Version 11 (modified by emca, 12 years ago) (diff)

--

Leica ALS50-II LIDAR

The ARSF LiDAR system, for data collected in 2009 onwards, is a Leica ALS50-II. This includes a full waveform upgrade for 2010 onwards.

The ALS50-II operates with a 8W class 4 laser with radiation at 1064 nm. It works by firing a pulse every 4ns or 9ns and measuring the round trip time to when a reflection is detected. This is then converted into a distance. There are 2 banks of timing cards - each one with 4 cards. This means that it can measure up to 4 independent returns for each pulse (it only uses the 2nd bank of cards when operated at the higher pulse rate). A minimum time separation between two returns means the minimum distance between two returns must be at least 2.7m for them to be counted as independent.

Specification summary

A lot of the system specs can be (and are) changed to tailor for individual flight purposes. If you need to know certain parameters that have been used for a specific flight that are not included in the delivery documents then please contact us. The listed parameters here are min/max values - not necessarily used for a specific collection.

Wavelength (nm) 1064
Beam divergence (mr) 0.22
Max FOV (degrees) 75
Laser power 0-8W (controlled by operator)
Max rate of acquiring waveform 120KHz

Raw data format

In the form of binary "SCN" files, which contains the raw data using compression and bit-masking. Can be viewed using the Leica SCNviewer graphical interface that comes with the Leica processing software. The files contain data records of ~32 bytes for each point.

Full waveform has the additional files that contain the digitised waveform (.LWV extension). These are binary and you get separate files per range bank with A or B postfix.

Further Information

For more in-depth and technical information about the sensor and processing please see the following pages. Note that these are written primarily for internal use and so may be technical in nature.

Discrete subsystem

Full waveform subsystem