LASER-BEAM SHAPING: Diode-laser system yields 11 kW homogenized output

摘要

Homogenization techniques to produce structured light (uniform lines or two-dimensional illumination in a square array, for example) are becoming more important for applications such as machine vision, liquid-crystal-display technology, the printing industry, and other surface applications like hardening or thermal annealing (see "Laser projections assist machine-vision applications," p. 131). Engineers at Dilas (Mainz-Hechtsheim, Germany, and Tucson, AZ) have developed a diode-laser system with an 11 kW output power at 940 nm--to their knowledge, the highest output power reported for a direct-diode system--that can deliver 1 kW/cm~(2) at a working distance of 400 mm with better than 90percent homogeneity in the intensity distribution over a 55 X 20 mm area. There are several known techniques for laser-beam homogenization, including overlapping the beams of several diode lasers (or laser bars) arranged in a line or array, using a waveguide structure to mix the intensity distribution from a single diode input, or by using a micro-optical lens array to create overlapping beamlets from a single diode source that simulates the overlapping effect from multiple sources. However, each of these methods can suffer from nonuniformity among the multiple source lasers and/or micro-optic diffraction effects that limit the output beam homogeneity.