title: Representing the behavior of partially coherent optical systems by using overcomplete basis sets.
abstract: A technique is described for representing the behavior of partially coherent optical systems by using overcomplete basis sets. The scheme is closely related to Gabor function theory. Through singular-value decomposition it is shown that if E is a matrix containing the sampled basis functions, then all of the information needed for optical calculations is contained in S = EE(dagger) and R = E(dagger)E. For overcomplete sets, S can be inverted to give a dual basis set, E = S(-1)E, which can be used to find the correlation matrix elements A of a sampled bimodal expansion of the spatial coherence function. Overcomplete correlation matrices can be scattered easily at optical components. They can be used to determine (i) the natural modes of a field; (ii) the total power in a field, Pt = Tr[RA]; (iii) the power coupled between two fields, A and B, that are in different states of coherence, Pc = Tr[RARB]; and (iv) the entropy of a field, Q = Tr[Zsigmar(I-Z)r/r], where Z = RA/Tr[RA].
authors.affiliation: Astrophysics Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 OHE, UK. stafford@mrao.cam.ac.uk
authors.forename: Stafford
authors.initials: S
authors.lastname: Withington
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hobson
authors.forename: Rachel H
authors.initials: RH
authors.lastname: Berry