This paper reports the reflective features of a water surface covered with
an oil film expressed by the dependence of the reflectance on the angle of
light incidence and wavelength a nd film thickness with respect to downward
and upward light fluxes. The sensitivity of the shape of these functions o
n the oil type appears especially strong in case of the upward light fluxes
as opposed to downward fluxes. (C)2000 Optical Society of America.