3D laser scanner

A laser rangefinder is a device that measures distance from the device to a target.

Laser radar cross section (LRCS) is a target property. It can be conveniently used to calculate the expected echo signal amplitude when system parameters and the target’s distance are known. The LRCS is the product of three components: the actual area interacting with the laser beam (for targets smaller than the laser footprint), the reflectance of the target, and the directivity of the reflection. The directivity is quite low for diffusely reflecting targets, but very high for retro-reflecting target.

LIDAR sensors emit short laser pulses of pulse widths of a few nanoseconds as collimated laser radiation.

The laser footprint describes the beam diameter at the target's range.

Lasers are classified by wavelength and maximum output power into four classes and a few subclasses. The classifications categorize lasers according to their ability to produce damage in exposed people, from class 1 (no hazard during normal use) to class 4 (severe hazard for eyes and skin).

The dynamic range is a property of the receiver within the laser scanner that gives information about the range of echo signal amplitudes the receiver can work with. Distant targets with a low laser radar cross section will give echo signal amplitudes near the detection threshold. Nearby retro-reflecting targets will give huge echo signal amplitudes. The ratio of the largest echo signal the receiver can handle to the detection threshold is the dynamic range of the receiver.

The beam divergence is an angular measure of the increase in beam diameter with distance from the optical centre from which the laser beam emerges. Angular width is an angle described by the beam at the source.

The diameter of the laser beam perpendicular to the beam axis. Since beams typically do not have sharp edges, the diameter can be defined in many different ways.

The angular resolution is a parameter of the scan mechanism. It corresponds to the minimum possible angular distance between two consecutive laser measurements.

Assuming a locally flat target (approximated by a plane), the angle of incidence is the angle between laser axis and the plane's normal vector.