METHOD AND APPARATUS FOR MEASUREMENT, AND METHOD AND APPARATUS FOR EXPOSURE

摘要

Any substance in predetermined gas is measured efficiently, quickly and accurately. An exposure device (S) comprises measurement part (M) for measuring a light-absorbing substance, a gas supply device (N) for supplying gas (GS) in the optical path space (LS) to the measurement part (M), a gas supply device (H) for supplying the measurement part (M) with clean gas (GT2) including a reduced amount of the light-absorbing substance, and a switch device (B) for alternately supplying the gas (GS) and the clean gas (GT2) to the measurement part (M). The concentration of the light-absorbing substance in the gas (GS) is measured accurately with a reduced amount of the light-absorbing substance remaining in the measurement part (M).