average down-range crosswind profile”. The wind data is combined with readings of temperature, humidity, and target range to provide a very sophisticated ballistic solution.
DARPA’s Spec for the One Shot program calls for a 12-42X Direct View Optic (DVO), a Riflescope Display Assembly (RDA), and an Integrated Spotting Scope (ISS) with rangefinder that ranges to 2 km, and provides “crosswind measurements”. The system will be “menu-selectable” for .308 Win, .338 Lapua, and .300 Win Mag. DARPA has budgeted big bucks for the One Shot system. The ISS, by itself, is expected to cost $85,000 per unit (for the first 15 units).
These systems will never replace the utility of an experienced shooter who possesses the skills of wind reading, but it is a real boon for less experienced shooters. In terms of military utility, it is a game changer. I’ve seen and used a prototype of the One Shot, and it does perform as advertised. — SFC Emil Praslick III, USAMU Coach
Can Wind-Reading Systems Work in the Real World?
From what we can tell, the LIDAR system, and America’s competing One Shot System, are both designed to measure crosswind speed and angle AT THE TARGET primarily. But as any experienced long-range shooter knows, wind is rarely constant along the entire path of the bullet. There can be a 10 mph left wind near the firing point, a 5 mph tailwind in mid-trajectory, and a 20 mph right wind 1000 yards away. Importantly, wind close to the shooter has more effect on the bullet’s path than wind far downrange — that’s a matter of simple geometry. Therefore, any wind-reading system could provide incorrect solutions if it is not able to read and calculate different wind vectors along the full bullet flight path. Presumably LIDAR and One Shot systems will attempt some kind of crosswind averaging, but that will be a very challenging task, without multiple wind sensors downrange.