Image intensifier device with power supply arranged upstream of the photocathode

Abstract

An image intensifier device (300) comprising: - an intensifier tube (350) having at least one photocathode (310), a microchannel plate (320) and a conversion element (330) arranged in this order, and - a power supply module (360) configured to provide at least one respective polarisation voltage to each of the elements of the intensifier tube (350). According to the invention, the power supply module (360) extends on the side of the photocathode opposite the microchannel plate, in a region located entirely upstream of the photocathode. Thus, the space downstream of the intensifier tube (350) in the direction of travel of the photons and electrons in the image intensifier device (300) is freed up. This makes it possible to reduce the size of the image intensifier device (300), for example by bringing the eyepiece (380) closer.

Description

Technical Field

[0001] The present invention pertains to image enhancement devices for observing scenes (especially night scenes) in dim light. Background Technology

[0002] Image enhancement devices are based on the principle of optical amplification performed sequentially by: photon-electron conversion operated by a photocathode, multiplication of electrons through secondary emission, and a final electron-photon conversion operated by a light-emitting screen called a phosphor screen.

[0003] Figure 1 An image enhancement device 100 according to the prior art is schematically shown. The image enhancement device includes elements arranged in the following order:

[0004] - Photocathode 110;

[0005] - Microchannel plate 120 (MCP); and

[0006] -Electron-to-photon conversion element 130.

[0007] A photocathode 110 is disposed on the input side of the image enhancement device 100. In use, the photocathode is polarized by a first polarization voltage. This stage enables the conversion of the incident photon beam into an initial electron beam through the photoelectric effect.

[0008] Microchannel plate 120 is a glass component consisting of multiple intersecting microchannels. In use, the microchannel plate is polarized by a second polarization voltage. This stage enables charge multiplication through secondary emission. An internal field is generated by applying the second polarization voltage between two surfaces (input and output) of the microchannel plate. When electrons enter the microchannels and strike the walls of the microchannels, this results in the emission of multiple so-called secondary electrons. These secondary electrons are accelerated by the internal field in microchannel plate 120 and again strike the walls of the microchannels, resulting in the emission of new secondary electrons. This constitutes a cascade phenomenon. In image intensification device 100, microchannel plate 120 is configured to receive an initial electron beam emitted by photocathode 110 and, in response, emit an enhanced electron beam. Each electron from the initial electron beam arriving from the photocathode results in the emission of multiple electrons from the enhanced electron beam.

[0009] Hereinafter, the electron-photon conversion element 130 will be simply referred to as the "conversion element". In use, the electron-photon conversion element is polarized by a third polarization voltage. The electron-photon conversion element is configured to receive an enhanced electron beam and, in response, emit an enhanced photon beam. Each electron in the enhanced electron beam is the origin of the corresponding photon in the enhanced photon beam. Therefore, the light distribution in the enhanced photon beam corresponds to the light distribution in the incident photon beam at the photocathode, which is significantly amplified by cascade emission at the microchannel plate. Thus, the low-brightness image provided at the photocathode is converted into an image with sufficient brightness to distinguish objects in the image with the naked eye. Preferably, the conversion element 130 comprises a fluorescent screen.

[0010] The photocathode 110, microchannel plate 120, and conversion element 130 extend sequentially along the axis (Ox). Therefore, the microchannel plate 120 is located between the photocathode 110 and the microchannel plate 120. The transmission directions of photons and electrons in the image enhancement device can be defined, and thus the transmission directions of photons and electrons here correspond to the axis (Ox) oriented from the photocathode 110 toward the conversion element 130.

[0011] In this document, the terms "upstream" and "downstream" refer to the direction of photon and electron transport in an image enhancement device.

[0012] The photocathode 110, microchannel plate 120, and conversion element 130 extend within a sealed chamber or reinforcing tube 150, where the pressure is extremely low. The pressure level in the reinforcing tube 150 is referred to by those skilled in the art as "ultra-high vacuum." Two regions 151 and 152 extend within the reinforcing tube 150 under ultra-high vacuum pressure. These regions 151 and 152 extend between the photocathode 110 and the microchannel plate 120, and between the microchannel plate 120 and the conversion element 130, respectively. In this configuration, the photocathode 110 is composed of a coating deposited on a window 111, which forms the input window of the reinforcing tube 150.

[0013] exist Figure 1 In the example shown, the image enhancement device also includes a fiber array 140 extending downstream of the conversion element 130, such that the conversion element 130 is located between the microchannel plate 120 and the fiber array 140. The enhancement tube 140 is then closed at one end of the fiber array 140 at the end opposite the photocathode 110. The conversion element 130 is in the form of a multilayered array of luminescent microparticles. Each luminescent particle extends on one or more fibers in the fiber array 140 on the microchannel plate 120 side.

[0014] The fiber optic array 140 is configured to invert (i.e., rotate 180°) the input image. In other words, the image provided at the input of the fiber optic array is rotated 180° around an axis (Ox) between the input and output of the fiber optic array. The image is also transmitted along the axis (Ox) from one end of the fiber optic array 140 to the other. The arrangement of the fibers at the input of the fiber optic array (on the side of the microchannel plate 120) and the arrangement of the fibers at the output of the fiber optic array (on the side opposite to the microchannel 120) are symmetrical about each other at an angle of 180° = π according to circular symmetry. The fiber optic array 140 enables the enhanced image obtained at the conversion element 130 to pivot 180°, so that in use, the user sees the enhanced image "face up". This is therefore to compensate for the image inversion imposed by the objective lens 170, which will be mentioned later.

[0015] An assembly including a photocathode 110, a microchannel plate 120, a conversion element 130, and a fiber array 140 is inserted between the objective lens 170 and the eyepiece 180.

[0016] Objective lens 170 comprises a set of one or more refractive optical elements (or one or more lenses). The objective lens is configured to optically conjugate between a focusing surface (or object surface) and an initial image forming surface P1, where the scene to be observed and / or imaged is located. The initial image forming surface is located inside intensifier tube 150 or at the inlet of intensifier tube. In this case, the initial image forming surface P1 extends directly onto photocathode 110, on the active surface of the photocathode.

[0017] The eyepiece 180 consists of a set of one or more refractive optics (or one or more lenses). The eyepiece is configured to perform optical conjugation between the image-forming surface P2 and the image surface, which is located outside the intensifier tube 150.

[0018] The enhanced image forming surface P2 refers to the surface on which an enhanced image is formed during use by photons emitted from the conversion element 130. Where appropriate, the enhanced image forming surface is the surface that satisfies this condition and is closest to the light output section 153 of the enhancement tube 150. The light output section 153 of the enhancement tube 150 refers to the interface through which the enhanced photon beam emitted by the conversion element 130 enters free space during use. In this case, the light output section 153 of the enhancement tube 150 is formed by one end of the fiber array 140 located on the side opposite to the microchannel plate 120. Therefore, the enhanced image forming surface P2 passes through the output surface of the fiber of the fiber array 140 located on the side opposite to the microchannel plate 120. The enhanced image formed at surface P2 corresponds to the image formed at the conversion element 130, which is offset and pivoted by the fiber array 140.

[0019] Preferably, the image surface corresponds to the surface that the user can clearly see with their eye in a static state through eyepiece 180. For optimal visual comfort, the diopter of eyepiece 180 can be adjusted. In use, the user places their eye behind eyepiece 180, on the side opposite to the fiber array 140. Therefore, the image surface and the retina of the eye are optically conjugate through an optical system formed by elements of the eye located between the retina and cornea, and, where appropriate, vision-correcting optics (e.g., contact lenses). For emmetropic eyes, the image surface extends to infinity.

[0020] Each of the photocathode 110, microchannel plate 120, and conversion element 130 is connected to a power module 160, which provides a corresponding polarization voltage (referred to as a first polarization voltage, a second polarization voltage, and a third polarization voltage, respectively) to each of the photocathode, microchannel plate, and conversion element. The power module 160 is connected at its input to a low-voltage power source (not shown), such as a battery. The power module is configured to convert the received low voltage into at least one high voltage that forms the first polarization voltage, the second polarization voltage, and the third polarization voltage, and to supply these polarization voltages to each of the photocathode 110, microchannel plate 120, and conversion element 130.

[0021] The power module 160 and the enhancement tube 150 typically extend together in the form of a tube inside the housing 190.

[0022] like Figure 1 As shown, the power module 160 extends around the fiber array 140.

[0023] Figure 1 Arrow 101 is also shown, indicating the back focal length of eyepiece 180, or in other words, the distance required between the enhanced image forming surface P2 (located here at the output of fiber array 140) and eyepiece 180 (at the junction 181 of eyepiece 180 positioned opposite conversion element 130). Back focal length 101 corresponds to the optically conjugate distance that enables eyepiece 180 to achieve the relationship between the enhanced image forming surface P2 and the image surface clearly observed by the user during use.

[0024] The object of the present invention is to provide an image enhancement device that has a reduced size compared to image enhancement devices according to the prior art. Summary of the Invention

[0025] This objective is achieved by an image enhancement device comprising an enhancement tube and a power module, wherein the enhancement tube includes:

[0026] - At least one photocathode, the at least one photocathode being configured to convert an incident photon beam into an initial electron beam;

[0027] - A microchannel plate, configured to generate multiple secondary electrons in response to the reception of incident electrons during use, and configured to receive an initial electron beam and generate an enhanced electron beam in response.

[0028] - A conversion element configured to receive an enhanced electron beam and, in response, emit an enhanced photon beam, with a microchannel plate positioned between the photocathode and the conversion element;

[0029] - Power module, configured to provide at least one corresponding voltage to each of the photocathode, microchannel plate and conversion element;

[0030] Furthermore, the power module extends on the side of the photocathode opposite to the microchannel plate, in the region upstream of the photocathode.

[0031] The conversion element can also be called a "photon-electron conversion element".

[0032] In use, each incident electron on the microchannel plate results in the emission of a large number (preferably more than ten) of secondary electrons.

[0033] make Figure 1 One solution to reduce the size of the type of image enhancement device shown is to reduce the length of the fiber array. In fact, recent developments have enabled the production of fiber arrays capable of inverting input images, with reduced lengths while maintaining optical transmission and contrast requirements, thus ensuring consistent image quality.

[0034] Figure 2 An image enhancement device 100' is shown, which is related to... Figure 1The only difference in the image intensifier is that the fiber array 140' has a reduced length. As with existing technology, the conversion element 130' extends at the input of the fiber array, and the image-forming surface P2 is located at the output of the fiber array 140. Due to the reduced length of the fiber array 140', the image-forming surface P2 is significantly recessed relative to the exit of the receptacle 190'. To maintain the required distance between the image-forming surface P2 and the eyepiece 180', it is necessary to bring the receptacle 190' and the eyepiece 180' closer together. The eyepiece 180' can be brought closer to the receptacle 190', up to an extreme position where the eyepiece 180' presses against the output edge 191' of the receptacle 190'. The output edge 191' of the receptacle 190' refers to the edge of the receptacle furthest from the objective lens 170. If the length of the fiber bundle 140' is significantly reduced, even at this extreme position, it is impossible to make the distance between the image-forming surface P2 and the eyepiece 180' equal to the back focal length 101' of the eyepiece (see [reference needed]). Figure 2 Therefore, those skilled in the art might consider reducing the length L of the receiving portion 190' to reduce the distance between the enhanced image forming surface P2 and the output edge 191' of the receiving portion 190'. However, those skilled in the art will be limited by the size of the power module 160'. An obvious solution to overcome this problem lies in miniaturizing the power module 160'.

[0035] Therefore, the idea behind this invention is to reconsider the overall arrangement of different components in an image enhancement device, and to move the power supply module, rather than simply modifying its size. According to the invention, the power supply module is moved towards the region located upstream of the photocathode (i.e., on the side of the photocathode opposite the microchannel plate), based on the direction of photon and electron transport in the image enhancement device. This new position allows the enhanced image forming surface P2 to be moved closer to the output edge 191' of the receptacle 190' without any limitations. This allows for adherence to the required distance between the enhanced image forming surface and the eyepiece, while maintaining a shorter fiber bundle. Furthermore, since the power supply module is moved rather than miniaturized, it is not necessary to completely alter the power supply module to integrate miniaturized internal components.

[0036] For those skilled in the art, moving the power module is not an obvious solution. Moving the power module allows it to maintain its previous arrangement, in particular avoiding the need to redesign the dimensions of different housings and covers in the image intensifier, and avoiding the need to reconsider the electrical insulation around the power module and the connections (high-voltage power lines that deliver very low current).

[0037] Based on the direction of photon and electron transport in the image intensifier, this new position of the power module clears space downstream of the conversion element. Clearing this space allows for a reduction in the size of the image intensifier. For example, clearing this space allows for a reduction in the distance between the conversion element and auxiliary elements (e.g., the eyepiece). This technological advantage is found when there is a fiber bundle downstream of the conversion element, but it is also found in the absence of such a fiber bundle.

[0038] Advantageously, the power module extends around the outer periphery of the objective lens, as shown in reference. Figure 1 As described, the diameter of the objective lens can be smaller than the diameter of the intensifier tube, thus allowing the power module to be housed within the space surrounding the objective lens without increasing the overall diameter of the image intensifier.

[0039] Preferably, the power module extends outside the enhancement tube.

[0040] Preferably, the device according to the invention further includes a first set of lenses, referred to as an objective lens, configured to optically conjugate the focusing surface and the initial image forming surface, the focusing surface being located outside the intensifier tube, the initial image forming surface being located inside the intensifier tube or at the input of the intensifier tube, and a power supply module extending around the periphery of the objective lens.

[0041] Advantageously, the power module protrudes from the objective lens on both sides along an axis parallel to the optical axis of the objective lens.

[0042] Preferably, the power module includes a through opening extending opposite the photocathode. The power module may have an annular shape.

[0043] According to an advantageous embodiment, the device according to the invention further includes an optical fiber bundle arranged downstream of a conversion element along the direction of photon and electron propagation in the image enhancement device, the optical fibers of the optical fiber bundle being arranged to pivot an image provided at an input portion of the optical fiber bundle, and an output surface of the optical fiber bundle on the side opposite to the conversion element forming a surface referred to as an enhanced image forming surface.

[0044] According to another advantageous embodiment, the device according to the invention further includes a transparent support member, the conversion element being formed by a coating covering at least a portion of a face of the transparent support member, the face of the transparent support member forming a surface referred to as an enhanced image forming surface.

[0045] The device according to the invention may further include a second set of lenses, referred to as an eyepiece, configured to optically conjugate the image enhancement forming surface and an image surface located outside the intensifier tube. The device according to the invention may also include a complementary image forming module and a partial reflective element, the complementary image forming module being configured to provide a complementary image, the partial reflective element extending between the eyepiece and the image enhancement forming surface, and the partial reflective element being configured to superimpose the complementary image and the enhanced image formed at the image enhancement forming surface.

[0046] According to an advantageous embodiment, the device according to the invention may further include an offset element configured to laterally offset an enhanced image derived directly or indirectly from the enhanced image forming surface. The offset element may be at least partially transparent in visible light so that the enhanced image offset by the offset element can be superimposed with a transparent view of the surrounding scene. Attached Figure Description

[0047] The invention will be better understood by reading the description of embodiments given for illustrative purposes only and without limitation, and by referring to the accompanying drawings, in which:

[0048] [ Figure 1 This schematically illustrates an image enhancement device according to the prior art;

[0049] [ Figure 2 This schematically illustrates an image enhancement device integrated with a reduced-length fiber optic array;

[0050] [ Figure 3 An image enhancement device according to a first embodiment of the present invention is schematically shown;

[0051] [ Figure 4A ]and[ Figure 4B Two examples of the arrangement of the power supply module in the image enhancement device according to the present invention are illustrated schematically;

[0052] [ Figure 5 An image enhancement device according to a second embodiment of the present invention is schematically shown;

[0053] [ Figure 6 The image enhancement device according to a third embodiment of the present invention is illustrated schematically. Detailed Implementation

[0054] For greater clarity, the axes of the orthogonal reference frame (Oxyz) are shown in the accompanying drawings. In this case, the axis (Ox) corresponds to the direction of light propagation in the image enhancement device according to the invention.

[0055] Figure 3An image enhancement device 300 according to a first embodiment of the present invention is schematically shown in a cross-sectional view. Only the image enhancement device 300 will be described. Figure 1 The differences compared to the embodiments.

[0056] In this configuration, the power module 360 ​​does not extend around the fiber array 340, and the fiber array 340 has a reduced length.

[0057] Here, the power module 360 ​​extends around the objective lens 370 in the region upstream of the photocathode 310 (i.e., on the side of the photocathode 310 opposite to the microchannel plate 320 and the conversion element 330).

[0058] As previously described, the photocathode 310, microchannel plate 320, and conversion element 330 extend into the reinforcement tube 350, as described in the introduction. The reinforcement tube 350 itself extends within the housing 390 together with the fiber array 340. Here, each of the photocathode 310, microchannel plate 320, and conversion element 330 extends in a plane parallel to the plane (Oyz).

[0059] As described previously, the output edge 391 is defined on the housing 390, located on the side of the fiber array 340, and facing the eyepiece 380. Here, the output edge 391 of the housing 390 extends in a plane (yOz) parallel to the plane of the microchannel plate 320.

[0060] As described in the introduction, the image enhancement surface P2 is located at the output end of the fiber array 340. Specifically, the image enhancement surface P2 is formed by a surface that passes through the output surface of the optical fiber of the fiber array 340, the output surface of which is located on the side of the optical fiber opposite to the microchannel plate 320. The image enhancement surface P2 is a non-planar surface, and its topology follows the topology of the first junction 381 belonging to the eyepiece 380, wherein the first junction 381 is located on the side of the conversion element 330.

[0061] The power module 360 ​​does not extend around the fiber array 340, but rather in a region upstream of the photocathode 310. Therefore, even with a reduced length Lf of the fiber array 340, the output edge 391 of the receptacle 390 is close to the output end 341 of the fiber array 340. Consequently, the output edge 391 of the receptacle 390 is close to the image enhancement surface P2. Therefore, despite the reduced length Lf of the fiber array 340, the distance between the image enhancement surface P2 and the first junction 381 belonging to the eyepiece 380 is equal to the back focal length 301 of the eyepiece 380 (as defined in the introduction).

[0062] Here, in the orthogonal projection of the power module and the photocathode into a plane parallel to the plane (Oyz), the power module 360 ​​extends around the photocathode 310.

[0063] In this configuration, the fiber array 340 protrudes slightly beyond the housing 390. Consequently, the image enhancement surface P2 extends beyond the housing 390.

[0064] Here, the power module 360 ​​is located outside the intensifier tube 350 and the housing 390. The power module has a length Lc measured along the axis (Ox), which is strictly smaller than the length Lb of the objective lens 370 measured along the same axis. Furthermore, the power module does not protrude beyond the objective lens 370 along the axis (Ox) (parallel to the optical axis BB' of the objective lens 370).

[0065] Figure 4A The image enhancement device 300 is shown in a cross-sectional view in plane AA', which is parallel to plane (yOz) and passes through power module 360. Figure 4A The power module 360 ​​is shown surrounding the objective lens 370 at an angle of 380°. In other words, the power module 360 ​​is provided with a through opening 361 in which the objective lens 370 extends. The through opening 361 is positioned opposite the photocathode 310. Preferably, the through opening 361 has an axisymmetric cylindrical shape, and the through opening has a rotation axis orthogonal to the plane (Oyz) of the photocathode 310, and this rotation axis preferably passes through the center of the photocathode. In this case, non-limitingly, the power module 360 ​​is shaped as a first axisymmetric cylinder open at the center through the through opening 361, and the through opening is shaped as a second axisymmetric cylinder concentric with the first axisymmetric cylinder. In other words, the power module 360 ​​has an annular shape. In variations not shown, the power module 360 ​​has any shape with a through opening shaped as an axisymmetric cylinder as described above. According to other variations, the opening at the center does not have an axisymmetric cylindrical shape, but has any shape that allows light to pass through to the photocathode 310.

[0066] exist Figure 4B In the variant 300' shown, the power module 360' surrounds the objective lens 370 only at an angle of less than or equal to 180°.

[0067] Many other forms of power modules can be implemented without departing from the scope of the invention, particularly power modules in which the power module is not centered on the optical axis BB'.

[0068] Preferably, in the orthogonal projection of the receiving portion 390 into the plane (Oyz), the power module 360 ​​does not protrude beyond the receiving portion 390. In other words, the orthogonal projection of the power module 360 ​​into the plane (yOz) is inscribed within the orthogonal projection of the receiving portion 390 into the same plane. For this purpose, the maximum diameter of the objective lens 370 is strictly smaller than the outer diameter of the receiving portion 390, and the power module 360 ​​extends within the space defined by the edge of the objective lens 370 and a tubular portion having the same diameter as the outer diameter of the receiving portion 390. Therefore, it is ensured that the power module 360 ​​does not increase the overall size of the image intensifier, particularly the diameter of the image intensifier.

[0069] Two embodiments are described below, in which the new arrangement of the power module offers advantages even when the output of the intensifier tube does not contain a fiber array. Specifically, in these embodiments, the new arrangement of the power module frees up space for inserting auxiliary components, enabling the addition of new functionality to the image enhancement device while maintaining a reduced size.

[0070] Figure 5 A second embodiment of the image enhancement device 500 according to the present invention is shown, wherein the space cleared by the power module is used to add additional functions to the device without increasing the size of the device.

[0071] Image enhancement device 500 and Figure 3 The only difference in the embodiment is that the image enhancement device does not include an optical fiber array at the output of the enhancement tube, and the image enhancement device includes a supplementary image generation and overlay device.

[0072] The supplementary image generation and overlay apparatus includes a supplementary image forming module 51 and a partial reflector 52.

[0073] A partial reflector 52 extends between the eyepiece 580 and the image-enhancing surface P2. The partial reflector 52 reflects a portion of the incident light and transmits another portion of it. In this case, the partial reflector 52 is a half-reflector. The partial reflector is tilted relative to the plane (Oyz) at an angle α (here, α = 45°). In a variant not shown, the partial reflector 52 is replaced by any other partial reflecting element (e.g., a beam splitter cube or beam splitter plate).

[0074] The complementary image forming module 51 is configured to generate a so-called complementary image and to project the complementary image in the direction of the partial reflector 52 (here, along the axis (Oz)). The complementary image forming module 51 includes a display screen, particularly an organic light-emitting diode (OLED) based screen. The complementary image forming module may also include a processor connected to the display screen, the processor integrating electronics for controlling and powering the screen, and electronics for exchanging data with an external source (to receive data related to the complementary image to be displayed on the screen).

[0075] The complementary image forming module 51 extends around the periphery of the partial reflector 52 and specifically occupies at least a portion of the area occupied by the power module 560 in the prior art.

[0076] The partial reflector 52 is configured to superimpose the complementary image projected by the complementary image forming module 51 with the enhanced image formed at the enhanced image forming surface P2. For this purpose, the complementary image forming module 51 is configured to project a complementary image that arrives at the partial reflector 52 at an incident angle of 45° and propagates along the axis (Oz). In use, this complementary image is reflected at least partially in the direction of the eyepiece 580. The enhanced image formed at the output end of the fiber bundle 540 arrives at the partial reflector 52 at an incident angle of 45° and propagates along the axis (Ox). In use, this enhanced image is transmitted at least partially in the direction of the eyepiece. Therefore, downstream of the partial reflector 52, in the direction of light (and electron) transmission in the device 500, the complementary image is superimposed on the enhanced image.

[0077] Advantageously, the complementary image has a similar size to the augmented image. For example, the complementary image is composed of graphic symbols. For instance, the complementary image can superimpose symbols (e.g., displays of base points, aiming lines, etc.) related to measurements provided by an additional sensor onto the augmented image.

[0078] In this case, the image enhancement forming surface P2 is a planar surface to simplify the overlay of the enhanced image and the complementary image. However, the invention also covers variations in which the image enhancement forming surface P2 is a non-planar surface (e.g., a concave surface).

[0079] Figure 6 A third embodiment of the image enhancement device 600 according to the present invention is shown. Only the third embodiment of the image enhancement device will be described in conjunction with... Figure 3 The differences compared to the embodiments.

[0080] In this embodiment, the image enhancement device 600 does not include an optical fiber array located at the output of the enhancement tube, but includes a real image overlay device.

[0081] This real image overlay device includes an offset element 61 and a focusing optics 62. Here, the offset element 61 extends between the image enhancement surface P2 and the focusing optics 62.

[0082] The focusing optics 62 here comprises a concave mirror with its optical axis parallel to the axis (Ox), and the reflecting surface of the concave mirror is located on the side of the image enhancement forming surface P2. The focusing optics 62 is configured to project the enhanced image P2 formed on the image enhancement forming surface P2 to infinity. In this case, the image is projected to infinity in the direction of the image enhancement forming surface P2.

[0083] The offset element 61 is attached here to the enhanced image forming surface P2. This arrangement is made possible by the space cleared by the forward movement of the power module.

[0084] As is not limiting here, the enhanced image forming surface P2 is planar to facilitate surface contact with the offset element 61.

[0085] This offset element 61 includes a waveguide that covers the image enhancement forming surface P2 and extends laterally beyond this surface to the so-called observation region RO. The waveguide is provided with an introduction element and an acquisition element. For example, the introduction and acquisition elements are composed of corresponding diffraction elements etched into the surface of the waveguide. In this case, the introduction element (not shown) extends opposite the image enhancement forming surface P2 on the focusing optics side. Furthermore, the acquisition element (not shown) extends here into the observation region RO on the focusing optics side.

[0086] The offset element 61 is at least partially transparent in the visible light spectrum. For example, the offset element has a transmittance of 95% or greater in the wavelength range from 400 nm to 700 nm.

[0087] In use, the enhanced image formed at surface P2 propagates to the focusing optics 62 while passing through the entire offset element 61. At the focusing optics, the light is collimated and reflected back in the opposite direction. In other words, the enhanced image is projected to infinity and then reflected back in the opposite direction. Therefore, the light reflected back by the focusing optics 62 returns to the offset element 62 at the introduction element as described above. Thus, the light penetrates into the waveguide within the offset element 62, and light guidance begins at the waveguide. In the waveguide, the light is guided along the axis (Oz) until the observation area RO. When the light reaches the acquisition element described above, light is acquired from the waveguide. The acquired light is collimated, just as the light initially introduced into the waveguide. Therefore, the offset element 61 is configured to receive the enhanced image at the input, to laterally offset the enhanced image to bring the enhanced image to the observation area RO, and to acquire the enhanced image outward from the offset element 61. The enhanced image laterally offset using the offset element 61 is directly or indirectly derived from the image formed on surface P2. In this case, the enhanced image is indirectly derived from the surface P2, because the enhanced image corresponds to the enhanced image formed on the surface P2 and then projected to infinity by the focusing optics 62.

[0088] In use, the user positions their eye relative to the offset element 61 and the viewing area RO. The enhanced image is projected to infinity at the viewing area and transmitted through the offset element 61. Thus, the user visualizes the enhanced image from the offset element 61 and the external scene observed transparently through the offset element 61 in a superimposed manner. The image enhancement device 600 thus forms an augmented reality vision device to provide a view corresponding to the superposition of the enhanced image and the image in natural vision.

[0089] In this embodiment, the image enhancement device 600 does not include an eyepiece disposed directly at the output of the fiber bundle.

[0090] Advantageously, the offset element 61 is fixed to the fiber bundle 640 by directly bonding it to or near the output surface of the fiber bundle.

[0091] In a variant not shown, the focusing optics extend between the image enhancement forming surface P2 and the offset element. The focusing optics are therefore composed of one or more refractive lenses. Similarly, the focusing optics are configured to project the enhanced image formed on the image enhancement forming surface P2 to infinity. Likewise, the image is projected in the direction of the offset element (here, on the side of the focusing optics opposite to surface P2). The image projected to infinity thus enters the offset element and is carried to the observation area, where the image is acquired from the offset element. The back focal length of the focusing optics can be very short. Due to the space cleared by the forward movement of the power module, the present invention allows the focusing optics to be sufficiently close to the plane P2.

[0092] This invention is not limited to the examples described above. For example, in a variant not shown, the image enhancement device does not include a fiber optic array but instead includes a transparent support (e.g., a glass block). In this case, the conversion element is in the form of a monolithic coating extending integrally onto one surface of the transparent support. The transparent support is transparent to the wavelength of the photons emitted by the conversion element. Therefore, the image-enhancing surface coincides with a surface on which the coating forming the conversion element extends onto the transparent support. The image "face up" inversion is achieved by refractive optics. The various embodiments and variants of the invention described above can be readily combined with this variant.

[0093] According to other variations, the enhancement device includes an optical fiber bundle that forms the optical input portion of the enhancement tube on the photocathode side. In this case, as described above, the initial image forming surface P1 is formed by one end of the optical fiber bundle on the side opposite to the photocathode. This embodiment can be combined with or without the presence of the optical fiber bundle at the output portion of the enhancement tube on the conversion element side. This embodiment can be combined with each of the examples, variations, and embodiments described above.

[0094] According to other variations, the power module may be located inside the housing that receives the enhancement tube and the fiber bundle.

[0095] The invention also includes a dual-type system comprising two image enhancement devices according to the invention, each image enhancement device being dedicated to a user’s corresponding eye.

[0096] The device according to the invention has advantageous uses in the field of night vision for observing scenes in dim light or in darkness.

[0097] This invention is applicable to night vision devices that do not use microchannel plates, but are based on CMOS sensors and photocathodes capable of converting the incident flux of electrons into electrical measurement signals. In such devices, a power supply module capable of providing polarization voltage to the photocathode can be arranged upstream of the photocathode in the direction of light and electron transport within the device.

Claims

1. An image enhancement device (300; 300'; 500; 600), the image enhancement device comprising an enhancement tube (350) and a power module (360; 360'; 560), wherein, The reinforcing tube (350) includes: - At least one photocathode (310), said at least one photocathode being configured to convert an incident photon beam into an initial electron beam; - A microchannel plate (320), the microchannel plate being configured to generate a plurality of secondary electrons in response to the reception of incident electrons during use, and being configured to receive the initial electron beam and, in response, generate an enhanced electron beam; and - A conversion element (330; 530) configured to receive the enhanced electron beam and, in response, emit an enhanced photon beam, the microchannel plate (320) being located between the photocathode (310) and the conversion element (330; 530); - A first set of lenses, referred to as the objective lens (370), is configured to optically conjugate the focusing surface and the initial image forming surface (P1), the focusing surface being located outside the intensifier tube (350), and the initial image forming surface being located inside the intensifier tube (350) or at the input of the intensifier tube; The power module (360; 360'; 560) is configured to provide at least one corresponding bias voltage to each of the photocathode (310), the microchannel plate (320), and the conversion element (330; 530); The power module (360; 360'; 560) extends on the side of the photocathode opposite to the microchannel plate, at the outer periphery of the objective lens (370), and in the region completely upstream of the photocathode (310).

2. The image enhancement device (300; 300'; 500; 600) according to claim 1, characterized in that, The power modules (360; 360'; 560) protrude from the objective lens (370) on both sides along an axis parallel to the optical axis (BB') of the objective lens.

3. The image enhancement device (300; 500; 600) according to claim 1 or 2, characterized in that, The power module (360; 560) includes a through opening (361) extending opposite to the photocathode (310).

4. The image enhancement device (300; 500; 600) according to claim 3, characterized in that, The power modules (360; 560) are ring-shaped.

5. The image enhancement device (300; 300'; 500; 600) according to claim 1 or 2, characterized in that, The image enhancement device further includes an optical fiber bundle (340; 540; 640) arranged downstream of the conversion element (330; 530) along the direction of photon and electron propagation in the image enhancement device. The optical fibers of the optical fiber bundle (340; 540; 640) are arranged to pivot the image provided at the input of the optical fiber bundle, and the optical fiber bundle is connected to the conversion element (330). 530) The output surface on the opposite side forms a surface called the enhanced image forming surface (P2).

6. The image enhancement device according to claim 1 or 2, characterized in that, The image enhancement device further includes a transparent support located downstream of the conversion element, the conversion element being formed by a coating covering at least a portion of one side of the transparent support, the other side of the transparent support forming a surface referred to as an enhanced image forming surface.

7. The image enhancement device (300; 300'; 500) according to claim 5, characterized in that, The image enhancement device also includes a second set of lenses (380; 580) referred to as an eyepiece, which is configured to optically conjugate the enhanced image forming surface (P2) and the image surface located outside the enhancement tube (350).

8. The image enhancement device (500) according to claim 7, characterized in that, The image enhancement device further includes a complementary image forming module (51) and a partial reflective element (52), the complementary image forming module being configured to provide a complementary image, the partial reflective element extending between the eyepiece and the enhanced image forming surface (P2), and the partial reflective element being configured to superimpose the complementary image and the enhanced image formed at the enhanced image forming surface (P2).

9. The image enhancement device (600) according to claim 5, characterized in that, The image enhancement device further includes an offset element (61) configured to laterally offset the enhanced image directly or indirectly derived from the enhanced image forming surface (P2).

10. The image enhancement device (600) according to claim 9, characterized in that, The offset element (61) is configured such that visible light is at least partially transmitted, so that the enhanced image offset by the offset element can be superimposed on a transparent view of the surrounding scene.

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