| 摘要 |
An optical measurement method and system are presented for imaging two target structures in two parallel layers, respectively, of a sample, to enable determination of a registration between the two target structures along two mutually perpendicular axes of the layer. The sample is illuminated with incident radiation to produce a radiation response of the sample. The radiation response is collected by an objective lens arrangement, and the collected radiation response is split into two spatially separated radiation components. The split radiation components are directed towards at least one imaging plane along different optical channels characterized by optical paths of different lengths, respectively. The two split radiation components are detected in said at least one imaging plane, and two image parts are thereby acquired, each image part containing images of the two target structures. This enables determination of the relative distance between the two target structures.
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