EP0225205A1 - Anordnung zur optischen Verarbeitung von Lichtbildern - Google Patents

Anordnung zur optischen Verarbeitung von Lichtbildern Download PDF

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Publication number
EP0225205A1
EP0225205A1 EP86402259A EP86402259A EP0225205A1 EP 0225205 A1 EP0225205 A1 EP 0225205A1 EP 86402259 A EP86402259 A EP 86402259A EP 86402259 A EP86402259 A EP 86402259A EP 0225205 A1 EP0225205 A1 EP 0225205A1
Authority
EP
European Patent Office
Prior art keywords
semi
modulator
processing system
image processing
reflecting plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP86402259A
Other languages
English (en)
French (fr)
Inventor
Jean-Pierre THOMSON-CSF Huignard
Gérard THOMSON - CSF Coussot
Bruno THOMSON - CSF Mourey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0225205A1 publication Critical patent/EP0225205A1/de
Withdrawn legal-status Critical Current

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06E—OPTICAL COMPUTING DEVICES; COMPUTING DEVICES USING OTHER RADIATIONS WITH SIMILAR PROPERTIES
    • G06E3/00—Devices not provided for in group G06E1/00, e.g. for processing analogue or hybrid data
    • G06E3/001—Analogue devices in which mathematical operations are carried out with the aid of optical or electro-optical elements
    • G06E3/005—Analogue devices in which mathematical operations are carried out with the aid of optical or electro-optical elements using electro-optical or opto-electronic means

Definitions

  • the invention relates to a system for optical processing of light images. It relates more particularly to a device for coherent optical image processing and is based on the use of an optical valve with electrical access.
  • the invention using the filtering principle thus described, makes it possible to produce a more compact optical image processing system because it does not require an alignment of the optical axes of the lenses.
  • its operation while being compatible with its operation at video rate, allows permanent memory of the filter.
  • the invention relates to an optical processing system for light images comprising: - a coherent light source located in the focal plane of a first lens and illuminating, using a beam, the lens which retransmits a collimated beam; - a first semi-transparent plate receiving the collimated beam; - A first spatial light modulator receiving, from the first semi-reflecting plate, said collimated beam, modulating it according to a first determined law, reflecting it and retransmitting a first modulated beam to the first semi-reflecting plate; - a second semi-reflecting plate receiving the first modulated beam supplied by the first semi-reflecting plate and transmitting it to a second lens; a second spatial light modulator located in the focal plane of the second lens receiving from said second said modulated beam, modulating it according to a second determined law, reflecting it and retransmitting a second modulated beam to the second semi-reflecting blade through the second lens; a light image detector receiving the second modulated beam supplied by the second
  • This system includes: - a two-dimensional SLM-1 spatial light modulator, the modulator is electrically accessible, that is to say that the optical modulation signal is registered on the modulator via a network of controlled electrodes and arranged orthogonally. - a lens L1 making it possible to generate the two-dimensional Fourier transform of the signal written on the SLM.1 spatial modulator. - A second SLM.2 spatial light modulator placed in the plane of the spectrum generated by the lens L1 and making it possible to obtain in this plane the product of the Fourier transform by a filtering function F (u, v) written on the SLM spatial modulator. 2. - A second lens L2 generating the inverse Fourier transformation. - A CCD detection device for the image thus processed, such as a camera detection device of the vidicon type or CCD solid-state camera.
  • the second SLM.2 spatial modulator Depending on the function entered on the second SLM.2 spatial modulator, it is possible to obtain in the plane of the detected image: - either a filtered image of certain spatial frequencies (for example by suppressing low frequencies for generating contours); - either a correlation peak translating the position and orientation of a reference object in a scene seen by the camera and whose video signal controls the first SLM.1 spatial modulator.
  • Each modulator can be produced using an electro-optical screen interposed on the path of the light beams, the light modulation effect of which is obtained by electrical control of the electro-optical material.
  • a screen is controlled by two networks of perpendicular electrodes: a network of horizontal electrodes H1 to Hn and a network of vertical electrodes V1 to Vn.
  • an inscription of the type represented in FIG. 3 can be carried out.
  • a transparency function of the high pass type is therefore in the plane of the Fourier transform of the signal, on the SLM.2 modulator.
  • This filter allows high spatial frequencies to pass, which leads to the generation of contours in the plane of the image detected on the camera.
  • the filter registered on the SLM.1 spatial modulator is dynamically modifiable and can be a function of the type of images to be analyzed.
  • R (x, y) represents the part of the image to be recognized and whose evolution we want to follow in real time.
  • R (u, v) is calculated by the numerical method from R (x, y) and is composed on the SLM.2 via the network of horizontal and vertical electrodes. This function constitutes the equivalent of a binary synthetic hologram registered in real time on the SLM.2 and whose generation algorithms are known.
  • the adapted filter can be modified dynamically depending on the type of object to be correlated and any changes in orientation and scale of this object in the scene to be analyzed.
  • This system comprises a light source S represented in the form of an optical fiber whose emission end is placed in a plane P1 corresponding to the focal plane of a first lens L1.
  • the lens L1 receives a divergent beam F1 emitted by the fiber S and provides a collimated beam F2 towards a first semi-reflecting plate M1.
  • This transmits part of the beam F2 to a first light modulator SLM.1 which reflects a beam F3 modulated according to the type of modulation imposed by the modulator SLM.1.
  • the semi-reflecting plate, M1 receiving the beam F3, reflects a beam F4 towards a second semi-reflecting plate M2. This reflects the beam F4 to a second lens L2.
  • the lens L2 performs in its focal plane (plane P2) the Fourier transform of the image conveyed by the beam F4.
  • plane P2 In this plane P2 is placed a second SLM.2 modulator on which a filtering function is displayed.
  • This second modulator reflects a filtered F5 beam.
  • the lens L2 receives this beam and performs a second Fourier transform.
  • the beam supplied by the lens is retransmitted, at least in part, to a CCD light image detector in the form of a beam F6.
  • the two modulators are identical. They are made using flat smectic liquid crystal screens.
  • FIG. 6 shows such a flat screen. It comprises: a substrate E2 carried by a heating plate E3 intended to bring the screen to a determined temperature; electrodes E5, of reflecting metallic material, deposited on the substrate E2; a transparent plate E1 carrying conductive and transparent electrodes E4, shims of thicknesses E6 delimiting a space between the substrate E2 and the plate E1, and intended to receive a liquid crystal E7.
  • the liquid crystal used is of smectic type A such that it has two stable structures which can coexist: - an optically transparent ordered structure shown in FIG. 6 in the representation on the left; - a disordered structure ("Focal conics") diffusing, represented in FIG. 6 in the representation on the right.
  • the passage from one to the other of these structures is obtained by local heating and application or not of an electric field.
  • the heating, as well as the application of the field to the single point of coordinates XY is done via a network of row and column electrodes.
  • the diagram in Figure 7 illustrates the operation of a smectic liquid crystal.
  • T SN smectic-nematic transition temperature
  • T NT Nematic-liquid transition temperature isotropic
  • the liquid crystal If, then the liquid crystal is simply cooled, it returns, as indicated by the arrow T2, to the smectic phase after having passed through a nematic phase.
  • the structure which it adopts is disordered and then has diffusing optical properties.
  • the liquid crystal returns to the smectic phase and adopts an ordered structure providing it with optical properties transparent to light.
  • the exemplary embodiment of FIG. 5 is adapted to a compact design of an image processing system.
  • the only L2 lens is used for the generation of Fourier transformations in both direct and reverse directions.
  • the two modulators SLM.1 and SLM.2 produced using liquid crystal screens operate in reflection of light using reflective electrodes (electrodes E5 in FIG. 6).
  • the liquid crystal displays used for modulators have row and column electrodes which are powered by generators G1 and G2.
  • the system of the invention further comprises a DET detection circuit receiving image signals detected by the CCD detection device. Depending on the value or the form of the signals received, the detection circuit DET supplies appropriate signals on outputs DET1 and DET2 to control circuits CSLM1 and CSLM2. These circuits supply on outputs CS1 and CS2 control signals transmitted to the generators G1 and G2 allowing the latter to adapt the supply of the line and column conductors of the SLM.1 and SLM.2 modulators to the detection carried out. .
  • a decision circuit DEC is connected to the detection circuit DET and, depending on the detection carried out, provides any decision signal necessary in the context of the application of the system of the invention.
  • the image is recorded electrically from a video signal by control of electrodes arranged orthogonally. Optically the image is re-read by reflection on the electrodes E5.
  • the image therefore consists of a network of reflecting or diffusing points.
  • the other characteristics of the SLM.1 and SLM.2 modulators are as follows: - no coupling between pixels, -possibility of selective erasure, -permanent memory of the image, -registering and erasing the image at video rate, -a few gray levels can be obtained by checking the registration parameters (heating time).
  • the SLM.1 and SLM.2 modulators may have the following characteristics: - resolution: 256 x 256 - pitch of the matrix: 40 ⁇ m - dimension: 10 x 10 mm2 - frame rate: video frequency - image contrast in operation in coherent light 1/100.
  • the SLM.1 modulator will be lit by a semiconductor laser or an optical fiber end emitting in the near infrared, ie a wavelength typically of 850 nm.
  • the SLM.2 modulator is placed in the Fourier plane of the image signal written on the SLM.1 modulator.
  • the CCD image detector is placed in the detection plane for reading the processed image or the correlation peak.
  • the system of the invention thus described has the advantage of allowing direct control of the space modulators from video signals and via the row and column electrodes.
  • the operation is dynamic both for the intro duction of the image signal and for the spatial filtering of the image.
  • the modulators used operate by controlling the diffusion of each elementary point: consequently the contrast of a point is high (1/100) in coherent and uniform light throughout the image plane. This is an important characteristic compared to other devices operating by variation of the birefringence of a liquid crystal and which exhibit poor uniformity.
  • each modulator of an elementary image point is adapted to the production of compact devices. For example, take a focal length of the lens L 20 cm; and a diameter of 2-3 cm.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal (AREA)
  • Mathematical Physics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
EP86402259A 1985-10-16 1986-10-10 Anordnung zur optischen Verarbeitung von Lichtbildern Withdrawn EP0225205A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8515304A FR2588675A1 (fr) 1985-10-16 1985-10-16 Systeme de traitement optique d'images lumineuses
FR8515304 1985-10-16

Publications (1)

Publication Number Publication Date
EP0225205A1 true EP0225205A1 (de) 1987-06-10

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EP86402259A Withdrawn EP0225205A1 (de) 1985-10-16 1986-10-10 Anordnung zur optischen Verarbeitung von Lichtbildern

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EP (1) EP0225205A1 (de)
FR (1) FR2588675A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU616640B2 (en) * 1986-10-17 1991-11-07 Global Holonetics Corporation Transform optical processing system
US6353673B1 (en) 2000-04-27 2002-03-05 Physical Optics Corporation Real-time opto-electronic image processor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0152186A2 (de) * 1984-02-07 1985-08-21 Stc Plc Optische Korrelationsvorrichtung

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0152186A2 (de) * 1984-02-07 1985-08-21 Stc Plc Optische Korrelationsvorrichtung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
APPLIED OPTICS, vol. 22, no. 16, 15 août 1983, pages 2401-2402, New York, US; R.P. BOCKER: "Advanced RUBIC cub processor" *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU616640B2 (en) * 1986-10-17 1991-11-07 Global Holonetics Corporation Transform optical processing system
US6353673B1 (en) 2000-04-27 2002-03-05 Physical Optics Corporation Real-time opto-electronic image processor

Also Published As

Publication number Publication date
FR2588675A1 (fr) 1987-04-17

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