Cumulative Aberrations of Two or More Lenses Suppose I have two lenses, and I can analyze and determine the Zernike aberrations coefficients of both lenses together in a given setup, and also the coefficients of one of the lenses seperately.
Can I, in principle, deduce from that data the aberration coefficients of the second lens?
How do the aberrations add up when combining the lenses?
Thanks!
 A: The wavefront aberrations imparted on a single wave travelling through the lenses simply add, as of course do the Zernike co-efficients (since these are simply the superposition weights the aberration functions when the latter are resolved into a vector basis - the completet set of Zernike functions).
So you can simply subtract the aberrations of one lens from the aberration imparted by the pair *as long as the excitation conditions for the measurement of the single lens on its own are the same as they would be if the lens were in a pair with the other lens the perfect (unaberrating) version of the actual second lens). In other words, the beamwidth and focus position of the lightfield at the input to the isolated tested lens must be the same as it would be if it were working in the pair.
Also, unless you are very, very careful, you can't practically expect to infer the tilt and pure defocus Zernike terms by this method. Switching lenses in and out of your test setup will always introduce a small amount of tilt and defocus.
