A model of lift-off sputter deposition is developed taking into account the shadowing effect and incident angular distribution of the incoming flux of sputtered atoms. On the basis of this model, an SiO2 microlens is fabricated by the lift-off technique with r.f. magnetron sputtering. The SiO2 microlens is successfully applied to two-dimensional, free-space optical switching devices with low-loss fibre-to-fibre coupling. The model of lift-off sputter deposition is demonstrated to be very useful for the fabrication of microlenses.