Abstract: This invention relates to an optical system, adapted to be disposed between a source capable of emitting a beam of light and a target. Near the upstream focal point of the first optics for focussing the beam, the beam provides an image which is at least substantially in section, but which, due to characteristics inherent in the beam of light, produces an image which is oblong in shape at the downstream focal point of the first optics for focusing the beam. The optical system successively comprises, in the direction of propagation of the beam, downstream of the first optics, first diaphragm disposed near the focal point of the first focussing optics, capable of removing a variable part of the area of the section of the beam at the focal point, and second focussing optics. The optical system may further include a second diaphragm disposed upstream from the first optics for focusing the beam for further limiting the ellipticity of the beam.

Abstract: A surgical apparatus for partially modifying the curvature of the cornea of an eye while the eye is within the patient is disclosed. The device is able to ablate a zone of corneal material in the form of a lenticular lamina. The thickness of the lamina at any particular point on the cornea surface varies as a function of the radial distance between that point and the central optical axis of the eye. The surgical apparatus comprises: a source of light (31) capable of emitting a beam of light (4) having a wavelength which is about 200 nanometers; an optical system (32) for directing and focusing the beam of light onto the desired zone of the cornea in order to ablate a lamina of material of the desired dimensions; and, a series of diaphragms and screens for obscuring varying portions of the zone of the cornea undergoing ablation in order to effect differential irradiation of the corneal surface.

Abstract: This invention relates to an optical system for determining the curvature or the modification of curvature of an object on a zone of small dimensions, wherein it comprises: a light source; first optics adapted to form a parallel light beam from the beam emitted by said source; a semireflecting element disposed on the path of said parallel beam; second focussing optics receiving the parallel beam reflected by said element and being capable of moving parallel to the direction of propagation of said light beam, so that their image focus merges with the center of curvature or the surface of said object; third focussing optics receiving the beam reflected by the object, and means for detecting the image formed by said system. The invention is more particularly applicable in keratometry.