ACOUSTIC EXCITATION OF THE CIRCULAR BRAGG-FRESNEL LENS IN BACKSCATTERING GEOMETRY

An increment of the x-ray flux in crystal Bragg-Fresnel lens (BFL) foc us in backscattering geometry obtained by means of acoustic excitation of the BFL crystal substrate has been investigated. The dependence of the x ray's total reflected power versus ultrasound parameters has be en studied in a low frequency range (10-50 MHz). The proposed techniqu e allows an increase in the flux in a BFL focus by a factor of 2 which almost achieves the kinematic limit. (C) 1997 American Institute of P hysics.