EN ISO 11146-2:2005

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Coordinate system
5 Test principles
   5.1 General
   5.2 Spatial second order moments of the Wigner distribution
   5.3 Second order moments of the Wigner distribution
   5.4 Derived quantities
6 Measurement arrangement and test equipment
   6.1 General
   6.2 Preparation
   6.3 Control of environment
   6.4 Detector system
   6.5 Beam-forming optics and optical attenuators
7 Measurement of the second order moments
   7.1 General
   7.2 Measurement of the second order moments of power density
       distributions
   7.3 Measurement of all second order moments of the Wigner
       distribution
8 Determination of effective beam propagation ratio
9 Determination of intrinsic astigmatism
10 Determination of the twist parameter
11 Test report
Bibliography

ISO 11146-2:2005 specifies methods for measuring beam widths (diameter), divergence angles and beam propagation ratios of laser beams. ISO 11146-2:2005 is applicable to general astigmatic beams or unknown types of beams. For stigmatic and simple astigmatic beams, ISO 11146-1 is applicable.Within ISO 11146-2:2005, the description of laser beams is accomplished by means of the second order moments of the Wigner distribution rather than physical quantities such as beam widths and divergence angles. However these physical quantities are closely related to the second order moments of the Wigner distribution. In ISO/TR 11146-3, formulae are given to calculate all relevant physical quantities from the measured second order moments.