Optical element and manufacturing method therefor

摘要

The optical unit has air gap-free adjoining ('physically glued') elements (6, 7). The element (7) of crystalline material has an amorphous inorganic layer (70) on the side adjacent the other element (6). Preferably, the crystalline material is a fluoride and the amorphous layer (70) consists of quartz glass. Also claimed are an optical system including the above optical unit, in which the elements (6, 7) consist of two different materials and a method of preparing an element of crystalline material (preferably a fluoride) for 'physical gluing' by applying an amorphous inorganic layer (preferably of quartz glass) onto the 'gluing' face. Further claimed is a process for producing a thin optical element of crystalline material, especially with a minimum thickness of less than 5 mm or of less than 5% of the diameter. In the process one face of a blank is optically machined to the final shape of the optical element and then coated with an amorphous inorganic layer; and the layer is optionally polished. The coated face is 'physically glued' to a part, especially a lens holder of a polishing machine and the opposite side is optically machined to final shape.