US Patent 7760326 Exposure apparatus and aberration correction method

An exposure apparatus for exposing a wafer to light through a pattern of a mask. The apparatus includes a projection optical system configured to project the pattern onto the wafer, a first barometer configured to measure pressure of an atmosphere in the apparatus, a second barometer configured to measure the pressure at a speed higher than that at which the first barometer measures the pressure, a calibration unit configured to calibrate an output of the second barometer based on an output of the first barometer, and an aberration correction unit configured to correct aberration of the projection optical system based on the calibrated output.