Abstract: A slit radiography apparatus is provided with an absorption device comprising electrically controllable piezoelectric tongues. Upper and/or lower deflections of the tongues are limited to a maximum by trips outside the X-ray fan beam. More than one strip can be present as seen in the length direction from the fixed ends of the tongues Thus deflections of the tongues are limited and great phase changes in the control signals without resultant oscillations can take place during the time the tongue are restricted in their movement by the strip.

Abstract: A slit radiography apparatus is provided with an absorption device comprising electrically controllable piezoelectric tongues. Upper and/or lower deflections of the tongues are limited to a maximum by trips outside the X-ray fan beam. More than one strip can be present as seen in the length direction from the fixed ends of the tongues. Thus deflections of the tongues are limited and great phase changes in the control signals without resultant oscillations can take place during the time the tongue are restricted in their movement by the strip.

Abstract: In an equalization radiography device an X-ray fan beam (3,4) is used to scan a body (7) under examination. The X-ray fan beam comprises a number of adjacent sectors. A modulator device (5) comprising a number of controllable beam sector modulators is present for controlling per sector the quantity of X-ray radiation transmitted. A detector (11) placed behind the body generates per sector a measurement signal representing a desired position of the beam sector modulator for that sector. During operation the instantaneous position of each beam sector modulator is continuously detected (20,21). Signals representing those positions are generated and compared with the respective measurement signals. Control signals are derived from the comparisons to control the positions of the respective beam sector modulators.

Abstract: An ultrasound transducer generates a received signal in response to a reflected ultrasound signal. Polarity and phase information of the reflected ultrasound signal can be obtained by time-selectively amplifying the received signal with a specific gain function. The specific gain function is derived from the received signal itself and is independent of the polarity of the received signal.

Abstract: An apparatus for slit radiography is provided with a slot diaphragm to form a fan-shaped X-ray beam with which a body can be scanned. Controllable attenuating elements interact with the slit diaphragm to influence sectors of the fan-shaped X-ray beam. They are controlled by signals representing the instantaneous transmission of the body in the corresponding sectors. The hardness of the fan-shaped X-ray beam is varied periodically in a predetermined manner. Synchronously with the periodic variation of the hardness of the X-ray beam the attenuating elements are oscillated. The oscillation of the attenuating elements is superimposed at each instant on the instantaneous position determined by the signals representing the instantaneous body transmission. The amplitude of the oscillation is less than the height of the slit of the slit diaphragm. The influence on the X-ray beam is most at the instants at which the hardness is greatest.

Abstract: In a method for slit radiography a fan-shaped X-ray beam scans a body to form an X-ray shadow image. The fan-shaped beam is formed by a number of sectors situated next to each other. For each sector the transmitted X-ray radiation is controlled instantaneously during a scan by means of controllable beam sector modulators. The X-ray radiation is cyclically modulated in a predetermined manner for all the sectors taken together. The controllable beam sector modulators are individually controlled to select cyclically and in synchronism with the predetermined cyclic modulation a part of the X-ray radiation for each sector.

Abstract: In a method for slit radiography a fan-shaped X-ray beam scans a body to form an X-ray shadow image. The fan-shaped beam is formed by a number of sectors situated next to each other. For each sector the transmitted X-ray radiation is controlled instantaneously during a scan by means of controllable beam sector modulators. The X-ray radiation is cyclically modulated in a predetermined manner for all the sectors taken together. The controllable beam sector modulators are individually controlled to select cyclically and in synchronism with the predetermined cyclic modulation a part of the X-ray radiation for each sector.

Abstract: A multi-way loudspeaker system comprising at least two series connected loudspeakers (Z.sub.H, Z.sub.L) connected to a common signal input (1, 2) for reproducing different parts of the full frequency spectrum of an audio signal applied to the signal input and being provided with a passive dividing network including a first impedance (Z.sub.1) connected in parallel to a first loudspeaker (Z.sub.H) for reproducing a first part of the audio-frequency spectrum and a second impedance (Z.sub.2) connected in parallel to a second loudspeaker (Z.sub.L) for reproducing a second part of the audio-frequency spectrum. The loudspeaker system is provided with a compensating circuit consisting of a transformer (T) and an impedance (Z.sub.

Abstract: An apparatus and method for slit radiography, in which a body to be irradiated is scanned at least twice by means of a planar, fan X-ray beam emitted from an X-ray source (1) via a slit diaphragm (2), the hardness of which beam increases with each next scanning motion, in which an X-ray detector (6) mounted behind the body collects the radiation passed, sections of detection means (10), which sections are juxtaposed in the longitudinal direction of the X-ray detector, produce electrical signals depending upon the radiation collected by the respective X-ray detector sections, which signals are sampled during each scanning motion and are stored in a memory, and the diaphragm (2) includes controllable elements juxtaposed in the longitudinal direction of the slit in a plurality corresponding to that of the sections of the detection means, which controllable elements are each operative to locally block the slit diaphragm during a next scanning motion if a stored signal produced by the corresponding section of the

Abstract: The blooming effect in pictures of a television camera tube (such as a vidicon, an orthicon or an isocon) is counteracted by setting the cathode potential to a first standard value during one scan of the scanning electron beam and to a second value during a number of subsequent scans of the scanning electron beam. During the one scan picture information is obtained both about bright and dark parts of the picture. During the subsequent scans only picture information is obtained from relatively bright parts of the picture. The videosignals of the different scannings are stored and combined. The resulting combined videosignal comprises picture information about bright or dark parts of the image that otherwise would have been lost.

Abstract: A method of forming tomographic images in cross-sectional tomography, in which a body is irradiated by a flat X-ray beam at different angles for successively forming a plurality of profiles on an X-ray screen or an X-ray detector, and a tomogram is constructed from the profiles, wherein the body and the X-ray detector are kept stationary and that, for forming the different profiles, the source of the flat X-ray beam is moved in a relatively short path extending on the side of the body remote from the X-ray detector.

Abstract: A device for directly viewing an image on a film transparency, in which the illuminating light source is controlled on the basis of discrete information elements written into and stored in a two-dimensional memory during a preliminary image brightness scanning operation. At option, the light beam produced by the light source either has its intensity or its scanning velocity controlled, in order to accordingly vary the brightness level of elementary film surface regions.Velocity modulation is to be preferred as the beam brightness level can then be maintained at an optimally constant value, while the dynamic contrast range of the image viewed by the observer is substantially determined by the beam velocity modulation range.

Abstract: A method of, and apparatus for, determining the image transfer quality of an imaging system on the basis of the signal-to-noise ratio. A reference pattern comprising at least two different portions is presented to an input of the system. One portion provides a television output signal which is a measure for the noise, and another portion provides a television output signal comprising the same amount of noise in a combination with an image signal component. The television output signals are compared to determine the signal-to-noise ratio.

Abstract: A method and apparatus for recording and superimposing image information on the target of a scan converter tube. The image information is supplied in the form of an electric video signal by means whereof the electron beam projected from the cathode of the tube onto the target is modulated so as to form a charge image. The scan converter tube is alternatingly operated in the beam landing mode and in the secondary emission mode respectively.

Abstract: There is disclosed a method and apparatus for convoluting a signal representing a profile formed during X-ray tomography and a filter function wherein a one-dimensional image of the signal is expanded in a direction transverse to the line by means of an optical system whereby the expanded image is moved past masks in the direction of the line with the masks containing regions that are either fully transmissive or fully non-transmissive.

Abstract: A system for decoding a coded aperture image of an object exposed to short-wave radiation from a plurality of point sources positioned in space in accordance with a given distribution. The coded aperture image is displayed by a cathode ray tube having its screen optically coupled to the entrance screen of an image intensifier tube. This image intensifier tube is effective to consecutively shift its entrance screen image in its entirety along a field pattern of lines. The images thus produced on the exit screen of the intensifier tube are transferred through a mask system having a transparency pattern related to the distribution pattern of said point sources, to a detector which position wise integrates the light transmitted through said mask system.

Abstract: A tomogram is constructed from a plurality of profiles by means of back projection, the effect of the point spread function being eliminated by analog convolution with a suitable one- or two-dimensional function.