Q. By what means can the laser speckle that limits hologram resolution be reduced? Dr. Leith: Speckle reduction can be accomplished by a number of methods. Introducing a phase diffuser such as a diffraction grating in a plane near the object can pro-duce a number of discrete planes in object space free from speckle. Dr. Thompson: However, the grain size and resolution of the hologram is limited by the grain size of the diffuser.