Patent ID: 7456371

Claim:
A laser apparatus, comprising: a laser source for emitting a laser light; a transmission-variable mirror for dividing the laser light into a first laser light and a second laser light; a homogenizer located between the laser source and the transmission-variable mirror wherein the homogenizer comprises a first cylindrical array lens, a second cylindrical array lens, a third cylindrical array lens, a fourth cylindrical array lens, a first cylindrical lens and a second cylindrical lens and the third and fourth cylindrical array lenses are located between the first and second cylindrical array lenses and the first and second cylindrical lenses; an optical system for guiding the first laser light and the second laser light onto a top surface and a back surface of an object to be treated, respectively; and a stage for holding a substrate provided with the object to be treated; wherein the transmission-variable mirror includes at least first and second regions, the first region having a first constant transmittance and the second region having a second constant transmittance which is different from the first constant transmittance, wherein the first region is adjacent to and in contact with the second region, and wherein the object to be treated comprises a semiconductor film.