Method of copying holograms

Claim 1

A method of copying an off-axis hologram of the front-beam type comprising the steps of: Directing an illuminating beam consisting of monochromatic spatially coherent light onto a recording surface of the off-axis front-beam hologram to an angle so as to produce on the opposite side thereof a diffracted image beam at a finite angle with respect to an undiffracted portion of said illuminating beam passing through said recording surface, placing a detector having a recording surface sensitive to coherent light and capable of detecting interference fringes with respect to the front-beam hologram so that the recording surfaces thereof are spaced apart at least a couple of wavelengths and so that the detector receives both the diffracted image beam and the undiffracted portion of the illuminating beam directly from the recording surface of the hologram, recording an interference pattern on the detector produced by the interaction of the undiffracted portion of the illuminating beam and the diffracted image beam as a front-beam copy of the front-beam hologram, positioning a reflector on the opposite side of the recording surface of the detector from the hologram to receive an undiffracted portion of said illuminating beam passing through the recording surfaces of both the hologram and the detector for reflection back to the detector, and recording a second interference pattern on the detector produced by the interaction of the reflected undiffracted portion of the illuminating beam and the diffracted image beam to produce a composite front-beam and back-beam hologram copy.

Claim 2

A method of copying an off-axis hologram of the front-beam type comprising the steps of: Directing an illuminating beam consisting of monochromatic spatially coherent light onto a recording surface of the off-axis front-beam hologram to an angle so as to produce on the opposite side thereof a diffracted image beam at a finite angle with respect to an undiffracted portion of said illuminating beam passing through said recording surface, placing a detector having a recording surface sensitive to coherent light and capable of detecting interference fringes with respect to the front-beam hologram so that the recording surfaces thereof are spaced apart at least a couple of wavelengths and so that the detector receives both the diffracted image beam and the undiffracted portion of the illuminating beam directly from the recording surface of the hologram, recording an interference pattern on the detector produced by the interaction of the undiffracted portion of the illuminating beam and the diffracted image beam as a front-beam copy of the front-beam hologram, positioning a reflector on the opposite side of the recording surface of the detector from the hologram to receive an undiffracted portion of said illuminating beam passing through the recording surfaces of both the hologram and the detector for reflection back to the detector, and recording a second interference pattern on the detector produced by the interaction of the reflected undiffracted portion of the illuminating beam and the diffracted image beam to produce a composite front-beam and back-beam hologram copy.

Claim 3

A method of copying an off-axis hologram of the back-beam type comprising the steps of: directing an illuminating beam of monochromatic spatially coherent light onto the recording surface of the off-axis back-beam hologram at an angle so as to produce for reflection therefrom a diffracted image beam at a finite angle with respect to said illuminating beam, placing in the path of said illuminating beam a detector at least a couple of wavelengths from the recording surface of said hologram to receive the diffracted image beam reflected from the hologram, the detector being sensitive to coherent light and capable of detecting interference fringes, recording an interference pattern on the detector produced by the interaction of the illuminating beam and the reflected diffracted image beam as a back-beam copy of the back-beam hologram, positioning a reflector on the opposite side of the recording surface of the hologram from the detector to receive an undiffracted portion of said illuminating beam passing through the recording surfaces of Both the hologram and the detector for reflection back through the hologram to the detector, and recording a second interference pattern on the detector produced by the interaction of the reflected undiffracted portion of the illuminating beam and the reflected diffracted image beam to produce a composite front-beam and back-beam hologram copy.

Claim 4

A method of copying an off-axis hologram of the back-beam type comprising the steps of: directing an illuminating beam of monochromatic spatially coherent light onto the recording surface of the off-axis back-beam hologram at an angle so as to produce for reflection therefrom a diffracted image beam at a finite angle with respect to said illuminating beam, placing in the path of said illuminating beam a detector at least a couple of wavelengths from the recording surface of said hologram to receive the diffracted image beam reflected from the hologram, the detector being sensitive to coherent light and capable of detecting interference fringes, recording an interference pattern on the detector produced by the interaction of the illuminating beam and the reflected diffracted image beam as a back-beam copy of the back-beam hologram, positioning a reflector on the opposite side of the recording surface of the hologram from the detector to receive an undiffracted portion of said illuminating beam passing through the recording surfaces of Both the hologram and the detector for reflection back through the hologram to the detector, and recording a second interference pattern on the detector produced by the interaction of the reflected undiffracted portion of the illuminating beam and the reflected diffracted image beam to produce a composite front-beam and back-beam hologram copy.