EXHIBIT 1307
`
`EUROPEAN PATENT APPL NO. 0 353 200, PUBLISHED JAN. 31, 1990
`
`("VENTURELLO")
`
`TRW Automotive U.S. LLC: EXHIBIT 1307
`PETITION FOR INTER PARTES REVIEW
`OF U.S. PATENT NUMBER 8,599,001
`
`

`

`®
`
`®
`
`Europaisches Patentamt
`European Patent Office
`Dffice europeen des brevets
`
`(J) Publication number:
`
`0 3 5 3 2 0 0
`A 2
`
`EUROPEAN PATENT APPLICATION
`
`(S) Application number: 89830261.7
`
`@ Date of filing: 13.06.89
`
`<§) lnt.CI.5: G 01 S 1 7 / 1 0
`G 01 S 17/88
`
`© Priority: 27.06.88 IT 6760688
`
`© Date of publication of application:
`31.01.90 Bulletin 90/05
`
`Designated Contracting States: DE ES FR GB SE
`
`© Applicant: FIAT AUTO S.p.A.
`Corso Giovanni Agnelli 200
`l-10135Torina (IT)
`
`@ Inventor: Venturello, Giorgio
`Via Modigliani, 5
`1-10137 Torino (IT}
`
`@ Representative: Bosotti, Luciano et al
`c/o Jacobacci-Casetta & Perani S.p.A. Via Alfieri, 17
`1-10121 Torino (IT)
`
`The title of the invention has been amended (Guidelines for Examination in the EPO, A-lll, 7.3).
`@ Method and device for instrument-assisted vision in poor visibility, particularly for driving in fog.
`@ The method comprises the steps of:
`- illuminating a portion of space situated in the region through
`which the vehicle is about to travel (1) by means of a plurality of
`pulses (5, 6) emitted at predetermined time intervals;
`- monitoring the scene in front of the vehicle (1), including the
`light which is reflected back by the obstacle (3) in respective
`time windows;
`- reconstructing the image graphically, and
`- displaying the reconstructed and processed image on the
`windscreen.
`
`CM
`<
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`CM
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`8
`CO
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`Q.
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`Bundesdruckerei Berlin
`
`1307-001
`
`

`

`Description
`Description
`A method and device for instrumental vision in conditions of poor visibility, particularly for driving in fog
`A method and device for instrumental vision in conditions of poor visibility, particularly for driving in fog
`The present invention relates in general to the display of scenes in conditions of low visibility.
`The present invention relates in general to the display of scenes in conditions of low visibility.
`In particular, the present invention has been developed with a view to its possible use for facilitating the
`In particular, the present invention has been developed with a view to its possible use for facilitating the
`driving of motor vehicles in conditions of poor visibility, for example in fog.
`driving of motor vehicles in conditions of poor visibility, for example in fog.
`Devices which use equipment with radar systems have already been proposed for identifying objects in fog.
`Devices which use equipment with radar systems have already been proposed for identifying objects in fog.
`Whilst they enable objects to be located in conditions of poor visibility, these devices are not without
`Whilst they enable objects to be located in conditions of poor visibility, these devices are not without
`disadvantages for use in motor vehicles since the instrumental information they supply is not readily
`disadvantages for use in motor vehicles since the instrumental information they supply is not readily
`understood by the average driver.
`understood by the average driver.
`In general, the problem with vision in fog, both during the day and at night, results from the low level of
`In general, the problem with vision in fog, both during the day and at night, results from the low level of
`illumination of the detector by the object to be detected compared with the level generated by the scattering of
`illumination of the detector by the object to be detected compared with the level generated by the scattering of
`the ambient light by the fog itself.
`the ambient light by the fog itself.
`In fact, the scattering by the fog obviously affects all of the illuminated space and the signal detected by the
`In fact, the scattering by the fog obviously affects all of the illuminated space and the signal detected by the
`receiver is dependent on the space itself and on the laws by which the light is attenuated/propagated in the
`receiver is dependent on the space itself and on the laws by which the light is attenuated/propagated in the
`receiving geometry in question.
`receiving geometry in question.
`The presence of an object to be detected in order to describe the scene, however, is connected only with
`The presence of an object to be detected in order to describe the scene, however, is connected only with
`reflection/scattering by the surface of the object which faces the receiver.
`reflection/scattering by the surface of the object which faces the receiver.
`As a result, the signal/noise ratio is largely dependent on the density of the scattering medium in the space
`As a result, the signal/noise ratio is largely dependent on the density of the scattering medium in the space
`between the observer and the object.
`between the observer and the object.
`Moreover, regardless of the method used for detecting the image of the scene, there are two basic
`Moreover, regardless of the method used for detecting the image of the scene, there are two basic
`aproaches to the problem of using the information obtained:
`aproaches to the problem of using the information obtained:
`a) the reproduction of a processed scene which still contains the shape and appearance of what the
`a) the reproduction of a processed scene which still contains the shape and appearance of what the
`observer would see if the visibility were better (interpretation and decision on the part of the observer) ;
`observer would see if the visibility were better (interpretation and decision on the part of the observer);
`b) the reproduction of summarised information concerning the contents of the scene without the
`b) the reproduction of summarised information concerning the contents of the scene without the
`"photographic" reconstruction thereof (interpretation -and decision - on the part of the automatic
`"photographic" reconstruction thereof (interpretation -and decision - on the part of the automatic
`system).
`system).
`Case a) includes television systems for detection in the visible and near-infrared; case b) includes
`Case a) includes television systems for detection in the visible and near-infrared; case b) includes
`microwave radar systems and passive thermographic systems, whilst far-infrared (10 micron) systems with
`microwave radar systems and passive thermographic systems, whilst far-infrared (10 micron) systems with
`active illumination belong to an intermediate category.
`active illumination belong to an intermediate category.
`Essentially, the object of the present invention is to provide means for seeing in conditions of poor visibility,
`Essentially, the object of the present invention is to provide means for seeing in conditions of poor visibility,
`which are suitable for application in the automotive field, particularly with regard to driving in fog, and at the
`which are suitable for application in the automotive field, particularly with regard to driving in fog, and at the
`same time ensure reliable monitoring, even in critical conditions, and the ability to reconstitute for the driver
`same time ensure reliable monitoring, even in critical conditions, and the ability to reconstitute for the driver
`visual information which is immediately recongisable as an image of the scene at which he is looking.
`visual information which is immediately recongisable as an image of the scene at which he is looking.
`According to the invention, this object is achieved by virtue of a method for detecting images of an object in
`According to the invention, this object is achieved by virtue of a method for detecting images of an object in
`conditions of poor visibility, characterised in that it comprises the steps of:
`conditions of poor visibility, characterised in that it comprises the steps of:
`- sending a train of light pulses towards the object,
`- sending a train of light pulses towards the object,
`- observing the object illuminated by the pulses in respective time windows,
`- observing the object illuminated by the pulses in respective time windows,
`- reconstructing images of the object from the observation in the respect time windows, and
`- reconstructing images of the object from the observation in the respect time windows, and
`- displaying the image thus reconstructed.
`- displaying the image thus reconstructed.
`A further object of the present invention is a device for detecting images of an object in conditions of poor
`A further object of the present invention is a device for detecting images of an object in conditions of poor
`visibility, particularly by the method specified above, characterised in that it comprises:
`visibility, particularly by the method specified above, characterised in that it comprises:
`- illumination means for sending a train of light pulses towards the object,
`- illumination means for sending a train of light pulses towards the object,
`- televisual means for observing the object illuminated by the pulses and for generating corresponding
`- televisual means for observing the object illuminated by the pulses and for generating corresponding
`television signals, the televisual means including a shutter which is operable selectively to make the televisual
`television signals, the televisual means including a shutter which is operable selectively to make the televisual
`45 means sensitive only in respective time windows,
`means sensitive only in respective time windows,
`45 (cid:9)
`- processor means for reconstructing images of the object from the television signals obtained, and
`- processor means for reconstructing images of the object from the television signals obtained, and
`- display means for presenting the reconstructed images.
`- display means for presenting the reconstructed images.
`For a better understanding of the invention, a description of an embodiment of the invention will now be
`For a better understanding of the invention, a description of an embodiment of the invention will now be
`given, purely byway of non-limiting example, with reference to the appended drawings, in which:
`given, purely by way of non-limiting example, with reference to the appended drawings, in which:
`- Figure 1 shows schematically a possible situation of use of an instrumental vision device according to
`- Figure 1 shows schematically a possible situation of use of an instrumental vision device according to
`the invention, and
`the invention, and
`- Figure 2 shows the structure of part of the device of Figure 1 in greater detail, in the form of a block
`- Figure 2 shows the structure of part of the device of Figure 1 in greater detail, in the form of a block
`diagram.
`diagram.
`With reference to Figure 1 , a car, indicated 1 , is provided with a device 2, 4 for detecting, in accordance with
`With reference to Figure 1, a car, indicated 1, is provided with a device 2, 4 for detecting, in accordance with
`the invention, the preence of a moving car 3 which is not visible to the driver of the vehicle because of fog
`the invention, the preence of a moving car 3 which is not visible to the driver of the vehicle because of fog
`between the two vehicles 1 and 3. A lamp, indicated 4, preferably with monochromatic emission (for example,
`between the two vehicles 1 and 3. A lamp, indicated 4, preferably with monochromatic emission (for example,
`operating at a wavelength X of the order of 900 nm), is mounted on the front part of the car 1 and can emit light
`operating at a wavelength 2‘., of the order of 900 nm), is mounted on the front part of the car 1 and can emit light
`pulses of a duration t (e.g. 10-8 seconds) with a frequency of repetition f=1/T equal to an average of 3 KHz,
`pulses of a duration ^c (e.g. 10-8 seconds) with a frequency of repetition f = 1/T equal to an average of 3 KHz,
`where T represents the interval between the pulses.
`where T represents the interval between the pulses.
`Each pulse emitted by the lamp 4 is propagated in the space in front of the car 1 and illuminates a respective
`Each pulse emitted by the lamp 4 is propagated in the space in front of the car 1 and illuminates a respective
`"window" or "slice" with a depth C x (where C is the speed of light in the medium) equal, for example, to
`"window" or "slice" with a depth C ti (where C is the speed of light in the medium) equal, for example, to
`approximate^ metres (not to scale in the drawings) . This window moves forwards towards the car 3 as shown
`approximately3 metres (not to scale in the drawings). This window moves forwards towards the car 3 as shown
`schematically in Figure 1 where 5 and 6 represent the successive positions reached by the window
`schematically in Figure 1 where 5 and 6 represent the successive positions reached by the window
`
`55
`55 (cid:9)
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`35
`35 (cid:9)
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`40
`40 (cid:9)
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`so
`50 (cid:9)
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`60
`60 (cid:9)
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`5
`5 (cid:9)
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`w
`10 (cid:9)
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`15
`15 (cid:9)
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`20
`20 (cid:9)
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`25
`25 (cid:9)
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`30
`30 (cid:9)
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`iP 0 353 200 A2
`EP 0 353 200 A2
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`2
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`1307-002
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`EP 0 353 200 A2
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`corresponding to a given light pulse or, alternatively, the positions reached at the same time by two pulses
`smitted in succession.
`In the case of the window 5, which illuminates a space without obstacles, it is clear that no image will be
`•etumed to the vehicle 1 , except that due to the backscattering caused by the fog.
`In the case of the window 6, however, both the fog and the obstacle (the vehicle 3) will contribute to the
`signal since, in this case, the useful back-scattering region 7, that is, the rear part of the car 3 is included in the
`space illuminated by the pulse.
`The reference numeral 2 indicates a processing system which is also mounted on the front part of the car t
`and is constituted by a lens 8 adapted to focus the reflected image of the obstacle 3 (whose intensity is very
`low) onto an image intensifier 10. In this way, a completely reconstructed image of the vehicle 3 is provided by
`the subsequent processing of the intensified signal by a televisual sensor 11 (for example, of the CCD type), by
`the respective management unit (television camera) 12, and by a processing and control system 13 and 14.
`The image reconstructed by the processing and control system 13, 14 (which also controls the operation of
`the lamp 4) can then be presented on the windscreen by means of a head-up display unit 15, according to
`criteria widely known in the aeronautical field. The driver can thus see the obstacle 3 with the exact dimensions
`and at the exact distance at which it is situated, under just the same conditions as those governing vision
`jnder conditions of normal visibility.
`The image intensifier 10 used in the device according to the invention is adapted for pulsed operation and
`thus also for performing the task of a shutter (as will be specified below) so as better to discriminate between
`the backscattering from the obstacle to be displayed and that from the fog.
`According to a variant of the invention, the rapid obturation of the television camera 11 , 12 carriedout by the
`intensifier device 10 may alternatively be achieved by control of the grid voltage of any vacuum tube (e.g. a
`i/idicon) which replaces the CCD televisual sensor 11, or at any rate other sensors for carrying out these
`Functions.
`In order better to understand the criteria governing the pulsed operation of the intensifier shutter 10 (or a
`member equivalent thereto) which is controlled by the system 14 through a piloting line 16, it should be noted
`that any object lying in a space illuminated by the pulses from the lamp 4 reflects back/scatters the incident
`light. The sources of the light "echo" are located in the space and are active continuously or in pulses at the
`moment when the illuminating wave front 5, 6 strikes them.
`If a scattering medium (fog) is present, in addition to the attenuation of all the light signals passing through
`it, there is also an emission (continuous or pulsed) of backscattered radiation constituting a background
`which can rapidly mask the other signal sources.
`However, if only pulsed illumination is considered, there is, at any moment, a layer (whose shape depends
`on the illuminating lens) with a thickness c x (c = the speed of light, t = pulse duration). If a receiving time
`window of a duration x is opened (by means of the actuator 10) with a delay nt(n= 1,2, 3...) relative to the
`illuminating pulse, an image of a "slice" of the space of a thickness c x at a distance
`
`n
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`"V.. c
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`2
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`is obtained.
`If there is an object in this slice, the ratio between the signal reflected back/scattered by the object and that
`scattered back by the fog in the space is at a maximum.
`This signal is propagated towards the receiver 2 and is attenuated due to the characteristics of the
`propagation medium, but the original signal/background ratio remains unaltered.
`This is because the receiving time selected by the shutter 10 excludes all the signal contributions outside
`the selected "slice".
`Since the positions of various objects in the scene are not known beforehand, it is necessary to carry out a
`scanning sweep through the entire space up to the greatest distance of interest in order to achieve complete
`monitoring.
`Quantitatively, and as a first approximation, the improvement in the signal/background (S/N) ratio resulting
`from the use of a pulsed illumination-detection system can be evaluated by considering that:
`1) with continuous illumination, this ratio (S/N) is proportional to Ro/Rv where Ro is the signal reflected
`back/scattered by the object to be displayed (vehicle 3) and Rv is the signal scattered back by the volume
`of fog concerned between the object 3 and the receiver 2;
`2) with pulsed illumination (of repetition N), the (S/N) ratio is proportional to
`
`N
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`i ..Ro
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`.
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`where D is the maximum distance monitored.
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`EP 0 353 200 A2
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`The convenience of having illumination pulses (lamp 4) and receiving windows (shutter 10) of equal and
`short duration (10 ns) is obvious. If a standard television earner (11, 12) is used as the sensor and it is
`proposed to take a "slice" for every frame (1/25 sec, 1/30 sec) with a maximum S/N ratio, pulses of 10 ns
`would be required.
`A reasonable number Nq of frames for the reconstruction of a scene would be approximately 50, thus
`covering a maximum monitored distance
`D = Nq . x . c=50 . 10-s . 3 . 10"8 = 150 m is 1.5 s.
`Information on the distance would thus be associated with each frame, enabling an immediate
`three-dimensional reconstruction of the scene.
`However, it is clearly necessary to increase the acquisition rate by one order of magnitude to achieve
`detection rates more appropriate for monitoring the road (0.1 s). This can also be achieved but, combined with
`the above requirement, involves rather complex management of the television camera.
`In order to simplify this management, it is possible to integrate the contributions of the Nq light pulses
`necessary to cover with slices the whole space concerned up to the distance D in the television camera, in a
`standard time frame (1/25s - 1/30s).
`This can be done by summing Nq light pulses of a duration x with Nq openings of a duration x with increasing
`delays until the maximum distance concerned is covered for each television frame; in this case, the total
`exposure (E) of the television camera for each television frame will be
`E = N x (= 5 . 10"7 s).
`Alternatively, with even simpler management, receiving windows with a duration T = -f - may be opened for
`each light pulse emitted.
`Thus, the total exposure (E) of the television camera for each frame is
`
`E = Nq
`
`2D
`c
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`= Nq 2
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`cNq
`c
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`(5= 5 . 1 0 _ 5 s )
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`5
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`55
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`It is considered that, apart from the contribution of any light sources other than the active one, this second
`hypothesis provides a signal/background ratio which is worse by a factor less than or equal to 2 than the
`previous one since the time for which the scattering space is illuminated is equal in both cases (Nq. x) and the
`accumulation of signals due to backscattering by the fog is Nq x in one case and 2Nq2 x in the other, whilst the
`contribution of the objects present in the scene remains constant but is summed only once in the first case
`and Nq times in the second (the factor is less than or equal to 2 because the additional integration relates to
`the space between D and 2D). Therefore, in the two cases:
`Case 1 - Background = E = Nq x
`Signal = 1
`S/N = 1/Nq
`40 Case - Background = Nq . -f- = 2 Nq2 x
`Signal = Nq x
`S/N = 1/2 Nq.
`In each case, however, it is possible to cancel out the contribution from the backscattering in the space in
`the immediate vicinity of the receiver where it is most intense (blind space).
`The attenuation of signals due to propagation in the scattering medium (which may possibly be
`compensated for by an increase in the power emitted by the light source 4 so as to retain visibility by virtue of
`the better signal/interference ratio) will not be considered herein, but that resulting from the pulsed-light
`method will be considered.
`It is clear that the pulsed method provides a signal which is inferior by a factor 1/N x to that with continuous
`light.
`With reference to the typical values indicated above, the order of magnitude of this reduction is
`approximately 6 . 104.
`The signal recovery can take place with the use of intensifying television cameras in which the intensifier 10
`acts both as such and as a rapid shutter.
`Television cameras of this type are currently available commercially. For example, known antiblooming CID
`television cameras which are produced by General Electric and intensify with an optical gain of 5000 are
`capable of pulsed operation with rise times of the order of 5ns.
`In order to minimise the interference generated by the environment, such as daylight or street lighting, it is
`possible to carry out optical filtering at the wavelength of the monochromatic light used for the active emission
`associated with a limited opening time of the television camera (e.g. 5.10-5 s of exposure per frame) or even to
`increase the power emitted by the lamp 4.
`As regards interference caused by passing vehicles, if they are provided with the same device 2, 4 operating
`at the same wavelength, frequency of repetition, and duration of acquisition time-windows, the law of casual
`coincidence between non-synchronised devices applies. The number of coincidences, that is, the direct
`illumination of the sensor unit 2 in one vehicle by the lamp 4 of another vehicle, is 2NT = 2 . 1.5 . 103 . 106 =
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`60
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`65
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`4
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`1307-004
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`P 0 353 200 AZ
`EP 0 353 200 A2
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`.10-3 for each vehicle passed.
`3.10-3 for each vehicle passed.
`This coincidence poses problems only of signal dynamics (which are easily resolved since they relate to
`This coincidence poses problems only of signal dynamics (which are easily resolved since they relate to
`ulses) whilst the probability of the passing vehicle being detected is increased and the performance of the
`pulses) whilst the probability of the passing vehicle being detected is increased and the performance of the
`ystem is therefore slightly improved.
`system is therefore slightly improved.
`
`ilaims
`Claims
`1 . A method for detecting images of an object (3) in conditions of poor visibility, characterised in that it
`1. A method for detecting images of an object (3) in conditions of poor visibility, characterised in that it
`comprises the steps of:
`comprises the steps of: (cid:9)
`- sending (4) a train of light pulses (5, 6) towards the object (3) ;
`- sending (4) a train of light pulses (5, 6) towards the object (3);
`- observing (2) the object (3) illuminated by the pulses (5, 6) in respective time windows (10) ;
`- observing (2) the object (3) illuminated by the pulses (5, 6) in respective time windows (10);
`- reconstructing (12 to 14) images of the object (3) from the observations in the respective time windows
`- reconstructing (12 to 14) images of the object (3) from the observations in the respective time windows
`(5, 6) and
`(5, 6) and
`- displaying (15) the images thus reconstructed.
`- displaying (15) the images thus reconstructed. (cid:9)
`2. A method according to Claim 1, characterised in that the pulses (5, 6) are monochromatic light
`2. A method according to Claim 1, characterised in that the pulses (5, 6) are monochromatic light
`pulses (4), preferably with a wavelength X substantially equal to 900 nm.
`pulses (4), preferably with a wavelength A. substantially equal to 900 nm.
`3. A method according to Claim 1 or Claim 2, characterised in that the object (3) is observed in
`3. A method according to Claim 1 or Claim 2, characterised in that the object (3) is observed in
`substantially monochromatic conditions.
`substantially monochromatic conditions.
`4. A method according to Claim 2 and Claim 3, characterised in that the object (3) is observed by means
`4. A method according to Claim 2 and Claim 3, characterised in that the object (3) is observed by means (cid:9)
`of filtering at a wavelength which corresponds substantially to the wavelength of the monochromatic light
`of filtering at a wavelength which corresponds substantially to the wavelength of the monochromatib light
`(14) of the pulses (5,6).
`(14) of the pulses (5, 6).
`5. A method according to any one of Claims 1 to 4 characterised in that the duration of each observation
`5. A method according to any one of Claims 1 to 4 characterised in that the duration of each observation
`time window is of the same order of magnitude as the duration of each light pulse (5, 6).
`time window is of the same order of magnitude as the duration of each light pulse (5, 6).
`6. A method according to any one of Claims 1 to 4, characterised in that each observation time window
`6. A method according to any one of Claims 1 to 4, characterised in that each observation time window (cid:9)
`has a duration equal to a plurality (Nq) of light pulses (5, 6).
`has a duration equal to a plurality (Nq) of light pulses (5, 6).
`7. A method according to Claim 1 or Claim 6, characterised in that each observation time window has a
`7. A method according to Claim 1 or Claim 6, characterised in that each observation time window has a
`duration T with
`duration T with
`T = -f-
`T =
`where c is the speed of light in the observation medium and D is the maximum permitted distance of the
`where c is the speed of light in the observation medium and D is the maximum permitted distance of the (cid:9)
`object.
`object.
`8. A device for detecting images of an object (3) in conditions of poor visibility, particularly by the
`8. A device for detecting images of an object (3) in conditions of poor visibility, particularly by the
`method according to Claim 1 , characterised in that it comprises:
`method according to Claim 1, characterised in that it comprises:
`- illumination means (14) for sending a train of light pulses (5, 6) towards the object (3) ;
`- illumination means (14) for sending a train of light pulses (5, 6) towards the object (3);
`- televisual means (10 to 12) for observing the object (3) illuminated by the pulses and for generating
`- televisual means (10 to 12) for observing the object (3) illuminated by the pulses and for generating (cid:9)
`corresponding television signals, the televisual means including a shutter (10) which is operable
`corresponding television signals, the televisual means including a shutter (10) which is operable
`selectively (14, 16) so as to make the televisual means sensitive only in respective time windows,
`selectively (14, 16) so as to make the televisual means sensitive only in respective time windows,
`- processor means (13) for reconstructing images of the object (3) from the television signals obtained,
`- processor means (13) for reconstructing images of the object (3) from the television signals obtained,
`and
`and
`- display means (15) for presenting the reconstructed images.
`- display means (15) for presenting the reconstructed images. (cid:9)
`9. A device according to Claim 8, characterised in that the illumination means (4) generate
`9. A device according to Claim 8, characterised in that the illumination means (4) generate
`monochromatic light, preferably with a wavelength X substantially equal to 900 nm.
`monochromatic light, preferably with a wavelength X substantially equal to 900 nm.
`10. A device according to Claim 8 or Claim 9, characterised in that the televisual means (10 to 12) have a
`10. A device according to Claim 8 or Claim 9, characterised in that the televisual means (10 to 12) have a
`substantially monochromatic sensitivity due to optical filtering.
`substantially monochromatic sensitivity due to optical filtering.
`11. A device according to Claim 9 and Claims 10, characterised in that the televisual means (10 to 12)
`11. A device according to Claim 9 and Claims 10, characterised in that the televisual means (10 to 12) (cid:9)
`have a monochromatic sensitivity which substantially corresponds to the monochromatic light generated
`have a monochromatic sensitivity which substantially corresponds to the monochromatic light generated
`. by the illumination means (4).
`by the illumination means (4).
`12. A device according to any one of Claims 8 to 10, characterised in that the televisual means (10 to 12)
`12. A device according to any one of Claims 8 to 10, characterised in that the tel