Propagation of the Angular Spectrum in the Up-conversion
  We study theoretical and experimentally the propagation of the angular spectrum of the light produced in the up-conversion process. The connection between the angular spectrum of the fundamental and the second harmonic is derived and measured. We show that even though they are connected, it is not possible to directly transfer images from the fundamental to the second harmonic. 
D.P. Caetano, M.P. Almeida, P.H. Souto Ribeiro, A.Z. Khoury, C.H.   Monken