Etendue Invariant and Lagrange Invariant 161 Lagrange Invariant

In general, an optical surface introduces aberrations at the focused image which deteriorate its sharpness. At first, this alteration of image quality is due to primary aberrations (cf. Sect. 1.8) and their analytic calculation require using the Lagrange invariant. Summarizing the results in the previous section, the two forms of the Lagrange invariant H are

In ray tracing analysis some other authors, such as for instance Welford [167] and Wilson [170], define the Lagrange invariant as the opposite sign above quantity.

0 0

Post a comment