ON THE CALIBRATION OF THE DISTANCE MEASURING COMPONENT 
OF A TERRESTRIAL LASER SCANNER 
P. Salo a ’ *, O. Jokinen a , A. Kukko b 
a Department of Surveying, Helsinki University of Technology, P.O. Box 1200, 02015 TKK, Finland - 
Panu.Salo@TKK.fi 
b Department of Remote Sensing and Photogrammetry, Finnish Geodetic Institute, P.O. Box 15, 02431 Masala, Finland 
Commission V, WG V/3 
KEYWORDS: Component calibration, Terrestrial laser scanner, Robot tacheometer, Error function, Fourier analysis 
ABSTRACT: 
This paper deals with component calibration of a terrestrial laser scanner Faro LS880 HE80. The calibration is based on relative 
distance measurements and is focused on the distance measuring component of the scanner. The measurement range of 1-30 meters 
was divided into two parts according to the used sampling interval, and observations were compared to the results obtained with a 
robot tacheometer. The differences were analyzed by using Fourier transform techniques. The wavelengths, which yielded large 
amplitudes in the frequency space, were observed. The Fourier series yielded an error function for the relative distances measured 
with the laser scanner. The results indicated that the relative distance measurements were biased by both constant and periodic non 
linear error, which we were able to correct using Fourier analysis. We also observed that the wavelengths of detected periodic errors 
often correlated with the wavelengths of the modulation frequencies of the instrument, or their harmonics. 
1. INTRODUCTION 
Laser scanning is a relatively new technology used in 3D 
mapping but is already widely used in different industry 
purposes. The technology offers products within a variety of 
different distance and accuracy ranges. New more developed 
scanners and softwares are released to the market one after an 
other. Users have most likely been interested in the accuracy of 
their scanner since the very first equipment and times of 
scanning. Total system calibration of a laser scanner is a quite 
challenging task, however. Lots of research has been done 
around the world to investigate the accuracy of different 
systems. Lichti and Licht (2006) and Lichti and Franke earlier 
(2005) have investigated the systematic error modeling of a 
terrestrial laser scanner. We have achieved the calibration of the 
distance measuring component of the terrestrial scanner in a 
relative measuring concept. An appropriate calibration setup 
was designed and implemented in the calibration baseline of the 
Institute of Geodesy of the Helsinki University of Technology 
on May 14, 2007. Tested terrestrial laser scanner was Faro 
LS880 HE80 and the reference equipment was tacheometer 
Leica TCA2003. 
2. INSTRUMENTS 
2.1 Terrestrial laser scanner 
The tested terrestrial laser scanner was Faro LS 880 HE80 
(S.No LLS 000500072) seen in Figure 1(a). The Faro LS 
scanner operates by emitting an infrared beam into the center of 
a rotating mirror. This deflects the laser beam on a vertical 
rotation around the environment being scanned. The beam is 
then reflected from the object surface back into the scanner, and 
the phase shift of the incoming light wave in relation to the 
emitted one is measured, thus giving the distance of the scanner 
from the object. Instead of a single pulse being reflected and the 
time of flight being measured, amplitude-modulated constant 
waves of multiple wavelengths are projected. The FARO LS 
splits the laser beam into three component parts operating on 
three different modulation wavelengths shown in Table 1 (Faro 
2005). 
Figure 1. (a) Tested scanner Faro LS 880HE80, (b) reference 
equipment tacheometer Leica TCA2003. 
Mm »im Dm Km 
Figure 2. Modulation wavelengths of the Faro LS (Faro 2005). 
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