SCAN ERROR CORRECTION IN LOW COHERENCE SCANNING INTERFEROMETRY

摘要

device of the present invention in combination with the reference light of the inspection light from the inspection object It comprises a wide scanning interferometer system having an optical device to form an interference pattern on the detector. Apparatus of the present invention is a detector for recording an interference pattern for each of the optical path difference between the test light and the reference light to the detector from a common light source (OPD) and the stage is configured to scan a series of OPD increments (OPD increment) It comprises a detector system with. Frequency of each incremental OPD prescribes the frame rate. Optical equipment is adapted to generate two or more monitors interference signals representing the change in OPD in accordance with the performing the scan. The detector system is monitored to record the interference signal. The apparatus of the invention includes a processor configured to determine information about the OPD increments with sensitivity to perturbation of OPD incremented at a frequency less than the frame rate.