Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...

12 2. Components of Terrestrial Laser Scanner400 600 800 1000 1200 1400WAVELENGTH, nmFigure 2.5: Eye transmission for electromagnetic waves.aperture and records the highest output power level of the laser beam. Due to the detected power level,lasers are classified. Table 2.1 shows the different laser classes and their characteristics. More informationconcerning laser safety can be found in [Henderson, 1997] and [Young, 1984].Table 2.1: Overview of Laser Safety Classes accordingto IEC 60825-1 and EN 60825-1.ClassDescription1 Eye-safe under all operating conditionsIMSafe for viewing directly with the naked eye, but maybe hazardous to view with the aid ofoptical instruments. In general, the use of magnifying glasses increases the hazard from a widelydivergingbeam, e.g. LEDs and bare laser diodes, and binoculars or telescopes increase the hazardfrom a wide, collimated beam; such as those used in open-beam telecommunications systems.2 These are visible lasers. This class is safe for accidental viewing under all operating conditions.However, it may not be safe for aperson who deliberately stares into the laser beam for longerthan 0.25 s, by overcoming their natural aversion response to the very bright light.2M These are visible lasers. This class is safe for accidental viewing with the naked eye, as long asthe natural aversion response is not overcome as with Class 2, but may be hazardous, even foraccidental viewing, when viewed with the aid of optical instruments, as with class IM.3RRadiation in this class is considered low risk but potentiallyhazardous. The class limit for 3R is5 times the applicable class limit for Class 1 (for invisible radiation) or class 2 (for visible radia¬tion). Hence, continuous wave visible lasers emitting between 1 and 5 mW are normallyVisible class 3R is similar to class IIIA in US regulations.Class 3R.3BRadiation in this class is very likely to be dangerous.For a continuous wave laser the maximumoutput into the eye must not exceed 500 mW. The radiation can be a hazard to the eyeor skin.However, viewing of the diffuse reflection is safe.4 This is the highest class of laser radiation. Radiation in this class is very dangerous, and viewingof the diffuse reflection may be dangerous.materials onto which they are projected.Class 4 laser beams are capable of settingfire toMost of the terrestrial laser scanners fit in class 3, e.g. HDS Leica Geosystems (Switzerland), Trimble (USA),Zoller+Fröhlich GmbH (Germany), FARO Technologies Inc. (USA), I-Site Pty Ltd. (Australia), 3rd Tech Inc.(USA). The laser scanners of Callidus Precision Systems GmbH (Germany), Optech Inc. (Canada) and RieglLaser Measurement Systems GmbH (Austria) are categorized as class 1.eye safety is frequently guaranteed since the operation of laser scanners in the scanningHowever, for all laser scanners,laser beam at a high speed. The laser beam does not hit the eyes long enough to cause damagemode deflects thedue to the