  We theoretically study the focusing of a quasi-continuous atom laser beam of
rubidium-85 ($^{85}$Rb). A two-sate model analysis based on the
Gross-Pitaevskii equation is used which comprises the effects of two-body
atom-atom interactions and three-body recombination losses. Utilizing optical
focusing potentials such as harmonic potentials, the essential factors such as
the width, peak density and atom loss rate of the focused atom laser beam
profile are investigated. Our analysis predicts that using an atom laser offers
a dramatic improvement in resolution of up to $8$ nm.
