Patent ID: 8019461

Claim:
A moulding tool for moulding a ceramic green body in a process for producing at least one rotationally symmetrical lens, said lens consisting of an opto-ceramic, wherein at least one surface of said lens is described by the following equation A: y = c ⁢ ⁢ x 2 1 + 1 - ( k + 1 ) ⁢ c 2 ⁢ x 2 + a 1 ⁢ x 2 + a 2 ⁢ x 4 + a 3 ⁢ x 6 + a 4 ⁢ x 8 + … , ( A ) wherein x designates a perpendicular distance from an optical axis of said lens; y gives a position on the optical axis; k is a conic constant and has a value of −200 to +200; c=1/R wherein R is a radius of curvature of the at least one surface; a 1 , a 2 , a 3 , a 4 , . . . are each <10 −1 ; wherein the moulding tool comprises a near-net-shape negative mould for shaping the ceramic green body, said near-net-shape negative mould having a shaping surface, which is described by the following equation B: y ⁢ ⁢ 1 = cz 2 1 + 1 - ( k + 1 ) ⁢ c 2 ⁢ z 2 + a 1 ⁢ z 2 + a 2 ⁢ z 4 + a 3 ⁢ z 6 + a 4 ⁢ z 8 + … , ( B ) wherein x, k, c, a 1 , a 2 , a 3 , a 4 , . . . have the same meaning and values as in said formula A; y1 is a location on the optical axis; z=|x|+b; and wherein b is a constant with a value greater than 0 and less than 0.3 mm and is a measure of a deviation of the shaping surface of the near-net-shape negative mould from the at least one surface of said lens to be moulded.