Hologram replicating method, and volume hologram

A method for replicating a volume hologram with an image of a scattering body recorded therein by a two-stage hologram replicating process comprising the two steps of:

• a first stage of illuminating a hologram to be replicated with illumination angle .theta..sub.x in one direction of two directions perpendicular to a surface of said hologram and replicating illumination light is incident on said hologram at an angle of incidence I.sub.1x at which a fringe can be recorded by replication, said fringe having a slant angle S.sub.gx at which said hologram can be observed at observation center angle .phi..sub.x ;
• and
• a second state of illuminating said hologram to be replicated with illumination angle .theta..sub.y in the other direction of two directions perpendicular to the surface of said hologram and replicating illumination light is incident on said hologram at an angle of incidence I.sub.1y at which a fringe can be recorded by replication, said fringe having a slant angle S.sub.gy at which said hologram can be observed at observation center angle .phi..sub.y,
• wherein I.sub.1x and I.sub.1y respectively satisfy the equation:
• ##EQU4## where:
• I.sub.0 is an angle of incidence of reference light to record the original volume hologram plate,
• .lambda..sub.0 is a wavelength at which the original volume hologram plate is recorded,
• .nu..sub.0 is a degree of shrinkage of a photographic material with the original volume hologram plate recorded therein,
• .tau..sub.0 is a slant angle change of fringes recorded in the original volume hologram plate,
• .lambda..sub.1 is a wavelength to replicate the original volume hologram plate,
• .tau..sub.1 is a slant angle change of replicated fringes,
• n.sub.0 is an external refractive index of the photographic material, and
• n.sub.1 is an internal refractive index of the photographic material.