SCAN ERROR CORRECTION IN LOW COHERENCE SCANNING INTERFEROMETRY

摘要

An apparatus includes a broadband scanning interferometry system including optics for combining test light from a test object with reference light to form an interference pattern on a detector. The apparatus includes a stage configured to scan an optical path difference (OPD) between the test and reference light from a common source to the detector and a detector system including the detector for recording the interference pattern for each of a series of OPD increments, the frequency of each OPD increment defining a frame rate. The optics are configured to produce at least two monitor interferometry signals indicative of changes in the OPD as it's scanned, the detector system being configured to record the monitor interferometry signals. The apparatus includes a processor configured to determine information about the OPD increments with sensitivity to perturbations to the OPD increments at frequencies greater than the frame rate.