Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/04—Synchronising
  • H04N5/06—Generation of synchronising signals
  • H04N5/067—Arrangements or circuits at the transmitter end
  • H04N5/073—Arrangements or circuits at the transmitter end for mutually locking plural sources of synchronising signals, e.g. studios or relay stations
  • H04N5/0733—Arrangements or circuits at the transmitter end for mutually locking plural sources of synchronising signals, e.g. studios or relay stations for distributing synchronisation pulses to different TV cameras
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/90—Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
  • H04N23/70—Circuitry for compensating brightness variation in the scene
  • H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof

Definitions

• the present invention relates to the field of image acquisition equipment.
• the present invention relates more particularly to a high-speed camera.
• the application EP 1 176 812 proposes to further increase the acquisition frequency by disclosing a fast camera comprising a means for separating incident rays to four acquisition means. The rays obtained are then intensified and imaged by four CCD cameras whose acquisition times are shifted relative to each other.
• Such a method is limited by the separation of the incident rays, which complicates the optical device which must include a pyramidal prism.
• ultrafast cameras of the type marketed by LaVision under the trade name UltraSpeedStar. Such cameras can achieve frequency performance of the order of 1 MHz for an image frame.
• Such a camera comprises a sensor segmented into different areas of CMOS, each CMOS area being successively activated.
• Such a camera has the disadvantage of being very expensive because of the need for a very specific segmented sensor.
• a further disadvantage of such a device is that the increase in the number of recorded images is to the detriment of the resolution of these images, the sensor used having a fixed resolution.
• the present invention relates to a fast camera comprising at least one objective (1) capable of forming an image, and a plurality of acquisition modules, each of said modules comprising a shutter means (2) and a means of image forming (2a), image scanning means (3) and means for storing a digitized image (3a), said fast camera further comprising control means (4) for each of said means for shutter capable of opening them during a predetermined exposure time, characterized in that said image forming means is arranged to receive said image of said shutter means, and in that said fast camera comprises a control means ( 5) arranged to drive said digitizing means (3), said control means being synchronized with said control means so as to activate the digitization when said shutter means associated with said digitizing means within a module of acquired ition is open.
• “Fast camera” the camera formed by all the acquisition modules according to the invention.
• the cameras possibly included in the acquisition modules will be called “standard camera”.
• control means is synchronized with the control means so as to activate the scanning when the shutter means is open allows the use of standard cameras with a relatively long acquisition time as acquisition module to form an ultra fast camera.
• FIG. 1 schematically represents one of the modules of FIG. acquisition included in the fast camera according to the invention
• FIG. 2 schematically represents a fast camera according to the invention comprising a plurality of acquisition modules.
• FIG. 3 represents the pulse times of the intensifiers and standard cameras within the fast camera according to the invention;
• FIG. 4 is an exemplary 400V pulse power supply card of the intensifiers;
• FIG. 5 is an example of a low voltage synchronization card used for the invention;
• FIG. 6 is an exemplary control card for standard cameras according to the invention;
• FIG. 7A represents a support plate for fixing the standard cameras according to the invention;
• FIG. 7B represents a support plate for fixing the standard intensifiers according to the invention;
• FIG. 7C represents a support plate for fixing the objectives according to the invention.
• the fast camera according to the invention consists of a plurality of acquisition modules 10 as illustrated in FIG.
• a module comprises an objective 1, an image intensifier 2, and a smart standard camera 3 of the type comprising a memory 3a.
• the lens forms the image on the front face 2b of the image intensifier 2, which acts as a shutter.
• the intensifier blocks the image on its front face.
• the intensifier transmits the intensified image to its rear face 2a.
• the image is formed on the rear face 2a and is visible by the camera 3 during the power supply period.
• the standard camera 3 is in permanent capture, so that the image is recorded and stored in the memory 3a as soon as it is available.
• the captured image therefore corresponds to the image displayed frozen in time by the shutter.
• the image capture zone by the camera of the acquisition module 10 is adapted according to this embodiment, to the rear part of the intensifier and to its resolution.
• a plurality of acquisition modules 10 are available by shifting the opening time of the different shutters while ensuring that the standard cameras 3 of the modules of FIG. acquisitions are in image capture during this time, as shown in Figure 3.
• an intensifier as a shutter is particularly advantageous in connection with the present invention for fast shutter frequency.
• the intensifier known under the trade name SuperGen®, developed by the company Photonis has in fact a shutter period of less than 100 ns, and typically of the order of 50 ns.
• the intensifier used according to the present invention therefore has the function of both rapid shutter, the formation of the image to be acquired on its rear face, and the intensification of light rays.
• the acquisition modules comprise, for example, a standard VCM type camera.
• This type of camera comprises, in a manner known per se, means for digitizing the image from the received light signals, for example CCD or CMOS sensors.
• the standard cameras used comprise at least one memory 3a making it possible to store the received image.
• This memory makes it possible to preserve the captured image in order to restore thereafter at a viewing station for example computer type.
• each standard camera remains in the integration position for a long time while the associated shutter is not open. No light is captured (no light), except during the opening time of the shutter.
• each standard camera independently manages the transfer of the image to a memory. In the absence of such a memory 3a, the skilled person will understand that the image captured during the opening time of the shutter would be lost, and could not be visualized later.
• the contents of the memory of the standard cameras corresponding to the opening time of the shutter are then recovered by a computer program.
• the set of images recovered from the different acquisition modules then allows the reconstruction of a succession of images at a high frequency.
• Modules 4 and 5 for control and synchronization of standard cameras and intensifiers are now described. By synchronizing these two means, it is ensured that a standard camera of an acquisition module is able to scan the image when the associated shutter is open.
• the module 4 comprises, for example, a clock and a 400V power supply and a means of synchronization with the module 5.
• the latter makes it possible to power and control the cameras from a standard computer, for example of the PC type.
• the clock signal used is defined so that its frequency corresponds to the image acquisition frequency and the duration of its high level corresponds to the shutter time of the intensifiers.
• This pulse power supply card as illustrated in FIG. 4 feeds, for example, independently 2 image intensifiers.
• This card is able to transform a pulse of a fixed duration and a voltage varying from 0 to 5V, in a pulse of the same duration but a voltage varying from + 20V (low level) to -400V (high level) .
• the electrical characteristics of the intensifiers mean that these power supplies must be floating.
• FIG. 5 An example of a low-voltage synchronization card is for example illustrated in FIG. 5. It is a demultiplexing card with an input to 32 outputs. The input is connected to the clock, and the outputs are connected in pairs to a pulse supply board as shown in Figure 4. At each rising edge of the clock, the demultiplexer activates a different output, and there sends a pulse whose duration of the high level is defined by the shape of the clock.
• the control can also be achieved by a DSP type processor integrated into the standard intelligent camera and controlling the scanning. This DSP is synchronized with the shutter control means to ensure that scanning is assured when the shutter is open.
• the system according to the invention finally contains a computer application installed on a computer, for example PC type.
• This application performs the functions of acquisition and transfer of images from different cameras.
• Each camera has an RS232 link, which must be connected to a computer to be able to dialogue and exchange programs and data.
• a splitter as shown in Figure 6 allows the dialogue of a single computer with 12 cameras. For this, we send a control word on the parallel port of the computer corresponding to the number of the camera with which we wish to communicate, and the map of Figure 6 directs the RS232 flow to the corresponding camera. Here again it is a multiplexing card 1 to 12.
• a succession of plates carrying the successive elements of the camera according to the invention a camera support plate, an intensifier support plate, and an objective support plate. These plates are illustrated in FIGS. 7A, 7B and 7C.
• the optical support plate is such that each lens can translate independently. This allows each camera to view the same image while, due to their different positions, their points of view are different. This process is for example known as "lens shift".
• said camera further comprising control means (4) for each of said shutter means for opening them during a predetermined exposure time, and control means (5) of the digitizing means (3) synchronized with said control means so as to activate the digitization when the shutter means associated with the digitizing means within a acquisition module is open.
• FIG. 2 Illustrated in FIG. 2 and on the optical support FIG. 7C, there is shown a plurality of objectives, for example one per acquisition module.
• the objective of the fast camera can be unique if the field of the lens corresponds to all the acquisition modules according to the invention.
• the field of the lens used is adapted to the number of acquisition module of the fast camera according to the invention.
• an intensifier in acquisition modules for performing the functions of shutter and image formation. It is understood that it is also possible to use any known type of fast shut-off means, such as electro-optical cells, LCD panels or acousto-optical modulators, as well as any means of forming the image as a result shutter so that the standard camera can view the image as a frosted blade, a translucent screen.
• the fast camera according to the invention by virtue of its image acquisition frequency, is particularly suitable for imaging fast phenomena such as crack propagation.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Studio Devices (AREA)
• Cameras In General (AREA)
• Exposure Control For Cameras (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2005
  • 2005-08-05 FR FR0508395A patent/FR2889639B1/fr not_active Expired - Fee Related
• 2006
  • 2006-08-03 EP EP06794283A patent/EP1920596A2/de not_active Withdrawn
  • 2006-08-03 JP JP2008524547A patent/JP2009504046A/ja active Pending
  • 2006-08-03 US US11/997,972 patent/US20080211930A1/en not_active Abandoned
  • 2006-08-03 WO PCT/FR2006/001892 patent/WO2007017582A2/fr not_active Ceased

Non-Patent Citations (1)

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