Abstract

The objective of this work was to develop a technique for converting a high power laser beam with a nonuniform intensity distribution into a rectangular image with a uniform top, trapezoidal intensity profile. Uniformity of the fluence distribution delivered from a laser to a working plane is a requirement in many applications such as metal heat treatment, laser function, laser radar. We describe a specific design, constrained by its application to automated laser paint stripping, but the concept is of general applicability. In our case, paint stripping requires a 10% fluence uniformity on target and an edge roll-off for effective traverse overlap. The high levels of laser power involved require an all-reflective system with no primary or secondary focusing of the beam. The high degree of uniformity involves combining a multimode laser with an optical beam shaper. We present the design concept of the beam shaper and the theoretical image intensity distribution. We also show the experimental verification of the concept using a multimode CO₂ laser beam and discuss the resulting IR images obtained.

© 1985 Optical Society of America