An alkali-metal vapor cell, particularly intended to be included in an atomic clock, capable of being connected, on the one hand, to a laser for emitting an incoming external laser beam striking the cell and, on the other hand, to a photodetector for receiving an outgoing external laser beam from the cell, with the laser beam having passed through the cell, said cell comprising, - on the one hand, a casing having an upstream optical window and a downstream optical window and forming an optical cavity filled with alkali-metal vapor such as vapor containing cesium, the upstream optical window and the downstream optical window being disposed on the same side of the cell; and - on the other hand, micro-optical means disposed in the optical cavity and comprising an upstream optical reflector and a downstream optical reflector for the laser beam, said reflectors being inclined relative to one another, the upstream reflector being inclined relative to the plane of the upstream window and to the axis of the incoming laser beam, such that the incoming external laser beam passes through the upstream window to form an incoming internal laser beam, such that the incoming internal laser beam is reflected onto the upstream reflector and deviated towards the downstream reflector to form an intermediate internal laser beam, such that the intermediate internal laser beam is reflected onto the downstream reflector and deviated towards the downstream window to form an outgoing internal laser beam, and such that the outgoing internal laser beam passes through the downstream window to form the outgoing external laser beam, characterised in that: - said cell also comprises upstream diffraction means for the incoming external laser beam, located upstream of the upstream reflector, and downstream diffraction means for the laser beam reflected by the downstream reflector, located downstream of the downstream reflector, so as to combine the deviation produced by the diffraction means (17, 18) with the deviation produced by the associated reflector (14, 15), with said upstream and downstream diffraction means being respectively connected to the upstream and downstream windows, the reflectors (14, 15) and the diffraction means (17, 18) being configured so as to maintain the circular polarisation state of the laser beam on its path, the incoming external laser beam and the outgoing external laser beam being disposed parallel to each other, the upstream and downstream diffraction means and the upstream and downstream reflectors being arranged so that the intermediate internal laser beam forms a 90° angle with the incoming external laser beam and with the outgoing external laser beam. - on the one hand, a casing having an upstream optical window and a downstream optical window and forming an optical cavity filled with alkali-metal vapor such as vapor containing cesium, the upstream optical window and the downstream optical window being disposed on the same side of the cell; and - on the other hand, micro-optical means disposed in the optical cavity and comprising an upstream optical reflector and a downstream optical reflector for the laser beam, said reflectors being inclined relative to one another, the upstream reflector being inclined relative to the plane of the upstream window and to the axis of the incoming laser beam, such that the incoming external laser beam passes through the upstream window to form an incoming internal laser beam, such that the incoming internal laser beam is reflected onto the upstream reflector and deviated towards the downstream reflector to form an intermediate internal laser beam, such that the intermediate internal laser beam is reflected onto the downstream reflector and deviated towards the downstream window to form an outgoing internal laser beam, and such that the outgoing internal laser beam passes through the downstream window to form the outgoing external laser beam, characterised in that: - said cell also comprises upstream diffraction means for the incoming external laser beam, located upstream of the upstream reflector, and downstream diffraction means for the laser beam reflected by the downstream reflector, located downstream of the downstream reflector, so as to combine the deviation produced by the diffraction means (17, 18) with the deviation produced by the associated reflector (14, 15), with said upstream and downstream diffraction means being respectively connected to the upstream and downstream windows,