Showing papers on "Real image published in 1972"

Characteristics and measurements of an aperture-limited in-line hologram image.

Abstract: The intensity distribution in the neighborhood of the real image reconstructed from an in-line Fraunhofer hologram was investigated. Assuming a finite amount of information recorded on the hologram in terms of a limiting aperture, the image is shown to possess intensity variations that are dependent on the argument of a first-order Bessel function recorded on the hologram. The theoretical results are presented on isophote diagrams and are verified experimentally. Three measurements of the image width are presented, and the inherent errors are found. The focal tolerance of the aperture-limited image relative to the recording parameters is discussed.

Surface contrast system and method

Abstract: A system and method for generating a shadow image of the surface of an object, the image capable of quantitative surface measurement by direct measurement of the slope of the surface at a given location, from which a surface roughness figure may be determined. Light of a defined angular distribution is directed upon the object surface. A collecting lens transmits an image of the surface to an image plane. An aperture located at the focal plane of the lens has at least a portion thereof in the light path to block out a portion of the possible angles of light passing through the collecting lens, limiting the reflected light from the surface to an angular light distribution in the beam to effect a contrast image between at least two areas in the image plane of an intensity contrast of at least two per cent.

Determination of three orthogonal displacement components from one double exposure hologram

Abstract: Another method for the interpretation of double-exposure holograms is presented It is shown that by a filtering procedure carried out in the plane of the real image, fringe patterns can be formed that also give information about the displacement undergone by the surface of the object An interpretation for those patternis presented fo rsmall out-or plane displacements presented for small out-of-plane displacements A method for determining the three orthogonal displacement components for those patterns and the virtual image is outlined

Three dimensional image reproduction with pseudo-scopy correction by image inversion optics which are capable of independently controlling z-axis placement in image space

Abstract: A method of producing multiple perspective, autostereoscopic images is disclosed along with a camera employing the method, which lends itself to inexpensive construction and which may be hand-held to take pictures with excellent depth illusion and virtually free of Z-axis compression with exposure times appropriate to conventional photography. The camera employs a selector screen and is constructed such that any point in object space viewed by the camera may be imaged anywhere along the depth axis of the picture, in image space, so that the image may be made of any extent desired, a virtual image, independently of camera focus by controlling the orientation relative to the camera axis of the optical image-reversal elements employed for pseudoscopy correction or by providing additional optical elements associated with each such image reversal element for optically effectively controlling such orientation.

Frequency responsive focus detecting apparatus

Abstract: A lens device traverses a predetermined portion of a light path between an external scene and an image plane on which an image of the scene is to be focused. A wobbulating mirror effects a rotation of the image on the image plane. A light detection device comprising a mask with apertures therein and a light responsive device, is positioned at the image plane. As the image is uniformly moved over the mask, the frequency characteristic of the output signal of the light detection device varies with the degree of sharpness of the scanned image. The high pass filter passes only the high frequency components of the output signal of the light detection device to a frequency-to-magnitude converter which, in turn, is connected to a peak detector circuit. The output of the peak detector circuit is related in time to the position of the lens at which the best focused image appeared at the image plane during the predetermined travel of the lens.

Compact imaging apparatus and projection display device

Abstract: A compact imaging apparatus and rear projection display device are described wherein an image of an object is focused on an image area which is displaced and rotated from the object plane. A pair of planar mirrors of predetermined shape are selectively located to fold the image beam from an image device and provide an image of desired orientation on the image area. A compact camera for producing a large image area in a small volume is described and is particularly useful in connection with so-called instantly developed photographic films. A rear projection device is described, having an optical arrangement which confers a high degree of immunity to ambient light. An image beam is projected upwardly against a first mirror, reflected toward a second mirror behind a projection screen, and then reflected forwardly to the projection screen. The display is highly immune to ambient light, since the general path of the image projection beam is always upward, whereas the general path of virtually all ambient light is downward. The use of two mirrors to fold the image beam in this manner introduces an unusual rotation of the projected image which, however, is taken into account in the design of the optical system. For the sake of ruggedness and precision, as well as economy of construction, the cabinet of a microform display device employing the described optical system is formed from a unitary block of polystyrene foam, the interior walls of which are faceted in an appropriate manner to provide mounting surfaces for the two mirrors. The same optical principle is applied also to the design of a combined electronic and optical display device enclosed within a CRT envelope, which is suitable for producing either an ephemeral read-out or hard copy.

X-Ray Image Intensifiers: Image Quality and Possibilities for Enhancement

Abstract: Publisher Summary This chapter elaborates the image quality and possibilities for enhancement for x-ray image intensifiers. X-ray image intensifiers have greatly changed and improved the diagnostic methods of the radiologist. In order to achieve improved image quality in X-ray image intensifiers, three techniques were investigated. The tube wall was replaced by a fiber-optic face-plate at the tube entrance. X-ray screens with increased quantum absorption and improved transfer characteristic were used and the electron-optical image surface at the output was made as flat as possible. The background due to scattered X-rays is much lower than in tubes with a conventional face-plate. There is only a small probability that X-rays scattered in the fiber-optic plate reach the screen and excite background light. For several object points on the photocathode, a number of tangential and sagittal electron trajectories were calculated and weighted in accordance with reasonable assumptions as to the distribution of initial direction and energy of the photoelectrons. It is suggested that it is possible to build X-ray image intensifiers of correspondingly improved image quality, provided that the viewing screen and the electron-optics are sufficiently good.

An optical system for attachment to a projector to reproduce a secondary image

Abstract: An optical system for use in reproducing a secondary image simultaneously with the main image of a projector. The secondary image is beamed in a direction which is 180* from the path of the beam of light from the projector causing the main image. The secondary image is caused by (a) a mirror arranged in the main beam path to intercept a component of the light, and by converging it to reduce the size of the secondary image and shorten the focal length of the image of the rays forming the secondary image, and (b) a second mirror in the reflected beam to direct the reflected beam onto a screen. Thus, the main beam can be utilized to project the main image to be viewed by a person whose eyes are being tested, while the eye examiner may sit facing the patient to adjust various lenses before his eyes and see the secondary image in front of him which is the same as that which the patient sees.

Storage and reconstitution of microphotographic images

Abstract: A process for the microscopy of transparent objects, in which the object is placed in a conventional photographic microscope with a diffraction grating system of predetermined spacing disposed in front of the photosensitive layer in which the photographic image is formed. Several images of the object are formed in the one photograph, each corresponding to a given focal plane and a given azimuthal orientation of the grating system with reference to the object. To reconstitute the multiple images recorded in the single photograph, the photograph is illuminated by means of a light source with a small, non-zero numerical aperture and a predetermined spectrum, and an afocal optical system providing at its image focus a real image of the photograph, with appropriate magnification. The beams diffracted by the photograph are selectively masked and the decoded images projected onto a suitable surface, for observation or analysis. The process finds application in three-dimensional microphotography.

Reflex camera and viewing device

Abstract: The specification describes a reflex camera and a viewing device particularly suited for use with it which forms an erect, unreverted viewing image of a subject to aid a user in focusing and aiming the reflex camera. One version of the viewing device employs the reflex camera''s mirror to direct light from a reflective focusing screen to an approximately ellipsoid concave mirror. An eye lens magnifies a real image formed by the concave mirror. Another version of the viewing device uses a hemispherical lens, having a substantially plano mirror on its rear surface, to form a real image and a concave mirror used obliquely to magnify the image for an observer.

II The Use of Image Tubes as Shutters

Abstract: Publisher Summary This chapter discusses the use of image tubes as shutters. The image tube, or image converter, is a method for making visible scenes illuminated by infrared radiation. At one end of the image tube is a photocathode at which the infra-red image of the scene is converted to a photoelectron image. This electron image is transferred by a simple electron-optical system to a phosphor screen. The electrons are given sufficient energy to excite the phosphor material and an image of the scene in the visible region of the spectrum is produced. Some important requirements of a high speed photographic system are (1) the provision of an adequately fast shutter, (2) the synchronization of this shutter to the event being studied, and (3) ensuring that enough light reaches the photographic film during the exposure to produce a recording. In principle, image tubes can be designed to meet all these requirements and the chapter reviews the image tubes and systems that have been investigated.

Materials research by holography

Abstract: The authors present a technique of producing a three-dimensional real image by taking normal x-radiographs from various perspectives which represent a sequence of individual pictures. A hologram is then constructed using coherent light and a photographic plate.