An apparatus for improving the surface quality of a rotary machine part in which a high density beam such as laser beam or electron beam is condensed with collimation to a parallelepiped spatial intensity distribution, the intensity being controllable. The beam is directed to a predetermined surface area of the rotary machine part rotating at a constant angular velocity. A solidified layer formed by rapid solidification of a surface portion of the rotary machine part, which is melted by irradiation by the condensed beam, and a transformation-hardened layer formed below the solidified layer are uniform in thickness, and the transformation-hardened layer is uniformly formed throughout the periphery of the rotary machine part, and thus no cracking and/or pitting occurs.

This invention relates to industrial physics and, in particular, to methods of laser treatment. The laser treatment method consists of irradiation of the surface of an object by laser beams directed to treatment zones having a desired shape, wherein laser beams are subjected to spatial phase modulation dictated by the shape of the treatment zone and the prescribed distribution of intensity and are, simultaneously, rotated. A device realizing this method comprises a source of laser radiation with an optical system for delivery of laser radiation to the object, which is positioned on the optical axis of the source and includes at least one phase computer-designed element made as a reflecting or transmitting plate with a micropattern on the surface thereof, which is dependent on the shape of the treatment zone, distribution of laser radiaiton intensity, and its wavelength (.lambda.), the height (h) of the peaks of the micropattern varying, from the base (a) to the top (b), from 0 to .lambda./2 for the reflecting plate and from 0 to .lambda./(n-1) for the transmitting plate, where n is the refractive index of the transmitting plate.

An illumination apparatus, usable for example as a slit lamp, comprises a light-emitter (2) and an optical element (12) having a free-form surface (13), and optionally a slit aperture (9) and an imaging optic (10). The concept of the present invention is that the free-form surface (13) is employed to generate a resultant illumination beam having a slit-shaped cross-section.

A reflection type optical device comprises a convex integration mirror and a concave mirror. The convex integration mirror prepared by arranging side by side a plurality of plane segment mirrors, each preferably having a rectangular or square shape, on a material having convex outer surface so that a laser beam is divided and reflected by the integration mirror as reflected laser beams which are then condensed on a plurality of focal points lying on one plane, preferably at which a metal plate having a plurality of pin-holes substantially corresponding to the numbers of the focal points is located on the plane so that the focal points coincide with locations of the pin-holes, respectively.

A laser annealing method for a semiconductor thin film for irradiating the semiconductor thin film with a laser beam having a section whose outline includes a straight-line portion, so as to change the crystallinity of the semiconductor thin film is provided, wherein the semiconductor thin film is overlap-irradiated with the laser beam while the laser beam is shifted in a direction different from a direction along the straight-line portion. A thin film semiconductor device fabricated by use of the laser annealing method is also provided.