High-efficiency line-forming optical systems and methods for defect annealing and dopant activation are disclosed. The system includes a CO2-based line-forming system configured to form at a wafer surface a first line image having between 2000 W and 3000 W of optical power. The line image is scanned over the wafer surface to locally raise the temperature up to a defect anneal temperature. The system can include a visible-wavelength diode-based line-forming system that forms a second line image that can scan with the first line image to locally raise the wafer surface temperature from the defect anneal temperature to a spike anneal temperature. Use of the visible wavelength for the spike annealing reduces adverse pattern effects and improves temperature uniformity and thus annealing uniformity.