Optical system for forming a laser beam and laser system with such an optical system

The system (2) has an optical element e.g. diffractive optical element, sectionally formed as a base body (7). A lateral surface (15) is formed in sections as a reflecting surface for a laser beam (6). The base body has a section (9) with a base surface (17) arranged in a base surface (10) of the base body. A top surface (18) is formed in sections as a transmitting surface for the laser beam. Another lateral surface (19) is adjacent to the base and top surfaces and formed in sections as another reflecting surface for an annular laser beam (22).