Electronics; Ranging Conditions - Safran LRF 7047 Manual

LRF 7047- Integrator Manual

2.2 Electronics

Safran Vectronix AG range finding technology is based on fiber lasers in combination with a multi-pulse
measurement system. This allows pulses with low energy compared to a single high energy pulse.

2.3 Ranging Conditions

In general two kinds of ranging conditions are described:
Range capability: The possible laser range performance on a beam filling target.

Range performance: The guaranteed range performance on a defined target under defined

conditions.
The range performance depends on visibility, target size and albedo (reflectivity) and is calculated relating
to a certain detection probability e.g. 90%.
Visibility
Visibility is the greatest distance from an observer where a prominent dark object against the sky on the
horizon can be seen and identified by an unaided eye. Good visibility allows the measuring of longer
ranges. Fog, snow, dust, sand, smog and rain reduce the visibility and therefore the range performance of
the LRF module.
Sunlight
Bright backlight or high sunlight reflections on the target can reduce the range performance.
Object Size
A typical target size for range performance comparison is the NATO target with a similar size to the front
of a tank. The size of a NATO target is 2.3x2.3 m. Additionally, the LRF performance is defined on a man
size target with a size of 1x1 m.
 Small targets reflect only a part of the laser beam and therefore only allow lower range performance.
 A large target allows longer ranges because more of the laser light is returned to the LRF module.
Object Albedo
The albedo is the surface's reflectivity of an object, or rather is the ratio of reflected to incident light in the
wavelength of the LRF Module (1550 nm).
 An object with a high albedo reflects more laser radiation and allows longer range performance. High
albedos on very short distances and low albedos on very long distances can either cause the LRF
module to provide an invalid range measurement or to be unable to find a target.
Object Orientation
The angle of the target in relation to the laser beam is also important. Similarly, targets with a very high
albedo can give only a very small reflection towards the LRF module when the reflected laser radiation is
not at 90° and reflected away, e.g. on water or pitched roofs.
 90° is optimal.
Object Hardness
The accuracy of "soft objects" like snow, smoke, clouds etc. depends on the condition of the object itself.
 Hard objects allow a longer range and higher accuracy.
914929_TML_LRF7047_en_Version B
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Figure 5: Example of a 0.5 mrad laser beam size on target
Public: 04.2019
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