Abstract: A processing device forms, in an object to be processed, a modified spot constituting a modified region. The processing device includes a first irradiation unit configured to irradiate the object with first light to temporarily increase absorptivity in a partial region of the object as compared with the absorptivity before irradiation of the first light, and a second irradiation unit configured to irradiate the partial region with second light in an absorptivity increase period in which the absorptivity of the partial region is temporarily increased.

Abstract: A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

Abstract: A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

Abstract: A plurality of modified parts are formed at a first formation pitch for a line arranged along the M-plane of a single-crystal sapphire substrate to construct a modified region and cause a fracture occurring from the modified region to reach a principal surface of the single-crystal sapphire substrate. A plurality of modified parts are formed at a second formation pitch narrower than the first formation pitch for a line arranged along the A-plane of the single-crystal sapphire substrate to construct a modified region and cause a fracture occurring from the modified region to reach the principal surface of the single-crystal sapphire substrate. Along the lines, a knife edge is pressed against a wafer from the side of the single-crystal sapphire substrate opposite from the principal surface of the single-crystal sapphire substrate where the fractures have reached, to cut the wafer along the lines.

Abstract: A plurality of modified parts are formed at a first formation pitch for a line arranged along the M-plane of a single-crystal sapphire substrate to construct a modified region and cause a fracture occurring from the modified region to reach a principal surface of the single-crystal sapphire substrate. A plurality of modified parts are formed at a second formation pitch narrower than the first formation pitch for a line arranged along the A-plane of the single-crystal sapphire substrate to construct a modified region and cause a fracture occurring from the modified region to reach the principal surface of the single-crystal sapphire substrate. Along the lines, a knife edge is pressed against a wafer from the side of the single-crystal sapphire substrate opposite from the principal surface of the single-crystal sapphire substrate where the fractures have reached, to cut the wafer along the lines.