Moment characterization of the position stability of laser beams

Michel Morin; Marc Levesque; Alain Mailloux; Pierre Galarneau

doi:10.1117/12.259899

20 November 1996 Moment characterization of the position stability of laser beams

Michel Morin, Marc Levesque, Alain Mailloux, Pierre Galarneau

Proceedings Volume 2870, Third International Workshop on Laser Beam and Optics Characterization; (1996) https://doi.org/10.1117/12.259899
Event: Third International Workshop on Laser Beam and Optics Characterization, 1996, Quebec City, Canada

Abstract

Laser beam profile measurements always involve integration of the incoming intensity profile over a finite time interval. Under this condition, the measured moments of the spatial profile of a time-varying laser beam are shown to follow the simple algebraic laws of propagation obeyed by the moments of the intensity profile of a purely monochromatic laser field. Transverse shifts of the intensity profile and angular tilts of the axis of propagation of a wandering beam, expressed as fluctuations of the first order moments of the beam, obey similar laws of propagation. The time-variance of first order moments actually propagate the same way as do second order moments. The moment approach thus provides a consistent description of the propagation of a wandering laser beam. Invariants can be defined to quantify the extent of the wandering, taking into account both transverse shifts and angular tilts. It is also possible to define a time-integrated M² factor, obtained by measuring the second order moments of the time- integrated fluence profile of a laser beam. The increase of this factor, as a function of the time of integration, provides a sense of the time scale and amplitude of the beam wandering.

Citation Download Citation

Michel Morin, Marc Levesque, Alain Mailloux, and Pierre Galarneau "Moment characterization of the position stability of laser beams", Proc. SPIE 2870, Third International Workshop on Laser Beam and Optics Characterization, (20 November 1996); https://doi.org/10.1117/12.259899

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