NASA ADS: Underwater lidar imaging in highly turbid waters: "Based on a newly-designed serial target, we firstly demonstrate the underwater LIDAR imaging in such a 3m short water tank with highly turbid waters successfully, and show the range-gated phenomenon in water much more clearly. The target-set comprises a series of three bar test targets, which are set at intervals of 22.5cm roughly along the laser illumination direction since the light speed in water is 22.5 cm/ns. We synchronize precisely the UWLI system to range-gate on the targets which we want to capture their images, and to range-gate out the targets which we don't want their images. The attenuation coefficients in waters are 1.0/m and 2.3/m. Compared with non-gated case, the most distinct difference between the gates images and non-gated im ages in turbid water is that the nearer the target is located, the clearer its image is on the non-gated photos, but for the gated case the situation will be inverted completely when the delay time is adjusted suitably; that is, the image of the farther target could be much clearer than the image of the nearer target even in very turbid water."
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Friday, May 25, 2012
Portable Underwater Lidar System Equipment (PULSE)
Portable Underwater Lidar System Equipment (PULSE): "Background
Conventional lidar terrain mapping will not penetrate water by more than a few centimeters. Bathymetric lidar systems use a different and more complex technology to measure seabed topography in shallow waters. Such surveys are typically performed for beach replenishment studies, near-shore surveys, seafloor mapping, nautical chart updates, and coastal zone erosion monitoring. They are used in fields like oceanography, marine biology, oil and gas exploration, and coastal and reef management, as well as by the Coast Guard and the Armed Forces.
Airborne bathymetric lidar surveys use the interaction of different laser wavelengths with the seafloor to perform seabed profiling. But the lasers also interact with particles or sediments in suspension in the water column between the surface and the seabed. These interactions need to be considered when mapping the seabed, failing which errors in topographic elevations and hydrographic depths may occur."
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Conventional lidar terrain mapping will not penetrate water by more than a few centimeters. Bathymetric lidar systems use a different and more complex technology to measure seabed topography in shallow waters. Such surveys are typically performed for beach replenishment studies, near-shore surveys, seafloor mapping, nautical chart updates, and coastal zone erosion monitoring. They are used in fields like oceanography, marine biology, oil and gas exploration, and coastal and reef management, as well as by the Coast Guard and the Armed Forces.
Airborne bathymetric lidar surveys use the interaction of different laser wavelengths with the seafloor to perform seabed profiling. But the lasers also interact with particles or sediments in suspension in the water column between the surface and the seabed. These interactions need to be considered when mapping the seabed, failing which errors in topographic elevations and hydrographic depths may occur."
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LIDAR detector - Wikipedia, the free encyclopedia
LIDAR detector
From Wikipedia, the free encyclopedia
A LIDAR detector or laser detector is a passive device designed to detect the infrared emissions of law enforcement agencies' LIDAR speed detection devices and warn motorists that their speed is being measured.
A limitation of LIDAR is that it cannot be used while a police car is in motion, because it requires the operator to actively target each vehicle, whereas traditional radar can be operated while the police officer is driving his car. Other restrictions include a precipitation free environment, as the laser can produce erratic readings from airborne moisture or smoke.[1] Popularity of LIDAR speed detection is on the rise, though, as costs decline, ease of operation approaches radar, and existing radar equipment reaches its end-of-service life and is rotated out of service.
LIDAR detectors are generally less effective than radar detectors as the emissions they monitor are more brief, more concentrated and less easily scattered than radar; a motorist may therefore not have sufficient time to respond to the burst transmission of a LIDAR device, or the narrow beam might be focused on a specific part of a vehicle where the sensor cannot "see" it.
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LIDAR detector - Wikipedia, the free encyclopedia:
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Wednesday, May 23, 2012
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