Beam intensity profile modulation for even surface treatment: Finite element modelling and optical design

Abstract

Common laser surface treatment problems arise when using a Gaussian or Top-Hat beam intensity profile to attempt to create an even surface temperature distribution profile (or heat affected zone) in a given material. Annular ring shaped beams have gone some way to achieving a more even temperature distribution and have improved process design in fields such as laser surface hardening and laser welding. The temperature distribution profiles created using various annular ring beam profiles are examined. The effect of varying the Peclet number on the resultant temperature distribution profile is modeled using a finite element modeling package. An investigation of the relationship between process tolerance levels and the optimum Peclet number for even treatment of surfaces is included for a number of different annular beam intensity profiles. Modulation of an annular beam intensity profile is examined in an attempt to achieve an even temperature distribution profile with well defined edges even at high Peclet numbers. Modulation of intensity profile is achieved through an optical design which includes only conventional compound optics.Common laser surface treatment problems arise when using a Gaussian or Top-Hat beam intensity profile to attempt to create an even surface temperature distribution profile (or heat affected zone) in a given material. Annular ring shaped beams have gone some way to achieving a more even temperature distribution and have improved process design in fields such as laser surface hardening and laser welding. The temperature distribution profiles created using various annular ring beam profiles are examined. The effect of varying the Peclet number on the resultant temperature distribution profile is modeled using a finite element modeling package. An investigation of the relationship between process tolerance levels and the optimum Peclet number for even treatment of surfaces is included for a number of different annular beam intensity profiles. Modulation of an annular beam intensity profile is examined in an attempt to achieve an even temperature distribution profile with well defined edges even at high Peclet...