Reduction of non-linear spatial distortion in holographic system employing different wavelengths for recording and playback

Claim 2

In a holographic system for recording a Fraunhofer hologram of a color scene employing coherent wave energy having a first predetermined wavelength and thereafter playing back said recorder hologram employing an imaging lens having a preselected focal length and coherent wave energy having a second predetermined wavelength substantially different from said first predetermined wavelength to obtain a reconstructed image from which a color-television display of said color scene may be derived; apparatus for recording said hologram comprising a converging lens having a given focal length defining its focal plane, a color-manifesting object situated in the focal plane of said converging lens, saiD object comprising first and second spatially separated, but corresponding, portions, one of said object portions defining the luminance information at each point of a particular color scene and the other of said portions defining the corresponding chrominance information at each point of that particular color scene, a wave energy sensitive recording medium located in given spaced relationship with respect to said object and said converging lens, and wave energy illuminating means oriented with respect to said object, said converging lens and said medium to illuminate a given area of said medium directly with a reference beam of coherent wave energy of said first predetermined wavelength which is directed thereto over a first preselected path and to also illuminate both portions of said objects with an object-illuminating plane-wave of coherent wave energy which is mutually coherent with said reference beam to obtain therefrom an object-information beam which is directed through said converging lens along a second preselected path to simultaneous incidence on said given area of said medium with said reference beam, said first and second preselected paths being such that said reference and object-information beams incident on said given area of said medium define a given plane with said object-information beam being disposed at a particular selected angle with respect to a line in said plane which is normal to the intersection of said plane and said medium and with said reference beam being disposed at an angle with respect to said line equal to the difference between a predetermined fixed angle and said particular selected angle, whereby a hologram of said luminance and chrominance portions is recorded on said given area of said medium, said particular selected angle having a value which results in substantially the least misregistration between corresponding points of said luminance and chrominance portions of said reconstructed image obtained during said playback with an imaging lens having said preselected focal length and with coherent wave energy having said second predetermined wavelength.

Claim 3

The system defined in claim 1, further including playback apparatus for reconstructing an image of said recorded hologram, said playback apparatus comprising second wave energy means for illumination of said recorded hologram with a plane-wave readout beam of coherent wave energy having said second predetermined wavelength and traveling in a given first direction with respect to said recorded hologram, whereby a first-order diffraction beam is derived from said hologram traveling in a second direction with respect to said first direction, said readout and diffraction beams defining a second given plane, said first and second directions being such that the line in said second given plane perpendicular to the intersection of said second given plane and said recorded hologram bisects the angle therebetween, and said imaging lens being located in the path of said first-order diffraction beam to reconstruct an image of said luminance and chrominance portions from said recorded hologram in the focal plane of said imaging lens.

Claim 4

The system defined in claim 2, further including television camera means having a surface sensitive to wave energy of said second predetermined wavelength located in the focal plane of said imaging lens to thereby focus said reconstructed image on said sensitive surface of said television camera means.

Claim 5

In a holographic system, playback apparatus employing wave energy having a second predetermined wavelength for playing back a Fraunhofer hologram of a color-manifesting object to obtain a reconstructed image from which a color-television display of said color scene may be derived, wherein said object includes first and second spatially separated, but corresponding, portions, one of said object portions defining the luminance information at each point of the particular color scene and the other of the object portions defining the corresponding chromInance information at each point of that particular color scene, and wherein said hologram was recorded employing (1) a converging lens having a preselected focal length defining its focal plane in which said object was located, (2) employing a wave energy sensitive recording medium located in given spaced relationship with respect to said object and said converging lens, and (3) employing wave energy illuminating means oriented with respect to said object, said converging lens and said medium to illuminate a given area of said medium directly with a reference beam of coherent wave-energy of said first predetermined wavelength which was directed thereto over a first preselected path and to also illuminate both portions of said object with an object-illuminating plane-wave of coherent wave-energy which was mutually coherent with said reference beam to obtain therefrom an object information beam which was directed through said converging lens along a second preselected path to start simultaneous incidence on said given area of said medium with said reference beam, said first and second preselected paths having been such that said reference and object-information beams incident on said given area of said medium defined a given plane with said object information beam having been disposed at a particular selected angle with respect to a line in said plane which is normal to the intersection of said plane and said medium and with said reference beam having been disposed at an angle with respect to said line equal to the difference between a predetermined fixed angle and said particular selected angle; said playback apparatus comprising second wave-energy means for illuminating said recorded hologram with a plane-wave readout beam of coherent wave energy having said second predetermined wavelength and traveling in a given first direction with respect to said recorded hologram, whereby a first-order diffraction beam is derived from said hologram traveling in a second direction with respect to said first direction, said readout and diffraction beams defining a second given plane, said first and second directions being such that the line in said second given plane perpendicular to the intersection of said second given plane and said recorded hologram bisects the angle therebetween, and an imaging lens having a given focal length defining its focal plane located in the path of said first-order diffraction beam to reconstruct an image of said luminance and chrominance portions from said recorded hologram in the focal plane of said imaging lens, said reconstructed image exhibiting a misregistration between corresponding points of its luminance and chrominance portions which is dependent upon the respective values of said first and said second predetermined wavelengths, said preselected and said given focal lengths and said particular selected angle, the value of said particular selected angle employed in recording said hologram having been that which results in substantially the least amount of misregistration between corresponding points of said luminance and chrominance portions of said reconstructed image.

Claim 6

In a holographic system, playback apparatus employing wave energy having a second predetermined wavelength for playing back a Fraunhofer hologram of a color-manifesting object to obtain a reconstructed image from which a color-television display of said color scene may be derived, wherein said object includes first and second spatially separated, but corresponding, portions, one of said object portions defining the luminance information at each point of the particular color scene and the other of the object portions defining the corresponding chromInance information at each point of that particular color scene, and wherein said hologram was recorded employing (1) a converging lens having a preselected focal length defining its focal plane in which said object was located, (2) employing a wave energy sensitive recording medium located in given spaced relationship with respect to said object and said converging lens, and (3) employing wave energy illuminating means oriented with respect to said object, said converging lens and said medium to illuminate a given area of said medium directly with a reference beam of coherent wave-energy of said first predetermined wavelength which was directed thereto over a first preselected path and to also illuminate both portions of said object with an object-illuminating plane-wave of coherent wave-energy which was mutually coherent with said reference beam to obtain therefrom an object information beam which was directed through said converging lens along a second preselected path to start simultaneous incidence on said given area of said medium with said reference beam, said first and second preselected paths having been such that said reference and object-information beams incident on said given area of said medium defined a given plane with said object information beam having been disposed at a particular selected angle with respect to a line in said plane which is normal to the intersection of said plane and said medium and with said reference beam having been disposed at an angle with respect to said line equal to the difference between a predetermined fixed angle and said particular selected angle; said playback apparatus comprising second wave-energy means for illuminating said recorded hologram with a plane-wave readout beam of coherent wave energy having said second predetermined wavelength and traveling in a given first direction with respect to said recorded hologram, whereby a first-order diffraction beam is derived from said hologram traveling in a second direction with respect to said first direction, said readout and diffraction beams defining a second given plane, said first and second directions being such that the line in said second given plane perpendicular to the intersection of said second given plane and said recorded hologram bisects the angle therebetween, and an imaging lens having a given focal length defining its focal plane located in the path of said first-order diffraction beam to reconstruct an image of said luminance and chrominance portions from said recorded hologram in the focal plane of said imaging lens, said reconstructed image exhibiting a misregistration between corresponding points of its luminance and chrominance portions which is dependent upon the respective values of said first and said second predetermined wavelengths, said preselected and said given focal lengths and said particular selected angle, the value of said particular selected angle employed in recording said hologram having been that which results in substantially the least amount of misregistration between corresponding points of said luminance and chrominance portions of said reconstructed image.

Claim 7

The system defined in claim 4, further including television camera means having a surface sensitive to wave energy of said second predetermined wavelength located in the focal plane of said imaging lens to whereby focus said reconstructed image on said sensitive surface of said television camera means.