4. The Minkwitz Theorem

The Minkwitz theorem links the lateral astigmatism increase in the direct neighbourhood of an umbilical principal meridian with the power increase along this meridian. The meridian may be situated in a symmetry plane or may be curved, both cases are analyzed. Using a simple model the evolution of the peripheral astigmatism for a non umbilical meridian is discussed.


4. The Minkwitz Theorem
4.1 The proof
4.2 A non umbilical meridian

> 4. The Minkwitz Theorem