Abstract: A method and apparatus for the production of an autostereoscopic and/or animated image on a lenticular screen is provided. In order to achieve the required accuracy for a good lenticular image, a detector is used to measure the location of an edge of the image bearing substrate and image data is positioned relative to this edge. The substrate may be a conventional print medium for subsequent attachment to the lenticular screen or the screen itself. As an alternative to the edge of the substrate, the lens elements of the screen can provide the frame of reference for accurate registration of the image. This is achieved by viewing a defined reference grid through the lenticular screen and converting the observed Moiré pattern into data suitable for positioning the elements of the required image, thereby accommodating dimensional variations within the screen.

Abstract: A stereoscopic image acquisition and display system and associated method, suitable for effective eye-hand co-ordination during videoscopic surgery, is provided. The problems of previous three-dimensional acquisition and display systems are addressed by ensuring that the convergence angle for image acquisition lies within the range of 3 to 16 degrees and that the observer's visual convergence is set within similar limits. Simultaneous display of left and right eye images avoids the problems of field sequential displays. By providing the observer with a displayed image which is sufficiently bright and ensuring that the binocular disparity between corresponding points in the left and right eye images is correct, the system allows the observer to fuse a pair of stereo-images, without causing conflict between visual accommodation and convergence. The location of the displayed image may be adjusted.

Abstract: Apparatus and method for providing stereo-image pairs, typically for use in endoscopy. A birefringent optical component creates two virtual pupils to provide spaced view points of an object field through a single real pupil, the light from each of the two view points having a respectively different polarization. The birefringent component may be in the form of a calcite slab or comprise liquid crystal material. By suitable orientation of two such components with respect to each other, the path lengths for the two polarizations of light may be made equivalent and rotation of the planes of polarization of this light through 90 degrees by means disposed between the birefringent components can improve the performance of the system. The rotation device may comprise a half-wave plate or a layer of liquid crystal material. By tilting the slab of calcite, the observer may be provided with a change in view point and, thereby, some motion parallax.

Abstract: A stereo-endoscope, by which two perspective views of an objective field are viewed, is provided. A divergent optical arrangement, positioned between the object field and two objective lenses, each of which forms a respective image of the object field, reduces the disparity between corresponding points in the two image fields, where such disparity is caused by distortion of the image formed.

Abstract: Apparatus and method for image enhancement in which an autostereoscopic image, comprising a different perspective view of an object field for each eye of an observer is, typically provided. The optical cross-talk, which is often a feature of autostereoscopic images, is suppressed when images are displayed, by preconditioning of the image intended for each eye. Supplementary image data is produced by mixing the different perspective image data and this is applied to the primary data. By inversion of a cross-talk matrix, two or more different perspective channels can be preconditioned to cancel the effects of such cross-talk, providing clear images for each eye without the unwanted interference from other views. The viewer's location with respect to the display device can be used to modify the characteristics of both the display and the level of cross-talk correction. A camera or endoscope for providing stereoscopic images can also suffer from optical cross-talk.

Abstract: Apparatus and method for the display of autostereoscopic images, in which two or more perspective views are generated by a single transmissive display screen, is provided. A structured light source behind the screen directs light through different sets of display elements to correspondingly different viewing zones. In certain embodiments, the structured source comprises a patterned mask which prevents light from passing through a particular set of elements and reaching the wrong zone. The pattern of the mask may be programmed. Observer co-ordinate data permits the correct viewing zone to be co-located with each of the observer's corresponding eyes. A tapered lenticular structure can provide the means for adapting to changes in the observer's distance from the display. In further embodiments a holographic optical element (HOE) may be used instead of an array of conventional lens elements.

Abstract: An image array comprising a cellular structure, typically comprising three-dimensional image data and apparatus for forming such an array, typically on photographic film. Each cell within the array comprises an image component and a reference mark formed by the same element of a microlens array. By use of the reference marks, the film may be separated from the lens array and image processed with improved flexibility and precision.

Abstract: Optical distance measuring apparatus has a focusing lens (16) directing light reflected from a target toward a detector (18), The lens has discrete or continuous zones each associated with a target distance. The area of the lens zones increases with an increase in associated target distance so as to compensate for a reduction in intensity according to the inverse square law.

Abstract: A dual beam spectrophotometer has a blazed concave reflective grating 25, formed using the interference fringes of a coherent light beam reflected back from a spherical convex mirror 73 having a center of curvature at a point 65. The point 65 is off the Rowland circle 79 of the grating 25, so as to provide a different surface of focus 81 at the position of a photodiode array 29 which detects the spectrum formed by the grating 25. This permits the angle of the photodiode array 29 to be selected for good linearity of the distribution of wavelength of the spectrum along the array while maintaining the spectrum in focus over the whole length of the array 29. In order to compensate for remaining non-linearities, the width of barrier zones 93 between adjacent diodes 49 in the photodiode array 29 may be varied, so that the pitch of the diodes 49 varies with position along the array 29.

Abstract: Apparatus for producing a record of an object field in which substantially perspective change in one direction only is recorded. The apparatus comprises elongate aperture means (35) and an array of lens elements (34) which extends in two dimensions and is disposed in an image field. Each lens element (34) is convergent in all planes orthogonal to the array. Recording means are so arranged that each lens element (34) forms an image thereon. Each recorded image (36) is derived from rays from a range of perspectives of the object field in one direction and a substantially smaller range in an orthogonal direction and each recorded image (36) is distinct from each other recorded image. Reproduction apparatus allows an autostereoscopic image to be formed on conventional lenticular material from an intermediate record produced by the recording apparatus.

Abstract: Stereoscopic apparatus is described in which the spectral components of each perspective of the image are supplied in sequence and in such a way that whilst the left eye is receiving one spectral component of one of the perspectives, the right eye receives the other spectral component of the other perspective, and in alternating periods the left eye receives the other spectral component of its perspective whilst the right eye receives the first spectral component of its perspective. Various means for producing the image and for viewing the two perspectives are illustrated.

Abstract: Apparatus such as a camera for producing autostereoscopic images from convergent optical assemblies and imaging devices including (in a preferred embodiment of FIG. 11) curved reflecting surfaces. Light from the object field represented by rays R1, R2 and R3 enters the camera through a horizontally long but vertically narrow slot 210. The light is split into reflected and transmitted components by semi-transparent mirror 211. Two horizontal apertures 212 and 213, one in each component beam, prevent unwanted vignetting. A plane mirror 214 folds the reflected component from mirror 211 so that it is approximately parallel to the transmitted component. A curved reflector assembly 215 which typically comprises a series of curved reflectors side by side horizontally creates one or more intermediate images of the object field at a retroreflective screen 216, which is arranged to move in its own plane during exposure of the film and receives both the transmitted and reflected components of light.

Abstract: Apparatus for producing a record of an object field in which substantially perspective change in one direction only is recorded. The apparatus comprises elongate aperture means (35) and an array of lens elements (34) which extends in two dimensions and is disposed in an image field. Each lens element (34) is convergent in all planes orthogonal to the array. Recording means are so arranged that each lens element (34) forms an image thereon. Each recorded image (36) is derived from rays from a range of perspectives of the object field in one direction and a substantially smaller range in an orthogonal direction and each recorded image (36) is distinct from each other recorded image. Reproduction apparatus allows an autostereoscopic image to be formed on conventional lenticular material from an intermediate record produced by the recording apparatus.

Abstract: Stereoscopic apparatus is described in which the spectral components of each perspective of the image are supplied in sequence and in such a way that while the left eye is receiving one spectral component of one of the perspectives, the right eye receives the other spectral component of the other perspective, and in alternating periods the left eye receives the other spectral component of its perspective while the right eye receives the first spectral component of its perspective. Various means for producing the image and for viewing the two perspectives are illustrated.

Abstract: Apparatus such as a camera for producing autostereoscopic images comprises imaging means, such as one or more lenses (60,61,68) arranged to capture rays from a range of perspectives of an object field (58) and recording means in an image field such as lenticular film (69), for recording composite stereoscopic information from the object field. Preferably the imaging means includes one or more retroreflectors (62,63) adapted to reture rays substantially along their incident paths. The lenticular film used may be adapted for fast processing.

Abstract: This invention relates to a scanning apparatus in which a spot of light is swept or scanned over a receiving surface (11,27). The intensity of the spot may be modulated during scanning to build up a two-dimensional image on the receiving surface, or alternatively, the spot of light may be used to analyze the receiving surface to monitor its reflectivity or transmissivity.