Reivindicaciones

1. A rotary objective lens switching device (1) for a planar laser beam microscope, comprising a cuvette (2) having the shape of a prism with an axis perpendicular to a plane parallel to a direction of detection (DD) and a lighting direction (DI) which are mutually perpendicular, characterised in that the cross-sectional shape of the prism parallel to said plane is a polygon with more than four sides which has pairs of mutually perpendicular faces (2a, 2a'; 2b, 2b'; 2c, 2c'; 2d, 2d'), wherein each of at least several pairs of mutually perpendicular faces (2a, 2a'; 2b, 2b'; 2c, 2c'; 2d, 2d') comprise one face (2a', 2b', 2c', 2d') designed to receive a planar light beam (6) in order to illuminate a sample (7) according to the lighting direction (DI) and a face (2a, 2b, 2c, 2c) with a coupled lens or objective lens (9a, 9b, 9c, 9d) to detect a fluorescent light (8) emitted by the sample (7) in the direction of detection (DD), and wherein the cuvette (2) can rotate about an axis perpendicular to said plane, allowing a specific lens or objective lens (9a, 9b, 9c, 9d) to be oriented in the direction of detection (DD). 2. The device (1) according to claim 1, wherein the polygon is a regular polygon with a number of faces that is a multiple of four. 3. The device (1) according to claim 2, wherein the regular polygon is an octahedron, a dodecahedron, or a hexadecahedron. 4. The device (1) according to any of the preceding claims, wherein the face (2a', 2b', 2c', 2d') designed to receive a planar light beam (6) in order to illuminate a sample (7) in the lighting direction (DI) is a planar transparent face. 5. The device (1) according to any of claims 1 to 3, wherein the face (2a', 2b', 2c', 2d') designed to receive a planar light beam (6) in order to illuminate a sample (7) in the lighting direction (DI) comprises a lighting objective lens. 6. The device (1) according to claim 5, wherein the lighting objective lens is an immersion lighting objective lens. 7. The device (1) according to claim 5, wherein the lighting objective lens is an air lighting objective lens. 8. The device (1) according to any of the preceding claims, wherein the front end of at least one objective lens (9a, 9b, 9c, 9d) crosses through a wall of the face to which it is coupled. 9. The device (1) according to any of the preceding claims, wherein the front end of at least one objective lens (9a, 9b, 9c, 9d) is externally adjacent to a wall of the face to which it is coupled. 10. The device (1) according to any of the preceding claims, comprising at least one additional cuvette (20) which has the same cross-sectional shape as the cuvette (2) and which is fastened to said cuvette (2) such that each face (20a, 20a'; 20b, 20b'; 20c, 20c'; 20d, 20d') of the additional cuvette (20) is coplanar with a corresponding face (2a, 2a'; 2b, 2b'; 2c, 2c'; 2d, 2d') of the cuvette (2), wherein faces (20a, 20b, 20c, 20d) of the additional cuvette (20) coplanar with faces (2a, 2b, 2c, 2d) with the lens or objective lens (9a, 9b, 9c, 9d) of the cuvette (2) have a coupled lens or objective lens (90a, 90b, 90c, 90d), and wherein the cuvette (2) and the additional cuvette (20) can rotate in an integral manner such that it is possible to simultaneously orient a specific lens or objective lens (9a, 9b, 9c, 9d) of the cuvette () and a specific lens or objective lens (90a, 90b, 90c, 90d) of the additional cuvette (20) in the direction of detection (DD).