OFFSPECULAR SCATTERING FROM OPTICAL GRATINGS. J.R.P. Webster, A. Zarbakhsh, R.M. Richardson, ISIS, Rutherford Appleton Laboratory, UK and Department of Chemistry, Bristol University, UK

Following after Tolan et al we have looked at the offspecular scatter from a series of optical gratings using both a 1 and a 2 dimensional multidetector. The Bragg reflections obtained from these systems occur at values of q_x=2[[pi]]/dx where dx is the periodicity in the scattering plane parallel to the interface. The limiting value of dx, which is related to the coherence length of the neutron beam, was found to be of order 40 microns.