LENS CONSISTING OF A CRYSTALLINE MATERIAL

摘要

The invention relates to a method for producing an optical blank (1) consisting of a crystalline material, as a preliminary stage for the production of a lens or a lens element for an objective, especially a projection objective for a microlithography projection exposure installation. According to the inventive method, the orientation of a first crystal direction (3) defined inside the crystalline structure is determined first of all. The optical blank (1) is then worked in such a way that the first crystal direction (3) is essentially perpendicular to an optical raw surface (7) of the optical blank (1). A marking is then applied to the optical blank (1) or to a holding mount of the optical blank (1), said marking being related to a second crystal direction (11) in a defined manner. The second crystal direction forms an angle different from zero with the first crystal direction (3).