Optical: systems and elements – Holographic system or element – Hardware for producing a hologram
Reexamination Certificate
1999-09-01
2001-02-27
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Holographic system or element
Hardware for producing a hologram
C359S003000, C359S009000, C359S012000, C359S015000, C359S030000, C352S222000
Reexamination Certificate
active
06195185
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10-249988 filed Sep. 3, 1998 which application is incorporated herein by reference to the extent permitted by law.
TECHNICAL FIELD
The present invention relates to an image recording apparatus for preparing a holographic stereogram which is recorded so that an actual image or a computer-generated image can be observed three-dimensionally.
BACKGROUND OF THE INVENTION
A holographic stereogram is prepared as follows. For example, an object is sequentially picked up from different observation view points, to obtain a number of images. These images which are used as original images are recorded sequentially as hologram elements in form of strips or dots onto a piece of hologram recording medium, by means of an image recording apparatus.
For example, as shown in
FIG. 1
, a holographic stereogram having parallax information in only the lateral direction is prepared in a manner in which a plurality of original images
101
a
to
101
e
obtained by sequentially picking up an object
100
from different observation points in the lateral direction are sequentially recorded as strip-like hologram elements
102
onto a hologram recording medium by an image recording apparatus. A plurality of original images which are recorded as hologram elements onto the hologram recording medium are not always limited to those images that are obtained by actually picking up the object
100
but may be CAD (Computer Aided Design) images or CG (Computer Graphics) images.
In case of this holographic stereogram, pieces of image information obtained by sequentially picking up an object from different observation points in the lateral direction are sequentially recorded as strip-like hologram elements in the lateral direction. Therefore, when this holographic stereogram is observed with eyes by an operator, two-dimensional images respectively projected on the left and right eyes are slightly different from each other. As a result, the operator feels parallax and understands these images as a three-dimensional image.
Meanwhile, an image recording apparatus records hologram elements of a holographic stereogram onto a hologram recording medium using a photosensitive material as a recording material, in the following manner. That is, in case of preparing a holographic stereogram of a reflection type, a laser beam having a good interference characteristic is branched into two beams, and one of the two beams is irradiated, as a projection image (object light) subjected to two-dimensional image modulation by an image display means such as a liquid crystal panel or the like, onto one surface of a hologram recording medium. Also, in the image recording apparatus, the other one of the two branched laser beams is irradiated, as reference light, onto the other surface of the hologram recording medium. As a result, an interference fringe is formed, as a change of the refraction factor or a change of the transmittance, in the photosensitive material ofthe hologram recording medium, and thus, ahologram element is recorded.
For the image recording apparatus for recording hologram elements of a holographic stereogram onto a hologram recording medium, it is necessary to fix perfectly the hologram recording medium during exposure of a recording image so that even a slight vibration which is as small as the order of wavelength of light might not be generated, in orderto prepare aholographic stereogram which provides an excellent reproduced image.
The image recording apparatus is arranged so as to record sequentially a large number ofhologram elements while transferring the hologram recording medium little by little. Therefore, in case where a hologram recording medium is transferred, for example, with use of an electrically movable stage, a vibration is caused in the hologram recording medium itself as the medium is transferred. Accordingly, in this kind of image recording apparatus, exposure must be carried out after a vibration caused by transfer of a hologram recording medium is attenuated, in order to prepare a holographic stereogram which provides an excellent reproduced image. Therefore, there is a problem that a very long time is required to prepare one holographic stereogram and the productivity is low.
The present invention hence has an object of providing an image recording apparatus by which vibrations of a hologram recording medium are reduced and a holographic stereogram which provides an excellent reproduced image can be prepared in a short time period.
SUMMARY OF THE INVENTION
According to the present invention, there is provided an image recording apparatus for irradiating object light onto one surface of a hologram recording medium and reference light onto another surface of the hologram recording medium thereby to record sequentially images of a parallax image sequence, as hologram elements, onto the hologram recording medium, comprising: transfer means for transferring the hologram recording medium; and a vibration restriction member provided on either a light path of the object light or a light path of the reference light, for restricting a vibration of the hologram recording medium by making an end side of the vibration restriction means contact with the hologram recording member transferred by the transfer means, the end side being provided with an opening portion, wherein the object light or the reference light is irradiated onto the hologram recording medium through the opening portion provided at the end side of the vibration restriction member which is made contact with the hologram recording medium.
According to the image recording apparatus described above, the hologram recording member is transferred by the transfer means. At this time, the hologram recording medium transferred by the transfer means is brought into contact with an end side ofthe vibration restriction member, so that a vibration caused by the transfer of the medium is restricted.
In addition, the object light or the reference light is irradiated onto the hologram recording medium through an opening portion formed at one end side ofthe vibration restriction member.
In the image recording apparatus, the opening portion of the vibration restriction member is desirably formed to have a size corresponding to the hologram element. In case where the opening portion ofthe vibration restriction member is thus formed to have a size corresponding to the hologram element, the width of the object light or the reference light is set to a width corresponding to the hologram element if the width of the object light or the reference light is determined by the opening portion of the vibration restriction member. Accordingly, it is possible to avoid a problem that the object light or the reference light is irradiated onto adjacent regions over the predetermined region where the hologram element should be recorded, thereby involving a decrease ofthe diffraction efficiency which deteriorates a recorded image.
Also, in the image recording apparatus, processing for improving wear resistance ofthe vibration restriction member is desirably made on at least the end side of the vibration restriction member which contacts with the hologram recording medium. If processing for improving the wear resistance of the vibration restriction member is thus made on the end side of the vibration restriction member which contacts with the hologram recording medium, damages on the vibration restriction member are reduced.
Also, in the image recording apparatus, light absorbing means for absorbing light is desirably provided at least on a part of the vibration restriction member. If light absorbing means is thus provided on the vibration restriction member, it is possible to avoid a problem that the object light or the reference light is irregularly reflected on the surface of the vibration restriction member and unnecessary interference fringes are thereby recorded on the hologram recording medium.
Also, the image recording apparatus desirably further comprises: position detection
Kihara Nobuhiro
Shirakura Akira
Suzuki Hirotsugu
Curtis Craig
Sonnenschein Nath & Rosenthal
Sony Corporation
Spyrou Cassandra
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