| 摘要 |
An exposure method, wherein a defocus quantity on the surface of a substrate to be exposed with respect to an image plane of a projection optical system is detected highly accurately even during exposing without lowering throughput much and focusing is made with an automatic focusing method. A first oblique-incident AF sensor including an illumination slit unit (54a) through an optical member (63a) and a second oblique-incident AF sensor including an illumination slit unit (54b) through an optical member (63b) are used to apply slit images (F1f, F2f) onto common measuring points and focus positions are measured respectively. One half of the difference between the two measured values is regarded as a drift and the drift is corrected for values measured by the AF sensors; the first or second AF sensor is then used to perform a focusing by the automatic focusing method. <IMAGE> |
