  We study light hadron leptoproduction at small $x$. Vector meson production
is analysed in terms of generalized gluon distributions with taking into
account the transverse quark motion. Within a two-gluon model the double spin
asymmetries for longitudinally polarized leptons and transversely polarized
protons in the diffractive $Q \bar Q$ production are investigated. The
predicted $A_{lT}$ asymmetry is large and can be used to obtain information on
the polarized gluon distributions in the proton.
