An optical coherence tomography (OCT) system comprises an interferometer configured to split incident light into a reference beam and a test beam, and to interfere the test beam reflected from the specimen with the reference beam reflected from a reference mirror to produce an interference pattern. The OCT system also comprises a spectrometer configured to analyze spectral components of the interference pattern at non-uniformly sampled wavenumbers. A computer-readable memory of the OCT system is configured to store a measurement model with elements connecting different depth values with different non-uniformly sampled wavenumbers and weighted with weights derived from a power spectral density (PSD) of the incident light for corresponding wavenumbers. The OCT system further comprises a processor configured to determine the profilometry measurements of the specimen as a maximum likelihood estimate of the specimen surface depth by back-projection of the measured intensities with the measurement model.

A method and related system for measuring a surface of a substrate including at least one structure using low coherence optical interferometry, the method being implemented with a system having an interferometric device, a light source, an imaging sensor, and a processing module, the method including: - acquiring, with the imaging sensor, an interferometric signal formed by the interferometric device between a reference beam and a measurement beam reflected by the surface at a plurality of measurement points in a field of view; the following steps being carried out by the processing module: classifying, by a learning technique, the acquired interferometric signals according to a plurality of classes, each class being associated with a reference interferometric signal representative of a typical structure; and analysing the interferometric signals to derive information on the structure at the measurement points, as a function of the class of each interferometric signal.

A method of assessing a tissue sample includes the steps of: 1) splitting source electromagnetic radiation into: a) sample arm radiation directed in a Z direction toward a sample thereby illuminating the sample at a first selected XY coordinate pair of the sample, and b) reflector arm radiation directed toward a reflector so that the reflector arm radiation travels a path length; 2) interfering sample-scattered electromagnetic radiation with reflector-reflected electromagnetic radiation thereby establishing an interference pattern associated with the sample; 3) comparing the sample interference pattern to a reference interference pattern; and 4) reaching a conclusion about the sample based on the comparison.

A wafer metrology system includes an interferometer sub-system and a controller. The interferometer sub-system is configured to generate an interferogram with an intensity map that corresponds to a modulated representation of a wafer surface. Further, the interferometer sub-system includes a detector configured to capture the interferogram. The controller includes one or more processors configured to generate a wrapped phase map of the interferogram, define patterns associated with features on the wafer, and correct phase discontinuities by applying a phase unwrapping procedure to the wrapped phase map to generate an unwrapped phase map and correcting phase discontinuities in the unwrapped phase map based on the patterns, or by combining phase unwrapping and correction in a unified step. Further, the patterns comprise two or more structures such that a portion of the unwrapped phase map associated with structures of the same type is continuous across borders separating structures of the same type.

An optical coherence tomography (OCT) system comprises an interferometer configured to split incident light into a reference beam and a test beam, and to interfere the test beam reflected from the specimen with the reference beam reflected from a reference mirror to produce an interference pattern. The OCT system also comprises a spectrometer configured to analyze spectral components of the interference pattern at non-uniformly sampled wavenumbers. A computer-readable memory of the OCT system is configured to store a measurement model with elements connecting different depth values with different non-uniformly sampled wavenumbers and weighted with weights derived from a power spectral density (PSD) of the incident light for corresponding wavenumbers. The OCT system further comprises a processor configured to determine the profilometry measurements of the specimen as a maximum likelihood estimate of the specimen surface depth by back-projection of the measured intensities with the measurement model.