  Optical levitation of a liquid droplet in gas phase was investigated under
timedependent change of the gravitational acceleration with specific flight
pattern of an airplane. Through multiple trials under linear increase of
effective gravitational acceleration, we performed the experiment of ptical
trapping of a droplet from 0.3g_0 to 0.9g_0, where g_0 = 9.8 m/s^2. During such
change of the effective gravitational acceleration, the trapping position on a
droplet with the radius of 14 &#956;m was found to be lowered by ca. 100
&#956;m. The essential feature of the change of the trapping position is
reproduced by a theoretical calculation under the framework of ray optics. As
far as we know, the present study is the first report on optical levitation
under time-dependent gravitational change.
