The most advanced military rangefinders can be integrated with computers. In the latter case the rangefinder module is integrated with on-board thermal, night vision and daytime observation equipment. The more powerful models of rangefinders measure distance up to 25 km and are normally installed either on a tripod or directly on a vehicle or gun platform. 338 Lapua Magnum rifle and VECTOR IV Leica/Vectronix laser rangefinder binoculars All these effects have to be taken into account.Ī Dutch ISAF sniper team displaying their Accuracy International AWSM. Alternatively, over distances longer than 1200 ft (365 m), the target, if in proximity to the earth, may simply vanish into a mirage, caused by temperature gradients in the air in proximity to the heated surface bending the laser light. Some of the laser light might reflect off leaves or branches which are closer than the object, giving an early return and a reading which is too low.
These atmospheric distortions coupled with the divergence of the laser itself and with transverse winds that serve to push the atmospheric heat bubbles laterally may combine to make it difficult to get an accurate reading of the distance of an object, say, beneath some trees or behind bushes, or even over long distances of more than 1 km in open and unobscured desert terrain. One that uses very sharp laser pulses and has a very fast detector can range an object to within a few millimeters.ĭespite the beam being narrow, it will eventually spread over long distances due to the divergence of the laser beam, as well as due to scintillation and beam wander effects, caused by the presence of air bubbles in the air acting as lenses ranging in size from microscopic to roughly half the height of the laser beam's path above the earth. The precision of the instrument is determined by the rise or fall time of the laser pulse and the speed of the receiver. It is possible to use Doppler effect techniques to judge whether the object is moving towards or away from the rangefinder, and if so, how fast. The pulse may be coded to reduce the chance that the rangefinder can be jammed.
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