Different strategies for down-sampling computer-generated holograms

A high-resolution computer-generated hologram can be displayed on a low resolution spatial light modulator with a high-resolution mask attached. Three different masks are discussed here. The regular grid down-sampling (RG) mask, the regular grid jittered down-sampling (RGJD) mask, and the asymmetrical regular grid jittered down-sampling (A-RGJD) mask. We found the RGJD method can retain the high-resolution information but also produce significant noise. By contrast, the RG method can produce clear image with reduced bandwidth. The two methods can be combined as the A-RGJD method, in which the horizontal bandwidth of the object remains large, and the noise is well controlled.