NEUTRON-DIFFRACTION BY LASER-GENERATED VOLUME PHASE GRATINGS

Cold neutrons are diffracted by thick phase gratings which have been produced by light-optical holography in poly-(methyl methacrylate) (PMMA). The neutron diffraction efficiency is investigated in the Laue case as a function of the angle of incidence by rocking the sample. The dynamical theory of neutron diffraction allows to relate the measured diffraction efficiency to the modulation amplitude of the neutron-optical refractive index. The absence of higher order diffraction peaks proves that this modulation is sinusoidal. Further experimental parameters are shown to influence the diffraction in accordance with the dynamical theory: the wavelength of neutrons, the sample thickness, and the grating period. Laser diffraction experiments allow us to give upper limits for the uniformity of the grating constant throughout the sample volume. The gratings show properties which are promising for the fabrication of high-precision control samples for cold and very cold neutron spectrometers, for the construction of neutron-optical instruments, and the possibility to measure photoinduced changes of neutron-optical potentials. © 1990 Springer-Verlag.