  We consider the gravitational magnification of light for binary systems
containing two compact objects: white dwarfs, a white dwarf and a neutron star
or a white dwarf and a black hole. Light curves of the flares of the white
dwarf caused by this effect were built in analytical approximations and by
means of numerical calculations. We estimate the probability of the detection
of these events in our Galaxy for different types of binaries and show that
gravitational lensing provides a tool for detecting such systems. We propose to
use the facilities of the Sloan Digital Sky Survey (SDSS) to search for these
flares. It is possible to detect several dozens compact object pairs in such a
programme over 5 years. This programme is apparently the best way to detect
stellar mass black holes with open event horizons.
