OR/15/057 Principles of laser range finding
| Jones, L D. 2015. Ground-based geomatic surveys at the BGS - a manual for basic data collection & processing (2015). British Geological Survey Internal Report, OR/15/057. |
Riegl Terrestrial Laser Measuring Systems are designed for the automatic and manual medium- to-long range capture of digital data for terrain modeling. The LPM scanning system (Figure 1) comprises a laser distance-measuring device mounted on a Pan and Tilt mechanism that rotates 360 degrees around the mounting axis and scans 150 degrees vertically to provide almost total coverage. The VZ scanning system (Figure 2) is a single-axis device that rotates 360 degrees but is limited to 100 degrees scanning arc.
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Figure 1 LPM-i800HA. -
Figure 2 VZ-1000.
Both scanning systems are pulse range-finding lasers, incorporating a signal processing unit, a transmitter and a receiver (Figure 3). The scanners are easily attached to a standard survey tribrach and tripod for field usage. The scanning systems are linked via a serial (LMP-2K) or ethernet (LPM-i800HA, VZ-1000) cable to a laptop to enable capture of the digital data.
Concept
- ‘Time-of-flight’ method
- Near-infrared wavelength
- Pulsed diode laser transmitter
- Sensitive narrow-band optical receiver
- Single pulse or multiple pulse signal detection
- Microprocessor-based post-processing and interfacing
Advantages
- Small size
- High reliability
- High interference immunity
- High accuracy
- Long range
- Quick data acquisition
- Highly collimated measuring beam
Reduction of the maximum range
- Very bright daylight
- Bad visibility
- Dirty or dusty front lenses