Night vision binoculars

Abstract

The present invention relates to night vision binoculars comprising: a. at least two optical units each having an optical axis, and b. a device (16) for harmonizing the optical axes of the two optical units, the harmonization device (16) comprising two prismatic optical plates (20, 22) permanently rotationally locked and oriented relative to each other and with respect to the optical units such that the optical axes of the at least two optical units are parallel.

Description

[0001] Night vision binoculars

[0002] The present invention relates to night vision binoculars.

[0003] It particularly concerns the axis harmonization devices between the optical paths of night vision binoculars.

[0004] The parallelism performance (collimation, convergence, divergence, supravergence) of night vision binoculars directly contributes to the user's viewing comfort and ensures that the binoculars impair the right eye / left eye image superposition capacity as little as possible and generate as little eye fatigue as possible over time.

[0005] Depending on the user typologies addressed, the optical axis harmonization needs expressed through these parallelism performances are more or less severe (harmonization less than 1° for low performance applications, and less than 0.5° or even 0.3° for high performance applications).

[0006] In the field of night vision binoculars, various hands-free devices exist. They all have a X1 magnification and require optical axis harmonizations (otherwise called optical invariant for X1 magnification systems) between the different optical inputs and outputs so as not to disturb the user's senses (orientation and viewing comfort). In particular:

[0007] - monocular devices, where the user looks with one eye through an optical system, require precise optical axis harmonization between the lens input and the eyepiece output.

[0008] - bi-ocular devices where the user looks with both eyes at an intensified image captured by a single lens, require precise optical axis harmonization between the output of the right eyepiece and that of the left eyepiece.

[0009] - binocular devices where the user looks through two independent optical paths, each comprising an intensifier tube, require precise optical axis harmonization between the two paths. In this case, the user has a stereoscopic view of the observed scene.

[0010] - panoramic devices otherwise called "quad-eyes" where the user looks through four intensified channels (2 central channels and 2 lateral channels) require both precise optical axis harmonization between the two central channels, but also precise axis harmonization between the central and left and right lateral channels respectively.

[0011] Binoculars typically available on the market offer a standard field of 40° for a numerical aperture of F / 1.2. The market for night vision binoculars is evolving and tends towards increasing fields and numerical aperture without loss of resolution while reducing the mass of the equipment. This evolution leads to the proposal of new, much more complex optical architectures and makes the relative positioning of the optics in relation to each other more sensitive.

[0012] However, the solutions identified in the known state of the art proposing internal adjustment devices in the binoculars are difficult to implement on new wide field and / or high numerical aperture optics:

[0013] They require increasingly precise and stable play-free mechanisms in thermal and mechanical environments.

[0014] They can generate losses in optical quality (resolution / MTF / distortion) when the displacement of the optics, favorable to axis alignment, generates optical aberrations.

[0015] They can lead to iterative adjustment strategies requiring phases of disassembly and reassembly of the binoculars.

[0016] There is therefore a need for an optical axis harmonization solution for night vision binoculars, simple to implement, not degrading image quality, and applicable to all types of night vision binoculars, in particular new generation binoculars with more complex optics with expanded field and numerical aperture.

[0017] For this purpose, the present description relates to night vision binoculars comprising: a. at least two optical blocks each having an optical axis, and b. a device for harmonizing the optical axes of the two optical blocks, the harmonizing device comprising two prismatic optical blades permanently locked in rotation and oriented relative to each other and relative to the optical blocks so that the optical axes of the at least two optical blocks are parallel.

[0018] According to particular embodiments, the binoculars comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0019] - the two optical blades are fixed to each other, preferably by gluing;

[0020] - the two optical blades are mounted in the same barrel; - the two optical blocks belong to different optical paths, one optical blade of the harmonization device being positioned on the optical path of one of the optical blocks, and the other optical blade of the harmonization device being positioned on the optical path of the other optical block;

[0021] - the two optical blades are inclined at the same non-zero angle relative to the normal to the optical axis of one of the optical blocks;

[0022] - at least one of the optical blocks comprises an objective, at least one optical blade of the harmonization device being positioned at the entrance of the objective of the or one of the blocks;

[0023] - the binoculars are monocular so that the two optical blocks belong to the same optical path, one of the optical blocks being an eyepiece and the other optical block being an objective;

[0024] - the binoculars are biocular so that the two optical blocks belong to different optical paths, one of the optical blocks being a first eyepiece and the other optical block being a second eyepiece;

[0025] - the binoculars are binocular so that the two optical blocks belong to different optical paths, one of the optical blocks comprising a first eyepiece and a first objective, the other optical block comprising a second eyepiece and a second objective;

[0026] - the binoculars are panoramic with four optical paths among: a right central path, a right lateral path, a left central path and a left lateral path, the two optical blocks each comprising an eyepiece and an objective, the two optical blocks belonging to two different optical paths among the following path combinations: the right central path and the right lateral path, the left central path and the left lateral path, and the two central paths, so that the harmonizing device harmonizes the optical axes of the two optical paths of the combination;

[0027] - the binoculars comprise two additional harmonizing devices positioned on the optical paths of the other two combinations of optical paths so as to harmonize the optical axes of said optical paths.

[0028] The present description also relates to a method for harmonizing the optical axes of two optical blocks of night vision binoculars, the harmonization method being implemented during the design of the binoculars, the method comprising: a. measuring a parallelism defect between the optical axes of the two optical blocks, b. rotating two prismatic optical blades relative to each other and together so as to compensate for the measured parallelism defect, c. permanently blocking the rotation of the two optical blades, and d. positioning the two prismatic optical blades on the optical path of at least one of the two optical blocks, the two optical blades forming a device for harmonizing the optical axes of the two optical blocks.

[0029] Other features and advantages of the invention will become apparent upon reading the following description of embodiments of the invention, given by way of example only and with reference to the drawings which are:

[0030] - Figure 1, a schematic representation of an example of night vision binoculars comprising two optical blocks on the same optical path and a device for harmonizing the optical axes of the two optical blocks,

[0031] - Figure 2, a schematic representation of an example of night vision binoculars comprising two optical blocks on different optical paths and a device for harmonizing the optical axes of the two optical blocks,

[0032] - Figure 3, a schematic representation of an example of a harmonization device comprising two prismatic optical blades, the blades being oriented relative to each other so as not to induce any deviation of the optical axis,

[0033] - Figure 4, a schematic representation similar to Figure 3, with respect to Figure 3, one of the blades having been rotated 180° with respect to the other blade so as to induce a maximum upward axis deviation,

[0034] - Figure 5, a schematic representation similar to Figures 3 and 4, with respect to Figure 4, the two blades having been rotated together by 180° so as to induce a maximum downward axis deviation,

[0035] - Figure 6, a schematic representation of a barrel in which the two prismatic optical blades forming the harmonization device are inserted, and

[0036] - Figure 7, a schematic representation similar to Figure 6, the two blades having been inclined relative to the normal to the optical axis of the optical block receiving the harmonization device.

[0037] Night vision binoculars 10 are schematically illustrated in Figures 1 and 2.

[0038] The binoculars 10 are, for example, intended to be mounted on a helmet or head harness. Alternatively, the binoculars 10 are carried by hand by the user.

[0039] Night vision binoculars 10 are any type of night vision binoculars, including monocular binoculars, biocular binoculars, binocular binoculars, or panoramic binoculars (4-way intensified). Binoculars 10 can also be connected binoculars and integrate data visualization elements.

[0040] As illustrated by figures 1 and 2, the binoculars 10 comprise at least two optical blocks 12, 14 each having an optical axis A1, A2, as well as a harmonization device 16 for the optical axes A1, A2 of the two optical blocks 12, 14. The harmonization consists of making the two optical axes A1, A2 parallel.

[0041] In the example illustrated by Figure 1, the two optical blocks 12, 14 belong to the same optical path. This is particularly the case for monocular binoculars where one of the optical blocks 12, 14 is an eyepiece and the other optical block 12, 14 is an objective.

[0042] In the example illustrated by Figure 2, the two optical blocks 12, 14 belong to different optical paths. This is particularly the case for biocular binoculars where one of the optical blocks 12, 14 is a first eyepiece and the other optical block 12, 14 is a second eyepiece. The harmonization thus consists of making the optical axes A1, A2 of the two eyepieces parallel.

[0043] This is also the case for binoculars where one of the optical blocks 12, 14 comprises a first eyepiece and a first objective and the other optical block 12, 14 comprises a second eyepiece and a second objective. The harmonization thus consists of making the optical axes A1, A2 of the two optical paths parallel.

[0044] Finally, this is also the case for panoramic binoculars having four optical paths among: a right central path, a right lateral path, a left central path and a left lateral path. In this case, a first optical block 12, 14 comprises the eyepiece and the objective of one of the paths, and the other optical block 12, 14 comprises the eyepiece and the objective of another of the paths, among the following combinations of optical paths: the right central path and the right lateral path, or the left central path and the left lateral path, or the two central paths. The harmonization thus consists of making the optical axes A1, A2 of the two optical paths of the combination parallel.

[0045] Preferably, in the case of panoramic binoculars, the binoculars 10 comprise two additional harmonizing devices positioned on the optical paths of the other two combinations of optical paths so as to also harmonize the optical axes A1, A2 of said optical paths. Thus, the right paths are harmonized with each other, the left paths also, as well as the right and left central paths.

[0046] As illustrated in the examples of Figures 3 to 7, the harmonization device 16 comprises two prismatic optical blades 20, 22. The two optical blades 20, 22 preferably have the same prismatic angle. The two optical blades 20, 22 thus form a diasporameter. The two optical blades 20, 22 are, for example, made of glass or polycarbonate. Preferably, the prismatic effect induced by the two blades 20, 22 is small, that is to say the total prismatic angle of the two blades 20, 22 is small, typically less than 5 degrees, preferably less than or equal to 2 degrees.

[0047] The two optical blades 20, 22 are permanently locked in rotation. The user therefore does not have the possibility of rotating the blades 20, 22. The two optical blades 20, 22 are, however, movable in translation if necessary.

[0048] For example, the two optical blades 20, 22 are locked by being fixed to each other and inserted into the same barrel locked in rotation, or by each being inserted into a barrel locked in rotation.

[0049] The two optical blades 20, 22 have been oriented beforehand (during design) relative to each other and relative to the optical blocks 12, 14 so that the optical axes A1, A2 of the at least two optical blocks 12, 14 are parallel.

[0050] In particular, in the examples of Figures 3 to 5, Figure 3 corresponds to an orientation of the two blades not introducing any axis deviation. Figure 4 corresponds to a rotation of the blade 20 of 180° relative to the configuration of Figure 3, so as to induce a maximum axis deviation upwards. Figure 5 corresponds to a rotation of the two blades together of 180° relative to the configuration of Figure 4, so as to induce a maximum axis deviation downwards.

[0051] As illustrated in Figures 4 and 5, for blades of index n and for a prismatic angle of 0 for each blade, the maximum angle of deviation is obtained in the case where the 2 blades are opposite. The prismatic angle is then 20 and the axis deviation is arcsin ((n-1) *sin (20)).

[0052] In an exemplary embodiment, corresponding to figures 3 to 7, the two optical blades 20, 22 are fixed to each other, and this in a permanent manner. For example, the two blades 20, 22 are fixed to each other by gluing. Preferably, the gluing is full face in order to reduce the internal reflection coefficient of the diasporameter in order to limit the level of parasitic images generated by multiple reflections on the faces of the blades.

[0053] Preferably, the two optical blades 20, 22 are mounted in the same barrel 30, as is the case in FIGS. 6 and 7. The barrel 30 is indexed on the optical path on which it is positioned (centered on the optical axis of the path).

[0054] In another exemplary embodiment, the two optical blocks 12, 14 belong to different optical paths. In this case, one optical blade 20, 22 of the harmonization device 16 is positioned on the optical path of one of the optical blocks 12, 14, and the other optical blade 20, 22 of the harmonization device 16 is positioned on the optical path of the other optical block 12, 14. In an exemplary implementation, the two optical blades 20, 22 are inclined at the same angle relative to the normal to the optical axis of one of the optical blocks 12, 14. This makes it possible to offset, or even to shift, out of the field any parasitic images due to the fixing (gluing) of the blades together. Such an inclination is shown in Figure 7.

[0055] Preferably, when at least one of the optical blocks 12, 14 comprises an objective (case of monocular, binocular and panoramic binoculars), at least one optical blade 20, 22 of the harmonization device 16 is positioned at the input of the objective of the or one of the optical blocks 12, 14. Advantageously, the two optical blades 20, 22 are positioned at the input of the objective of the or one of the optical blocks 12, 14.

[0056] Preferably, the focusing mechanism of the objective (or objectives) of the binoculars 10 is said to be "translating" so that the orientation of the axis deviation introduced by the diasporameter does not vary as a function of the focusing of the objective.

[0057] An example of a method for harmonizing the optical axes A1, A2 of two optical blocks 12, 14 of night vision binoculars 10 will now be described. Such a harmonization method is implemented during the design of the binoculars 10. The harmonization is then fixed so that the parallelism obtained is maintained during the operation of the binoculars 10.

[0058] The harmonization method comprises the measurement of a parallelism defect between the optical axes A1, A2 of the two optical blocks 12, 14. Such a defect has an amplitude A and an orientation p relative to a reference (XY). The correction to be applied to the diasporameter is the inverse of the measured defect.

[0059] Outside the binoculars 10, the two prismatic optical blades 20, 22 of the harmonization device 16 are rotated relative to each other so as to compensate for the measured parallelism defect, that is to say to generate an axis deviation making it possible to compensate for the measured parallelism defect. In particular, the amplitude of the correction is obtained by rotating one blade relative to the other. The orientation of the axis correction is obtained by rotating the two blades together.

[0060] The two optical blades 20, 22 are then permanently locked in rotation, for example, either by being fixed to each other and inserted into the same barrel 30 locked in rotation, or by each being inserted into a barrel locked in rotation.

[0061] The two blades 20, 22 are then positioned on the optical path of one of the optical blocks 12, 14 (case where the two blades are fixed to each other) or each on the optical path of a respective optical block 12, 14. Thus, the optical axis harmonization device 16 is simple to integrate into night vision binoculars. It also does not degrade the quality of the images. It is also applicable to all types of night vision binoculars, in particular to new generation binoculars having more complex optics with an enlarged field and numerical aperture.

[0062] In addition, the proposed solution allows the harmonization adjustments between the optical paths to be externalized. It therefore simplifies the optomechanical designs internal to the binoculars and optimizes the tolerance balances by eliminating the need for axis adjustment by relative displacements of optical subassemblies internal to the binoculars.

[0063] The harmonization device 16 does not require precise mechanical positioning of the blades 20, 22 and advantageously replaces internal fine adjustment devices.

[0064] Since the adjustment is external, it avoids iterative adjustment strategies requiring phases of disassembly and reassembly of the binocular bodies in the case of complex night vision binoculars and particularly in the case of panoramic binoculars with 4 optical channels.

[0065] Those skilled in the art will understand that the embodiments and variants previously described can be combined with each other provided that they are technically compatible.

Claims

CLAIMS 1. Night vision binoculars (10) comprising: a. at least two optical blocks (12, 14) each having an optical axis (A1, A2), and b. a harmonization device (16) for the optical axes (A1, A2) of the two optical blocks, the harmonization device (16) comprising two prismatic optical blades (20, 22) permanently locked in rotation and oriented relative to each other and relative to the optical blocks (12, 14) so ​​that the optical axes (A1, A2) of the at least two optical blocks (12, 14) are parallel.

2. Binoculars (10) according to claim 1, in which the two optical blades (20, 22) are fixed to each other, preferably by gluing.

3. Binoculars according to claim 1 or 2, in which the two optical blades (20, 22) are mounted in the same barrel (30).

4. Binoculars (10) according to claim 1, in which the two optical blocks (12, 14) belong to different optical paths, one optical blade (20, 22) of the harmonization device (16) being positioned on the optical path of one of the optical blocks (12, 14), and the other optical blade (20, 22) of the harmonization device (16) being positioned on the optical path of the other optical block.

5. Binoculars (10) according to any one of claims 1 to 4, in which the two optical blades (20, 22) are inclined at the same non-zero angle relative to the normal to the optical axis (A1, A2) of one of the optical blocks (12, 14).

6. Binoculars (10) according to any one of claims 1 to 5, in which at least one of the optical blocks (12, 14) comprises an objective, at least one optical blade (20, 22) of the harmonization device (16) being positioned at the entrance to the objective of the or one of the optical blocks (12, 14).

7. Binoculars (10) according to any one of claims 1 to 6, wherein the binoculars (10) are monocular so that the two optical blocks (12, 14) belong to the same optical path, one of the blocks optics (12, 14) being an eyepiece and the other optical block (12, 14) being an objective. binoculars (10) according to any one of claims 1 to 5, wherein the binoculars (10) are biocular so that the two optical blocks (12, 14) belong to different optical paths, one of the optical blocks (12, 14) being a first eyepiece and the other optical block (12, 14) being a second eyepiece. binoculars (10) according to any one of claims 1 to 6, wherein the binoculars (10) are binocular so that the two optical blocks (12, 14) belong to different optical paths, one of the optical blocks (12, 14) comprising a first eyepiece and a first objective, the other optical block (12, 14) comprising a second eyepiece and a second objective.Binoculars (10) according to any one of claims 1 to 6, wherein the binoculars (10) are panoramic with four optical paths among: a right central path, a right lateral path, a left central path and a left lateral path, the two optical blocks (12, 14) each comprising an eyepiece and an objective, the two optical blocks (12, 14) belonging to two different optical paths among the following path combinations: the right central path and the right lateral path, the left central path and the left lateral path, and the two central paths, so that the harmonizing device (16) harmonizes the optical axes (A1, A2) of the two optical paths of the combination.Binoculars (10) according to claim 10, wherein the binoculars (10) comprise two additional harmonizing devices positioned on the optical paths of the other two combinations of optical paths so as to harmonize the optical axes (A1, A2) of said optical paths. Method for harmonizing the optical axes (A1, A2) of two optical blocks (12, 14) of night vision binoculars (10), the harmonization method being implemented during the design of the binoculars (10), the method comprising:. a. measuring a parallelism defect between the optical axes (A1, A2) of the two optical blocks (12, 14), b. rotating two prismatic optical blades (20, 22) relative to each other and together so as to compensate for the measured parallelism defect, c. permanently blocking the rotation of the two optical blades (20, 22), and d. positioning the two prismatic optical blades (20, 22) on the optical path of at least one of the two optical blocks (12, 14), the two optical blades (20, 22) forming a harmonization device (16) for the optical axes (A1, A2) of the two optical blocks (12, 14).

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