Manifestation of mechanical properties of light waves in vortex beam optical systems

It is shown that variations in the frequency and phase of the light beam upon a deformation of the optical system can be caused by the work produced by the light pressure. It is proposed to use this fact to demonstrate and measure mechanical properties of the beam: the momentum, the angular momentum, and peculiarities of their spatial distribution. The possible schemes of experiments for determination of the angular momentum of the Laguerre-Gaussian beam with a screw dislocation of the wave front and the circularly polarized beam with a smooth front are presented. The relationship between the mechanical and geometric characteristics of such beams is discussed.