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 equipped with lenses 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, we can cite the American patent application US 2015 / 0377587 which discloses a night vision system comprising an infrared video camera, an eyepiece for observing the video image and an optical device equipped with an optical separator to reflect a portion of the video image towards the eyepiece and to transmit an optical image from a scene to be observed. The device comprises an optical attenuator which can vary between a transparent mode for using the system in day vision and an opaque mode for using the system in night vision by preventing light from escaping from the optical device in order to operate discreetly at night. But this system is not suitable for optimizing the image observed by a user for use of the system in day and night vision.Documents EP 2 416 201 A2, WO 2019 / 097522 A1, and WO 2007 / 044582 A1 constitute prior art for the present invention. SUMMARY OF THE INVENTION

[0004] One object is to overcome these drawbacks, and more particularly to provide means to improve the observation of a scene in day and night vision.

[0005] Another object is to provide observation means to minimize energy consumption.

[0006] According to one aspect, an observation system is proposed, comprising a first optical channel capable of receiving a first optical radiation emitted by a scene to be observed and comprising a main sensor configured to produce a first digital image from the first optical radiation; a second optical channel capable of receiving a second optical radiation from the scene to be observed and comprising a variable opacity optical attenuator capable of modifying a light intensity of the second optical radiation; a display configured to display a second digital image from the first digital image; and a third optical channel coupled to the display and to the optical attenuator and shaped to observe the second digital image and a third optical radiation transmitted by the optical attenuator.

[0007] The system comprises an electronic control unit comprising an image processing unit configured to determine a light intensity of at least one pixel of the first digital image and in that the electronic control unit is configured to control a variation of the opacity of the optical attenuator from the determined light intensity.

[0008] 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 observation. Such a system is particularly suitable for simultaneous observation of a scene using two optical paths. It also makes it possible to optimize observation of the scene in intermediate conditions between day vision and night vision for which the scene information is shared between the two optical paths.

[0009] According to one embodiment, the optical attenuator comprises at least one liquid crystal cell.

[0010] According to another embodiment, the optical attenuator comprises at least one electrochromic cell.

[0011] According to one embodiment, the optical attenuator is configured to transparently transmit the third optical radiation.

[0012] According to another embodiment, the optical attenuator is configured to transmit by reflection the third optical radiation.

[0013] 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.

[0014] The system may comprise a fourth optical channel capable of receiving a fourth optical radiation emitted by the scene and comprising an additional sensor configured to develop a third digital image from the fourth optical radiation; the image processing unit being configured to develop the second digital image from a fusion between the first and third digital images.

[0015] The first optical path may include an optical element configured to transmit a first portion of the first optical radiation to the first sensor and to transmit a second portion of the first optical radiation corresponding to the second optical radiation to the optical attenuator.

[0016] The system may further include an optical assembly comprising the optical element and the optical attenuator, the optical assembly being a single-piece assembly.

[0017] 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 main sensor producing a first digital image from the first optical radiation; a reception of a second optical radiation from the scene to be observed from a second optical channel provided with an optical attenuator with variable opacity capable of modifying a light intensity of the second optical radiation; a display of a second digital image from the first digital image; and an observation from a third optical channel of a third optical radiation transmitted by the optical attenuator and of the second digital image.

[0018] The method comprises determining a light intensity of at least one pixel of the first digital image and varying the opacity of the optical attenuator based on the determined light intensity. BRIEF DESCRIPTION OF THE FIGURE

[0019] 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 drawing, in which: [ Fig. 1 ] there figure 1 , schematically illustrates an embodiment of an observation system according to the invention.

[0020] The drawing is given by way of example and is not limiting of the invention. It constitutes a schematic representation of principle intended to facilitate the understanding of the invention and is not necessarily on the scale of practical applications. DETAILED DESCRIPTION

[0021] On the figure 1, an observation system 1 of a scene has been shown. Generally, the system 1 comprises a first optical channel 2, a second optical channel 10, 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 channel 2 comprises a first sensor 7, denoted main sensor, configured to produce 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 display 4 is configured to display at least the first digital image from the first sensor 7. In particular, the display 4 is configured to display a second digital image from the first digital image. The display 4 is powered by the battery. For example, the first optical channel 2 may be a daytime digital observation channel, that is to say that the first sensor 7 is sensitive to the light visible to an eye of the user 9.According to another embodiment, the first optical channel 2 is a digital night observation channel, that is to say that the first sensor 7 is sensitive to infrared light, for example light whose wavelength is greater than or equal to 700 nm.

[0022] The second optical path 10 is capable of receiving a second optical radiation 12 from the scene to be observed and 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 second optical radiation 12. The second optical radiation 12 can be emitted by the scene, and in this case, the second optical path 10 directly receives the second optical radiation 12. Alternatively, as illustrated in the figure 1, the second optical path 10 connects the first and third optical paths 2, 5. According to this variant, the second optical radiation 12 corresponds to a part of the first optical radiation 60. In this case, the second optical path 10 indirectly receives the first optical radiation 60.

[0023] Furthermore, the third optical channel 5 is coupled to the optical attenuator 90 and is shaped to observe the second digital image displayed by the display 4 and a third optical radiation 91 transmitted by the optical attenuator 90.

[0024] The system 1 further comprises an electronic control unit 92, for example a microprocessor, comprising an image processing unit 15 configured to determine a light intensity of at least one pixel of the first digital image. The image processing unit 15 is a specific microprocessor integrated within the electronic control unit 92 and capable of performing calculations on the digital image from the main sensor 7. For example, the image processing unit 15 is capable of performing the steps of image processing algorithms. The electronic control unit 92 is coupled to the attenuator 4 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. Alternatively, the optical attenuator 90 comprises one or more electrochromic 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.

[0025] Advantageously, the system 1 comprises a fourth optical channel 3. The fourth optical channel 3 is capable of receiving a fourth optical radiation 70 emitted by the scene to be observed and comprises a second sensor 8 configured to develop a third digital image from the fourth optical radiation 70. The second sensor 8 is distinct from the first sensor 7, and is also referred to as an additional sensor. The first and fourth optical channels 2, 3 are also considered to be digital observation channels because they each comprise a digital sensor 7, 8 configured to develop a digital image. The first and fourth optical channels 2, 3 are also referred to as the first and second digital channels. The second sensor 8 is also powered by the battery.

[0026] The image processing unit 15 is further configured to develop the second digital image from the first and third digital images originating respectively from the first and second sensors 7, 8. For example, the second image is developed from a digital fusion between the first and third digital images. The image processing 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 image processing unit 15 is coupled to the display 4, by a connection 18, to transmit the second digital image to the display 4. The display 4 is further configured to display the second digital image from the first and third digital images originating respectively from the first and second sensors 7, 8.

[0027] Preferably, the first sensor 7 is sensitive to light visible to an eye of the user 9, for daytime vision, and the second sensor 8 is sensitive to infrared light, for nighttime vision. Advantageously, 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 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. The image processing unit 15 is also configured to determine a light intensity of at least one pixel of the third digital image. 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 third digital image is greater than or equal to a second threshold.This way, the phenomenon of local glare, for example created by a light in an urban area in night vision, can be avoided.

[0028] The image processing unit 15 is also configured to determine the light intensities of each of the pixels of the first and third digital images originating from the first and second sensors 7, 8 respectively. In addition, 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 third 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. For example, the opacity of the attenuator 90 may be zero in the absence of power. This makes it possible to ensure observation by the second optical channel 10 in the absence of a power source.

[0029] 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. Generally, 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.

[0030] Advantageously, the first optical path 2 further comprises an optical element 11 configured to transmit the part 12 of the first optical radiation 60 to the second optical path 10. For example, the optical element 11 transmits the part 12 of the first optical radiation 60 to the second optical path 10, while another part 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 part 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 second 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 second optical path 10 allows direct observation of the scene by the user. It is also called a direct optical path. In other words, the second 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.

[0031] Advantageously, the system 1 comprises an optical assembly 13 comprising at least the optical element 11. Advantageously, the optical assembly 13 may further comprise other optical elements. These other optical elements are denoted optical systems 23, 24. The optical element 11 and the optical systems 23, 24 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.

[0032] On the figure 1, an embodiment of the optical assembly 13 has been 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 elements coupled together are understood to mean two elements which are in contact with each other. They can be fixedly mounted together, or be removably mounted. 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.

[0033] 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 second 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 second optical path 10. The first optical system 23 is configured to transmit the first portion 12 of the first optical radiation 60 from the second 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 between the second 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 second 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.

[0034] The second optical system 24 is an optical separator. 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 portion of the third optical radiation 91 to a neutral output diopter 79, corresponding to an output diopter of the optical assembly 13. This output diopter 79 transmits the optical radiation from the scene to be observed and from the second digital image to the eyepiece 21, in order to be able to observe the scene and the second digital image.

[0035] 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 second 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 second digital image displayed by the display 4.

[0036] Advantageously, the prisms 11, 23, 70, 71 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 can be fixedly mounted on the optical assembly 13. Furthermore, when elements 4, 7, 14, 90 are fixedly mounted on a single-piece optical assembly 13, the single-piece optical assembly 13 and the fixed elements 4, 7, 14, 90 form a single-piece assembly 50. By single-piece, we mean a set of elements fixed together so that the removal of one of the elements from the assembly results in mechanical destruction of the assembly.

[0037] 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, the display 4, and the optical attenuator 90 are fixedly mounted on the single-piece optical assembly 13. This makes it possible to make harmonization of the first, second and third optical paths 2, 10, 5 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 an eyepiece 21 located at the output of the third optical path 5. The fourth 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 second and third optical channels 10, 5. The single-piece assembly 50 makes it possible to superimpose the second digital image, resulting from the first and third digital images, on the image of the scene resulting from the second optical channel 10, that is to say the third optical radiation 91, without shift between the fields. The superposition of images is also noted as optical fusion. The single-piece assembly 50 allows robust harmonization, maintaining harmonization during possible shocks and vibrations. In other words, the single-piece assembly 50 makes it possible to minimize the risk of deharmonization.

[0038] Advantageously, the optical assembly 13 may comprise a sighting reticle 14. More particularly, the second 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, second and third optical paths 2, 10, 5 with the aiming reticle 14 robust to all relative movements between the different elements of these optical paths 2, 10, 5. Advantageously, the aiming reticle 14 is fixedly mounted on the output diopter 76 of the first optical system 23.

[0039] The observation system 1 advantageously comprises a housing 19 within which are housed the sensors 7, 8, the optical element 11, the display 4, the attenuator 90, the optical assembly 13 and the reticle 14, and the battery. Furthermore, the first optical path 2 may comprise the objective 20 mounted on the housing 19. The fourth 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 second image from the display 4 and the third optical radiation 90 transmitted by the attenuator 90. Advantageously, in the event of relative movement between the objective 20 and the single-piece assembly 50, the first, second and third optical paths 2, 10 and 5, the reticle 14 and the attenuator 90 remain harmonized with respect to each other.

[0040] An observation method can be implemented by the observation system 1 defined above.

[0041] The system and method just described are particularly suitable for monocular or binocular-type systems, portable and for day and night vision. The system makes it possible to improve the observation of a scene in day and night vision. The observation system also 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.

Claims

1. Observation system, comprising a first optical path (2) capable of receiving a first optical radiation (60) emitted by a scene to be observed and including a main sensor (7) configured to produce a first digital image from the first optical radiation (60); a second optical path (10) capable of receiving a second optical radiation (12) from the scene to be observed and including an optical attenuator (90) with variable opacity capable of modifying a light intensity of the second optical radiation (12); a display (4) configured to display a second digital image from the first digital image; and a third optical path (5) coupled to the display (4) and to the optical attenuator (90) and conformed to observe the second digital image and a third optical radiation (91) transmitted by the optical attenuator (90); characterised in that it includes an electronic control unit (92) including an image processing unit (15) configured to determine a light intensity of at least one pixel of the first digital image and in that the electronic control unit (92) is configured to command a variation of the opacity of the optical attenuator (90) from the determined light intensity.

2. System according to claim 1, wherein the optical attenuator (90) includes at least one liquid crystal cell.

3. System according to claim 1, wherein the optical attenuator (90) includes at least one electrochromic cell.

4. System according to any one of claims 1 to 3, wherein the optical attenuator (90) is configured to transmit the third optical radiation (91) by transparency.

5. System according to any one of claims 1 to 3, wherein the optical attenuator is configured to transmit the third optical radiation by reflection (91).

6. System according to any one of the preceding claims, 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.

7. System according to any one of the preceding claims, comprising a fourth optical path (3) capable of receiving fourth optical radiation (70) emitted by the scene and including an additional sensor (8) configured to generate a third digital image from the fourth optical radiation (70); the image processing unit (15) being configured to generate the second digital image from a fusion between the first and third digital images.

8. System according to any one of the preceding claims, wherein the first optical path (2) comprises an optical element (11) configured to transmit a first part (22) of the first optical radiation (60) to the first sensor (7) and to transmit a second part (12) of the first optical radiation (60) corresponding to the second optical radiation (12) to the optical attenuator (90).

9. System according to claim 8, comprising an optical assembly (13) including the optical element (11) and the optical attenuator (90), the optical assembly (13) being in one piece.

10. Observation method, comprising receiving first optical radiation (60) emitted by a scene to be observed from a first optical path (2) provided with a main sensor (7) producing a first digital image from the first optical radiation (60); receiving second optical radiation (12) originating from the scene to be observed from a second optical path (10) provided with an optical attenuator (90) having a variable opacity and capable of modifying a light intensity of the second optical radiation (12); displaying a second digital image from the first digital image; and observing, from a third optical path (5), third optical radiation (91) transmitted by the optical attenuator (90), and the second digital image, characterised in that it includes a determination of a light intensity of at least one pixel of the first digital image and a variation in the opacity of the optical attenuator (90) from the light intensity determined.