Method for producing a rotationally symmetric lens from a ceramic green body and moulding tool for performing the method

A method for producing at least one rotationally symmetrical lens, said lens consisting of an opto-ceramic, comprising the following process step:

• moulding a green body using a moulding tool, wherein at least one surface of said lens is described by the following equation A:
• y
• =
• cx
• 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;
• a1, a2, a3, a4, . . . 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, a1, a2, a3, a4, . . . 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.