Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
  • G01T1/16—Measuring radiation intensity
  • G01T1/20—Measuring radiation intensity with scintillation detectors
  • G01T1/2012—Measuring radiation intensity with scintillation detectors using stimulable phosphors, e.g. stimulable phosphor sheets
  • G01T1/2014—Reading out of stimulable sheets, e.g. latent image
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
  • H04N1/40—Picture signal circuits

Definitions

• the object of the present invention is to provide a method for reading visual information stored on an image sheet t with a stimulating beam, whereby the stimulating beam is made to scan the sheet line by line and the light generated by the stimulating beam and emitting from the image sheet 10 is measured and converted into a signal which corresponds to visual information.
• Such a method is particularly used in connection with X-ray photography for reading so-called RIM plates (radiation 15 image plates) .
• RIM plates radiation 15 image plates
• Such a method and device is disclosed, for instance in U.S. patent 4,527,060.
• the reading of the RIM plate is carried out in such a way that a very small laser point is conducted on the surface
• the laser beam is made to scan the surface of the RIM plate by using a turnable mirror
• the mirror moves the laser point in a reciprocating movement across the RIM plate, while the plate is moved in a linear direction.
• the luminescent substances on the RIM plate comprise an 30 after-glow property which impairs image contrasts, however, particularly with respect to the image points subsequent to the highly irradiated spots.
• the invention is characterized by that which is disclosed in appended Claim 1.
• An essential feature of the invention is thus that the stimulating beam, generally a laser beam, is interrupted ' at a certain frequency and the light emitting from the RIM plate is measured and analyzed in synchronization with the interrupting of the stimulating beam. The light is always measured while the laser beam is on, and also is preferably measured at least once between the image points, that is, while the laser beam is off.
• Fig. 1 represents schematically the device for the reading of the RIM plate
• Fig. represents the functions related to the description of the method according to the invention.
• Reference number 1 of Fig. 1 denotes the laser source which emits laser beam L via turnable mirror 2 to RIM plate 3 which is to be read.
• the light emitting from the surface of the RIM plate is collected by light-conducting member 5 and guided via filter 6 to light multiplier 7, from which the signal is taken to processor 8 of the system.
• laser beam L is interrupted in the control of processor 8 at a certain frequency, for instance, approximately 1000 times per each line or the turning cycle of mirror 2.
• Galvanometer 10 which turns mirror 2 as well as the linearly moving carrier 4 of RIM plate 3, is controlled by processor 8.
• the digital information formed by processor 8 which corresponds to the visual information of RIM plate 3, is transferred to memory 9 where it can be further outputted in a suitable manner.
• system can further comprise other parts, such as amplifiers, additional optical members, etc., which have been omitted from figure 1, however, since they are not essential from the point of view of the invention.
• Point b represents the state of laser beam L; that is, the beam is switched on and off several hundred times during one line.
• Point c represents a measured signal or a signal of light multiplier 7, when the signal is always measured once per the state of the laser beam, that is, once while the laser beam is on and once while the laser beam is off.
• Point d represents, respectively, the signal of light multiplier 7 when two measurements are taken per each state of the laser beam.
• the portion of after-glow in the signal coming to the light multiplier can be compensated by subtracting the portion of after-glow of the previous image points from the signal which is measured while the laser is on, the latter portion of which can in turn be determined by the signal which is measured while the laser is off. Because the after-glow is gradually attenuated, the accuracy of compensation naturally improves as the number of measurements during each state of the laser beam is increased.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Physics & Mathematics (AREA)
• High Energy & Nuclear Physics (AREA)
• Molecular Biology (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Facsimile Scanning Arrangements (AREA)
• Image Input (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8530861

Family Applications (1)

Country Status (3)

Cited By (1)

Citations (7)

• 1990
  • 1990-07-30 FI FI903800A patent/FI86228C/fi not_active IP Right Cessation
• 1991
  • 1991-07-29 DE DE19914191827 patent/DE4191827T/de not_active Withdrawn
  • 1991-07-29 WO PCT/FI1991/000231 patent/WO1992002850A1/en active Application Filing

Patent Citations (7)

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