Patent ID: 7511247

Claim:
A method for controlling a shape of an area laser machined by a pulse of laser light on a surface of a workpiece to be a predetermined elliptical shape with a predetermined major axis aligned in a predetermined direction, the predetermined major axis having a predetermined major axis length less than or equal to a diameter of a beam spot of the pulse of laser light, the method comprising the steps of: a) generating the pulse of laser light; b) focusing the pulse of laser light to the beam spot within a target area of the microstructure workpiece such that the pulse of laser light has a substantially circularly symmetric beam intensity profile at the beam spot; c) adjusting a polarization of the pulse of laser light such that in the beam spot the pulse of laser light is elliptically polarized and an axis of a polarization ellipse of the pulse of laser light is oriented in the predetermined direction, the polarization ellipse having a major axis different from a minor axis, while maintaining the substantially circularly symmetric beam intensity profile of the pulse of laser light at the beam spot; d) adjusting an ellipticity of the polarization of the pulse of laser light such that the pulse of laser light has contours of constant machining capacity on the surface of the microstructure workpiece, the constant machining capacity contours having a substantially similar shape to the predetermined elliptical shape, while maintaining the substantially circularly symmetric beam intensity profile of the pulse of laser light at the beam spot; and e) controlling fluence of the focused pulse of laser light in the beam spot such that the area of the surface of the workpiece laser machined by the pulse of laser light is substantially the predetermined elliptical shape.