SINGLE CRYSTAL DIAMOND ELEMENTS HAVING CONVEX SURFACES AND METHODS OF ITS FABRICATION

A single crystal diamond element having a convex surface is disclosed, the convex surface including a spherical segment for which the maximum peak to valley deviation from a perfect spherical surface is less than about 5 mum. Alternatively or in addition, the RMS deviation from a perfect spherical surface may be less than about 500 nm, or the RMS roughness less than about 30 nm. A single crystal diamond element with a radius of curvature less than about 20 mm is also disclosed. In one aspect a single crystal diamond element having a conical half-angle greater than about 10° is described. The invention also provides a method for forming a rotationally symmetrical surface on a single crystal diamond element, comprising rotating the element about a first axis, applying a laser beam to the element in a direction perpendicular to the first axis, and translating the laser beam in two dimensions in a plane perpendicular to the direction of the beam. If the two-dimensional path follows the arc of a circle a spherical surface may be formed. The invention also provides improving a spherical surface on a single crystal diamond element by pressing a rapidly rotating cup onto a slowly rotating element. The element may be a lens, in particular a solid immersion lens.