A high, energy, high repetition rate workpiece surface heating apparatus is disclosed which comprise a XeF laser producing a laser output light pulse beam, an optical system narrowing the laser output light pulse beam in the short axis of the laser output light pulse beam and expanding the laser output light pulse beam to form in a long axis of the beam a workpiece covering extent of the long axis, the optical system focuses the laser output light pulse beam at a field stop with a magnification sufficient to maintain an intensity profile that has sufficiently steep sidewalls to allow the field stop to maintain a sufficiently steep beam profile at the workpiece.