Let V be a complex vector space of dimension n, G (resp. G) the Grass
mann manifold of p-dimensional (resp. (n-p)-dimensional) subspaces of
V, and of Omega the relation of transversality in G x G. We announced
in [6] equivalences between derived categories of sheaves and of D-mo
dules on G and G defined by the integral transforms associated to Ome
ga. We show here that these transforms exchange the D-modules associat
ed to the holomorphic lines bundles on G and G. This is equivalent to
''quantizing'' the underlying contact transformation between certain
open dense subsets of the contangent bundles. In the case p = 1, we re
cover already known results for the projective duality (see [1] and [5
]).