| 摘要 |
A system includes multiple optical Fourier transform cells (FTC1, FTC2, ... FTCN) which simultaneously scan a device under test (190). Each Fourier transform cell comprises a light source (110), a Fourier transform lens (130), a spatial filter (140) in the Fourier plane, and a photodetector (160). The illuminated area for each cell (FTC1, FTC2, ... FTCN) is small to provide high resolution, while the number of cells (FTC1, FTC2, ... FTCN) is large to cover a relatively wide area and keep inspection speeds high. The Fourier transform cells (FTC1, FTC2, ... FTCN) can be offset from each other perpendicularly to the scan direction by less than the width of an illuminated area to provide complete coverage during scanning of a device under test.
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