Optical: systems and elements – Stereoscopic – Having record with lenticular surface
Reexamination Certificate
1999-07-12
2001-04-03
Henry, Jon (Department: 2872)
Optical: systems and elements
Stereoscopic
Having record with lenticular surface
C359S465000
Reexamination Certificate
active
06212007
ABSTRACT:
The invention relates to an auto-stereoscopic display screen for several viewers, which can show a plurality of perspectives of an article at the same time and is accordingly called a “stereo-hologram display”. Such an auto-stereoscopic display or in other words 3-D display screen is known from the patent specification [1] which, however, in contrast to the invention described here can only show two perspectives of an article at the same time. This invention is based on the object of ensuring an auto-stereoscopic representation which does not relate only to one viewer position but to a whole range of viewer positions, from which a represented article can be observed true to nature, in three dimensions; several viewers can thus perceive the represented article three-dimensionally at the same time. This object is met by the characterizing features in claim
1
. The plurality of perspectives of an article here required to be displayed are obtained through an arrangement, in which a black and white micro display (or even a photo mask) is located in the vertical focal lines of a lens raster plate, on which display (or mask) the many different views of an article can be represented interleaved with each other in the narrowest of strips. The different grey and colour values are then achieved by fixedly arranged colour and brightness masks located therebetween.
The invention relates to 3-dimensional, hologram-like colour picture displays and processing in which a plurality of stereoscopic views of an object can be displayed in dependence on the position of an viewer. The viewer standing in front of the stereo-hologram display can view a displayed article from several perspectives by lateral movements of the head—within a previously selectable “round view”. In particular this high resolution display is suitable for radiology in computer tomography for medical technology, in which arises the ability to be able to perceive the third dimension of depth without additional auxiliary means (e.g. glasses). The colour hologram computed by a computer can be written by means of modulated laser beams within a few minutes on a digital display and archived on an inexpensive black and white photo of like size. Alternatively however, only this black and white photo mask can be produced and be placed behind a display attachment, so that the same stereo hologram is visible. In the representation of objects it is not necessary to restrict oneself to external views. For example the presence of a three-dimensional tissue description from nuclear spin tomography allows internal and external views (e.g. of a kidney) to be combined and represented one after the other on a stereo-hologram.
STATE OF THE ART
Stereoscopic film and projection methods have been used for years. Polarised light (horizontal, vertical, circular) is used mostly, in order to separate the left and right images [10]. With advances in LCD technology it has become possible to control the light transmission coefficient of crystals electronically. This made the development of the shutter technique possible, in which the right and left spectacle glasses become opaque alternately at half the picture frequency and right and left images appear sequentially in synchronism on the display screen [6].
Auto-stereoscopic projections are implemented with the aid of screens with strip lens rasters with several projection directions. The correct perspective image is associated with the corresponding direction [1], [2]. A smooth transition from one perspective to the next can hardly be achieved, since the number of the projection directions cannot be increased arbitrarily. In an auto-stereoscopic display, which is intended for one person only, only two perspectives are used, which require a specific direction of view [7], [8]. To display a fully stereoscopic image as in a hologram is achieved by using “head tracking” sensors, which control on the one hand a high-power real-time computer to calculate the matching stereoscopic image perspectives and on the other hand the auto-stereoscopic screen for the mechanical follow up of the lens raster plate. The precise head position and movement are detected and the associated images are generated simultaneously. Furthermore there are expensive VR systems (virtual reality) using “head mounted displays” which require getting used to.
Nuclear spin resonance and computer tomography are the most important fields of use for stereoscopic 3D visualisations in medical technology. In order to compute specific desired perspectives, high power special computers for “volume tracking algorithms” have been developed [5]. Combined computer visualisations and real-time transmissions from endoscopes are becoming one of the most important neuro-surgical tools. Stereoscopic endoscopes are already in use. Electronic movement control through a “head tracking sensor” operating on an infrared basis is easy to combine with a person-related auto-stereoscopic display screen system.
Prototype auto-stereoscopic image reproduction systems are being developed at the present time in many places. Most of them require high-precision mechanical parts for the movement follow-up with changes in the position of the viewer. However electronic adaptive shutter systems are also known, which require two displays [8], [9].
Holographically stored 3d images have been known for many years, in which the picture information is retained on highest resolution photographic material in the form of wave images. These arise from the superposition of coherent or even monochromatic light which has been reflected from bodies to be recorded. The 3D image can then be made visible again by illumination with coherent light. Unfortunately the colour information is lost.
Displays built on the basis of bistable liquid crystals, which can be written with laser beams, have been known for some years. Liquid crystals can be flipped—by supplying laser power—over regions of some &mgr;m
2
from the transparent state into a dispersive, i.e. scattering state. This state can then be retained for years without supplying laser power or can be reset by application of an electrical voltage [12]. Binary information can thus be stored here. These writeable surfaces will be called scatter displays in the following.
FORMULATION OF THE PROBLEM
The objective is so to store 3-dimensional images that represented bodies appear stereoscopically from different observing positions, moreover with different perspectives. Accordingly a hologram-like change of the represented colour image is to occur with lateral movement of the head of an viewer. The problem formulation which emerges from this, is to create such colour image stereo-holograms with the aid of scatter displays and further special arrangements, so that such a stereo colour hologram can be written with laser beams within an acceptable time. The colour hologram should then be maintained as far as possible without supplying power, or be capable of being reset so that this display can be used again for the next stereo-hologram.
It should moreover be possible to save the same image on a black and white film of normal type on the market. At the same time it should be possible for this film to be so used that a stereo-hologram stored i binary form thereon can be made visible by means of an existing attachment. It would be advantageous if this attachment were identical with that which is required for the scatter display.
Up until now no writable stereo-hologram displays are known which have had the features recited above.
REFERENCES:
patent: 3161509 (1964-12-01), Howe et al.
patent: 3582984 (1971-06-01), Kurokawa
patent: 5629797 (1997-05-01), Ridgway
patent: 5850269 (1998-12-01), Kim
patent: 39 21 061 A1 (1991-01-01), None
patent: 41 14 023 A1 (1992-11-01), None
patent: 195 00 315 C1 (1995-10-01), None
patent: 0 332 268 A1 (1989-09-01), None
patent: WO 92/22989 (1992-12-01), None
Boener: “Autosterescopic 3-D Imaging by Front and Rear Projec
Henry Jon
Striker Michael J.
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