| 摘要 |
An apparatus and method for focus error detection operable to receive light reflected from an inspected object and to determine a focus error on a surface of the inspected object, the focus error detection apparatus including optics and at least one detection apparatus, whereas the optics and the at least one detection apparatus define at least a first focus error detection path and a second focus error detection path, the first focus error detection path detects focus errors with a greater sensitivity than the second focus error detection path, while the second focus error detection path detects focus errors over a greater focus error range than the first focus error detection path.
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