OBSERVATION SYSTEM AND PROCEDURES

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the observation of a scene, and more particularly to observation using a portable system. STATE OF THE ART

[0002] Currently, there are monocular systems, or binoculars, used to observe scenes. These systems can be purely optical, that is, they include direct observation channels, for example, binoculars to observe a distant scene with magnification. Other systems, for example, digital cameras, include both a direct observation channel and a digital observation channel, that is, a channel using a digital sensor to develop a digital image of the observed scene. But these systems do not allow for effective observation of a scene at night.

[0003] Some systems allow viewing a night scene, including patent documents CN109974857 A, WO2018215066 A1, US9723227B2, US9167179B2 and US5254852 A, which disclose systems having a digital observation channel equipped with an infrared sensor; and European patent application EP1857854 A1, which discloses a system equipped with two independent infrared cameras.

[0004] Other systems can be adapted to observe a scene both day and night. For example, we can cite the international patent application WO201218812 which discloses an observation system comprising a direct observation channel, a digital observation channel using an infrared sensor and an optical fusion of the two channels. However, these systems are not effective enough for night observation.

[0005] The following patent documents can be cited: WO201216794 A1, WO200744582 A1, US7307793 B2, WO200569056 A2, WO2003104877 A1 and US6195206, which disclose observation systems having a digital observation channel provided with an infrared type sensor, a digital observation channel having a light intensity amplification device and which use optical fusion of the two channels.

[0006] We can also cite the American patent US8836793 B1, which discloses a system having two digital observation channels each equipped with an infrared type sensor, and which uses a digital fusion of the images from the sensors, and the following other patent documents: US6560029 B1 US7345277 B2, which disclose observation systems having a digital observation channel equipped with an infrared type sensor, a digital observation channel having a light intensity amplification device and which use a digital fusion of the images from the sensor and the amplification device.

[0007] But these systems consume a lot of energy and also require sufficient batteries, which make the systems heavier. SUMMARY OF THE INVENTION

[0008] One aim is to overcome these drawbacks, and more particularly to provide means of observation which are suitable for day and night vision, and whose consumption of electronic devices is reduced.

[0009] Another object is to provide lightweight portable means of observation.

[0010] Yet another object is to improve the observation of a scene in day and night vision.

[0011] Another object is to provide an observation system suitable for illuminating the scene to be observed while being sufficiently compact.

[0012] According to one aspect, an observation system is proposed, comprising a first optical path capable of receiving a first optical radiation emitted by a scene to be observed and comprising a first sensor configured to develop a first digital image from the first optical radiation; a second optical path capable of receiving a second optical radiation emitted by the scene and comprising a second sensor configured to develop a second digital image from the second optical radiation; a display configured to display a third digital image from the first and second digital images; and a third optical path coupled to the display and shaped to observe the third digital image.

[0013] The system comprises a fourth optical path connecting the first and third optical paths, and in that the first optical path comprises an optical element configured to transmit a portion of the first optical radiation to the fourth optical path.

[0014] The fourth optical channel allows direct observation of the scene, it is also called direct observation channel. Thus, we provide an observation system that limits the consumption of the sensors, since it is suitable for use in daytime vision in the absence of a battery.

[0015] According to one embodiment, the system comprises an optical assembly comprising the optical element and an optical system configured to transmit the portion of the first optical radiation from the fourth optical path to the third optical path.

[0016] According to another embodiment, the system comprises an optical assembly comprising the optical element and an optical system configured to transmit the first optical radiation towards the optical element.

[0017] The optical assembly can be a single unit.

[0018] This provides a particularly simple and rigid structure.

[0019] The first sensor and the display can be fixedly mounted on the optical assembly.

[0020] Harmonization can then be guaranteed between the direct observation channel and a digital observation channel equipped with a sensor, in order to present images to the operator while limiting the shift between the fields.

[0021] The fourth optical path may include an aiming reticle fixedly mounted on the optical assembly.

[0022] The system may include an image processing unit configured to generate the third digital image from a fusion between the first and second digital images.

[0023] The fourth optical channel may comprise an optical attenuator with variable opacity capable of modifying a light intensity of the part of the first optical radiation, the image processing unit being further configured to determine a light intensity of at least one pixel of at least one of the first and second digital images, the system comprising an electronic control unit configured to control a variation of the opacity of the optical attenuator from the determined light intensity.

[0024] Thus, a system is provided that improves the observation of a scene. In particular, an automated system is provided that takes into account the light intensity of the optical radiation emitted by the scene to improve the observation.

[0025] The electronic control unit may be configured to control an increase in the opacity of the optical attenuator when the light intensity of said at least one pixel is greater than or equal to a threshold.

[0026] The optical element may further be configured to transmit another portion of the first optical radiation to the first sensor.

[0027] The system may further comprise an emitter configured to emit a third optical radiation in the infrared range, the optical element being further configured to transmit the third optical radiation towards the scene to be observed.

[0028] Thus, a compact observation system is provided which allows the illumination of a scene to be observed.

[0029] The third optical radiation may be of the pulsed type, the system further comprising a receiver configured to receive a portion of the third pulsed optical radiation returned by the scene to be observed and an electronic control unit configured to determine a distance relative to the scene to be observed from the portion of the third pulsed optical radiation returned.

[0030] This provides a compact observation system which allows both to illuminate a scene to be observed and to measure a distance between the scene and the observation system.

[0031] According to another aspect, an observation method is proposed, comprising a reception of a first optical radiation emitted by a scene to be observed from a first optical channel provided with a first sensor developing a first digital image from the first optical radiation; a reception of a second optical radiation emitted by the scene from a second optical channel provided with a second sensor developing a second digital image from the second optical radiation; and an observation of a third digital image from a third optical channel provided with a display displaying the third digital image from the first and second digital images.

[0032] The method comprises transmitting a portion of the first optical radiation to the third optical path.

[0033] The method may comprise an optical attenuator with variable opacity capable of modifying a light intensity of the portion of the first optical radiation, and a determination of a light intensity of at least one pixel of at least one of the first and second digital images and a variation of the opacity of the optical attenuator from the determined light intensity.

[0034] The method may further comprise emitting a third optical radiation in the infrared range and transmitting the third optical radiation from the first optical path to the scene to be observed. BRIEF DESCRIPTION OF THE FIGURE

[0035] Other advantages and characteristics will emerge more clearly from the following description of particular embodiments and implementations of the invention given as non-limiting examples and represented in the appended drawings, in which: there figure 1, schematically illustrates an embodiment of an observation system according to the invention; the figure 2 schematically illustrates another embodiment of the observation system; the figure 3 schematically illustrates another embodiment of an observation system; the figure 4 schematically illustrates another embodiment of an observation system; and the Figure 5 schematically illustrates yet another embodiment of an observation system.

[0036] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications. DETAILED DESCRIPTION

[0037] On the figures 1 to 5, an observation system 1 of a scene has been shown. Generally, the system 1 comprises a first optical channel 2, a second optical channel 3, a display 4 and a third optical channel 5 coupled to the display 4. Advantageously, the observation system 1 is portable, that is to say it can be carried by hand by a user. In addition, the first optical channel 2 is capable of receiving a first optical radiation 60 emitted by the scene to be observed, the latter not being shown in the figures for the sake of simplification. Optical radiation is understood to mean electromagnetic radiation comprising the ultraviolet, visible and infrared ranges. The scene to be observed can be located outside, as well as inside a building, and the system 1 is particularly suitable for observing the scene during the day and at night.The first optical path 2 comprises a first sensor 7 configured to develop a first digital image from the first optical radiation 60. The first sensor 7 is an electronic device, it is powered by a battery, not shown in the figures for the sake of simplification. The second optical path 3 is capable of receiving a second optical radiation 70 emitted by the scene and comprises a second sensor 8 configured to develop a second digital image from the second optical radiation 70. The first and second optical paths 2, 3 are also considered to be digital observation paths because they each comprise a digital sensor 7, 8 configured to develop a digital image. The first and second optical paths 2, 3 are also denoted first and second digital paths. The second sensor 8 is also powered by the battery.The display 4 is configured to display a third digital image from the first and second digital images originating respectively from the first and second sensors 7, 8. The display 4 is powered by the battery. For example, the first optical channel 2 may be a daytime digital observation channel, i.e. the first sensor 7 is sensitive to light visible to an eye of the user 9. Advantageously, the second optical channel 3 may be a nighttime digital observation channel, i.e. the second sensor 8 is sensitive to infrared, in particular to infrared whose wavelength is greater than or equal to 700 nm. According to another embodiment, the first sensor 7 is sensitive to infrared light, for example light whose wavelength is greater than or equal to 700 nm. Furthermore, the third optical channel 5 is shaped to observe the third digital image originating from the display 4.Generally speaking, optical channel is understood to mean a channel in which optical radiation propagates.

[0038] In particular, the system 1 comprises a fourth optical path 10 connecting the first and third optical paths 2, 5. The first optical path 2 further comprises an optical element 11 configured to transmit a portion 12 of the first optical radiation 60 to the fourth optical path 10. For example, the optical element 11 transmits the portion 12 of the first optical radiation 60 to the fourth optical path 10, while another portion 22 of the first optical radiation 60 is directed towards the first sensor 7. Optical element 11 is understood to mean an element making it possible to modify the trajectory of an optical radiation or the properties of the optical radiation, such as a mirror, a lens, a diffraction grating, a prism, etc. Preferably, the optical element 11 is an optical splitter, for example a semi-reflecting mirror, that is to say an optical element making it possible to transmit a portion of the light and to reflect the rest.In other words, when the optical element 11 is an optical splitter, it allows the part 12 of the first optical radiation 60 to be transmitted to the fourth optical path 10 and the other part 22 of the first optical radiation 60 to the first sensor 7. The optical element 11 may be a prism having a semi-reflecting input diopter 72. A prism is understood to mean a block of cut glass comprising at least five faces, or diopters. The fourth optical path 10 allows direct observation of the scene by the user. It is also called a direct optical path. In other words, the fourth optical path 10 does not include an electronic device configured to transform photons into electrons, such as an amplification device, nor an electronic sensor transforming light radiation into a digital image.

[0039] Advantageously, the system 1 comprises an optical assembly 13 comprising at least the optical element 11. The optical assembly 13 may further comprise other optical elements. These other optical elements are denoted optical systems 23, 24, 111. The optical element 11 and the optical systems 23, 24, 111 may be prisms and the optical assembly 13 is then a prismatic assembly, that is to say a set of prisms. The optical assembly 13 is a particularly simple and rigid structure and makes it possible to simplify while lightening the observation system 1.

[0040] On the figure 1, an embodiment of the optical assembly 13 is shown. The optical assembly 13 comprises the optical element 11, a first optical system 23 coupled to the optical element 11, and a second optical system 24 coupled to the first optical system 23. Generally, two optical elements coupled together are understood to mean two optical elements which are in contact with each other. They can be mounted fixedly, or removably, one on the other. In this embodiment, the optical element 11 and the first optical system 23 are respectively two prisms and the second optical system 24 comprises two prisms 70, 71.

[0041] The optical element 11 comprises the input diopter 72 and an output diopter 73. The output diopter 73 is a neutral diopter coupled to the first sensor 7. A neutral diopter is understood to mean a transparent diopter that allows optical radiation to pass through. The input diopter 72 is a semi-reflecting mirror for transmitting a first portion 12 of the first radiation 60 to the fourth optical path 10 and a second portion 22 of the first radiation 60 to the first sensor 7, via the output diopter 73. In this embodiment, the first portion 12 of the first optical radiation 60 is transmitted, by reflection, to the fourth optical path 10. The first optical system 23 is configured to transmit the first portion 12 of the first optical radiation 60 from the fourth optical path 10 to the third optical path 5.The first optical system 23 comprises a first neutral input diopter 74a for receiving the first radiation 60, a second neutral input diopter 74b coupled to the input diopter 72 of the optical element 11 for receiving the first part 12 of the radiation. Furthermore, the first optical system 23 comprises a neutral output diopter 76 and an intermediate diopter 75 reflecting the first part 12 of radiation to transmit it to the third optical channel 5, via the output diopter 76. The role of the second optical system 24 is to establish an optical fusion, that is to say a superposition of optical radiation, between the third digital image displayed and the first part 12 of the first optical radiation 60 coming from the scene to be observed.In other words, the second optical system 24 is configured to transmit the first part 12 of the first optical radiation 60 to an eyepiece 21 and to transmit the third digital image from the display 4 to the eyepiece 21. The second optical system 24 is an optical splitter. It comprises a first prism 70 having a neutral input diopter 77 coupled to the output diopter 76 of the first optical system 23, a semi-reflecting intermediate diopter 78 for transmitting a part of the first part 12 of radiation to a neutral output diopter 79, corresponding to an output diopter of the optical assembly 13. This output diopter 79 transmits the radiation from the scene to be observed and from the third digital image to the eyepiece 21, in order to be able to observe the scene and the third digital image.Furthermore, the second optical system 24 comprises a second prism 71 having a neutral input diopter 80 coupled to the display 4 and a neutral output diopter 81 coupled to the intermediate diopter 78 of the first prism 70. Thus, the second prism 71 makes it possible to transmit the third digital image to the output diopter 79 of the optical assembly 13. The third optical channel 5 comprises the second optical system 24 and makes it possible to observe the scene from the first optical radiation 60 and the third digital image displayed by the display 4.

[0042] Advantageously, the prisms 11, 23, 70, 71, 111 of the optical assembly 13 can be glued together to form a single-piece optical assembly 13. According to yet another advantage, other elements 4, 7, 14, 90, 107 can be fixedly mounted on the optical assembly 13. Furthermore, when elements 4, 7, 14, 90, 107 are fixedly mounted on a single-piece optical assembly 13, the single-piece optical assembly 13 and the fixed elements 4, 7, 14, 90, 107 form a single-piece assembly 50. The term single-piece is understood to mean a set of elements fixed together such that the removal of one of the elements from the assembly results in mechanical destruction of the assembly.

[0043] Thus, a single-piece assembly 50 is provided which prevents relative movement between the elements of the assembly 50, which may occur, for example, during shocks or vibrations. It is also said that the single-piece assembly 50 has a role of optical invariant. Advantageously, the first sensor 7, and the display 4 are fixedly mounted on the single-piece optical assembly 13. This makes it possible to make a harmonization of the first, third and fourth optical paths 2, 5, 10 robust to all relative movements between the different elements of the optical paths, in particular movements relative to an objective 20 located at the input of the first optical path 2 or to the eyepiece 21 located at the output of the third optical path 5. The second optical path 3 can be harmonized with digital image processing with the first digital path 2, according to conventional image processing techniques.Thus, after the digital harmonization of the first and second digital channels 2, 3, the single-piece assembly 50 makes it possible to harmonize the first and second digital channels 2, 3 with the third and fourth optical channels 5, 10. The single-piece assembly 50 makes it possible to superimpose the third digital image, resulting from the first and second digital images, on the image of the scene resulting from the fourth optical channel 10, that is to say the part 12 of the first optical radiation 60, without offset between the fields. The single-piece assembly 50 allows robust harmonization, by maintaining harmonization during possible shocks and vibrations. In other words, the single-piece assembly 50 makes it possible to minimize the risk of deharmonization.

[0044] Advantageously, the optical assembly 13 may comprise a sighting reticle 14. More particularly, the fourth optical path 10 comprises the sighting reticle 14. For example, the reticle 14 is a figure deposited on a surface of a glass by screen printing or photolithography. The reticle 14 may also be made of stretched wires. It is thus possible to superimpose a figure on the image of the scene to be observed. The aiming reticle 14 can be mounted on the optical assembly 13, preferably in a fixed manner so as to then form part of the single-piece assembly 50. This makes it possible to make the harmonization of the first, third and fourth optical paths 2, 5, 10 with the aiming reticle 14 robust to all relative movements between the different elements of these optical paths 2, 5, 10. Advantageously, the aiming reticle 14 is fixedly mounted on the output diopter 76 of the first optical system 23.

[0045] The system 1 may also comprise an image processing unit 15, for example a microprocessor, configured to develop the third digital image from the first and second digital images. For example, the third image is developed from a digital fusion between the first and second digital images. The unit 15 is coupled to the first sensor 7 by a connection 16, and to the second sensor 8 by a connection 17. Furthermore, the unit 15 is coupled to the display 4, by a connection 18, to transmit the third digital image to the display 4.

[0046] The observation system 1 advantageously comprises a housing 19 within which the sensors 7, 8, the optical element 11, the display 4, the optical assembly 13, the reticle 14, and the battery are housed. In addition, the first optical path 2 may comprise the objective 20 mounted on the housing 19. The second optical path 3 may also comprise an additional objective 26 mounted on the housing 19. The eyepiece 21 allows the user 9 to observe the third image from the display 4 and the first part 12 of the first optical radiation 60. Advantageously, in the event of relative movement between the objective 20 and the single-piece assembly 50, the first, third and fourth optical paths 2, 5 and 10 and the reticle 14 remain harmonized with respect to each other.

[0047] Advantageously, the third optical path 5 comprises an image rectification prism 25 placed between the second optical system 24 and the eyepiece 21, as illustrated in the figures 1 ,2 And 4 . The straightening prism 25 has seven faces, including two faces parallel to each other and not shown in the figures 1 , 2 And 4 , three reflecting faces, a transparent input face and a transparent output face. Preferably, the eyepiece 21 and the rectifying prism 25 are not fixedly mounted on the optical assembly 13. Thus, relative movements of the eyepiece 21 or the rectifying prism 25 do not involve relative variations between the fields.

[0048] On the figure 2 , another embodiment is shown, in which the optical element 11 is also an optical splitter for transmitting the part 12 of the first optical radiation 60 to the fourth optical path 10 and for transmitting the other part 22 of the first optical radiation 60 to the first sensor 7. On the figure 2, the four prisms defined above are also shown but arranged differently. In particular, the optical element 11 comprises an additional neutral input diopter 72a for transmitting the first optical radiation 60 to the semi-reflecting input diopter 72.

[0049] Advantageously, the objective 20 of the first optical path 2 may comprise an optical device 6, for example one or more focusing lenses, configured to transmit the first optical radiation 60 to the optical element 11. In particular, the optical device 6 makes it possible to modify the focusing of the first optical radiation 60. The system 1 may further comprise other focusing lenses 32 placed between the rectifying prism 25 and the eyepiece 21, as illustrated in the figure 2 . On the figure 2 , the second optical path has not been shown for simplification purposes. In the embodiment illustrated in figure 2, the first part 12 of the first optical radiation 60 is transmitted, by transparency, towards the first optical system 23.

[0050] On the figure 3 , another embodiment has been shown, in which the optical assembly 13 comprises the four prisms defined above but arranged differently. In this other embodiment, the first optical system 23 is further configured to transmit the first optical radiation 60 towards the optical element 11. In particular, the first optical system 23 is placed so that its intermediate reflecting diopter 75 reflects the first optical radiation 60 towards the input diopter 72 of the optical element 11. This optical assembly 13 makes it possible to significantly reduce the length of the first optical path 2, and makes it possible to reduce the size of the observation system 1.

[0051] On the figure 3 , the second optical path has not been shown for simplification purposes.

[0052] On the figure 4, another embodiment of the observation system has been shown, in which the fourth optical channel 10 further comprises an optical attenuator 90 with variable opacity. That is to say that the optical attenuator 90 is capable of modifying a light intensity of the first part 12 of the first optical radiation 60. In particular, the optical attenuator 90 receives the first part 12 of the first optical radiation 60 and transmits a third optical radiation 91 to the third optical channel 5. It is therefore possible to observe, using the third optical channel 5, the third optical radiation 91 superimposed on the third digital image displayed by the display 4. More particularly, the second optical system 24 receives the third optical radiation 91 and makes it possible to establish an optical fusion between the third digital image and the third optical radiation 91 transmitted by the attenuator 90.In other words, the second optical system 24 is configured to transmit the third optical radiation 91 to the eyepiece 21 and to transmit the third digital image from the display 4 to the eyepiece 21. The attenuator 90 can be fixedly mounted on the output diopter 76 of the first optical system 23, and transmit the third optical radiation 91 by transparency. Alternatively, the attenuator 90 can be fixedly mounted on the intermediate diopter 75 of the first optical system 23, and transmit the third optical radiation 91 by reflection. Advantageously, the optical attenuator 90 is fixedly mounted on the single-piece optical assembly 13.

[0053] The system 1 further comprises an electronic control unit 92, for example a microprocessor, comprising the image processing unit 15. The image processing unit 15 is further configured to determine a light intensity of at least one pixel of at least one digital image among the first and second digital images. The image processing unit 15 may be a specific microprocessor integrated within the electronic control unit 92 and capable of performing calculations on the first and second digital images originating respectively from the first and second sensors 7, 8, and on the third digital image produced. For example, the image processing unit 15 is capable of performing the image processing algorithm steps. The electronic control unit 92 is coupled to the optical attenuator 90 by a connection 93.The electronic control unit 92 is further configured to control a variation in the opacity of the optical attenuator 90. For example, the optical attenuator 90 comprises one or more liquid crystal cells. The optical attenuator 90 receives an electric current, via the connection 93, delivered by the electronic control unit 92. The opacity of the attenuator 90 varies depending on the value of the electric current received. More particularly, the electronic control unit 92 modifies the opacity of the attenuator 90 from the light intensity determined by the image processing unit 15.

[0054] Preferably, the first sensor 7 is sensitive to optical radiation having a wavelength in the visible range, for daytime vision, and the second sensor 8 is sensitive to optical radiation having a wavelength in the infrared range, for nighttime vision. In this case, the electronic control unit 92 is configured to control an increase in the opacity of the attenuator 90 when the light intensity of at least one pixel of the first determined digital image is greater than or equal to a first threshold. Thus, the phenomenon of glare, for example created by the sun, can be avoided in daytime vision. Furthermore, the electronic control unit 92 is configured to control an increase in the opacity of the attenuator 90 when the light intensity of at least one pixel of the second digital image is greater than or equal to a second threshold.Thus, the phenomenon of local glare, for example created by a luminaire in an urban area in night vision, can be avoided. Thus, an observation system 1 is provided which improves the observation of a scene. In particular, an automated system is provided which takes into account the luminous intensity of the optical radiation emitted by the scene to improve the observation.

[0055] The image processing unit 15 is also configured to determine the light intensities of each of the pixels of the first and second digital images. Furthermore, the electronic control unit 92 controls a reduction in the opacity of the attenuator when the light intensities of the pixels of the first and second digital images are lower than the first and second thresholds. When the battery no longer powers the observation system 1, the attenuator 90 has a default opacity value corresponding to maximum transmission or reflection. Preferably, the opacity of the attenuator 90 may be zero in the absence of power. This makes it possible to ensure observation by the fourth optical channel 10 in the absence of a power source.

[0056] Furthermore, the electronic control unit 92 may be configured to control a variation in the opacity of the attenuator 90 according to a continuous function following an analog, linear or piecewise continuous control law, for example a logarithmic function. According to a variant, the electronic control unit 92 may be configured to control a variation in the opacity of the attenuator 90 according to a discrete function following a digital control law, i.e. with several steps or opacity levels, preferably with at least three steps, for example with 128, 256 or 512 steps. In general, the electronic control unit 92 transmits a command, for example in the form of a voltage in volts, to the attenuator 90. The command in volts thus transmitted may follow a continuous or discrete function as defined above.

[0057] On the Figure 5, another embodiment of the observation system 1 has been shown. In this other embodiment, the observation system 1 comprises an emitter 100 configured to emit a fourth optical radiation 101 in the infrared range, i.e. having a wavelength greater than or equal to 700 nanometers. Preferably, the fourth optical radiation 101 has a wavelength in the near infrared range, i.e. a wavelength between 700 and 2000 nanometers. Furthermore, in this embodiment, the optical element 11 is configured to transmit the fourth optical radiation 101 to the scene to be observed. In particular, the emission of the fourth optical radiation 101 is carried out from the first optical path 2, which makes it possible to reduce the size of the observation system 1.Furthermore, when the first optical path 2 of the system 1 comprises an optical device 6, the optical element 11 transmits the fourth optical radiation 101 to the optical device 6. Thus, the scene to be observed can be illuminated with visible light from a device equipped with an infrared type sensor. More particularly, the optical element 11 is transparent to infrared type optical radiation while being semi-transparent to optical radiation in the visible range, that is to say to optical radiation whose wavelength is between 380 nanometers and 750 nanometers. In other words, the optical element 11 is configured to allow the second part 22 of the first optical radiation 60 to pass to the main sensor 7, to reflect the first part 12 of the first optical radiation 60 to the fourth optical path 10 and to transmit the fourth optical radiation 101 to the optical device 6.

[0058] Generally, the optical device 6 is transparent to optical radiation in the visible and infrared range.

[0059] The transmitter 100 may comprise an amplifier 103 configured to emit the fourth laser-type optical radiation 101. Thus, illumination of the scene is provided with a laser point

[0060] Furthermore, the transmitter 100 is configured to emit a fourth optical radiation 101 of wavelength in the infrared range of the pulsed type. The system 1 further comprises a receiver 104 configured to receive a portion 105 of the fourth pulsed optical radiation 101 returned by the scene to be observed. The system 1 also comprises an electronic control unit 106, for example a microprocessor, configured to determine a distance relative to the scene to be observed from the portion 105 of the pulsed optical radiation 101 returned. In other words, the determination of the distance is carried out by emitting on the scene to be observed a series of short laser pulses, then by collecting the energy backscattered by the illuminated scene. The measurement of the time of flight then makes it possible to deduce therefrom the distance traveled by the fourth optical radiation 101, and therefore the distance between the scene and the observation system 1.

[0061] The battery powers the transmitter 100, the amplifier 103, the receiver 104 and the electronic control unit 106.

[0062] Advantageously, the observation system 1 comprises an optical connector 107 and an optical fiber 108. The optical fiber 108 comprises a first part 109 connecting the optical connector 107 to the transmitter 100, and a second part 110 connecting the optical connector 107 to the receiver 104. Preferably, the first part 109 corresponds to a central part of the optical fiber 108, and the second part 110 corresponds to a sheath which surrounds the central part 109. The first and second parts 109, 110 of the optical fiber 108 are configured to allow the propagation of optical radiation, in particular optical radiation in the infrared range.

[0063] The optical connector 107 is configured to transmit the fourth optical radiation 101. For example, the optical connector 107 comprises an optical prism 40, preferably a straight prism, and a ferrule 41 connecting the optical fiber 108 to the optical prism 40. Thus, the fourth optical radiation 101 emitted by the transmitter 100 propagates in the first part 109 of the optical fiber 108, and the second part 110 of the optical fiber 108 makes it possible to receive the part 105 of the returned pulsed optical radiation 101.

[0064] The optical prism 40 can be glued to the ferrule 41. Preferably, a glue-free space, for example an air layer or an empty space, is created between the ferrule 41 and the optical prism 40 so as to prevent a laser emission of the fourth optical beam 101 from passing through a layer of glue.

[0065] Thus, the optical fiber 108 can be used to determine the distance of the scene to be observed. In particular, the use of the optical fiber 108 makes it possible to juxtapose the reception and the emission of the fourth optical radiation 101 to determine the distance, which reduces the size of the observation system 1.

[0066] Furthermore, when it is desired to illuminate the scene to be observed, using laser-type radiation, the transmitter 100 amplifies the fourth optical radiation 101, using the amplifier 103, which propagates in the first part 109 of the optical fiber 108 towards the optical connector 107.

[0067] Thus, the optical connector 107 provides a single optical interface for the emission of the fourth optical radiation 101 of the pulsed type, the reception of the portion 105 of the returned pulsed optical radiation in order to determine a distance, and for the emission of the fourth optical radiation 101 of the laser type for illumination of the scene to be observed.

[0068] The optical element 11 is further configured to transmit the portion 105 of the fourth optical radiation 101 returned by the scene to the optical connector 107. In particular, its input diopter 72 is transparent to optical radiation of the infrared type, and semi-reflective, or semi-transparent, for optical radiation in the visible range. Its output diopter 73 is a diopter transparent to optical radiation of visible wavelength, and reflective to optical radiation of infrared wavelength. The output diopter 73 makes it possible to transmit the second portion 22 of the first radiation 60 to the main sensor 7, and to reflect on the one hand the fourth optical radiation 101 towards its input diopter 72 and on the other hand the portion 105 of the fourth optical radiation 101 returned to the optical connector 107.The optical element 11 further comprises an additional neutral output diopter 112 coupled to the optical prism 40 of the optical connector 107, to allow the infrared type optical radiation to pass which propagate between the optical connector 107 and the optical device 6. The system 1 further comprises a third optical system 111, preferably a prism, coupled to the first sensor 7 and to the optical element 11. The third optical system 111 makes it possible to transmit the second part 22 of the first optical radiation 60 to the first sensor 7. The third optical system 111 comprises a neutral input diopter 113 coupled to the output diopter 73 of the optical element 11 and a neutral output diopter 114 coupled to the main sensor 7.

[0069] In this embodiment, the first optical system 23 is similar to the first optical system 23 of the embodiment of the figure 3. In this embodiment, its first input diopter 74a is neutral to receive the first optical radiation 60 and to allow the optical radiation of infrared wavelength 101, 105 to pass. Its second input diopter 74b is also neutral to optical radiation in the visible and infrared range. Furthermore, its intermediate diopter 75 is reflective to optical radiation 101, 105, 60.

[0070] Advantageously, the third optical system 111 and the optical prism 40 of the optical connector 107 are fixedly mounted on the single-piece optical assembly 13 and form part of the single-piece assembly 50.

[0071] An observation method can be implemented by the observation system 1 defined above. The method comprises the following main steps: reception of the first optical radiation emitted by the scene to be observed from the first optical channel 2 provided with the first sensor 7 producing the first digital image from the first optical radiation 60; then, reception of the second optical radiation 70 emitted by the scene from the second optical channel 3 provided with the second sensor 8 producing the second digital image from the second optical radiation 70. Furthermore, the method comprises observation of a third digital image from the third optical channel 5 provided with the display 4 displaying the third digital image from the first and second digital images. In particular, the method comprises transmission of a portion 12 of the first optical radiation 60 to the third optical channel 5.

[0072] Furthermore, a method for manufacturing the observation system 1, comprising a transmitter 100 for illuminating a scene and calculating a distance between the scene and the observation device 1, is described below. The manufacturing method comprises a provision of the first, second, third and fourth optical channels 2, 3, 5, 10 and a provision of the transmitter 100. Furthermore, the method comprises a mounting of an optical assembly 13 comprising at least the optical element 11.

[0073] Advantageously, the method comprises mounting the first sensor 7 in a fixed manner on the optical assembly 13.

[0074] According to another advantage, the method comprises mounting the aiming reticle 14 on the optical assembly 13. According to a variant, the display 4 can be configured to display an aiming reticle in the third optical channel 5. For example, the aiming reticle can be a cross, a circle or more generally a figure. The displayed aiming reticle makes it possible, in particular, to identify the location on the scene of the fourth optical radiation 101. Thus, when the display 4 is fixedly mounted on the optical assembly 13, for example on the input diopter 80 of the second optical system 24, the first, third and fourth optical channels 2, 5, 10 are harmonized with the displayed aiming reticle.

[0075] The method may further comprise mounting the optical fiber 108 on the optical connector 107. Then the method comprises mounting the optical connector 107 on the optical assembly 13. Such a method makes it possible both to optimize coupling of the part 105 of the fourth optical radiation 101 returned by the scene with the second part 110 of the optical fiber 108, that is to say the fiber for receiving the part 105 of radiation returned by the scene, and to center, relative to the aiming reticle 14, the point of the scene targeted by the fourth optical radiation 101.

[0076] Advantageously, after mounting the ferrule 41 on the optical prism 40 of the optical connector 107, the step of mounting the optical connector 107 comprises adjusting a position of the optical connector 107 along an axis parallel to a longitudinal axis A of the ferrule 41. This adjustment makes it possible to optimize the emission and reception of the pulsed optical radiation to determine the distance from the scene. During this adjustment, the position of the center of a point formed by the fourth optical radiation 101 on the scene does not change but the diameter of the point is modified. Unlike conventional methods, the aim is not to place the optical connector 107 in a position where the diameter of the point is as small as possible.Indeed, if the optical connector 107 is placed in this position, the divergence of the emission of the fourth optical radiation 101 is the lowest and the return photons propagate essentially within the first part 109 of the optical fiber 108. These photons are then lost for the distance measurement, the coupling between the emission and the reception decreases and the measurement is less precise. The optical connector 107 is therefore positioned so as to increase the divergence of the emission of the fourth optical radiation 101 to increase the diameter of the point and to increase the number of return photons within the second part 110 of the optical fiber 108. Thus, the coupling between the emission and the reception is improved to improve the accuracy of the distance measurement.

[0077] The step of mounting the optical connector 107 may include adjusting a position of the optical connector 107 along an axis perpendicular to the longitudinal axis A of the ferrule 41. This adjustment makes it possible to harmonize the position of the point formed by the fourth optical beam 101 on the scene with the aiming reticle 14, that is to say to bring the point as close as possible to the scene aimed at by the user. The adjustment is carried out so as to minimize the relative difference between the position of the point and the position of the aiming reticle 14. To carry out this adjustment, the aiming reticle 14 is illuminated by the lower part of the optical assembly 13. At the same time, the fourth optical beam 101 is emitted. Thanks to a telescope looking at infinity at the beams exiting from the optical device 6 towards the telescope, it is possible to view the aiming reticle 14 and the relative position of the point at the same time.The position of the optical connector 107 is then chosen so as to reduce the gap, seen by the scope, between the point and the aiming reticle 14. The two aforementioned adjustments can be carried out sequentially, one after the other. By carrying out the adjustments along two axes perpendicular to each other, there is little influence of one adjustment on the other.

[0078] The method may comprise, after at least one of the adjustment steps, fixing the optical connector 107 to the optical assembly 13.

[0079] The system and method just described are particularly suitable for monocular or binocular-type systems, portable and for day and night vision. The observation system makes it possible to reduce the size of the batteries, it is particularly light. It also makes it possible to avoid shifts between the image fields, during shocks and vibrations, and facilitates the observation of scenes when the user is moving. The observation system makes it possible to improve the observation of a scene in day and night vision. Such an observation system makes it possible to illuminate the scenes to be observed and to calculate distances between the scenes and the observation system, while being compact.

Claims

1. Observation system comprising a first optical path (2) capable of receiving first optical radiation (60) emitted by a scene to be observed and including a first sensor (7) configured to generate a first digital image from the first optical radiation (60); a second optical path (3) capable of receiving second optical radiation (70) emitted by the scene and including a second sensor (8) configured to generate a second digital image from the second optical radiation (70); a display (4) configured to display a third digital image from the first and second digital images; and a third optical path (5) coupled to the display (4) and designed to observe the third digital image; characterised in that it includes a fourth optical path (10) connecting the first and third optical paths (2, 5), and in that the first optical path (2) includes an optical element (11) configured to transmit a part (12) of the first optical radiation (60) to the fourth optical path (10).

2. System according to claim 1, comprising an optical assembly (13) including the optical element (11) and an optical system (23) configured to transmit the part (12) of the first optical radiation (60) from the fourth optical path (10) to the third optical path (5).

3. System according to claim 1, comprising an optical assembly (13) including the optical element (11) and an optical system (23) configured to transmit the first optical radiation (60) to the optical element (11).

4. System according to claim 1 or 2, wherein the optical assembly (13) is a one-piece assembly.

5. System according to any one of claims 2 to 4, wherein the first sensor (7) and the display (4) are fixedly mounted on the optical assembly (13).

6. System according to any one of claims 2 to 5, wherein the fourth optical path (10) comprises a crosshair (14) fixedly mounted on the optical assembly (13).

7. System according to any one of the preceding claims, comprising an image processing unit (15) configured to produce the third digital image from a merging between the first and second digital images.

8. System according to claim 7, wherein the fourth optical path (10) includes an optical attenuator (90) having a variable opacity and capable of modifying a light intensity of the part (12) of the first optical radiation (60), the image processing unit (15) is further configured to determine a light intensity of at least one pixel of at least one of the first and second digital images, the system comprising an electronic control unit (92) configured to command a variation in the opacity of the optical attenuator (90) based on the determined light intensity.

9. System according to claim 8, wherein the electronic control unit (92) is configured to command an increase in the opacity of the optical attenuator (90) when the light intensity of said at least one pixel is greater than or equal to a threshold.

10. System according to any one of the preceding claims, wherein the optical element (11) is furthermore configured to transmit a further part (22) of the first optical radiation (60) to the first sensor (7).

11. System according to any one of the preceding claims, comprising an emitter (100) configured to emit third optical radiation (101) in the infrared range, the optical element (11) being furthermore configured to transmit the third optical radiation (101) to the scene to be observed.

12. System according to claim 11, wherein the third optical radiation (101) is of the pulsed type, the system furthermore comprising a receiver (104) configured to receive a part (105) of the third pulsed optical radiation (101) returned by the scene to be observed and an electronic control unit (106) configured to determine a distance to the scene to be observed based on the returned part (105) of the third pulsed optical radiation (101).

13. Observation method, comprising receiving first optical radiation (60) emitted by a scene to be observed from a first optical path (2) provided with a first sensor (7) generating a first digital image from the first optical radiation (60); receiving second optical radiation (70) emitted by the scene from a second optical path (3) provided with a second sensor (8) generating a second digital image from the second optical radiation (70); and observing a third digital image from a third optical path (5) provided with a display (4) displaying the third digital image from the first and second digital images; characterised in that it includes transmitting a part (12) of the first optical radiation (60) to the third optical path (5).

14. Method according to claim 13, including an optical attenuator (90) having a variable opacity and capable of modifying a light intensity of the part (12) of the first optical radiation (60), and determining a light intensity of at least one pixel of at least one of the first and second digital images, and varying the opacity of the optical attenuator (90) based on the determined light intensity.

15. Method according to claim 13 or 14, comprising emitting third optical radiation (101) in the infrared range and transmitting, from the first optical path (2), the third optical radiation (101) to the scene to be observed.