Optics: image projectors – Plural projection paths with single light source
Patent
1987-04-06
1989-05-16
Arnold, Bruce Y.
Optics: image projectors
Plural projection paths with single light source
350 386, 353 88, 353 99, G02H 124
Patent
active
048304450
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to holographic display means, that is to say to means arranged to display images of three dimensional objects by means of illuminated holograms, which images portray in life-like manner the real objects used in producing the holograms, and give the impression to a viewer that the object whose image is portrayed in the display is really present. For example, with such displays, the image is seen to move in a realistic way when the viewer moves his observation position relative to the object portrayed in the display means.
BACKGROUND OF THE PRIOR ART
Holographic display means currently available are bulky pieces of scientific or industrial equipment which have large dimensions and volumes, use long light paths and divergent light beams, and utilize in a very inefficient way the light emanating from the light source incorporated therein. Such equipment is thus not at all suitable in commercial fields of display, such as in shops, exhibitions and advertising locations; nor is it particularly convenient to use or productive of accurate reproduction of holographic images in scientific work.
The present invention seeks to overcome the disadvantages of the prior art display means, and to provide a display apparatus which is more compact, and efficient in utilising the light sources that are currently available.
Disclosure of the Invention
According to the present invention a holographic display means for displaying an image holographically embodied in a hologram comprises a unit which incorporates - reflection or a transmission type, in a viewing position; support in a predetermined position such that light emanating from the source when enerigized cannot fall directly on to a hologram supported on the support; and and arranged to direct light from the source on to a hologram supported on the support so as to be incident on the hologram at a predetermined acute reference angle, which angle corresponds substantially to the angle of incidence relative to the hologram of a predetermined reference light used in producing that hologram.
The reflecting means preferably includes reflecting surface means arranged to reflect light from the source not more than twice before it becomes incident on the hologram; and in some cases it is preferred that the reflecting surface means reflects light from the source only one before it becomes incident on the hologram.
The reflecting surface means may comprise a planar reflecting surface for reflecting light from the source directly on to the hologram at the said acute reference angle.
Alternatively, or in addition, the reflecting surface means may include a reflecting surface which is curved in a first manner such as to collimate the light reflected thereby on to the hologram. That reflecting surface may also be curved in a second manner orthogonal to the first curvature of that reflecting surface, thereby to concentrate light received from the source on to the hologram.
The support may be arranged to receive and support holograms having, for example, planar, cylindrical, convex or concave form, or any combination of such forms, e.g. plano-concave form, plano-convex form or a combination of those forms. The reflecting surface means are shaped accordingly to suit the form of the hologram.
Other preferred features of the present invention will appear from a reading of the description that follows hereafter, and of the claims appended at the end of that description.
Various different forms of holographic display apparatus according to the present invention, and various modifications thereof, will now be described by way of example and with reference to the accompanying diagrammatic drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows schematically in side view the optical arrangement of an illumination system incorporated in a first embodiment of a holographic display unit or device of the present invention;
FIG. 2 shows pictorially the general arrangement of that illumination system;
FIG. 3 shows a cross section tak
REFERENCES:
patent: 3751589 (1973-08-01), Patels et al.
patent: 3826555 (1974-07-01), Matsumoto
patent: 3887276 (1975-06-01), Clay et al.
patent: 3917379 (1975-11-01), Noguchi
patent: 4390234 (1983-06-01), Embach
patent: 4429947 (1984-02-01), Benton
patent: 4486070 (1984-12-01), Benton
patent: 4623215 (1986-11-01), Bazargan
Sato et al., "Cylindrical Rainbow Hologram," Applied Optics, vol. 24, No. 14, Jul. 15, 1985, pp. 2161-2165.
Arnold Bruce Y.
Lerner Martin
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