Optical component consisting of a body provided with at least one positive side face and at least one negative side face

Abstract

The invention relates to an optical component (6) that consists of a body (8) provided with an upper face (10), a lower face (12), and at least three reflective side faces, each side face extending from the upper face (10) to the lower face (12), the body (8) being intended to be rotatable about an axis that extends between the upper and lower faces (10, 12). At least one of the side faces (14b, 14d) is said to be "positive". At least one of the side faces (14c, 14e) is said to be "negative".

Description

[0001] DESCRIPTION

[0002] TITLE: Optical component consisting of a body having at least one positive lateral face and at least one negative lateral face

[0003] technical field

[0004] The invention relates technically to reflective optical components.

[0005] In particular, the invention relates to an optical component having at least three reflective lateral faces and an observation system comprising a laser remote sensing device and a device for orienting a laser beam emitted by the remote sensing device, the orientation device being equipped with such an optical component.

[0006] Previous techniques

[0007] With reference to Figure 1, we know the state of the art of LiDar detectors used in the automotive sector capable of performing a telemetry measurement for an observation field suitable for the automotive field, for example an observation field of more than 120 degrees horizontally and more than 20 degrees vertically.

[0008] Figure 2 illustrates one way to obtain such an observation field in an orthonormal coordinate system (X, Y, Z).

[0009] The LiDar detector comprises a plurality of laser sources 2 juxtaposed along the Y-axis, each laser source 2 emitting laser radiation along the Z-axis. The LiDar detector is capable of performing a range measurement for each laser source 2.

[0010] The entire laser beam strikes a rotating mirror 4. The rotating mirror 4 is parallel to the Y-axis and rotates about the Y-axis. The rotational movement of the rotating mirror defines, from the entire laser beam, the shape of the observation field of the LiDAR detector illustrated in Figure 1. In order to increase the refresh rate of the LiDAR detector, the rotating mirror 4 is generally replaced by a rotating optical component equipped with two mirrors back to back so as to perform two LiDAR measurements per complete rotation of the optical component.

[0011] For certain applications, and particularly in the aeronautical field, it is sometimes necessary to carry out laser rangefinding measurements, or LiDar measurements, over a square or approximately square field of view, for example over a field of view of 90 degrees horizontally and 90 degrees vertically.

[0012] Description of the invention

[0013] The present invention therefore aims to provide an optical component that allows increasing the vertical and / or horizontal amplitude of an observation field of an observation system.

[0014] In particular, an objective of the invention is to provide an optical component that allows a form ratio of an observation field of the observation system to be modified compared to the use of a known rotating mirror, this form ratio being defined as the ratio between the vertical and horizontal amplitudes of the observation field.

[0015] A secondary objective is to increase the refresh rate of a measurement in the observation system.

[0016] Another secondary objective is to obtain an observation field of the observation system such that a measurement of the observation system has a variable angular resolution depending on the area of ​​the observation field considered.

[0017] The present invention relates to an optical component consisting of a body having a top face, a bottom face, and at least three reflective lateral faces, each lateral face extending from the top face to the bottom face, the body being intended to be rotatable about an axis extending between the top and bottom faces, wherein: - at least one of said lateral faces is such that the dot product between, on the one hand, a vector normal to a theoretical mirror equivalent to said lateral face and directed outwards from the body, and on the other hand, a vector directed along the axis of rotation of the body from the bottom face to the top face is strictly positive, said lateral face being said to be "positive", said theoretical mirror equivalent to said positive lateral face being a theoretical plane mirror having the same reflective function as said positive lateral face; and

[0018] - at least one of said lateral faces is such that the scalar product between on the one hand a vector which is normal to a theoretical mirror equivalent to said lateral face and which is directed outwards from the body, and on the other hand a vector directed along the axis of rotation of the body from the lower face to the upper face is strictly negative, said lateral face being said to be "negative", said theoretical mirror equivalent to said negative lateral face being a theoretical plane mirror which has the same reflective function as said negative lateral face.

[0019] The term "theoretical mirror equivalent to said lateral face" refers to a plane mirror positioned at the location of said lateral face and inclined to perform the reflective function of said lateral face. This term encompasses the various technical solutions for creating said lateral face. The theoretical mirror equivalent to said lateral face has the same complex reflection coefficient as said lateral face.

[0020] The angle formed by the theoretical plane mirror, which has the same reflective function as the considered positive lateral face, with the axis of rotation of the body allows for reflections on the considered positive lateral face towards the side of the upper face of the body.

[0021] The angle formed by the theoretical plane mirror, which has the same reflective function as the considered negative lateral face, with the body's axis of rotation allows for reflections from the considered negative lateral face towards the side of the body's underside. The optical component thus increases the amplitude, along the body's axis of rotation, of the field of view of a suitable observation system.

[0022] The optical component is preferably intended to equip a device for orienting a laser beam emitted by a remote sensing device.

[0023] According to a first conception, at least one of the said positive and negative lateral faces is flat.

[0024] Optionally, each of the said positive and negative lateral faces is flat.

[0025] According to a second conception, at least one of the said positive and negative lateral faces is formed by a Fresnel prism.

[0026] Optionally, each of the said positive and negative lateral faces is formed by a Fresnel prism.

[0027] The body can, particularly according to the first or second design, be obtained by injection molding. Thus, the body is a single piece.

[0028] According to a third conception, at least one of the said positive and negative lateral faces is formed by a scalloped lattice, said scalloped lattice being in particular made by engraving or by a metasurface.

[0029] Optionally, each of the said positive and negative lateral faces is formed by a ladder lattice.

[0030] When all the lateral faces of the body are flat:

[0031] - at least one of said lateral faces forms a non-zero angle with the axis of rotation of the body such that the dot product between, on the one hand, a vector that is normal to said lateral face and directed outwards from the body, and on the other hand, a vector directed along the axis of rotation of the body from the lower face to the upper face is strictly positive, said lateral face being said to be "positive"; and

[0032] - at least one of said lateral faces forms a non-zero angle with the axis of rotation of the body such that the dot product between on the one hand a vector which is normal to said lateral face and which is directed outwards from the body, and on the other hand a vector directed along the axis of rotation of the body from the lower face to the upper face is strictly negative, said lateral face being said to be "negative".

[0033] Advantageously, when the body is provided with an even number of reflective lateral faces, an even and strictly positive quantity of said lateral faces are each planar and parallel to the axis of rotation of the body, half of said other lateral faces being each positive, the other half of said other lateral faces being each negative.

[0034] Advantageously, when the body is provided with an even number of reflective lateral faces, half of said lateral faces are each positive, the other half of said lateral faces being each negative.

[0035] Advantageously, when the body is provided with an odd number of reflective lateral faces, an odd quantity of said lateral faces are each planar and parallel to the axis of rotation of the body, half of said other lateral faces being each positive, the other half of said other lateral faces being each negative.

[0036] Alternatively, the number of positive lateral faces of the body may be different from the number of negative lateral faces of the body.

[0037] In a particular embodiment, the body comprises at least one pair of lateral faces, the first lateral face of said pair being positive, the second lateral face of said pair being negative, the angle formed between the theoretical mirror equivalent to the first lateral face of said pair and the axis of rotation of the body being equal in absolute value to the angle formed between the theoretical mirror equivalent to the second lateral face of said pair and the axis of rotation of the body.

[0038] Optionally, the area of ​​the first lateral face of said pair is equal to the area of ​​the second lateral face of said pair.

[0039] Thus, this pair of lateral faces allows for reflections towards the upper face of the body and towards the lower face of the body in equal proportion. Advantageously, the upper and lower faces are flat and parallel to each other, with the axis of rotation of the body being orthogonal to the upper and lower faces.

[0040] The theoretical mirror equivalent to one of the said lateral faces can form an angle with the axis of rotation of the body which is greater than or equal to 5 degrees, in particular greater than or equal to 10 degrees, and more particularly greater than or equal to 15 degrees.

[0041] When all the lateral faces of the body are flat, one of said lateral faces may form an angle with the axis of rotation of the body which is greater than or equal to 5 degrees, in particular greater than or equal to 10 degrees, and more particularly greater than or equal to 15 degrees.

[0042] Preferably, a section at mid-height of the body is a regular convex polygon.

[0043] The general shape of the body is thus that of a right prism whose base is made up of this regular convex polygon, this right prism having notably been modified so as to tilt at least some of its lateral faces or at least some of the theoretical mirrors equivalent to its lateral faces.

[0044] The present invention also relates to a laser beam orientation device comprising an optical component as defined above and an optical component orientation mechanism configured to rotate the optical component around the axis of rotation of the body.

[0045] The present invention also relates to an observation system comprising a laser remote sensing device and a device for orienting a laser beam emitted by the remote sensing device, the orientation device being equipped with an optical component as defined above, the body of the optical component being mobile in rotation and arranged so that the laser beam emitted by the remote sensing device is incident successively on each of said lateral faces during the rotational movement of the body of the optical component.

[0046] The reflective lateral surfaces of the body reflect the laser radiation emitted by the remote sensing device. Brief description of the drawings

[0047] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0048] [Fig 1] is a schematic representation of an observation field of a LiDar detector adapted to the automotive field according to the state of the art;

[0049] [Fig 2] is a schematic representation of a telemetry measurement, according to the state of the art, which allows obtaining the field of observation of figure 1;

[0050] [Fig 3] is a perspective view of an optical component equipped with three reflective lateral faces according to a first embodiment of the invention;

[0051] [Fig 4] is a perspective view of an optical component equipped with five reflective lateral faces according to a second embodiment of the invention;

[0052] [Fig 5] is a schematic representation of an observation system according to an example of an embodiment of the invention;

[0053] [Fig 6A], [Fig 6B], [Fig 6C] and [Fig 6D] are, for a first configuration of instantaneous vertical field, numerical simulations of the observation field of the observation system of figure 5 which includes respectively an optical component equipped with four, five, six and seven reflective lateral faces;

[0054] [Fig 7A] is, for a second vertical instantaneous field configuration, a numerical simulation of the observation field of the observation system in Figure 5, which includes an optical component with four reflective lateral faces; and

[0055] [Fig 7B] is, for a third vertical instantaneous field configuration, a numerical simulation of the observation field of the observation system in Figure 5, which includes an optical component with four reflective lateral faces. Detailed description

[0056] Figure 3 illustrates an optical component 6 consisting of a body 8, for example one-piece and obtained by injection molding.

[0057] The body 8 comprises an upper face 10, a lower face 12 opposite the upper face 10, and three flat and reflective lateral faces 14.

[0058] The upper and lower faces 10, 12 of the body 8 are here planar and parallel to each other. An axis of rotation R of the body 8 is defined as orthogonal to the upper and lower faces 10, 12. This axis of rotation R passes through the center of the body 8, which is defined as the center of the mid-height section of the body 8, this section being a regular convex polygon, here an equilateral triangle.

[0059] Each lateral face extends from the upper face 10 to the lower face 12 of the body 8.

[0060] The three lateral faces 14 of the body 8 consist of a lateral face 14a which is parallel to the axis of rotation R, a lateral face 14b which is said to be positive, and a lateral face 14c which is said to be negative.

[0061] The positive lateral face 14b forms a non-zero angle, here an angle of 10 degrees, with the axis of rotation R. The scalar product between on the one hand a vector which is normal to the positive lateral face 14b and which is directed outwards from the body 8, and on the other hand a vector directed along the axis of rotation R of the body 8 from the lower face 12 to the upper face 10 is strictly positive.

[0062] The negative lateral face 14c forms a non-zero angle, here an angle of 10 degrees, with the axis of rotation R. The scalar product between on the one hand a vector which is normal to the negative lateral face 14c and which is directed outwards from the body 8, and on the other hand a vector directed along the axis of rotation R of the body 8 from the lower face 12 to the upper face 10 is strictly negative.

[0063] The positive and negative lateral faces 14b, 14c form a pair of lateral faces, each forming the same angle with the axis of rotation R. The positive and negative lateral faces 14b, 14c are not parallel. A plane containing the positive lateral face 14b intersects a plane containing the negative lateral face 14c. The second embodiment shown in Figure 4 differs from the first embodiment shown in Figure 3 in that the body 8 comprises five lateral faces 14.

[0064] The five lateral faces 14 of the body 8 consist of one lateral face 14a which is parallel to the axis of rotation R, two positive lateral faces 14b, 14d, and two negative lateral faces 14c, 14e.

[0065] One of the positive lateral faces 14d forms an angle of 5 degrees with the axis of rotation R, the other positive lateral face 14b forms an angle of 10 degrees with the axis of rotation R.

[0066] One of the negative lateral faces 14e forms an angle of 5 degrees with the axis of rotation R, the other negative lateral face 14c forms an angle of 10 degrees with the axis of rotation R.

[0067] The mid-height section of body 8 is here a regular convex pentagon.

[0068] In the embodiments illustrated in Figures 3 and 4, the body comprises an odd number of lateral faces. Alternatively, the body may comprise an even number of lateral faces. For example, the body may comprise four lateral faces, such as two positive and two negative lateral faces, or two lateral faces that are each parallel to the axis of rotation, one positive and one negative lateral face. Of course, the body may comprise six lateral faces or seven or more lateral faces.

[0069] In the embodiments illustrated in Figures 3 and 4, the positive and negative lateral faces form an angle of at most 10 degrees with the axis of rotation. Alternatively, at least one of the positive and negative faces may form an angle of more than 15 degrees with the axis of rotation.

[0070] In the embodiments illustrated in Figures 3 and 4, the lateral faces of the body are flat. Alternatively, all or part of the lateral faces of the body could each consist of a Fresnel prism reproducing the same reflective function as the flat lateral face in question. Alternatively, all or part of the lateral faces of the body could each consist of a ladder-like grating reproducing the same reflective function as the flat lateral face in question. This ladder-like grating can be produced by etching or by a metasurface.

[0071] According to this variant or alternative, each positive lateral face is such that the dot product between, on the one hand, a vector normal to a theoretical mirror equivalent to the lateral face in question and directed outwards from the body, and on the other hand, a vector directed along the axis of rotation of the body from the lower face to the upper face, is strictly positive. The theoretical mirror equivalent to the positive lateral face in question is a theoretical plane mirror that has the same reflective function as the positive lateral face in question.

[0072] According to this variant or alternative, each negative lateral face is such that the dot product between, on the one hand, a vector normal to a theoretical mirror equivalent to the lateral face in question and directed outwards from the body, and on the other hand, a vector directed along the axis of rotation of the body from the lower face to the upper face, is strictly negative. The theoretical mirror equivalent to the negative lateral face in question is a theoretical plane mirror that has the same reflective function as the negative lateral face in question.

[0073] Figure 5 schematically illustrates an observation system 16 comprising a laser remote sensing device 18 and a laser beam orientation device 20 emitted by the remote sensing device 18.

[0074] The remote sensing device 18 includes a laser source (not shown) and is capable of performing a telemetry measurement in the direction of the laser radiation emitted by the laser source and reoriented by the orientation device 20.

[0075] The orientation device 20 includes an optical component 6 and an orientation mechanism (not shown) capable of rotating the optical component 6 around the axis of rotation R of the body 8.

[0076] The body 8 of the optical component 6 is arranged so that the laser radiation emitted by the remote sensing device 18 is successively incident on each of the lateral faces of the body 8 during its rotational movement. For example, the body 8 of the optical component 6 is positioned in the path of the laser radiation such that the axis of rotation R of the body 8 forms an angle of 45 degrees with the laser radiation emitted by the remote sensing device 18.

[0077] Such an observation system 16 can be carried by an aircraft, in particular by a drone, and can notably allow observation of the aircraft's landing zone.

[0078] Figures 6A, 6B, 6C, and 6D each represent a numerical simulation of the observation system's field of view for a first configuration of the system's vertical instantaneous field. The numerical simulation in Figure 6A is performed for an optical component with four lateral faces, the numerical simulation in Figure 6B for an optical component with five lateral faces, the numerical simulation in Figure 6C for an optical component with six lateral faces, and the numerical simulation in Figure 6D for an optical component with seven lateral faces.

[0079] The first instantaneous vertical field of view of the observation system is here 23 degrees and corresponds to a first configuration of the remote sensing device.

[0080] Figures 6A, 6B, 6C, and 6D show that, for a given instantaneous vertical field of view of the observation system, increasing the number of lateral faces of the body modifies the shape of the observation field, and in this case, allows for a vertical and horizontal expansion of the field of view. Specifically, when using an optical component with seven lateral faces, the field of view is approximately 120 degrees by 120 degrees, represented by a square.

[0081] The different zones of the observation field, which are different shades of color, illustrate the reflection of the laser beam on each of the lateral faces. A consequence of the shape of these zones, which correspond to the reflections of the laser beam on positive and negative lateral faces, is that the observation system is able to perform measurements with greater angular resolution on the upper half of square 22 than on the lower half. Another consequence of the shape of these zones is that the observation system's field of view is more extensive on the lower half of square 22 than on the upper half.

[0082] Figure 7 A represents a numerical simulation of the observation field of the observation system for a second vertical instantaneous field configuration of the observation system and for an optical component equipped with four lateral faces, in particular equipped with two positive lateral faces and two negative lateral faces.

[0083] The second instantaneous vertical field of view of the observation system is here 41 degrees and corresponds to a second configuration of the remote sensing device.

[0084] Figure 7B represents a numerical simulation of the observation field of the observation system for a third vertical instantaneous field configuration of the observation system and for an optical component equipped with five lateral faces.

[0085] The third instantaneous vertical field of view of the observation system is here 34 degrees and corresponds to a third configuration of the remote sensing device.

[0086] A need for measurement, corresponding here to the square 22 representing an observation field of 120 degrees by 120 degrees, is met for the configurations illustrated in figures 7A and 7B.

Claims

DEMANDS 1. Optical component (6) consisting of a body (8) having an upper face (10), a lower face (12), and at least three reflective lateral faces, each lateral face extending from the upper face (10) to the lower face (12), the body (8) being intended to be mobile in rotation about an axis extending between the upper and lower faces (10, 12), characterized in that: - at least one of said lateral faces (14b, 14d) is such that the dot product between, on the one hand, a vector normal to a theoretical mirror equivalent to said lateral face and directed outwards from the body (8), and on the other hand, a vector directed along the axis of rotation (R) of the body (8) from the lower face (12) to the upper face (10) is strictly positive, said lateral face being said to be "positive", said theoretical mirror equivalent to said positive lateral face (14b, 14d) being a theoretical plane mirror which has the same reflective function as said positive lateral face (14b, 14d); and - at least one of said lateral faces (14c, 14e) is such that the scalar product between on the one hand a vector which is normal to a theoretical mirror equivalent to said lateral face and which is directed outwards from the body (8), and on the other hand a vector directed along the axis of rotation (R) of the body (8) from the lower face (12) to the upper face (10) is strictly negative, said lateral face being said to be "negative", said theoretical mirror equivalent to said negative lateral face (14c, 14e) being a theoretical plane mirror which has the same reflective function as said negative lateral face (14c, 14e).

2. Optical component (6) according to claim 1, wherein at least one of said positive and negative lateral faces (14b, 14c, 14d, 14e) is planar.

3. Optical component (6) according to claim 1 or 2, in which at least one of said positive and negative lateral faces (14b, 14c, 14d, 14e) is formed by a Fresnel prism.

4. Optical component (6) according to any one of claims 1 to 3, in which the body (8) is obtained by injection molding.

5. Optical component (6) according to any one of claims 1 to 3, wherein at least one of said positive and negative side faces (14b, 14c, 14d, 14e) is formed by a scaling array, said scaling array being in particular made by etching or by a metasurface.

6. Optical component (6) according to any one of claims 1 to 5, wherein the body (8) is provided with an even number of reflective lateral faces and wherein: - an even and strictly positive quantity of said lateral faces are each planar and parallel to the axis of rotation (R) of the body (8), half of said other lateral faces being each positive (14b, 14d), the other half of said other lateral faces being each negative (14c, 14e); or - half of said lateral faces being each positive (14b 14d), the other half of said lateral faces being each negative (14c, 14e).

7. Optical component (6) according to any one of claims 1 to 5, in which the body (8) is provided with an odd number of reflective lateral faces, an odd quantity of said lateral faces each being planar and parallel to the axis of rotation (R) of the body (8), half of said other lateral faces each being positive (14b, 14d), the other half of said other lateral faces each being negative (14c, 14e).

8. Optical component (6) according to any one of claims 1 to 7, wherein the body (8) comprises at least one pair of lateral faces, the first lateral face of said pair being positive (14b, 14d), the second lateral face of said pair being negative (14c, 14e), the angle formed between the theoretical mirror equivalent to the first lateral face of said pair and the axis of rotation (R) of the body (8) being equal in absolute value to the angle formed between the mirror theoretical equivalent to the second lateral face of said pair and the axis of rotation (R) of the body (8).

9. Optical component (6) according to any one of claims 1 to 8, wherein the upper and lower faces (10, 12) are planar and parallel to each other, the axis of rotation (R) of the body (8) being orthogonal to the upper and lower faces (10, 12).

10. Optical component (6) according to any one of claims 1 to 9, wherein the theoretical mirror equivalent to one of said lateral faces forms an angle with the axis of rotation (R) of the body (8) which is greater than or equal to 5 degrees, in particular greater than or equal to 10 degrees, and more particularly greater than or equal to 15 degrees. 1 1. Observation system (16) comprising a laser remote sensing device (18) and a laser beam orientation device (20) emitted by the remote sensing device (18), the orientation device (20) being provided with an optical component (6) according to any one of claims 1 to 10, the body (8) of the optical component (6) being rotationally movable and arranged so that the laser beam emitted by the remote sensing device (18) is incident successively on each of said lateral faces during the rotational movement of the body (8) of the optical component (6).

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