Optical device for deflecting a light beam and inelastic diffusion spectrometer comprising such a device

An optical light-beam deflection device comprising:

• a first flat reflective element, extending in a first plane, the first reflective element being arranged in such a way as to reflect an incoming light beam into a reflected light beam, said incoming light beam and said reflected light beam defining a plane of incidence;
• and
• a second flat reflective element extending in a second plane transverse to the plane of incidence, the second reflective element being arranged in such a way as to reflect said reflected light beam into an outgoing light beam;
• said first plane and said second plane being secant along a line of intersection and forming between each other a dihedral angle, said first reflective element and said second reflective element being jointly rotatable about an axis of rotation coincident with said line of intersection, said axis of rotation being transverse to the plane of incidence.