| 摘要 |
An exposure apparatus for exposing a first object to a radiation energy passed through a second object, having a pattern, thereby to transfer the pattern of the second object onto the first object, the exposure apparatus including a radiation energy source, at least one spare radiation energy source and an arrangement for substituting the first-mentioned radiation energy source by the second-mentioned, spare, radiation energy source when the service life of the first-mentioned radiation energy source becomes over or nearly over, wherein the spare radiation energy source is energized or actuated when the intensity of irradiation of the first-mentioned radiation energy source is decreased to a predetermined value and, at the same time or after elapse of a predetermined time, the first-mentioned radiation energy source is sustituted by the spare radiation energy source.
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