## 1 Introduction  
The control of a spin-orbit conversion (SOC) in spintronics by managing the spin of electrons is well known (see recent review [1]). In optics, works on the control of SOC parameters have appeared recently. In [2], SOC was controlled utilizing excitation of a superposition of vortex laser modes with different spins in thin annular fibers with an empty core, although the first work on SOC in multimode fibers was carried out much earlier [3]. In [4], SOC is the cause of the emission of an optical vortex perpendicular to the plane of a ring cavity with defects, along which two whispering gallery modes with different spins (different polarization states) propagate. It was shown in [5] that SOC can be controlled using q-plates, which transform light with left-handed circular polarization into an optical vortex with right-handed circular polarization. The theoretical aspects of the spin-orbit interaction of light were considered in [6, 7]. Spin-orbit conversion was observed during light scattering [8], in a sharp focus [9], in an anisotropic medium [10], and upon reflection from an interface of two media [11]. Spin-orbit interaction was also observed in plasmonics [12], in nonlinear optics [13], and in electron optics [14]. One of the clear manifestations of the spin-orbit light conversion is the optical Hall effect, which appears when the light is reflected from multilayer structures [15] and when it passes through metasurfaces [16]. The Hall effect in optics appears as the spatial separation of light beams with different directions of circular polarization (left- and right-handed)--this is the spin Hall effect in optics [17; 18]. Alternatively, it leads to the spatial separation of light beams with an orbital angular momentum of a different sign--this is the orbital Hall effect [19; 20]. For further consideration, it is useful to mention works on the optical Hall effect in a sharp focus [21; 22; 23]. The Hall effect at the focus appears not only due to SOC [24], but also due to the preservation of the total longitudinal SAM equals to zero during beam propagation [25]. As was shown in [26], when a linearly polarized light is sharply focused, the spin is zero in the initial plane and in the focus, but before and after the focus, four local areas appear with nonzero spin of different sign. In [27], SOC was studied in the light reflected from two crossed metasurfaces. In [28], the geometric spin Hall effect was considered. SOC in a freely propagating vector cylindrical laser beam with a vortex phase was considered in [29]. In [17], the spin-controlled Hall effect was implemented based on a spin-dependent beam splitting into two beams. Sometimes, the Hall effect is understood as a transverse shift of the beam center in the focus because of symmetry violation of a vortex beam or due to the displacement [30]. In this paper, we consider a spin-orbit conversion of a superposition of two identical optical vortices with circular polarization of different signs and with different amplitudes at a sharp focus. The ratio of the amplitudes of the beams included in this superposition is a parameter that can be varied in order to manage the reduction in spin angular momentum (SAM) and the increase in the orbital angular momentum (OAM) during focusing. The change in the total spin and orbital angular momentum occurs immediately after the light passes through the spherical lens. Further, during propagation in the free space from the lens to the focus, the total spin and orbital angular momentums remain unchanged. Controlling the spin-orbit conversion in the focus of a spherical lens can be used for changing the rotation velocity of dielectric microparticles. Continuous variation of the parameter (the ratio between the beam amplitudes in the considered superposition) allows changing the SAM in the focus, and changing the rotation velocity of a nonspherical microparticle around its center of mass from zero to maximal.