| 摘要 |
PURPOSE:To obtain a nonocrystalline thin film adapted to efficiently obtain an intensity distribution of laser beam suitable for forming a monocrystalline thin film by radiating a laser beam through Fresnel double prisms. CONSTITUTION:Fresnel double prisms 21, 22 are arranged so that the faces in which a vertical angle theta is formed are opposed to each other, and so that the faces 21a, 22a opposite the faces in which the vertical angle theta is formed are maintained in parallel with each other. With this structure, a laser beam 23 of Gaussian distribution is divided by the first Fresnel double prism 21 at the center thereof, causing the exiting beam from an exit face 21b to enter an entrance face 22c of the second Fresnel double prism 22, and the exiting beam from an exit face 21c to an entrance face 22b. The laser beams divided by the first Fresnel double prism 21 at the center thereof are combined by the second Fresnel double prism 22 in a manner that they are replaced with respect to the right and left positions, and converted to a laser beam 24 of a distribution which is low at the center and has peaks at both ends thereof. |
