An exposure apparatus fills an optical path space on a side of an image
plane of a projection optical system with liquid and exposes a substrate
via the projection optical system and the liquid. The exposure apparatus
has a measurement unit which measures an optical property of the liquid.
According to the measurement result, it is possible to adjust the optical
characteristic of the liquid by a liquid mixing unit. Thus, it is
possible to maintain the exposure accuracy at a desired state when
performing immersion exposure.