Device for connecting a laser emission optical path and a reception optical path

Abstract

Device for securing a laser emission optical path and a reception optical path The invention relates to an optronic device (1) with two optical paths (2', 2'') in a direction of sight (D1), the two optical paths (2', 2'') comprising an emission optical path (2') and a reception optical path (2''), the optronic device (1) comprising: a first reflective face (10') configured to reflect a light beam from the first emission optical path (2'), a second reflective face (10'') configured to reflect a light beam from the second reception optical path (2''), the first reflective face (10') and the second reflective face (10'') being orthogonal to each other. Figure for the abstract: Fig. 1

Description

Title of the invention: Device for connecting a laser emission optical path and a reception optical path

[0001] The invention relates to the field of optronic systems. In particular, it relates to systems with two optical channels consisting of an optical emission channel and a reception channel sensitive to this same optical radiation, both orientable in a direction called "line of sight", and in which the relative orientation of one channel with respect to the other must be controlled with great precision. The field of the invention relates more particularly to systems using a laser but can be adapted to any optical flow.

[0002] There are several solutions in the prior art aimed at controlling the orientation of an optical path relative to another optical path.

[0003] For example, the use of an orientable plane mirror common to both optical paths is known. This type of solution presents a high risk of light pollution of the reception path by the laser emission path, which can render the reception path inoperative.

[0004] In order to prevent the crossing of the optical paths and therefore the risk of light pollution, the plane mirror of each path is separated. However, since the two plane mirrors are separated, the orientation of one plane mirror is not reflected on the second plane mirror and an orientation difference can be observed, also called bias. It has also been considered to measure the relative position of one optical path with respect to the other optical path in order to have knowledge and a precise measurement of the bias, or orientation difference, between the two optical paths. It is thus possible to adapt the positioning of one path with respect to the other thanks to this measurement of the optical bias.However, this bias measurement is only valid at a given time, and is potentially no longer representative of the real bias in the event of changes in operating conditions, particularly mechanical or thermal (change in temperature, thermal gradients) and in the event of a change in the orientation of the two channels. It is then necessary to carry out the bias measurement for the different possible orientations of the line of sight, and to repeat this set of measurements as soon as the temperature changes significantly. This solution of measuring the bias then requires multiplying the number of measurements according to the different operating cases observed, which is not desirable.

[0005] In order to reduce the number of bias measurements at each change in operating conditions, it may be envisaged to make the movement of a mirror of one optical path dependent on the mirror of the other optical path, so that the movement of the first optical path induces movement of the second optical path and therefore that any positioning errors of the orientable mirrors are common to both optical paths, their movement being identical, no relative movement of one in relation to the other is observable.

[0006] To do this, a servo device such as an arm, a connecting rod or even a belt is added to the two plane mirrors. However, this type of device is not optimal with respect to vibrations and thermal environments, because the quality of the mechanical connection between the two plane mirrors is then insufficient, which can generate a bias between the two mirrors.

[0007] In order to control the relative orientation between a laser emission path and a reception path, an orientable platform allowing the two paths to be oriented as a whole can also be used. However, the main limitation of this solution is the need to orient the entire system, which leads to significant inertia, a large footprint and therefore a significant power requirement on the part of the actuator.

[0008] The invention aims to overcome all or part of the problems cited above by proposing a simple optical device making it possible to reduce or even eliminate any risk of pollution of the reception channel by the optical transmission channel.

[0009] For this purpose, the invention relates to an optronic device with two optical paths along a sighting direction, the two optical paths comprising an optical emission path and an optical reception path, the optronic device comprising: - a first reflective face configured to reflect a light beam from the first optical emission path, - a second reflective face configured to reflect a light beam from the second optical reception channel,

[0010] the first reflecting face and the second reflecting face being orthogonal to each other.

[0011] According to one aspect of the invention, the optronic device comprises a two-sided mirror, the first reflecting face being a first face of the mirror, the second reflecting face being a second face of the mirror, the first reflecting face being mechanically secured to the second reflecting face.

[0012] According to one aspect of the invention, the first reflective face is in contact with the second reflective face.

[0013] According to one aspect of the invention, the mirror is movable in rotation around a first axis of rotation perpendicular to the direction of view, the first axis of rotation being intersecting the first reflecting face and the second reflecting face.

[0014] According to one aspect of the invention, the transmit optical path comprises a transmit optical path input and wherein the receive optical path comprises a receiving optical path output, the transmitting optical path input and the receiving optical path output being merged with the first axis of rotation.

[0015] According to one aspect of the invention, the first axis of rotation forms an angle of 45° with the normal to the first reflecting face and the first axis of rotation forms an angle of 45° with the normal to the second reflecting face.

[0016] According to one aspect of the invention, the mirror is movable in rotation along a second axis of rotation perpendicular to the first axis of rotation and perpendicular to the direction of view.

[0017] According to one aspect of the invention, the first reflecting face or the second reflecting face is offset along the first axis respectively relative to the second reflecting face or relative to the first reflecting face so as to bring the first reflecting face closer to the second reflecting face.

[0018] According to one aspect of the invention, the first reflective face comprises a first end and the second reflective face comprises a second end, the projection of the first end and the projection of the second end being merged along the first axis of rotation.

[0019] According to one aspect of the invention, the mirror is made from a single material.

[0020] According to one aspect of the invention, the mirror is monolithic.

[0021] The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the attached drawings in which:

[0022] [Fig-1] [Fig.l] represents an optronic device according to the invention;

[0023] [Fig.2] [Fig.2] represents the optronic device of [Fig.l] with an axis additional mobility;

[0024] [Fig.3] [Fig.3] represents the optronic device in an optimized architecture.

[0025] For the sake of clarity, the same elements will bear the same references in the different figures.

[0026] [Fig.l] represents an optronic device 1 with two optical paths 2. The two optical paths 2 comprise an optical path 2' for transmitting an optical flow and an optical path 2" for receiving the optical flow. The optical flow transmission path 2' comprises an optical path input 20' and an optical path output 22'. The optical path 2" for receiving the optical flow of the optical flow comprises an optical path input 20" and an optical path output 22". The optronic device 1 is configured so as to allow the generation and transmission of an optical flow, such as for example laser radiation, which passes through the optical flow transmission path 2' via the input of the optical path 20' and then via the output of the optical path 20". The optical flow is then reflected in an external medium 3 to the optronic device 1 and overlaps with the flow directly emitted by the external environment 3, in order to cross the optical reception path 2”. More precisely, this same optical flow emitted through the optical emission path 2' is received at the level of the input of the optical reception path 20” before being transmitted towards the output of the optical reception path 22”.

[0027] The optronic device 1 is also configured to emit the optical flow in a direction of sight D1. Thus, the output of the optical emission channel 22' is oriented so as to be parallel to the direction of sight D1. The direction of sight D1 determines the direction of emission of the optical flow so that the optronic device 1 is oriented in the direction of the direction of sight D1 and emits the optical flow parallel to this direction of sight DL. Similarly, the input of the reception channel 20” is also oriented so as to be parallel to the direction of sight DL. In other words, the output of the emission channel 22' and the input of the reception channel 20” are both directed parallel to the direction of sight D1, as shown in [Fig.l].

[0028] The output of the optical transmission path 22' and the input of the optical reception path 20” are oriented in directions parallel to each other.

[0029] The input of the optical transmission path 20' is oriented along a first axis Al coincident with the direction of the output of the optical reception path 22”. In other words, the direction of the optical flow passing through the input of the optical transmission path 20' and passing through the output of the optical reception path 22” are coincident with the first axis Al perpendicular to the first direction DL.

[0030] Thus, the input of the optical transmission path 20' and the output of the optical reception path 22” are oriented in the same direction D2, coincident with the first axis A1, and the output of the optical transmission path 20” and the input of the optical reception path are parallel to the first direction DL.

[0031] To do this, the optronic device 1 comprises a first reflecting face 10' configured to reflect the light beam, namely the optical flow such as the laser radiation, in the first optical emission path 2'. The first reflecting face 10' makes it possible to orient the optical flow between the input of the optical emission path 20' and the output of the optical emission path 22'.

[0032] It should be noted that the direction of sight D1 is orthogonal to the second direction D2. The first reflecting face 10' then makes it possible to reflect the optical flow with an angle of 90° between the entrance of the optical emission path 20' and the exit of the optical emission path 22'.

[0033] For information purposes, the first reflective face 10' is positioned at 45° from the second direction D2 in the clockwise direction and at 135° from the viewing direction D1 in the clockwise direction.

[0034] In other words, the normal to the first reflecting face 10' forms an angle of 45° with the direction of the entrance of the optical emission path 20' and with respect to the second direction D2 to the first reflecting face 10' in a clockwise direction. And, the normal to the first reflecting face 10' forms an angle of 45° with the direction of exit of the optical emission path 22' and with respect to the first direction DI to the first reflecting face 10' in a counterclockwise direction.

[0035] The optronic device 1 also comprises a second reflective face 10” configured to reflect the light beam, namely the optical flux such as laser radiation or the flux directly emitted by the external environment 3, in the second optical reception path 2”.

[0036] The second reflective face 10'' makes it possible to orient the optical flow between the input of the optical reception path 20” and the output of the optical reception path 22”.

[0037] The second reflective face 10” then makes it possible to reflect the optical flow with an angle of 90° between the input of the optical reception path 20” and the output of the optical reception path 22”.

[0038] For information purposes, the second reflective face 10” is positioned at 135° from the second direction D2 in the clockwise direction and at 45° from the viewing direction DI in the clockwise direction.

[0039] In other words, the normal to the second reflecting face 10'' forms an angle of 45° with the direction of exit of the optical reception path 22'' and with respect to the second direction D2 to the second reflecting face 10” in a counterclockwise direction. And, the normal to the second reflecting face 10” forms an angle of 45° with the direction of entry of the optical reception path 20” and with respect to the first direction DI to the first reflecting face 10' in a clockwise direction.

[0040] The first reflective face 10' and the second reflective face 10” are orthogonal to each other.

[0041] The optronic device 1 has the advantage of preventing any crossing between the optical emission flow included in the optical emission path 2' and the optical reception flow included in the optical reception path 2”. Indeed, these two optical flows, namely the optical emission flow and the optical reception flow, are systematically parallel to each other and distant from each other. Thus, the risk of optical flow crossing is eliminated.

[0042] Advantageously, the first reflective face 10' can be mechanically secured to the second reflective face 10”. Therefore, the orientation of the second reflective face 10” depends on the orientation of the first reflective face 10' so that no bias is detectable between the first reflective face 10' and the second reflective face 10”.

[0043] Advantageously, the first reflective face 10' can be connected, along a first end 102' of the first reflective face 10', to the second reflective face 10” along a second end 104” of the second reflective face 10”. The first reflective face 10' is mechanically connected to the second reflective face 10”. Therefore, the first reflective face 10' and the second reflective face 10” are mechanically connected to each other. The movement of the first reflective face 10' induces the movement of the second reflective face 10” and vice versa. The first reflective face 10' and the second reflective face 10” thus form a reflective component.

[0044] In other words, the optronic device 1 may comprise a two-sided mirror 10 of which the first reflecting face 10' is a first face of the mirror 10 and of which the second reflecting face 10” is a second face of the mirror 10.

[0045] The mirror 10 may consist of a supporting structure 100 on which the first reflecting face 10' and the second reflecting face 10” are fixed. In this configuration, it may be envisaged to use the same material for the different parts, namely the supporting structure 100, the first reflecting face 10' and the second reflecting face 10”, in order to make thermal deformations negligible.

[0046] In other words, the two-sided mirror 10 can be made from a single material. The mirror 10 is then an assembly of several components, namely the supporting structure 100, the first reflecting face 10' and the second reflecting face 10” all made from a single material. As an indicative example, the supporting structure 100, the first reflecting face 10' and the second reflecting face 10” can be made from metal, a metal alloy, ceramic or even glass.

[0047] Alternatively, it may advantageously be envisaged to directly machine the first reflecting face 10' and the second reflecting face 10” on the supporting structure 100, in order to better secure the first reflecting face 10' and the second reflecting face. The mirror 10 is then a monolithic structure directly comprising the supporting structure 100, the first reflecting face 10' and the second reflecting face 10”. The monolithic mirror 10 makes it possible to reduce thermal deformations at the level of the first reflecting face 10' and the second reflecting face 10”, but also to increase the stiffness between the first reflecting face 10' and the second reflecting face 10”, and therefore to reduce the amplitude of the vibrations of one reflecting face relative to the other reflecting face.

[0048] It may also be envisaged to add a coating on the first reflective face 10' and on the second reflective surface 10” to modify the reflection of the first reflecting face 10' and the reflection of the second reflecting face 10”.

[0049] In order to vary the aiming direction DI of the optronic device 1, the optronic device 1 can be movable around the first axis Al. More precisely, the mirror 10 is movable in rotation along the first axis Al parallel to the second direction D2 of the input of the optical emission path 20' and to the second direction D2 of the output of the optical reception path 22”.

[0050] The first axis Al can form an angle of 45° with the normal to the first reflecting face 10' and an angle of 45° with the normal to the second reflecting face 10”.

[0051] The mirror 10 can also be movable in rotation along a second axis A2 perpendicular to the first direction D1, and perpendicular to the first axis A1, as shown in [Fig.2]. The first direction D1, the first axis A1 and the second axis A2 are thus perpendicular two by two. The direction of sight D1 can then vary in a plane perpendicular to the second axis A2 and passing through the first axis A1. Nevertheless, the angular variation along this second axis A2 is limited due to the need to have contact between the optical flow of the emission optical path 2' and the first reflecting face 10' and between the optical flow of the reception optical path 2” and the second reflecting face 10”.

[0052] In other words, the mirror 10 is movable in rotation along two axes of rotation, a first axis of rotation which is the first axis A1 and a second axis of rotation which is the second axis A2.

[0053] The mobility of the second reflecting face 10' is thus dependent on the mobility of the first reflecting face 10' so that the relative orientation of the optical emission path 2' with respect to the optical reception path 2” is controlled with great precision along two axes, namely the first axis A1 and the second axis A2, including in the event of thermal variations and / or vibrations. In other words, no bias can appear between the first reflecting face 10' and the second reflecting face 10”.

[0054] It may also be envisaged to optimize the shape of the mirror 10 with respect to the size of the optronic device 1 or with respect to the optical flow emitted or received. More precisely, the two-sided mirror 10 may be hollowed out, as shown in [Fig. 3] according to any one of its reflective faces among the first reflective face 10' or the second reflective face 10”.

[0055] The hollowed-out reflective face 11” is a flat reflective surface, like the second reflective face 10” whose position along the first axis Al is offset, and brought closer to the first reflective face 10'. The hollowed-out reflective face 11” has structural dimensions, in the plane formed by the first direction DI and the first axis Al, and in particular a length L less than the structural dimensions, and in particular the length L', of the second reflective face 10”.

[0056] The hollowed-out reflective face 11” is connected to the first reflective face 10' by means of the supporting structure 100 of the mirror 10. The hollowed-out reflective face 11” is thus brought closer to the first reflective face 10' relative to the second reflective face 10”.

[0057] In an optimized mirror configuration 10, as shown in [Fig.3], the second reflecting face 10” can then be replaced by the hollowed-out reflecting face 11”. In other words, the second face of the mirror 10 is offset along the first axis A1 relative to the first reflecting face 10' so as to bring the face of the mirror 10, namely the hollowed-out reflecting face 11”, closer to the first reflecting face 10'. As a result, the reflecting face of the receiving path, i.e. the second face of the mirror 10, is reduced in size.

[0058] Alternatively, this optimization may concern the first reflecting face rather than the second reflecting face. In this case, the first face of the mirror 10 is offset along the first axis A1 relative to the second reflecting face 10” so as to bring the first face of the mirror 10 closer to the second reflecting face 10”. And, the reflecting face of the emission path, i.e. the first face of the mirror 10, is reduced in size.

[0059] Advantageously, it may also be envisaged that the first axis Al is intersecting at the median of the first reflecting face 10' in the plane formed by the first axis Al and by the normal to the first reflecting face 10'. In other words, the first axis Al of the mirror 10 is intersecting the first reflecting face 10' so as to divide the length L' by two in the plane formed by the first axis Al and the normal to the first reflecting face 10'. The first axis Al is centered on the first reflecting face 10' so that the entire optical flux emitted in the optical emission path 2' is reflected by the first reflecting face 10'.

[0060] And, similarly, it can be envisaged that the first axis Al is intersecting at the median of the second reflecting face 10” in the plane formed by the first axis Al and by the normal to the second reflecting face 10”. In other words, the first axis Al of the mirror 10 is intersecting with the second reflecting face 10” so as to divide the length L” of the second reflecting face 10” by two in the plane formed by the first axis Al and by the normal to the second reflecting face 10”. The first axis Al is centered on the second reflecting face 10” so that the entirety of the re-emitted optical flux or the flux directly emitted by the external medium 3 in the 2” optical reception path is reflected by the second 10” reflective face.

[0061] And, if it is a mirror 10 optimized as shown in [Fig.3], then it can also be envisaged that the first axis Al is intersecting with the median of the hollowed-out reflecting face 11” in the plane formed by the first axis Al and by the normal to the hollowed-out reflecting face 11”. In other words, the first axis Al of the mirror 10 is intersecting with the hollowed-out reflecting face 11” so as to divide the length L of the hollowed-out reflecting face 11' by two in the plane formed by the first axis Al and by the normal to the hollowed-out reflecting face 11”. The first axis Al is centered on the hollowed-out reflecting face 11” so that the entirety of the re-emitted optical flux or the flux directly emitted by the external medium 3 in the optical reception path 2” is reflected by the hollowed-out reflecting face 11”.

[0062] As indicated above, it can be envisaged that the two faces of the mirror 10, namely the first reflecting face 10' and the second reflecting face 10” or a reflecting face, among the first reflecting face 10' and the second reflecting face 10”, and the hollowed-out reflecting face 11', are substantially orthogonal.

[0063] Indeed, a right angle between the two reflecting faces makes it possible to have an optical flow at the output 22' of the optical emission path 2' and an optical flow at the input 20” of the optical reception path 2” oriented in a substantially parallel manner and to avoid any crossing.

[0064] By substantially orthogonal is understood an angular deviation less than or equal to 1 mrad relative to a right angle between the two reflecting faces of the mirror 10. Ideally, the two reflecting faces of the mirror 10 are orthogonal.

[0065] Nevertheless, an angular variation greater than 3° can be accepted provided that significant optical measurements and specific dimensioning of the optronic device 1 are carried out.

Claims

Claims

1. Optronic device (1) with two optical paths (2', 2”) along a viewing direction (Dl), the two optical paths (2', 2”) comprising an optical transmission path (2') and an optical reception path (2”), the optronic device (1) comprising: - a first reflective face (10') configured to reflect a light beam from the first optical transmission path (2'), - a second reflective face (10”) configured to reflect a light beam from the second optical reception path (2”), the first reflective face (10') and the second reflective face (10”) being orthogonal to each other.

2. Optronic device (1) according to claim 1, comprising a two-sided mirror (10), the first reflecting face (10') being a first face of the mirror (10), the second reflecting face (10”) being a second face of the mirror (10), the first reflecting face (10') being mechanically secured to the second reflecting face (10”).

3. Optronic device (1) according to claim 2, the first reflective face (10') being in contact with the second reflective face (10”).

4. Optronic device (1) according to claim 2 or 3, wherein the mirror (10) is rotatable about a first axis of rotation (Al) perpendicular to the direction of view (Dl), the first axis of rotation (Al) being intersecting the first reflecting face (10') and the second reflecting face (10”).

5. Optronic device (1) according to claim 4, wherein the optical transmission path (2') comprises an optical transmission path input (20') and wherein the optical reception path (2”) comprises an optical reception path output (22”), the optical transmission path input (20') and the optical reception path output (22”) being coincident with the first axis of rotation (Al).

6. Optronic device (1) according to claim 4 or claim 5, in which the first axis of rotation (Al) forms an angle of 45° with the normal to the first reflecting face (10') and in in which the first axis of rotation (Al) forms an angle of 45° with the normal to the second reflecting face (10”).

7. Optronic device (1) according to claim 1 to 6, wherein the mirror (10) is movable in rotation along a second axis of rotation (A2) perpendicular to the first axis of rotation (A1) and perpendicular to the direction of sight (Dl).

8. Optronic device (1) according to claim 1 to 7, wherein the first reflective face (10') or the second reflective face (10”) is offset along the first axis (Al) respectively relative to the second reflective face (10”) or relative to the first reflective face (10') so as to bring the first reflective face (10') closer to the second reflective face (10”).

9. Optronic device according to one of claims 1 to 8, in which the first reflecting face (10') comprises a first end (102') and in which the second reflecting face (10”) comprises a second end (104”), the projection of the first end (102') and the projection of the second end (104”) being merged along the first axis of rotation (Al).

10. Optronic device (1) according to one of claims 2 to 9, in which the mirror (10) is made from a single material.

11. Optronic device (1) according to one of claims 2 to 10, in which the mirror (10) is monolithic.

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