Holographic readout system employing predispersion diffraction grating

Claim 1

A system for reading out a hologram with broad-band wave energy, wherein said hologram has been recorded employing respective angularly-separated object-information and reference beams of mutually coherent wave energy of a predetermined wavelength, whereby said hologram constitutes a spatiallymodulated spatial carrier in which said spatial carrier has a period which is determined by said predetermined wavelength and the angular separation between said respective object-information and reference beams; said system comprising: a. a predispersion diffraction grating having a selected line spacing responsive to illumination thereof by a beam of broadband wave energy for angularly dispersing said broad-band wave energy by an amount which is determined by the respective wavelengths included in said broad-band wave energy and by said selected line spacing, b. first means for illuminating said predispersion diffraction grating with a beam of broad-band wave energy including component wavelengths having predetermined values with respect to that of said predetermined wavelength to thereby derive an angularly-dispersed output beam of wave energy in which each component wavelength thereof has an angular orientation determined by the value of that component wavelength and the value of said selected line spacing of said grating, c. second means including said hologram disposed in cooperative spaced relationship with said grating to effect the illumination of said hologram with wave energy of said angularly-dispersed output beam and resulting in respective reconstructed images being formed by said hologram for each of said component wavelengths, the relative position in space of each of said respective reconstructed images being determined by the value of each respective component wavelength with respect to the period of the spatial carrier of said hologram and the angular orientation of that respective component wavelength, d. wherein the value of said selected line spacing of said predispersion diffraction grating with respect to the value of the period of said spatial carrier of said hologram is that which results in the appropriate amount of angular dispersion of said broad-band wave energy required to register the positions of said respective reconstructed images in substantial coincidence with each other, and e. wherein said respective object-information and reference beams employed in recording said hologram were spherical waves having substantially the same incident curvature at the hologram recording, wherein said first means includes third means for illuminating said predispersion grating with a substantially plane wave of said broad-band wave energy, and wherein said second means includes fourth means responsive to said angularly-dispersed output beam for converting said output beam to a spherical-wave beam having a curvature incident on said hologram which corresponds with the incident curvature of said respective object-information and reference beams at said hologram recording.

Claim 2

A system for reading out a hologram with broad-band wave energy, wherein said hologram has been recorded employing respective angularly-separated object-information and reference beams of mutually coherent wave energy of a predetermined wavelength, whereby said hologram constitutes a spatiallymodulated spatial carrier in which said spatial carrier has a period which is determined by said predetermined wavelength and the angular separation between said respective object-information and reference beams; said system comprising: a. a predispersion diffraction grating having a selected line spacing responsive to illumination thereof by a beam of broadband wave energy for angularly dispersing said broad-band wave energy by an amount which is determined by the respective wavelengths included in said broad-band wave energy and by said selected line spacing, b. first means for illuminating said predispersion diffraction grating with a beam of broad-band wave energy including component wavelengths having predetermined values with respect to that of said predetermined wavelength to thereby derive an angularly-dispersed output beam of wave energy in which each component wavelength thereof has an angular orientation determined by the value of that component wavelength and the value of said selected line spacing of said grating, c. second means including said hologram disposed in cooperative spaced relationship with said grating to effect the illumination of said hologram with wave energy of said angularly-dispersed output beam and resulting in respective reconstructed images being formed by said hologram for each of said component wavelengths, the relative position in space of each of said respective reconstructed images being determined by the value of each respective component wavelength with respect to the period of the spatial carrier of said hologram and the angular orientation of that respective component wavelength, d. wherein the value of said selected line spacing of said predispersion diffraction grating with respect to the value of the period of said spatial carrier of said hologram is that which results in the appropriate amount of angular dispersion of said broad-band wave energy required to register the positions of said respective reconstructed images in substantial coincidence with each other, and e. wherein said respective object-information and reference beams employed in recording said hologram were spherical waves having substantially the same incident curvature at the hologram recording, wherein said first means includes third means for illuminating said predispersion grating with a substantially plane wave of said broad-band wave energy, and wherein said second means includes fourth means responsive to said angularly-dispersed output beam for converting said output beam to a spherical-wave beam having a curvature incident on said hologram which corresponds with the incident curvature of said respective object-information and reference beams at said hologram recording.