Posted by
Lopes on Friday, January 30, 2009 5:21:49 PM
Discrimination
Some instruments are able to determine multiple returns, as above. These instruments use waveform-resolving detectors, which means they detect the amount of light returned over a certain time, usually very short. The waveform from a laser pulse that hits a tree and then the ground would have two peaks. The first peak would be the distance to the tree, and the second would be the distance to the ground.
The ability for aircraft-mounted instruments to see "through" dense canopies and other semi-reflective surface such as the ocean provide many applications for airborne instruments such as:
Creating "bare earth" topographic maps - removing all trees
Creating vegetation thickness maps
Bathymetry (measuring topography under the ocean)
Forest fire hazar
Overwash threat in barrier islands
Technologies
Time of flight - this measures the time taken for a light pulse to travel to the target and back. With the speed of light known, and an accurate measurement of the time taken, the distance can be calculated. Many pulses are fired sequentially and the average response is most commonly used. This technique requires very accurate sub-nanosecond timing circuitry.
Multiple frequency phase-shift - this measures the phase shift of multiple frequencies on reflection then solves some simultaneous equations to give a final measure.
Interferometry - the most accurate and most useful technique for measuring changes in distance rather than absolute distances.
Applications
Military
An American soldier with the GVS-5 laser rangefinder.
Rangefinders provide an exact distance to targets located beyond the distance of point-blank shooting to snipers and artillery. They can also be used for military reconciliation and engineering.
Handheld military rangefinders operate at ranges of 2 km up to 25 km and are combined with binoculars or monoculars. When the rangefinder is equipped with a compass and inclinometer it is capable of providing magnetic azimuth, inclination, and height(length) of targets. Some rangefinders can also measure a target's speed in relation to the observer. Some rangefinders have cable or wireless interfaces to enable them to transfer their measurement(s) data to other equipment like fire control computers. Some models also offer the possibility to use add-on night vision modules. Handheld rangefinders use standard or non-magnetic batteries.[1]
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. In the latter case rangefinder module is integrated with on-board thermal, night vision and daytime observation equipment. The most advanced military rangefinders can be integrated with computer.
In order to make laser rangefinders and laser-guided weapons less useful against military targets, various military arms may have developed laser-absorbing paint for their vehicles. Regardless, some objects don't reflect laser light very well and using a laser rangefinder on them is difficult.rangefinders rangefinder best wide rangefinder digital camera nikon archer's choice rangefinder laser rangefinder rangefinder forum nikon rangefinder mm rangefinder laser rangefinders bushnell elite with arc rangefinder mossy oak fed rangefinder adjustment bushnell rangefinder bushnell tour v with pinseeker laser rangefinder ultrasonic rangefinder rangefinder magazine rangefinder reviews record iii and rangefinder rangefinder cameras hunting rangefinder golf rangefinder how does a rangefinder work leica rangefinder nikon laser rangefinder nikon rangefinders what is the best golf rangefinder burris rangefinder cheap rangefinders golf rangefinders konica camera repair rangefinder leupold rangefinder nikon archers choice rangefinder ansco viking and rangefinder laser rangefinder review optical rangefinder cameras repair yashica rangefinder yellow repair rangefinder yellow cheap rangefinder rifle scope crossbow sight with rangefinder digital laser rangefinders laser rangefinder receiver counter leica rangefinders rangefinder photography riflescope rangefinder barska optics aa rangefinder best rangefinder hunting best rangefinder hunting elite bosch dlr laser rangefinder bushnell elite rangefinder bushnell elite rangefinder information bushnell tour v laser rangefinders callaway rangefinder consumer report laser rangefinder hunting crossbow rangefinder digital laser rangefinder discount rangefinders golf rangefinder review illuminated rangefinder silver scope laser rangefinder scope reviews leupold rx-ii rangefinder nikon monarch rangefinder oem- rangefinder rangefinder replace yellow color tlr rangefinder used laser rangefinder riflescope zeiss ikon digital rangefinder best golf rangefinder bino rangefinders bruntont echo laser rangefinders bushnell elite with arc rangefinder reviews and ratings bushnell golf laser rangefinder bushnell rangefinders bushnell scout arc laser rangefinder review bushnell? scout a.r.c. laser rangefinder golf gps rangefinder golf rangefinder reviews hamilton rangefinder horn hunter rangefinder case hunting rangefinders laser rangefinder clinometer laser rangefinder riflescope review laser rangefinder scopes leica crf rangefinder leupold digital rx-ii rangefinder nikon prostaff laser rangefinder nikon rangefinder reviews rangefinder magazine editors rangefinder rebates redfield laser rangefinder riflescope laser rangefinder sale world war ii japanese handheld rangefinder yardage pro sport laser rangefinder antelope hunting rangefinder bosch dlrk laser rangefinder bowhunting rangefinder bushnell golf rangefinder bushnell pinseeker rangefinder with slope bushnell rangefinder cart mount bushnell scout arc rangefinder bushnell yardage pro sport laser rangefinder bushnell yardage pro sport rangefinder price