1. A process for making an achromatic holographic stereogram, comprising the steps of: projecting a sequence of transparencies onto a predetermined projection plane; sequentially holographically recording each of the sequence of projected images on contiguous narrow elongated strips of a first photographic plate, said sequential holographic recording being made with a collimated reference beam, said photographic plate being inclined to a normal to said projection plane at an angle .alpha. of from 35.degree. to 41.degree.; illuminating the resulting hologram with a beam conjugate to said reference beam; and holographically recording the image produced by said illuminating beam onto a second photographic plate, said second photographic plate being in a position corresponding to the location of said projected images relative to said hologram, said second holographic recording being effected by using a second collimated reference beam to illuminate said second photographic plate at an angle of incidence .phi. related to the angle .alpha. at which said first recited plate is inclined to said normal by .phi.=sin.sup.-1 tan .alpha..