AMSTERDAM, The Netherlands, June 16 -- Physicists at the University of Amsterdam have been able to improve the laser-based port-wine stain removal process by increasing the wavelength of the laser light by a few nanometers, making it redder and better able to penetrate blood vessels. The Dutch scientists developed a model enabling them to mimic the effect of various different types of laser light. They found that laser light at the currently used wavelength of 585 nm could hardly reach the center of the large blood vessels responsible for the distinctive port-wine birthmarks. By increasing the wavelength to 590 nm, the researchers were able to reach the deeper blood vessels and thus better treat the birthmarks without damaging the surrounding skin.