  Minimization of internal degrees of freedom is an important step in the
cooling of atomic species to degeneracy temperature. Here, we report on the
loading of 6*10^5 thulium atoms optically polarized at maximum possible
magnetic quantum number mf=-4 state into dipole trap operating at 532 nm. The
purity of polarizations of the atoms was experimentally verified using a
Stern-Gerlach-type experiment. Experimental measured polarization of the state
is 3.91(26).
