Hologram writing apparatus and method

In a hologram writer adapted to write a holographic record of an object beam and a reference beam from input signals corresponding to x, y, z coordinates, the improvement comprising

• mounting means for a holographic recording member,
• a source of a narrow beam of coherent radiation,
• a diffuser element adapted to transform a point of light from said source to an expanding light beam,
• an object beam scanner adapted and positioned to receive a light beam from said source and to scan said beam as essentially a moving point on said diffuser element to form an expanding object beam,
• a reference beam scanner adapted and positioned to receive a beam of coherent radiation and scan said beam on said recording member,
• relaying means positioned to receive said expanding object beam and to relay said beam to said holographic recording member,
• and means to move said holographic recording member with respect to said diffuser element.

In a hologram writer adapted to write a holographic record of an object beam and a reference beam from input signals corresponding to x,y,z coordinates, the improvement comprising

• mounting means for a holographic recording member,
• a source of a narrow beam of coherent rediation,
• a diffuser element adapted to transform a point of light from said source to an expanding light,
• an object beam scanner adapted and positioned to receive a light beam from said source and to scan said beam as effectively a moving point on said diffuser element in positions corresponding to three coordinates,
• means to direct said expanding object beam to said holographic recording member,
• a reference beam scanner adapted and positioned to receive a beam from said source and to scan said beam on said holographic recording member,
• means to vary the size of said reference beam in coordination with the size of said object beam at said holographic recording member,
• and means to move one of said holographic recording member and said diffuser element with respect to one another to vary the beam distance therebetween.

In a method of hologram writing wherein an information-containing object beam and a reference beam are simultaneously scanned across a holographic recording member, the improvement comprising

• scanning an object beam as substantially a point in two coordinate directions on a diffuser element to form a diverging object beam from a scanning equivalent point source on said diffuser element,
• directing said beam to a holographic recording member from said point source, thereby scanning said expanding object beam on said member in two coordinate directions,
• varying the distance between said point source and said holographic recording member to represent a varying third coordinate direction, and
• simultaneously scanning said reference beam on said holographic recording member synchronously with said scanning object beam and controlling the area and shape of said reference beam synchronously with the area and shape of said expanding object beam as the size of said expanding object beam varies with the distance between said point source and said holographic recording member.