  Chang-Refsdal (C-R) lensing, which refers to the gravitational lensing of a
point mass perturbed by a constant external shear, provides a good
approximation in describing lensing behaviors of either a very wide or a very
close binary lens. C-R lensing events, which are identified by short-term
anomalies near the peak of a high-magnification lensing light curves, are
routinely detected from lensing surveys, but not much attention is paid to
them. In this paper, we point out that C-R lensing events provide an important
channel to detect planets in binaries, both in close and wide binary systems.
Detecting planets through the C-R lensing event channel is possible because the
planet-induced perturbation occurs in the same region of the C-R
lensing-induced anomaly and thus the existence of the planet can be identified
by the additional deviation in the central perturbation. By presenting the
analysis of the actually observed C-R lensing event OGLE-2015-BLG-1319, we
demonstrate that dense and high-precision coverage of a C-R lensing-induced
perturbation can provide a strong constraint on the existence of a planet in
the wide range of the planet parameters. The sample of an increased number of
microlensing planets in binary systems will provide important observational
constraints in giving shape to the details of the planet formation scenario
which has been restricted to the case of single stars.
