Claims

[Claim 1] Optical assembly (10) for collecting radiation, adapted to form an optical input of a self-steering device for guiding a self-propelled machine, said optical assembly comprising:

- a convex mirror (1), which has a reflecting face and an optical axis (A-A);

- a concave mirror (2), which is arranged in front of the reflecting face of the convex mirror (1) and turned towards said convex mirror, the concave mirror being provided with an opening (O) through a central part of said concave mirror , the concave and convex mirrors having the same optical axis (AA), and said optical axis passing through the opening of the concave mirror at a central point of said opening; and

- at least one window (3) which is transparent to radiation, and which extends behind the convex mirror (1), on a side opposite to the reflecting face of said convex mirror,

the assembly being adapted so that part of an electromagnetic radiation which passes through the opening (O) of the concave mirror (2) in the direction of the convex mirror (1) is reflected by said convex mirror then by the concave mirror, then crosses the window (3), and then propagates behind the convex mirror,

and being further adapted so that a fluid which passes through the opening (O) of the concave mirror (2) towards the convex mirror (1) is deflected past said convex mirror acquiring a radial velocity component divergent with respect to l optical axis (AA), then flows between the window (3) and the concave mirror,

the convex (1) and concave (2) mirrors being adapted and arranged so that electromagnetic radiation (Fi) which passes through the opening (O) of the concave mirror parallel to the optical axis (AA), is focused by the 'collection optical assembly at an image point (h) which is located on said optical axis behind the convex mirror.

[Claim 2] An optical assembly (10) according to claim 1, wherein at least part of the convex mirror (1), which is effective to reflect radiation, consists of a solid portion of homogeneous material with a thickness greater than 0 , 5 mm, or even greater than 1 mm.

[Claim 3] An optical assembly (10) according to any one of the preceding claims, wherein said at least one window (3) is distributed symmetrically around the optical axis (AA), or comprises several windows which are distributed symmetrically around of the optical axis.

[Claim 4] An optical assembly (10) according to any preceding claim, wherein the mirrors (1, 2) and the window (3) are adapted so that said optical assembly is effective in collecting electromagnetic radiation having at least a wavelength of between 2 pm and 2.5 pm, or between 3 pm and 5 pm, or alternatively between 8 pm and 14 pm.

[Claim 5] Self-steering device (20) for guiding a self-propelled vehicle (100), comprising:

- an optical assembly (10) for collecting radiation, which is in accordance with any one of the preceding claims;

- at least one optical detector (11), arranged to receive the radiation which has passed through the opening (O) of the concave mirror (2), has been reflected by the convex mirror (1) then by the concave mirror, then which has passed through said at least one window (3);

- a control unit (12), adapted to determine a direction of origin of the radiation as it exists before said radiation reaches the optical assembly (10) of collection, from at least one signal which is delivered by the optical detector (1 1), and adapted to control an orientation of a speed of movement of the machine (100) as a function of the direction determined for the origin of the radiation; and

- at least one discharge opening (E), arranged to discharge the fluid which has passed through the opening (O) of the concave mirror (2) in the direction of the convex mirror (1), and which has flowed between the porthole (3) and the concave mirror.

[Claim 6] A homing device (20) according to claim 5, wherein the optical assembly (10) for collecting and the optical detector (1 1) are arranged and adapted so that said homing device has a half-opening angle. of input optical field which is greater than 10 °, preferably greater than 15 °, still more preferably greater than 18 °.

[Claim 7] A homing device (20) according to claim 5 or 6, wherein the optical detector (1 1) is a matrix image sensor which is disposed in an imaging focal plane.

[Claim 8] A homing device (20) according to claim 7, wherein the matrix image sensor (1 1) is disposed in a focal plane of said collection optical assembly.

[Claim 9] Self-propelled machine (100), comprising a self-steering device (20) which conforms to any one of claims 5 to 8, and which is arranged to automatically guide a movement of the machine to a point of origin of u radiation, said machine comprising an evacuation passage arranged to guide towards an exhaust outlet of the machine, the fluid which comes from the evacuation opening (E) of the self-steering device, so that said fluid has, at the exhaust outlet, a velocity component which is oriented in the same direction as a fluid velocity through the opening (O) of the concave mirror (2).