US Patent 7285744 Method and apparatus for simultaneously heating materials

A method and apparatus for simultaneously heating materials, in particular for welding plastic components, having an arbitrary shape of a flat heating contour by laser radiation is provided. The apparatus has, an appropriate optical arrangement that is used to convert a laser beam into an annular laser beam and focus it onto the end wall of a light-guiding tube and couple it in. At an exit end, the tube is deformed in accordance with the desired heating contour such that the emerging laser beam has this heating contour.