Abstract: Taking advantage of atom lithography to produce the nano level grating has become a mature process technology in nano fabrication. When the atoms pass through a standing wave field, using the dipole force on the atoms is a new technology to build the nanostructures. The grating obtained by this method has its special characteristic. Its period is directly related to the wavelength of laser and this can be reviewed to the transition frequency of the atom. It is hoped to use a new kind of light mask to improve the deposition quality. Using double-layer light mask have been mentioned for several times. In the experiment, geometrical optics were used to achieve what we need. A prism was designed to generate this special beam. From the experiment result, the beam is well generated. This kind of beam can be easily used in the subsequent experiment.