| 摘要 |
An inspection system using dark field imaging includes a multiple beam laser scanning unit and at least one multiple beam dark field imaging unit. The laser scanning unit generates multiple beams which illuminate multiple spots on a surface to be scanned. The imaging unit separately detects light scattered from the multiple spots. The spots are separated by a separation distance which ensures that scattered light from each associated spot are received only by its associated photodetector. Each imaging unit includes collection optics and multiple photodetectors, one per spot. The collection optics and photodetectors are mounted so as to separate the light scattered from the different scan lines. In one embodiment, this separation is provided by arranging the collection optics and photodetectors according to the principles of Scheimpflug imaging.
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